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Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

444 points by chablent 8y ago

scblock 8y ago
Oh geez they could have left this statement out: "When I wrote my previous article, class-D audio was fairly new, and audiophiles were still arguing about whether class-D amps could sound as good as class-AB or class-A units. Nobody is having those arguments anymore." Those arguments are still front and center when it comes to amplifier design, both on the manufacturer and consumer sides.
- AceJohnny2 8y ago
  Tangentially, the placebo effect is everywhere. If it can affect tasting (wine) and hearing (audiophile gear), I'm surprised not to have noticed its affect in discussing photography. Will "computational photography" (as touted in the latest iPhones) that alters photos based on criterion of perceived quality end up bringing these kind of inane discussions there too? Edit: Never mind, I didn't factor in all the arguments about Photoshop altering.
  - taejo 8y ago
    While there are endless debates about manipulation, when it comes to actual capturing of images, the photographic community (in my experience) has a healthy dose of "the best camera is the one you're carrying" and "a great photographer can take great photographs with any camera but even a great camera won't help a lousy photographer take great photographs" to go with its love of gear (who can help but love gear?)
    - beat 8y ago
      Camera nerds are the worst. They're worse than audiophiles, if that's possible. Good photography requires nothing more than a bit of reason and observable standard practice, applied to aesthetics. You don't have to look hard to find someone with a $5000 camera/lens combo who doesn't know what the Rule of Thirds is or how to apply it. Last weekend, I was in DC, and snapping pictures of the Washington Monument on my phone. My sister was shocked at how good they were. It's not hard, really.
      - airbreather 8y ago
        Girl at work has 20k camera with 100k megapixels, but then again Huawei just asked to use her pics for their phone screen savers, so...
  - rectang 8y ago
    I made my living as a mastering engineer for two years... To do good work in mixing and mastering, it's important to study the human perceptual mechanism and its propensity for illusion, and it's also important to understand masking effects and how to amplify certain components long enough to tweak them before dialing them back to recede into the gestalt. It's also important to understand that in sound reproduction the vast majority of the distortion on the analog side comes from transducers (microphones and speakers), not amplifiers. (I'm not even going to bother with the article, because amplifiers aren't an important problem: buy something decently engineered and overpowered, and you're basically all set. Then worry about your speakers and your room, because they're the hard part.) But it's likewise crucial to grok that the distortion introduced by digital components is disproportionately disturbing because it is enharmonic. And that practically speaking a lot of the damage that gets done in practice happens because people don't handle gain staging right and often don't understand the fundamental principle of preserving high resolution throughout production and only exporting to lower resolution as a final step. In summary, there are a whole lot of interesting conversations to have on the subject of audio and how perception relates to production. But it's basically impossible to find a community to discuss these subjects with. Either it will be overrun by audiophiles and their pseudoscience, or well-meaning but undereducated skeptics will dominate the discussion with plausible but misguided debunking. So every once in a while I throw up a piece like this into the middle of a giant discussion, with about as much hope as tossing a message in a bottle into the ocean.
    - ericdykstra 8y ago
      This is pretty fascinating. I can't add to a discussion, but I would certainly read more about this if you have produced it somewhere. I'm also curious, what made you leave your job as a mastering engineer?
      - rectang 8y ago
        The profession of audio production is extremely competitive because there is a perpetual oversupply of labor. The total amount of money in the music industry is also deceptively small compared to its high public profile. I left the field (back in about 2003) because although I felt that I was good enough to compete and survive, I didn't love it enough to grind out a life as a workaholic and just get by. Most of my writings from that time were forum posts with the perspective of the well-meaning but undereducated skeptic and wouldn't be that interesting to read today. Also, what was probably my best writing happened in forums which don't have public archives which have survived 15-20 years later. (Which amuses me as a former mastering engineer because one of our primary objectives is long-term archival.) PS: not "enharmonic", "non-harmonic" dammit. The point is that while analog distortion is mostly harmonically related, digital distortion is not and therefore is much more poisonous in small quantities. Mixing especially (though mastering is similar) is all about making changes near or below the threshold of perception which sum to a cumulative perceptible effect.
  - paulie_a 8y ago
    Whenever I see the term audiophile I mentally replace it with "over priced bullshit" It's just someone being sold snake oil.
  - ken 8y ago
    It's already here, for displays. I've seen lots of internet comments claiming I need the >450ppi screen on the new high-end iPhone, not the miserable old cheapo 326ppi one.
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- 01100011 8y ago
  I think it might boil down to your philosophy on sound reproduction. Do you want accuracy with some potentials for ugliness if you clip, or do you want coloring and musical distortion? I don't think AM radio sounds good at all, but it is sometimes emotionally comforting to listen to. Fidelity isn't everything. That said, many high end audio folks are straight up whack jobs.
- milesvp 8y ago
  I'm not convinced audio engineers are having that argument anymore (which is more the audience of IEEE). I get the impression from an engineer I know who's specialized in digital signal processing, and who's done a significant amount of analog work, that anyone who's still having some of these arguments doesn't understand some of the basic maths of the problem space. That basically, you can always digitally encode an analog signal at a higher resolution and fidelity than you can reliably read said signal at any given technology level/pricepoint. Which means that using an ADC -> DAC pipeline will almost always give you better audio output with better signal to noise ratios than strict analog -> analog systems (though possibly at the cost of latency). Where it gets tricky, is the arguments for how things like tube amps sound. There is nothing that analog components add to a sound that can't be simulated with digital transforms, but the trick is figuring out how various analog components effect the signal. For instance, my friend found that certain tube amps would overdrive components and force them out of spec, and this caused a non linearity in the response of the signal coming from the component that gave the amp it's distinctive distortion effect. Once he figured that out he was able to reproduce the effect digitally. Incidently, he's found that some guitar amps can never be made today, because they were built around a specific batch of a given component, and newer batches didn't have the same out of bounds responses. But this seems to be why so many people are still so big into analog amps, because it takes considerable effort (and apparently engineering skill) to reproduce some of the classic sounds. Mind you, I'm biased by one of the best engineers I've ever met, so I could be wrong about the general consensus with audio engineers. I'm also mostly using a sample size of 1, though I have corroborated some of his assertions with some of the blogging I've read on the topic. One of the best (I wish I'd bookmarked), was a good overview of encoding by a prolific codec writer, who pointed out that even though a digitized sine wave looks lossy at a low sample rate, it's trivial to rebuild that sine wave perfectly, with just the digitized version (so long as the sample rate was above some multiple of the Nyquist frequency?).
  - raphlinus 8y ago
    Likely that was xiph on why excessively high sample rates don't do much for the listening experience: https://people.xiph.org/~xiphmont/demo/neil-young.html https://people.xiph.org/~xiphmont/demo/neil-young.html
vichu 8y ago
I don't know much when it comes to audio amp design, but this reminds me greatly of the O2 headphone amp[0] - that anecdotally a few of my friends have soldered for their personal use. [0] http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html
- korethr 8y ago
  I thought of the same thing. Both are inexpensive, straightforward, no-BS projects that leverage the advances made in electronics over the years to deliver quality audio. If I made one of these, I 'd be tempted to put an ODAC and O2 board in the same chassis to have a complete amplifier.
  - wolfgke 8y ago
    > If I made one of these, I 'd be tempted to put an ODAC and O2 board in the same chassis to have a complete amplifier. Such a product is available commercially: > https://www.jdslabs.com/products/48/objective2-odac-combo-revb/ https://www.jdslabs.com/products/48/objective2-odac-combo-re...
  - syntaxing 8y ago
    Hearing the ODAC name is quite a throw back! I remember reading NwAvGuy's blog when I first started getting into headphones. I always wondered what happened to him.
    - sjwright 8y ago
      Given the way he suddenly went to radio silence, I just assumed he was hired by Apple...
- dejv 8y ago
  O2 is great and it is quite simple to build. There is even simpler amp called CMoy[1] which is simple enough to be first project for somebody just starting out. I would start by taking look on some oss version[2] and order PCB from OSH Park[3]. I've built this version few years ago and it works well. [1] https://tangentsoft.net/audio/cmoy/ https://tangentsoft.net/audio/cmoy/ [2] https://github.com/akafugu/cmoy https://github.com/akafugu/cmoy [3] https://oshpark.com/shared_projects/dRKK4dgN https://oshpark.com/shared_projects/dRKK4dgN
korethr 8y ago
Interesting. I'm tempted to try this out. I have access to a quality soldering iron and can use it decently well (I'm typing this on an ergodox keyboard I built from a kit). There is something very satisfying about building something yourself that you get use out of every day. Such an amplifier is likely to fall into that category for me.
jelling 8y ago
Any recommendations for people that are tempted to build this but should really put their time elsewhere?
- korethr 8y ago
  I'm not sure I understand your question; what do you mean by "but should really put their time elsewhere"? Are you asking for an amplifier that would deliver similar performance to this, because you don't have the time to build one, or that you suspect you'll come out ahead on build vs buy because of the price you value your time at?
- janekm 8y ago
  If you are looking for something already built, the eBay/aliexpress shops of the Shenzhen companies often have the option of selling you a complete amplifier made up of their modules. Which will probably end up cheaper than getting all the parts yourself...
  - Matsta 8y ago
    Bang on. A popular amp is a TPA3116 module. You can see thousands of examples on Aliexpress: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20181031152231&SearchText=tpa3116 https://www.aliexpress.com/wholesale?catId=0&initiative_id=S... For speakers, the cheapest option is to buy some second-hand ones on eBay/Gumtree/Craigslist. Just Google model names and look for ones with good reviews. I like British speakers, so I usually search for Tannoy, B&W, KEF etc.
- 01100011 8y ago
  Just do some research and get a cheap class D amp off a chinese website. I forgot the one I chose(I'm at work now), but other than some sparks if you jiggle the power connector(haha seriously. can be fixed with a tiny bit of effort), it is an amazing little amp. It also supports optical and bluetooth connections which is really nice. I put my efforts into building speakers instead. I got a cheap kit (https://www.diysoundgroup.com/overnight-sensations.html https://www.diysoundgroup.com/overnight-sensations.html) and spent my time learning how to apply a french polish finish. I really enjoyed learning french polishing. It's one of those things that when you finally get it, it becomes immensely satisfying. Yeah, shellac isn't the most durable finish, but it sure is pretty.
watersb 8y ago
Very cool. I was very interested when the IEEE Spectrum original feature was published, and got one of the Tripath amplifiers to play with. It was a commercial product, marketed as inexpensive toy. Then people on Head-Fi Forums started taking these things further. One of the forum members started modding home-theater amplifiers, so I purchased one and it was great. Vinnie Rossi, Red Wine Audio. It is still amazing. But his stuff is now quite out of my price range. These amplifiers are great fun, though.
Matsta 8y ago
The majority of all active speakers produced nowadays are Class-D, it's nothing really new (and the fact they are super cheap). No idea how this guy wrote this article and didn't come across DIY Audio (or he just didn't mention it in the article). There is a tonne of information here: https://www.diyaudio.com/forums/class-d/ https://www.diyaudio.com/forums/class-d/
- matt4077 8y ago
  Your first point seems to be reflected in the article, except that, if they are correct, the high end of Class D amplifiers apparently is not "super cheap". I don't quite get the aggressiveness of your second point: surely just leaving whatever your first association to a topic is out cannot warrant such outrage? It's not like they present this article as groundbreaking innovation. Not only do they cite other DIY efforts. The whole premise of the article is that the author himself already did this ten years ago,.
  - Matsta 8y ago
    It comes more down to the design of the board and the quality of the other components on the board. The TPA3250 he mentions is quite a new chip, but if you look on Aliexpress for an older chip like the TPA3116 there is literally thousands of examples: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20181031150947&SearchText=TPA3116 https://www.aliexpress.com/wholesale?catId=0&initiative_id=S... I imagine this guy must have found the components of a site similar to DIY Audio. It would have been a nice addition to steer people in the direction of more information if they are interested in the topic (which a lot of the comments here seem to be asking about).
- irrational 8y ago
  I have some questions. My son has been taking guitar lessons using a classic guitar. Using the advice of his instructor we are getting him a begginer's electric guitar for christmas. We also need to get him an amp. Is the amp in this article the same kind of amp that you could plug an electric guitar into? I know nothing about music or instruments, but I do know about electronics so I was thinking it might be fun to build an amp with my son. I went to the diyaudio link you suggested, but I didn't immediately see information like in the article (buy this, this, this and this to build the amp). Can you point to where I could find a similar purchase list and assembly instructions on diyaudio? Thanks!
Scoundreller 8y ago
I don’t build audio amplifiers often, but when I do, I always use top-quality components like HPOO.
fermienrico 8y ago
It is refreshing to see these types of articles. Of all disciplines of human interests and hobbies, Audiophiles are one of the most stubborn, misinformed, anecdotal and delusional bunch. Of course I am generalizing, but every time I engage in a discussion about audio quality, it is a losing battle. Not because of lack of data or supporting evidence, but because of the fundamental dissent for data driven arguments. You cannot argue reason when the first step is to be born with "audiophile ears". Why is it hard to understand that we have sophisticated metrology and instrumentation that can analyze things better than human ears can? I can understand a separate discussion about personal opinions regarding how "warm" a particular sound is, but that should remain distinctly as - subjective and that's perfectly OK. It feels like the entire audio industry is promoting pseudoscience barring a very few vendors that actually care. We have a $8500 mp3 player from Sony claiming all kinds of things to the overwhelming abundance of cheap Shenzhen exports. There is just so much noise. I absolutely abhor audiophiles.
- ohazi 8y ago
  Someone I know was recently trying to have a conversation with an audiophile about the possibility of re-purposing some audio equipment to make noise floor measurements for another system that had similar frequency and dynamic range characteristics. The technique worked just fine, but man, that guy was loony. He was trying to claim, with a straight face, that a GPS disciplined oscillator wasn't stable enough for his audiophile-grade Rube Goldberg machine.
  - brokenmachine 8y ago
    Oh god, jitter... If ever there was a more pseudoscience audio term, I haven't heard it. I wish there was a separate term between audiophiles who just want to spend a lot of money on hocus pocus, and audiophiles who want the measurably best performance. Then the audiophile forums would not be polluted with people who spend thousands on cables and other rubbish, when the room response/treatment and speaker selection has a million times more effect on the actual sound.
- albertgoeswoof 8y ago
comboy 8y ago
Any DAC chip and some usb interface for it that you could recommend to go with this? And slightly OT, but does anybody know any ABX test of balanced input/output signal? I find it hard to believe that there is a single person who can hear the difference.
- jacquesm 8y ago
  The big gain for balanced inputs is rejection of signals induced into the wire. Of course optical is the way to go if you are really worried about that. Personally I don't care, my ears are old enough that I no longer hear the difference between a high end and a low end amp.
- Matsta 8y ago
  There's thousands of options. Schiit are generally regarded for having high quality products that are relatively cheap. A good place to find DAC reviews is head-fi: https://www.head-fi.org/forums/dedicated-source-components.7/ https://www.head-fi.org/forums/dedicated-source-components.7...
  - comboy 8y ago
    Thousands of options is why I asked for a recommendation. I know Schiit has good reviews but I'm just interested in ICs. Something like PCM2707C for USB communication or PCM1794A for DAC or whatever else.
- aidenn0 8y ago
  There are cases where the difference is huge; particularly when you have very long runs between the preamp and the amp. This is on reason why you usually see XLR inputs to monitors. Any noise induced is amplified and a long unbalanced wire is a big antenna. I've heard of cases where you could receive AM radio stations from such a setup; I lean towards "urban legend" for that though. While it seems theoretically possible (since many amplifier topologies can have resonance when fed signals outside their expected operating range), it seems a bit farfetched to actually end up with intelligible audio.
esaym 8y ago
Hmm, I'd much rather build a Class-D amp from scratch with no chips involved... any tips?
- jacquesm 8y ago
  https://www.elektormagazine.com/labs/200w-class-d-audio-power-amplifier-150511 https://www.elektormagazine.com/labs/200w-class-d-audio-powe... Not quite chipless but pretty close.
- heavenlyblue 8y ago
  https://www.amb.org/audio/ https://www.amb.org/audio/
- mbell 8y ago
  That's not realistic, particularly if you're after a full range amp.
proee 8y ago
Audio is a great way to get kids excited about electronics. When I was in the 6th grade, my father helped me build my own high power amplifier using an LM3876 opamp. I remember clear as day the first time I powered up my amplifier circuit and nothing happened. Hmmm... I brought my face closer to my circuit board and suddenly "BANG!!!!" an electrolytic capacitor blew up right in my face and scared the living daylights out of me. I unknowingly connected the power supply capacitor backwards. I soldered in a new capacitor, and then plugged it in again. Like magic, my home-brewed subwoofer was now cranking out serious bass by an amplifier that "I" built. That moment was magical and surreal - I still get goose bumps thinking about it!
rubatuga 8y ago
If you just want the amp without building it, you can get a TPA3116 Class D amplifier. It is only $21 USD from aliexpress (with free shipping of course!). It accepts a supply voltage of up to 24V meaning that you can just dig around for your old laptop power supply (19V). It comes with a nice and sleek aluminum case, and has low enough noise floor that I can't detect it at all unless my ear is right up against the speaker. Although slightly less power output compared to the chip from the article, it gets loud enough to drown out someone yelling. This amp from aliexpress has gold plated banana plug terminals, RCA inputs, and a smooth volume potentiometer. Link: https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-D-Power-Amplifier-Audio-Amp-TAP3116-Mini-Digital-Amplifier-Hi-fi-Audio/32888620869.html https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-D-P...
- blattimwind 8y ago
  I guess in technical terms this article is about "making" an amplifier as opposed to "building" an amplifier. "Making" as in "Maker", since the electronics come as pre-made assemblies connected together and put in a case.
  - trentlott 8y ago
    Basically a model kit that inhibits your ability to generalize.
    - imtringued 8y ago
      The first step of generalization is copying.
  - compiler-guy 8y ago
    "If you wish to make an apple pie from scratch, you must first create the universe." --Carl Sagan
    - blattimwind 8y ago
      "There are only two colors in the world: black and white." --Ansel Adams
kposehn 8y ago
> Nobody is having those arguments anymore. There are many class-D amplifiers on the market now, and the best of these are dominating the upper reaches of the high end. Not quite. Frankly, Class A or AB still has the upper hand from a pure sound quality perspective, and class D struggles to output sufficiently at high levels with lower levels of distortion in my experience. That said, there have been many small class-D Amps from Lepai and Dayton that are excellent choices for near-field and non-demanding applications. They definitely have their place. The tech is advancing rapidly but it has not supplanted A or AB. If you want some background in why there is still debate, I highly suggest reading some of Nelson Pass’ interviews and writings: https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/21/an-interview-with-hifi-legend-nelson-pass/amp/ https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/... https://www.passlabs.com/press/single-ended-class https://www.passlabs.com/press/single-ended-class https://www.passlabs.com/press/leaving-class https://www.passlabs.com/press/leaving-class
- radus 8y ago
  This may be true of Class D amps commonly used in home equipment, but many high end powered PA speakers use Class D amps and get very loud with minimal distortion.
  - TylerE 8y ago
    You'd be surprised how much you can get away with in a PA. Being powerful and reliable is more important than being all that good, since the room always sounds bad anyway.
mrob 8y ago
It's bizarre how none of these chips seem to have a digital input. All my music is digital, and despite the modern rise of vinyl, I don't think that's unusual. If I want an amplifier like this then I'm forced to have a completely useless DAC/ADC pair degrading the signal quality. Does anybody know of an easily available class-D amplifier with digital input? You'd think that would be an obvious feature for a digital amplifier.
- blattimwind 8y ago
  > You'd think that would be an obvious feature for a digital amplifier. That's because these amplifiers are not digital. The control loop is generally analog. Though there are chips which do in fact use digital inputs and do most of the work via fixed-function DSP, but those are mostly bigger chips targeted at 5.1 or 7.1 systems.
  - mrob 8y ago
    From Wikipedia: "The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time." So what's it called if it is time quantized? The simple open-loop design depicted on the Wikipedia page could have the analog comparator + triangle wave generator replaced with a digital delta-sigma modulator (1-bit DAC). Then the switching times of the power stage would be quantized to the sample rate multiplied by the oversampling ratio. (Although it seems this open-loop model is an oversimplification, and real class-D amplifiers have feedback, so it wouldn't be that simple in practice.)
- kazinator 8y ago
  It's not a digital amplifier. A class-D amplifier is basically somewhat like a switched-mode power supply that varies its output voltage in response to swings in the input signal.
- evancox100 8y ago
  Uh, if you want to "amplify" a digital signal, just multiply all the samples by some number.
dbrgn 8y ago
How would one best control the output volume on such a DIY amp? 2-channel logarithmic 10K potentiometer in front of both inputs? What if you use balanced input?
- kazinator 8y ago
  If your input is balanced, it will be handled by some op-amp circuit or whatever, which converts to single-ended internal signal, like the "balanced line input module" shown in this page: http://sound.whsites.net/project30a.htm http://sound.whsites.net/project30a.htm You can easily insert a volume control right after such a stage.
  - dbrgn 8y ago
    Yeah, but in the context of this article, I'd have to cut some traces on the PCB to get there. Doesn't sound like the ideal solution to me :)
    - brokenmachine 8y ago
      The 3e Audio board has jumpers to choose between single-ended and balanced I believe.
    - deleted 8y ago
      [deleted]
    - kazinator 8y ago
      Perhaps, perhaps not. The schematics don't seem to be available, but let's imagine there is a stage in there which looks roughly like this: |\ C |\ | >--||-+-----| > |/ | |/ < < R < | V If we simply remove/desolder components C and R, we should be able to then install hookup wires for a potentiometer (which includes the C also). It looks like this particular board has tiny SMT components, which make this sort of thing a pain in the but.
MrTonyD 8y ago
I'm probably the only one with this opinion...but I sure miss the old days of tube amps that weren't able to be highly accurate. They would roll-off the on the high end, distort a bit all over, and gave a very warm and relaxing feel to the albums I played obsessively. Now I've owned high-end tube and solid-state gear, and the music hasn't sounded good for decades. Combine that with the very limited bits provided by CDs, preventing any possibility of good playback, and music has been completely destroyed. Old timers like me are dying off, and most of the people who remember good music will be dead. Kind of makes me sad.
- mrob 8y ago
  >Combine that with the very limited bits provided by CDs, preventing any possibility of good playback 16 bits gives you 96dB SNR (and subjectively more with dithering), which is plenty at non-deafening listening volumes. It's more than even the highest quality vinyl ever had. High bit depth is mostly useful so you've got some headroom during editing.
  - MrTonyD 8y ago
    That is absurd. Anybody who has read about the history of CD bit depth would know just how absurd that is. And I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. All these claims about how great digital is are just crazy - claims made by people who are relying on old data about hearing accuracy and a religious faith in technology. Anybody who has actually designed instruments using the known laws of physics understands the incredible limitations - and those limitations apply to both characterizing hearing as well as reproducing sound digitally.
    - mrob 8y ago
      >I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. I can believe that, but the standard was designed to tolerate high bit error rates. 25% of the bits are redundant, as part of a error correction code: https://en.wikipedia.org/wiki/Cross-interleaved_Reed%E2%80%93Solomon_coding https://en.wikipedia.org/wiki/Cross-interleaved_Reed%E2%80%9... This scheme works very well, as proved by people consistently ripping bit-for-bit identical copies of CDs pressed or burned with the same audio.
aidenn0 8y ago
On a similar note, anybody know why you can get a very good A/V receiver for ~$500 but not a pre/pro for under $1k? Is it just the lower manufacturing volume?
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jpmoral 8y ago
>When I wrote my previous article, class-D audio was fairly new Not sure what this means. I had a group undergrad project in 2002 to build and characterise a class-D audio amp. The idea was well-established at the time.
KamiCrit 8y ago
It's great that with some research and drive one can make something better and cheaper than the engineered factory version. Time well invested.
S_A_P 8y ago
Audiophilia is a study in contradiction. The ask is a flat "uncolored" accurate sound. The gear that sells for ridiculous prices is usually tube gear with limited bandwidth and makes ~15 watts at 5-10% (admittedly usually even order harmonic) thd. Hardly uncolored. That said, and Ive mentioned this before on HN. My (now late) uncle had a bunch of audiophile friends in Dallas. He hung around folks who had spent upwards of 500,000 (yes you read that right) on audio gear. I can't forget the time I rolled up to a modest middle class home, only to find out that inside of this house was a pair of Focal Grand Utopias (selling retail for 250k at the time, though he said he paid around 60k for the pair). He had 2 750 watt tube amps, current era but the brand escapes me. For source material he had a heavily modified Technics SP-10 with 2 tone arm/cartridge combinations and a boutique tube phono preamp. This fed into a similarly heavily modified Dynaco tube preamp from the 1960s. When he really wanted to get serious, though, he had a studer 2" tape machine and a sizable collection of low generation master tape copies. If I hadn't seen this with my own eyes I would say my uncle was full of shit when he told me about it. You know what? it sounded freaking amazing.Im sure it is 90% placebo, and 10% the fact that he was able to play high bandwidth audio to concert levels with no stress or strain from the amplifiers. Was it worth 6 figures of money? not to me. But I am glad I got to hear it...
- sjwright 8y ago
  The three critical paths for high end sound reproduction are: loudspeakers, speaker placement, room acoustics. Of course all parts of sound reproduction matter, but those three are the ones that affect real systems in practice. Most other factors are rarely an issue and/or inferior parts have a much lower magnitude of impact on sound quality. Sufficiently good source material (256kbps AAC or better) is widely available. Most amplifiers are fine. Almost all wire/cable is perfectly good. High quality DACs are more abundant than you might think (e.g. the digital inputs of any half-decent AV receiver made in the past decade). Good speakers. Good placement. Good acoustics. Those are the ones to focus on. They're the ones to spend money on. If you wanted to add a fourth to that list, I'd add an honourable mention to in-room calibration systems like Audyssey and DIRAC. Depending on the sorts of imperfections in a given system the opportunity for improvements with DSP might be substantial and dramatic, or marginal to the point of being irrelevant. (For most systems it's somewhere in the middle.)
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mnemotronic 8y ago
{quote} ... I connected it to a pair of 30-year-old, three-way Panasonic speakers, which I frequently use for testing.{/quote} Ummmm. I'm tempted to dismiss the author's entire project based on that. Why not use a pair of decent speakers or some high-end headphones like the Stax electrostatics or Audeze planars? Weakest link in the chain and all that.
WalterBright 8y ago
What's the output power of the amp?
mmaunder 8y ago
Google audiophile headphones. Then go to sweetwater and search for studio headphones. If the price of source gear is a quarter of the price of gear attempting to reproduce source, something is broken.
- Tsiklon 8y ago
  I like to look on high end headphones as I would any other luxury item - I'm willing to pay for nice materials of a higher quality or a better experience, if the item is right. That could perhaps explain some of the price - plus I think we're at the point where many of the headphone companies have discovered that there is an ultra-high end market for some of these products. You can see this in the prices of many top brand flagship headphones - the majority of the well regarded brands have been gradually putting out exceedingly expensive flagships in the past 2-3 years. 10 years ago - then the Sennheiser HD650 was seen as a flagship at $400, now look at the Sennheiser HD820 released earlier this year at $2200. You aren't going to find too many people who will say that the sound improvements between the two justify an $1800 increase in MSRP. However if you reframe the perspective to that of a luxury good, given the perception of headphones (regardless of use case) has changed somewhat in the interim and are seen as a fashion accessory and there's a larger enthusiast pool - you can see that manufacturers would be willing to push new boundaries when it comes to price. However I think it's only the lunatics, or the conspicuous consumers who are ignorant to the law of diminishing returns when it comes to headphones and audio in general.
  - beat 8y ago
    Some people understand the law of diminishing returns, but have the resources to not care. If a $2000 pair of headphones is no more real financial pain for you than a $200 pair, and they're better despite diminishing returns, then why not get them?
    - Tsiklon 8y ago
      Very correct, that's a perfectly reasonable explanation, especially in terms of the usual consumers of high end luxury goods.
neya 8y ago
After I started building my own audio gear, I am no longer impressed by what you can buy in the consumer market, no longer how much "audiophile" these systems claim to be. Usually, it's just a simple 2-way boombox sold for $xxx - $xxxx. I started my project after being disappointed with the sound quality of the Apple Homepod. So, I built my own version with inbuilt basic voice command integration. And I couldn't be happier. Funny, that I just finished building mine this week[1][2]. It's also based on Tubes, and the sound is very, very satisfying. Will be happy to share a detailed guide, if anyone's interested. [1] https://www.instagram.com/p/Bpl71mUHLbm/?taken-by=discovery.diary https://www.instagram.com/p/Bpl71mUHLbm/?taken-by=discovery.... [2] https://www.instagram.com/p/BplhIIqHNhl/?taken-by=discovery.diary https://www.instagram.com/p/BplhIIqHNhl/?taken-by=discovery....
- jollyrogerbass 8y ago
  That looks awesome, post the guide please!
  - neya 8y ago
    Alright, will post it soon on my Medium1: https://medium.com/build-ideas https://medium.com/build-ideas Thank you :)
beat 8y ago
Modern class D amps are terrific, but it's annoying to see THD brought up as a measure of audio quality. THD is terrible measurement - its value is not that it's relevant (except to demonstrate things aren't actually broken), but rather that it's easy to measure. An amplifier's ability to reproduce a 1khz sine wave into a resistive load tells us nothing about how it behaves in the face of 8-10 octaves of frequency range and the real dynamic range and harmonic complexity of actual musical content, when hooked up to the absurdly complex and nonmusical behavior of real speakers. The 5% THD of single-ended tube amps that people who've never heard one tell us proves how "inaccurate" they are is inaudible, but the grimy, dull sound of cheap amps that have excellent THD specs is plain to hear. It's frustrating, in part because this stuff is, so far, mostly impossible to measure. It's hard to get a sense of how an amplifier will sound from specs.
- mark-r 8y ago
  I'll never forget my wakeup call on the differences of sound between amplifiers. I had been listening to headphones on my Techniqs receiver, a well regarded unit with a THD of 0.04%. For some reason I plugged the headphones into my Nakamichi cassette recorder instead, and was blown away by how much better they sounded. Until then I had thought that amplifiers were a solved problem and the inaccuracies of transducers like headphones would mask the tiny differences between them. I never expected to be wrong.
linsomniac 8y ago
I kind of want to build one of these amps and connect it to a set of speaker built with these cheap exciters... One of the Youtube channels I follow messed around with them https://youtu.be/zMCyF400l1c https://youtu.be/zMCyF400l1c but he got that from this other video https://youtu.be/zdkyGDqU7xA https://youtu.be/zdkyGDqU7xA where he goes into all sorts of experiments he ran on the exciters to find the right design.
kunkurus 8y ago
A DIY 0.0001% THD Amplifier: The MJR7-Mk5 Mosfet Power Amplifier http://www.renardson-audio.com/mjr7-mk5.html http://www.renardson-audio.com/mjr7-mk5.html
neuralRiot 8y ago
there seems to be too many different thinghs mixed up, "professional amplifier" "high end audio" and "class D" are three different worlds. It's like a Humvee a Maybach and a Prius in the same vehicle.
lalorieri 8y ago
[for guitars] Depends on what you consider professional. We've made a simple, cheap, modular project that works in hard conditions for a long period of time and has enough quality for a gig. https://medium.com/@leolorieri/underground-bands-get-more-watts-for-less-money-a8fdcdff98b0 https://medium.com/@leolorieri/underground-bands-get-more-wa...

444 points by chablent 8y ago

Oh geez they could have left this statement out: "When I wrote my previous article, class-D audio was fairly new, and audiophiles were still arguing about whether class-D amps could sound as good as class-AB or class-A units. Nobody is having those arguments anymore." Those arguments are still front and center when it comes to amplifier design, both on the manufacturer and consumer sides.

AceJohnny2 8y ago
Tangentially, the placebo effect is everywhere. If it can affect tasting (wine) and hearing (audiophile gear), I'm surprised not to have noticed its affect in discussing photography. Will "computational photography" (as touted in the latest iPhones) that alters photos based on criterion of perceived quality end up bringing these kind of inane discussions there too? Edit: Never mind, I didn't factor in all the arguments about Photoshop altering.
- taejo 8y ago
  While there are endless debates about manipulation, when it comes to actual capturing of images, the photographic community (in my experience) has a healthy dose of "the best camera is the one you're carrying" and "a great photographer can take great photographs with any camera but even a great camera won't help a lousy photographer take great photographs" to go with its love of gear (who can help but love gear?)
  - beat 8y ago
    Camera nerds are the worst. They're worse than audiophiles, if that's possible. Good photography requires nothing more than a bit of reason and observable standard practice, applied to aesthetics. You don't have to look hard to find someone with a $5000 camera/lens combo who doesn't know what the Rule of Thirds is or how to apply it. Last weekend, I was in DC, and snapping pictures of the Washington Monument on my phone. My sister was shocked at how good they were. It's not hard, really.
    - airbreather 8y ago
      Girl at work has 20k camera with 100k megapixels, but then again Huawei just asked to use her pics for their phone screen savers, so...
- rectang 8y ago
  I made my living as a mastering engineer for two years... To do good work in mixing and mastering, it's important to study the human perceptual mechanism and its propensity for illusion, and it's also important to understand masking effects and how to amplify certain components long enough to tweak them before dialing them back to recede into the gestalt. It's also important to understand that in sound reproduction the vast majority of the distortion on the analog side comes from transducers (microphones and speakers), not amplifiers. (I'm not even going to bother with the article, because amplifiers aren't an important problem: buy something decently engineered and overpowered, and you're basically all set. Then worry about your speakers and your room, because they're the hard part.) But it's likewise crucial to grok that the distortion introduced by digital components is disproportionately disturbing because it is enharmonic. And that practically speaking a lot of the damage that gets done in practice happens because people don't handle gain staging right and often don't understand the fundamental principle of preserving high resolution throughout production and only exporting to lower resolution as a final step. In summary, there are a whole lot of interesting conversations to have on the subject of audio and how perception relates to production. But it's basically impossible to find a community to discuss these subjects with. Either it will be overrun by audiophiles and their pseudoscience, or well-meaning but undereducated skeptics will dominate the discussion with plausible but misguided debunking. So every once in a while I throw up a piece like this into the middle of a giant discussion, with about as much hope as tossing a message in a bottle into the ocean.
  - ericdykstra 8y ago
    This is pretty fascinating. I can't add to a discussion, but I would certainly read more about this if you have produced it somewhere. I'm also curious, what made you leave your job as a mastering engineer?
    - rectang 8y ago
      The profession of audio production is extremely competitive because there is a perpetual oversupply of labor. The total amount of money in the music industry is also deceptively small compared to its high public profile. I left the field (back in about 2003) because although I felt that I was good enough to compete and survive, I didn't love it enough to grind out a life as a workaholic and just get by. Most of my writings from that time were forum posts with the perspective of the well-meaning but undereducated skeptic and wouldn't be that interesting to read today. Also, what was probably my best writing happened in forums which don't have public archives which have survived 15-20 years later. (Which amuses me as a former mastering engineer because one of our primary objectives is long-term archival.) PS: not "enharmonic", "non-harmonic" dammit. The point is that while analog distortion is mostly harmonically related, digital distortion is not and therefore is much more poisonous in small quantities. Mixing especially (though mastering is similar) is all about making changes near or below the threshold of perception which sum to a cumulative perceptible effect.
- paulie_a 8y ago
  Whenever I see the term audiophile I mentally replace it with "over priced bullshit" It's just someone being sold snake oil.
- ken 8y ago
  It's already here, for displays. I've seen lots of internet comments claiming I need the >450ppi screen on the new high-end iPhone, not the miserable old cheapo 326ppi one.
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01100011 8y ago
I think it might boil down to your philosophy on sound reproduction. Do you want accuracy with some potentials for ugliness if you clip, or do you want coloring and musical distortion? I don't think AM radio sounds good at all, but it is sometimes emotionally comforting to listen to. Fidelity isn't everything. That said, many high end audio folks are straight up whack jobs.
milesvp 8y ago
I'm not convinced audio engineers are having that argument anymore (which is more the audience of IEEE). I get the impression from an engineer I know who's specialized in digital signal processing, and who's done a significant amount of analog work, that anyone who's still having some of these arguments doesn't understand some of the basic maths of the problem space. That basically, you can always digitally encode an analog signal at a higher resolution and fidelity than you can reliably read said signal at any given technology level/pricepoint. Which means that using an ADC -> DAC pipeline will almost always give you better audio output with better signal to noise ratios than strict analog -> analog systems (though possibly at the cost of latency). Where it gets tricky, is the arguments for how things like tube amps sound. There is nothing that analog components add to a sound that can't be simulated with digital transforms, but the trick is figuring out how various analog components effect the signal. For instance, my friend found that certain tube amps would overdrive components and force them out of spec, and this caused a non linearity in the response of the signal coming from the component that gave the amp it's distinctive distortion effect. Once he figured that out he was able to reproduce the effect digitally. Incidently, he's found that some guitar amps can never be made today, because they were built around a specific batch of a given component, and newer batches didn't have the same out of bounds responses. But this seems to be why so many people are still so big into analog amps, because it takes considerable effort (and apparently engineering skill) to reproduce some of the classic sounds. Mind you, I'm biased by one of the best engineers I've ever met, so I could be wrong about the general consensus with audio engineers. I'm also mostly using a sample size of 1, though I have corroborated some of his assertions with some of the blogging I've read on the topic. One of the best (I wish I'd bookmarked), was a good overview of encoding by a prolific codec writer, who pointed out that even though a digitized sine wave looks lossy at a low sample rate, it's trivial to rebuild that sine wave perfectly, with just the digitized version (so long as the sample rate was above some multiple of the Nyquist frequency?).
- raphlinus 8y ago
  Likely that was xiph on why excessively high sample rates don't do much for the listening experience: https://people.xiph.org/~xiphmont/demo/neil-young.html https://people.xiph.org/~xiphmont/demo/neil-young.html

vichu 8y ago

I don't know much when it comes to audio amp design, but this reminds me greatly of the O2 headphone amp[0] - that anecdotally a few of my friends have soldered for their personal use. [0] http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html http://nwavguy.blogspot.com/2011/07/o2-headphone-amp.html

korethr 8y ago
I thought of the same thing. Both are inexpensive, straightforward, no-BS projects that leverage the advances made in electronics over the years to deliver quality audio. If I made one of these, I 'd be tempted to put an ODAC and O2 board in the same chassis to have a complete amplifier.
- wolfgke 8y ago
  > If I made one of these, I 'd be tempted to put an ODAC and O2 board in the same chassis to have a complete amplifier. Such a product is available commercially: > https://www.jdslabs.com/products/48/objective2-odac-combo-revb/ https://www.jdslabs.com/products/48/objective2-odac-combo-re...
- syntaxing 8y ago
  Hearing the ODAC name is quite a throw back! I remember reading NwAvGuy's blog when I first started getting into headphones. I always wondered what happened to him.
  - sjwright 8y ago
    Given the way he suddenly went to radio silence, I just assumed he was hired by Apple...
dejv 8y ago
O2 is great and it is quite simple to build. There is even simpler amp called CMoy[1] which is simple enough to be first project for somebody just starting out. I would start by taking look on some oss version[2] and order PCB from OSH Park[3]. I've built this version few years ago and it works well. [1] https://tangentsoft.net/audio/cmoy/ https://tangentsoft.net/audio/cmoy/ [2] https://github.com/akafugu/cmoy https://github.com/akafugu/cmoy [3] https://oshpark.com/shared_projects/dRKK4dgN https://oshpark.com/shared_projects/dRKK4dgN

korethr 8y ago

Interesting. I'm tempted to try this out. I have access to a quality soldering iron and can use it decently well (I'm typing this on an ergodox keyboard I built from a kit). There is something very satisfying about building something yourself that you get use out of every day. Such an amplifier is likely to fall into that category for me.

jelling 8y ago

Any recommendations for people that are tempted to build this but should really put their time elsewhere?

korethr 8y ago
I'm not sure I understand your question; what do you mean by "but should really put their time elsewhere"? Are you asking for an amplifier that would deliver similar performance to this, because you don't have the time to build one, or that you suspect you'll come out ahead on build vs buy because of the price you value your time at?
janekm 8y ago
If you are looking for something already built, the eBay/aliexpress shops of the Shenzhen companies often have the option of selling you a complete amplifier made up of their modules. Which will probably end up cheaper than getting all the parts yourself...
- Matsta 8y ago
  Bang on. A popular amp is a TPA3116 module. You can see thousands of examples on Aliexpress: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20181031152231&SearchText=tpa3116 https://www.aliexpress.com/wholesale?catId=0&initiative_id=S... For speakers, the cheapest option is to buy some second-hand ones on eBay/Gumtree/Craigslist. Just Google model names and look for ones with good reviews. I like British speakers, so I usually search for Tannoy, B&W, KEF etc.
01100011 8y ago
Just do some research and get a cheap class D amp off a chinese website. I forgot the one I chose(I'm at work now), but other than some sparks if you jiggle the power connector(haha seriously. can be fixed with a tiny bit of effort), it is an amazing little amp. It also supports optical and bluetooth connections which is really nice. I put my efforts into building speakers instead. I got a cheap kit (https://www.diysoundgroup.com/overnight-sensations.html https://www.diysoundgroup.com/overnight-sensations.html) and spent my time learning how to apply a french polish finish. I really enjoyed learning french polishing. It's one of those things that when you finally get it, it becomes immensely satisfying. Yeah, shellac isn't the most durable finish, but it sure is pretty.

watersb 8y ago

Very cool. I was very interested when the IEEE Spectrum original feature was published, and got one of the Tripath amplifiers to play with. It was a commercial product, marketed as inexpensive toy. Then people on Head-Fi Forums started taking these things further. One of the forum members started modding home-theater amplifiers, so I purchased one and it was great. Vinnie Rossi, Red Wine Audio. It is still amazing. But his stuff is now quite out of my price range. These amplifiers are great fun, though.

Matsta 8y ago

The majority of all active speakers produced nowadays are Class-D, it's nothing really new (and the fact they are super cheap). No idea how this guy wrote this article and didn't come across DIY Audio (or he just didn't mention it in the article). There is a tonne of information here: https://www.diyaudio.com/forums/class-d/ https://www.diyaudio.com/forums/class-d/

matt4077 8y ago
Your first point seems to be reflected in the article, except that, if they are correct, the high end of Class D amplifiers apparently is not "super cheap". I don't quite get the aggressiveness of your second point: surely just leaving whatever your first association to a topic is out cannot warrant such outrage? It's not like they present this article as groundbreaking innovation. Not only do they cite other DIY efforts. The whole premise of the article is that the author himself already did this ten years ago,.
- Matsta 8y ago
  It comes more down to the design of the board and the quality of the other components on the board. The TPA3250 he mentions is quite a new chip, but if you look on Aliexpress for an older chip like the TPA3116 there is literally thousands of examples: https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20181031150947&SearchText=TPA3116 https://www.aliexpress.com/wholesale?catId=0&initiative_id=S... I imagine this guy must have found the components of a site similar to DIY Audio. It would have been a nice addition to steer people in the direction of more information if they are interested in the topic (which a lot of the comments here seem to be asking about).
irrational 8y ago
I have some questions. My son has been taking guitar lessons using a classic guitar. Using the advice of his instructor we are getting him a begginer's electric guitar for christmas. We also need to get him an amp. Is the amp in this article the same kind of amp that you could plug an electric guitar into? I know nothing about music or instruments, but I do know about electronics so I was thinking it might be fun to build an amp with my son. I went to the diyaudio link you suggested, but I didn't immediately see information like in the article (buy this, this, this and this to build the amp). Can you point to where I could find a similar purchase list and assembly instructions on diyaudio? Thanks!

Scoundreller 8y ago

I don’t build audio amplifiers often, but when I do, I always use top-quality components like HPOO.

fermienrico 8y ago

It is refreshing to see these types of articles. Of all disciplines of human interests and hobbies, Audiophiles are one of the most stubborn, misinformed, anecdotal and delusional bunch. Of course I am generalizing, but every time I engage in a discussion about audio quality, it is a losing battle. Not because of lack of data or supporting evidence, but because of the fundamental dissent for data driven arguments. You cannot argue reason when the first step is to be born with "audiophile ears". Why is it hard to understand that we have sophisticated metrology and instrumentation that can analyze things better than human ears can? I can understand a separate discussion about personal opinions regarding how "warm" a particular sound is, but that should remain distinctly as - subjective and that's perfectly OK. It feels like the entire audio industry is promoting pseudoscience barring a very few vendors that actually care. We have a $8500 mp3 player from Sony claiming all kinds of things to the overwhelming abundance of cheap Shenzhen exports. There is just so much noise. I absolutely abhor audiophiles.

ohazi 8y ago
Someone I know was recently trying to have a conversation with an audiophile about the possibility of re-purposing some audio equipment to make noise floor measurements for another system that had similar frequency and dynamic range characteristics. The technique worked just fine, but man, that guy was loony. He was trying to claim, with a straight face, that a GPS disciplined oscillator wasn't stable enough for his audiophile-grade Rube Goldberg machine.
- brokenmachine 8y ago
  Oh god, jitter... If ever there was a more pseudoscience audio term, I haven't heard it. I wish there was a separate term between audiophiles who just want to spend a lot of money on hocus pocus, and audiophiles who want the measurably best performance. Then the audiophile forums would not be polluted with people who spend thousands on cables and other rubbish, when the room response/treatment and speaker selection has a million times more effect on the actual sound.
albertgoeswoof 8y ago

comboy 8y ago

Any DAC chip and some usb interface for it that you could recommend to go with this? And slightly OT, but does anybody know any ABX test of balanced input/output signal? I find it hard to believe that there is a single person who can hear the difference.

jacquesm 8y ago
The big gain for balanced inputs is rejection of signals induced into the wire. Of course optical is the way to go if you are really worried about that. Personally I don't care, my ears are old enough that I no longer hear the difference between a high end and a low end amp.
Matsta 8y ago
There's thousands of options. Schiit are generally regarded for having high quality products that are relatively cheap. A good place to find DAC reviews is head-fi: https://www.head-fi.org/forums/dedicated-source-components.7/ https://www.head-fi.org/forums/dedicated-source-components.7...
- comboy 8y ago
  Thousands of options is why I asked for a recommendation. I know Schiit has good reviews but I'm just interested in ICs. Something like PCM2707C for USB communication or PCM1794A for DAC or whatever else.
aidenn0 8y ago
There are cases where the difference is huge; particularly when you have very long runs between the preamp and the amp. This is on reason why you usually see XLR inputs to monitors. Any noise induced is amplified and a long unbalanced wire is a big antenna. I've heard of cases where you could receive AM radio stations from such a setup; I lean towards "urban legend" for that though. While it seems theoretically possible (since many amplifier topologies can have resonance when fed signals outside their expected operating range), it seems a bit farfetched to actually end up with intelligible audio.

esaym 8y ago

Hmm, I'd much rather build a Class-D amp from scratch with no chips involved... any tips?

jacquesm 8y ago
https://www.elektormagazine.com/labs/200w-class-d-audio-power-amplifier-150511 https://www.elektormagazine.com/labs/200w-class-d-audio-powe... Not quite chipless but pretty close.
heavenlyblue 8y ago
https://www.amb.org/audio/ https://www.amb.org/audio/
mbell 8y ago
That's not realistic, particularly if you're after a full range amp.

proee 8y ago

Audio is a great way to get kids excited about electronics. When I was in the 6th grade, my father helped me build my own high power amplifier using an LM3876 opamp. I remember clear as day the first time I powered up my amplifier circuit and nothing happened. Hmmm... I brought my face closer to my circuit board and suddenly "BANG!!!!" an electrolytic capacitor blew up right in my face and scared the living daylights out of me. I unknowingly connected the power supply capacitor backwards. I soldered in a new capacitor, and then plugged it in again. Like magic, my home-brewed subwoofer was now cranking out serious bass by an amplifier that "I" built. That moment was magical and surreal - I still get goose bumps thinking about it!

rubatuga 8y ago

If you just want the amp without building it, you can get a TPA3116 Class D amplifier. It is only $21 USD from aliexpress (with free shipping of course!). It accepts a supply voltage of up to 24V meaning that you can just dig around for your old laptop power supply (19V). It comes with a nice and sleek aluminum case, and has low enough noise floor that I can't detect it at all unless my ear is right up against the speaker. Although slightly less power output compared to the chip from the article, it gets loud enough to drown out someone yelling. This amp from aliexpress has gold plated banana plug terminals, RCA inputs, and a smooth volume potentiometer. Link: https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-D-Power-Amplifier-Audio-Amp-TAP3116-Mini-Digital-Amplifier-Hi-fi-Audio/32888620869.html https://www.aliexpress.com/item/Breeze-Audio-BA100-Class-D-P...

blattimwind 8y ago
I guess in technical terms this article is about "making" an amplifier as opposed to "building" an amplifier. "Making" as in "Maker", since the electronics come as pre-made assemblies connected together and put in a case.
- trentlott 8y ago
  Basically a model kit that inhibits your ability to generalize.
  - imtringued 8y ago
    The first step of generalization is copying.
- compiler-guy 8y ago
  "If you wish to make an apple pie from scratch, you must first create the universe." --Carl Sagan
  - blattimwind 8y ago
    "There are only two colors in the world: black and white." --Ansel Adams

kposehn 8y ago

> Nobody is having those arguments anymore. There are many class-D amplifiers on the market now, and the best of these are dominating the upper reaches of the high end. Not quite. Frankly, Class A or AB still has the upper hand from a pure sound quality perspective, and class D struggles to output sufficiently at high levels with lower levels of distortion in my experience. That said, there have been many small class-D Amps from Lepai and Dayton that are excellent choices for near-field and non-demanding applications. They definitely have their place. The tech is advancing rapidly but it has not supplanted A or AB. If you want some background in why there is still debate, I highly suggest reading some of Nelson Pass’ interviews and writings: https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/21/an-interview-with-hifi-legend-nelson-pass/amp/ https://www.google.com/amp/s/parttimeaudiophile.com/2018/02/... https://www.passlabs.com/press/single-ended-class https://www.passlabs.com/press/single-ended-class https://www.passlabs.com/press/leaving-class https://www.passlabs.com/press/leaving-class

radus 8y ago
This may be true of Class D amps commonly used in home equipment, but many high end powered PA speakers use Class D amps and get very loud with minimal distortion.
- TylerE 8y ago
  You'd be surprised how much you can get away with in a PA. Being powerful and reliable is more important than being all that good, since the room always sounds bad anyway.

mrob 8y ago

It's bizarre how none of these chips seem to have a digital input. All my music is digital, and despite the modern rise of vinyl, I don't think that's unusual. If I want an amplifier like this then I'm forced to have a completely useless DAC/ADC pair degrading the signal quality. Does anybody know of an easily available class-D amplifier with digital input? You'd think that would be an obvious feature for a digital amplifier.

blattimwind 8y ago
> You'd think that would be an obvious feature for a digital amplifier. That's because these amplifiers are not digital. The control loop is generally analog. Though there are chips which do in fact use digital inputs and do most of the work via fixed-function DSP, but those are mostly bigger chips targeted at 5.1 or 7.1 systems.
- mrob 8y ago
  From Wikipedia: "The term "class D" is sometimes misunderstood as meaning a "digital" amplifier. While some class-D amps may indeed be controlled by digital circuits or include digital signal processing devices, the power stage deals with voltage and current as a function of non-quantized time." So what's it called if it is time quantized? The simple open-loop design depicted on the Wikipedia page could have the analog comparator + triangle wave generator replaced with a digital delta-sigma modulator (1-bit DAC). Then the switching times of the power stage would be quantized to the sample rate multiplied by the oversampling ratio. (Although it seems this open-loop model is an oversimplification, and real class-D amplifiers have feedback, so it wouldn't be that simple in practice.)
kazinator 8y ago
It's not a digital amplifier. A class-D amplifier is basically somewhat like a switched-mode power supply that varies its output voltage in response to swings in the input signal.
evancox100 8y ago
Uh, if you want to "amplify" a digital signal, just multiply all the samples by some number.

dbrgn 8y ago

How would one best control the output volume on such a DIY amp? 2-channel logarithmic 10K potentiometer in front of both inputs? What if you use balanced input?

kazinator 8y ago
If your input is balanced, it will be handled by some op-amp circuit or whatever, which converts to single-ended internal signal, like the "balanced line input module" shown in this page: http://sound.whsites.net/project30a.htm http://sound.whsites.net/project30a.htm You can easily insert a volume control right after such a stage.
- dbrgn 8y ago
  Yeah, but in the context of this article, I'd have to cut some traces on the PCB to get there. Doesn't sound like the ideal solution to me :)
  - brokenmachine 8y ago
    The 3e Audio board has jumpers to choose between single-ended and balanced I believe.
  - deleted 8y ago
    [deleted]
  - kazinator 8y ago
    Perhaps, perhaps not. The schematics don't seem to be available, but let's imagine there is a stage in there which looks roughly like this: |\ C |\ | >--||-+-----| > |/ | |/ < < R < | V If we simply remove/desolder components C and R, we should be able to then install hookup wires for a potentiometer (which includes the C also). It looks like this particular board has tiny SMT components, which make this sort of thing a pain in the but.

MrTonyD 8y ago

I'm probably the only one with this opinion...but I sure miss the old days of tube amps that weren't able to be highly accurate. They would roll-off the on the high end, distort a bit all over, and gave a very warm and relaxing feel to the albums I played obsessively. Now I've owned high-end tube and solid-state gear, and the music hasn't sounded good for decades. Combine that with the very limited bits provided by CDs, preventing any possibility of good playback, and music has been completely destroyed. Old timers like me are dying off, and most of the people who remember good music will be dead. Kind of makes me sad.

mrob 8y ago
>Combine that with the very limited bits provided by CDs, preventing any possibility of good playback 16 bits gives you 96dB SNR (and subjectively more with dithering), which is plenty at non-deafening listening volumes. It's more than even the highest quality vinyl ever had. High bit depth is mostly useful so you've got some headroom during editing.
- MrTonyD 8y ago
  That is absurd. Anybody who has read about the history of CD bit depth would know just how absurd that is. And I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. All these claims about how great digital is are just crazy - claims made by people who are relying on old data about hearing accuracy and a religious faith in technology. Anybody who has actually designed instruments using the known laws of physics understands the incredible limitations - and those limitations apply to both characterizing hearing as well as reproducing sound digitally.
  - mrob 8y ago
    >I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. I can believe that, but the standard was designed to tolerate high bit error rates. 25% of the bits are redundant, as part of a error correction code: https://en.wikipedia.org/wiki/Cross-interleaved_Reed%E2%80%93Solomon_coding https://en.wikipedia.org/wiki/Cross-interleaved_Reed%E2%80%9... This scheme works very well, as proved by people consistently ripping bit-for-bit identical copies of CDs pressed or burned with the same audio.

aidenn0 8y ago

On a similar note, anybody know why you can get a very good A/V receiver for ~$500 but not a pre/pro for under $1k? Is it just the lower manufacturing volume?

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jpmoral 8y ago

>When I wrote my previous article, class-D audio was fairly new Not sure what this means. I had a group undergrad project in 2002 to build and characterise a class-D audio amp. The idea was well-established at the time.

KamiCrit 8y ago

It's great that with some research and drive one can make something better and cheaper than the engineered factory version. Time well invested.

S_A_P 8y ago

Audiophilia is a study in contradiction. The ask is a flat "uncolored" accurate sound. The gear that sells for ridiculous prices is usually tube gear with limited bandwidth and makes ~15 watts at 5-10% (admittedly usually even order harmonic) thd. Hardly uncolored. That said, and Ive mentioned this before on HN. My (now late) uncle had a bunch of audiophile friends in Dallas. He hung around folks who had spent upwards of 500,000 (yes you read that right) on audio gear. I can't forget the time I rolled up to a modest middle class home, only to find out that inside of this house was a pair of Focal Grand Utopias (selling retail for 250k at the time, though he said he paid around 60k for the pair). He had 2 750 watt tube amps, current era but the brand escapes me. For source material he had a heavily modified Technics SP-10 with 2 tone arm/cartridge combinations and a boutique tube phono preamp. This fed into a similarly heavily modified Dynaco tube preamp from the 1960s. When he really wanted to get serious, though, he had a studer 2" tape machine and a sizable collection of low generation master tape copies. If I hadn't seen this with my own eyes I would say my uncle was full of shit when he told me about it. You know what? it sounded freaking amazing.Im sure it is 90% placebo, and 10% the fact that he was able to play high bandwidth audio to concert levels with no stress or strain from the amplifiers. Was it worth 6 figures of money? not to me. But I am glad I got to hear it...

sjwright 8y ago
The three critical paths for high end sound reproduction are: loudspeakers, speaker placement, room acoustics. Of course all parts of sound reproduction matter, but those three are the ones that affect real systems in practice. Most other factors are rarely an issue and/or inferior parts have a much lower magnitude of impact on sound quality. Sufficiently good source material (256kbps AAC or better) is widely available. Most amplifiers are fine. Almost all wire/cable is perfectly good. High quality DACs are more abundant than you might think (e.g. the digital inputs of any half-decent AV receiver made in the past decade). Good speakers. Good placement. Good acoustics. Those are the ones to focus on. They're the ones to spend money on. If you wanted to add a fourth to that list, I'd add an honourable mention to in-room calibration systems like Audyssey and DIRAC. Depending on the sorts of imperfections in a given system the opportunity for improvements with DSP might be substantial and dramatic, or marginal to the point of being irrelevant. (For most systems it's somewhere in the middle.)

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mnemotronic 8y ago

{quote} ... I connected it to a pair of 30-year-old, three-way Panasonic speakers, which I frequently use for testing.{/quote} Ummmm. I'm tempted to dismiss the author's entire project based on that. Why not use a pair of decent speakers or some high-end headphones like the Stax electrostatics or Audeze planars? Weakest link in the chain and all that.

WalterBright 8y ago

What's the output power of the amp?

mmaunder 8y ago

Google audiophile headphones. Then go to sweetwater and search for studio headphones. If the price of source gear is a quarter of the price of gear attempting to reproduce source, something is broken.

Tsiklon 8y ago
I like to look on high end headphones as I would any other luxury item - I'm willing to pay for nice materials of a higher quality or a better experience, if the item is right. That could perhaps explain some of the price - plus I think we're at the point where many of the headphone companies have discovered that there is an ultra-high end market for some of these products. You can see this in the prices of many top brand flagship headphones - the majority of the well regarded brands have been gradually putting out exceedingly expensive flagships in the past 2-3 years. 10 years ago - then the Sennheiser HD650 was seen as a flagship at $400, now look at the Sennheiser HD820 released earlier this year at $2200. You aren't going to find too many people who will say that the sound improvements between the two justify an $1800 increase in MSRP. However if you reframe the perspective to that of a luxury good, given the perception of headphones (regardless of use case) has changed somewhat in the interim and are seen as a fashion accessory and there's a larger enthusiast pool - you can see that manufacturers would be willing to push new boundaries when it comes to price. However I think it's only the lunatics, or the conspicuous consumers who are ignorant to the law of diminishing returns when it comes to headphones and audio in general.
- beat 8y ago
  Some people understand the law of diminishing returns, but have the resources to not care. If a $2000 pair of headphones is no more real financial pain for you than a $200 pair, and they're better despite diminishing returns, then why not get them?
  - Tsiklon 8y ago
    Very correct, that's a perfectly reasonable explanation, especially in terms of the usual consumers of high end luxury goods.

neya 8y ago

After I started building my own audio gear, I am no longer impressed by what you can buy in the consumer market, no longer how much "audiophile" these systems claim to be. Usually, it's just a simple 2-way boombox sold for $xxx - $xxxx. I started my project after being disappointed with the sound quality of the Apple Homepod. So, I built my own version with inbuilt basic voice command integration. And I couldn't be happier. Funny, that I just finished building mine this week[1][2]. It's also based on Tubes, and the sound is very, very satisfying. Will be happy to share a detailed guide, if anyone's interested. [1] https://www.instagram.com/p/Bpl71mUHLbm/?taken-by=discovery.diary https://www.instagram.com/p/Bpl71mUHLbm/?taken-by=discovery.... [2] https://www.instagram.com/p/BplhIIqHNhl/?taken-by=discovery.diary https://www.instagram.com/p/BplhIIqHNhl/?taken-by=discovery....

jollyrogerbass 8y ago
That looks awesome, post the guide please!
- neya 8y ago
  Alright, will post it soon on my Medium1: https://medium.com/build-ideas https://medium.com/build-ideas Thank you :)

beat 8y ago

Modern class D amps are terrific, but it's annoying to see THD brought up as a measure of audio quality. THD is terrible measurement - its value is not that it's relevant (except to demonstrate things aren't actually broken), but rather that it's easy to measure. An amplifier's ability to reproduce a 1khz sine wave into a resistive load tells us nothing about how it behaves in the face of 8-10 octaves of frequency range and the real dynamic range and harmonic complexity of actual musical content, when hooked up to the absurdly complex and nonmusical behavior of real speakers. The 5% THD of single-ended tube amps that people who've never heard one tell us proves how "inaccurate" they are is inaudible, but the grimy, dull sound of cheap amps that have excellent THD specs is plain to hear. It's frustrating, in part because this stuff is, so far, mostly impossible to measure. It's hard to get a sense of how an amplifier will sound from specs.

mark-r 8y ago
I'll never forget my wakeup call on the differences of sound between amplifiers. I had been listening to headphones on my Techniqs receiver, a well regarded unit with a THD of 0.04%. For some reason I plugged the headphones into my Nakamichi cassette recorder instead, and was blown away by how much better they sounded. Until then I had thought that amplifiers were a solved problem and the inaccuracies of transducers like headphones would mask the tiny differences between them. I never expected to be wrong.

linsomniac 8y ago

I kind of want to build one of these amps and connect it to a set of speaker built with these cheap exciters... One of the Youtube channels I follow messed around with them https://youtu.be/zMCyF400l1c https://youtu.be/zMCyF400l1c but he got that from this other video https://youtu.be/zdkyGDqU7xA https://youtu.be/zdkyGDqU7xA where he goes into all sorts of experiments he ran on the exciters to find the right design.

kunkurus 8y ago

A DIY 0.0001% THD Amplifier: The MJR7-Mk5 Mosfet Power Amplifier http://www.renardson-audio.com/mjr7-mk5.html http://www.renardson-audio.com/mjr7-mk5.html

neuralRiot 8y ago

there seems to be too many different thinghs mixed up, "professional amplifier" "high end audio" and "class D" are three different worlds. It's like a Humvee a Maybach and a Prius in the same vehicle.

lalorieri 8y ago

[for guitars] Depends on what you consider professional. We've made a simple, cheap, modular project that works in hard conditions for a long period of time and has enough quality for a gig. https://medium.com/@leolorieri/underground-bands-get-more-watts-for-less-money-a8fdcdff98b0 https://medium.com/@leolorieri/underground-bands-get-more-wa...