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I recently bought the equipment to do a similar adaptive-audio job for my living room music / home-theater setup. I have the usual multi-decade collection of on
by wintry757 11y ago
I recently bought the equipment to do a similar adaptive-audio job for my living room music / home-theater setup. I have the usual multi-decade collection of once-fashionable home stereo equipment, some in use, some collecting dust in the basement. I decided I needed a bit more bass to enjoy more thoroughly the gunshots and explosions of gameplay and epic action films.
I listened to a stereophile friend eager to give advice, and convinced myself to add a self-powered subwoofer to the existing setup. Adding one shook the house but (to my ear) muddied the sound of music when no explosions were taking place. I could blame the equipment, or more properly myself, and replace some or all of the former. But I thought there must be some way to modulate all this unruly gear so that it produced a provably balanced and pleasant sound.
I will skip over some intermediate steps where I tried to learn the science and engineering of acoustics, using a neutral reference microphone and several fine pieces of audio software available to all of us interwebbily. I learned that I was overdriving the subwoofer, which made sense, but I couldn’t seem to go from spectrum graphs and suchlike to an actual balanced sound system. My final setup worked out quite satisfactorily and is an affordable alternative to building the computer-driven speaker cluster for room modeling.
> I have been looking at the idea of doing lots of small speakers with microphones on them attached to a fat lump of computer hardware, that you stick all over and they bleep each other and build an acoustic model of the space they are in, then adjust for it properly.
When I played in a band, we had to work with the club’s sound engineer or bring our own to get a balanced sound setup before the audience showed up. The more recent gigs showcased an interesting technology, a system that generated pink noise through the actual sound system, from the original sound sources before the mixing board, all the way through power amplifiers to the speakers at front of house. The engineer put a reference microphone in a strategic position, turned on the pink noise generator, and twiddled equalizer knobs to get a roughly even spectrograph (plus unavoidable “sound-guy magic” to de-equalize somewhat for specific gig purposes like dancing or seated listening) for the whole room, using the actual speakers and sound-reinforcement equipment we would be using.
This seemed to me to be the thing I needed in my home theater setup. It would let me balance and compensate for the (now) ten speaker cabinets in the living room (including the powered subwoofer), their real-life positions, the walls and floor coverings, the furniture, and even the cat. I think I could also do it with some combo of REW (Room Equalization Wizard) software, reference mike, and pink noise streamed through the amplifier. But while I was trying to get that approach figured out, I found a cheap piece of audio hardware with all that functionality built-in – no need to dedicate a computer to EQing the sound.
This is the Behringer DEQ-2496, a configurable digital equalization gizmo. It has a room equalization function built in, which is a home version of the room-equalization setup we saw in the clubs, and as a bonus it basically automates the sound engineer’s fingers on the equalizer sliders. I am not sure if it’s the latest model supporting this function, as I got mine used, but it was well below $200 and probably the best money I’ve spent on pretending to be an audiophile.
You set up the room for your listening preference (for me, this involves rolling the softest armchair into the center of the room the best to enjoy all those gunshots and explosions), put the reference mike about where your head will be, activate the automated room EQ process on the DEQ-2496, and sit down in your regular seating position to read for a while. It sends pink noise through the power amplifier and speakers and starts modifying an equalization curve to produce a “flat” room signal across all audible frequencies.
After about 15-20 minutes the EQ settings stop changing and the Behringer has generated the EQ setup for acoustically-neutral room sound. You can save the setup and create others (e.g., for group seating), or modify it manually to match your preferences (bigger bass for film audio, slight high-frequency boost for classical music listening, etc.), and save the modified versions as well. All my digital sound sources pass through it (game consoles, video, and music) in digital format and are equalized before they hit the amplifier and speakers – just as it worked in the clubs.
There are usable reference materials on the web to make up for the DEQ-2496’s obtuse user interface and execrable user manual. It’s not quite the super-flexible software-driven system I might have gravitated toward, but it does what I needed without tying up a computer.
What I like most is that it deals with the real world sound of my setup and room – if I change my setup or furnishings (as has happened a couple of times), I just re-run the balancing process and use the new settings as the baseline for my preferred room EQ. If my subwoofer, say, is turned too high the Behringer sets up a balancing cut in the affected frequencies. If the carpet soaks up some high-frequency signals, they’re boosted to compensate.
If my audiophile buddy gushes about the spectacularly flat frequency response of some new bookshelf system, I relax knowing that even my second-hand and slightly dinged-up speakers have been magically upgraded to subjectively flat (or not, as I wish) frequency responses – in the real world of my living room, not just in the lab or the store. It even has a full panel display of das blinkenlites should I need confirmation things are working properly. Very satisfying!
- vilda 11y agoEQ itself adds distortion. You may end up with flat characteristic, but poor sound quality. Amplifier designers are avoiding capacitors in signal path to minimize harmonic distortion. Now imagine you would put such a beast as EQ in the path...
- wintry757 11y agoI understand this argument, but I choose to treat it lightly it in real life because I am mostly interested in the sound I get in my own living room with my own real equipment making sounds for my skeptical human ears. There is a large and creative cohort of audiophiles generating and repeating numerous claims about audio. I cannot really credit many of these claims because they cannot to be reproduced in blind ABX tests, much like the spirits of the departed or the spoon-benders of yore. In truth, the presence of a side-table for my refreshments has a far larger and more measurable effect on the sound I hear than many of the possibly apocryphal sonic indecencies of the electronic components in front of me. To address your point directly, equalization (the feature of the Behringer DEQ 2496 I am using and discussing) does change the incoming signal, or it would not be a very useful audio component. My hands-on experience with oscilloscopes and digital audio analysis suites indicates that equalization does induce phase changes in the signal – you can see that by comparing input and output signals, or alternatively by doing the simple math that creates band equalization in the digital domain. These phase changes are pretty much unavoidable by-products of the audio filtering process, whether analog or digital. Better ears than mine sometimes claim to hear the effects of phase retardation, and I can conceive of extreme situations where this might be plausible. Those with golden ears can test themselves by doing a controlled blind ABX test with a conventional EQ system (as I am led to understand the Behringer implements) and a linear-phase EQ system, and publish results from which we all may learn. But I cannot hear phase retardation effects with current audio equipment and I would be interested to see the blind ABX tests that showed them to exist at all in normal human hearing. Ethan Winer has addressed the real-world impact of phase shifting in high fidelity audio on several occasions – for example: “More to the point, phase shift occurs naturally and unavoidably in all speakers and crossovers, and in every EQ circuit, with no obvious detriment as far as I can discern. Phase shift can be an important factor in speaker and crossover designs, but only because a tone whose frequency is near the crossover point is radiated by two speakers at once. In that case phase shift could cause the two acoustic outputs to partially cancel each other as they combine in the air in front of the speakers. But any time you stand in front of a loudspeaker and then simply take one step backward, you are inducing a large amount of phase shift at the higher frequencies.” [1] As to the more general implication that the Behringer DEQ 2496 introduces distortion, specifically the kind of distortion I would hear and dislike, this claim may still be argued. I will say that I have not yet run the full suite of digital audio analytics on the signal coming out of the Behringer DEQ 2496, and it may (against the general practice and standards of commercial audio equipment) distort the heck out of the incoming gunshots, explosions, and piccolos. You cannot prove it by me, and if I live up to my responsibilities I will check the manufacturer’s specifications with a digital audio reference suite some quiet week in the future. I would note, however, in case anyone else is concerned about the capacitors that may be magnifying harmonic distortion in the Behringer signal path, that its EQ process in my setup is conducted entirely in the digital domain, from SP/DIF digital input to TOSLink output. Only the infinitely delicate fingers of the Fourier transform and its ilk have touched those bits, and the reputedly foul influence of capacitors appears, if at all, downstream in the amplifier. References [1] From “Dispelling Popular Audio Myths” (http://ethanwiner.com/myths.html http://ethanwiner.com/myths.html, retrieved 2015-05-11).