6 ms·

Couple of notes from someone who has "designed" (adapted old schematics, really) and built tube amps for both hifi and electric guitar: - These things run at l

Couple of notes from someone who has "designed" (adapted old schematics, really) and built tube amps for both hifi and electric guitar: - These things run at low voltages (5-80VDC), which is fantastic for a designer, because 'real' vacuum tubes need several hundred volts DC, which means a big power supply transformer/rectifier/filter network. - These things don't appear to be able to source a lot of current, which makes them good for preamp and tone circuits, not so much for power amp circuits. Classic tube guitar amps got a lot of their tone from the phase splitter, power amp tubes, and power amp transformers. Don't expect an all-nutube-amp. - Utility for guitar amps would be for "hybrid" amps with a tube preamp and tone circuit feeding a solid-state power amp. There's certainly room for experimentation by amp designers here, since most contemporary tube amps just copy old circuits (mostly Fender and Vox) and use the same tubes they used (12AX7 being the ubiquitous preamp tube). I doubt the NuTube sounds like a 12AX7 when dropped into the same circuit. - Utility for hifi is questionable. An all-tube design allows for a very linear, low-parts-count amplifier. These will need to be mated to a solid-state power amp, which nullifies the advantage of a tube amp and enters "vacuum tube as marketing gimmick" territory.

jdietrich 8y ago
>Classic tube guitar amps got a lot of their tone from the phase splitter, power amp tubes, and power amp transformers. 100% this. A tube gain stage in isolation isn't especially difficult to imitate using solid-state electronics or DSP, but sounds nothing like a tube amp. >Utility for guitar amps would be for "hybrid" amps with a tube preamp and tone circuit feeding a solid-state power amp. The Vox MV50 amps make a decent attempt at this, pairing a Nutube with a class D power stage. It's tiny, it's reasonably loud and it sounds pretty good. I suspect the lack of interest from other manufacturers is mainly due to cost; for the price of a single Nutube module, you could add a decent DSP chip and gain a whole bunch of extra functionality. An ornamental 12AX7 and an orange LED has better showroom appeal and costs significantly less. Purists will still want real tubes and real transformers, budget-oriented players will want an amp with all the DSP bells and whistles, leaving the Nutube caught in an uncomfortably narrow niche.
- WalterBright 8y ago
  I don't understand why a tube's profile cannot be emulated with a DSP and so be indistinguishable.
  - Filligree 8y ago
    Oh, it absolutely can. The target market for tubes isn't people who do double blind tests, though.
    - ehnto 8y ago
      They want tubes and the tube sound, not just the sound. I can understand, it's a matter if authenticity rather than practicality. Just like a kit car replica versus an original car. The original will always be more authentic, and there will be some who care more than others.
  - Applejinx 8y ago
    Indistinguishable is a mighty strong word. We haven't completely mastered digital audio and to think we have is foolish (I do DSP for digital audio for a living, I'm Chris from Airwindows) Also, a tube has absolutely no latency.
    - TimTheTinker 8y ago
      > a tube has absolutely no latency I think that's the primary key here. We can decently emulate a tube amp in software even (and that can improve indefinitely as our knowledge improves), but we'll never create drop-in circuit element emulators either in silicon or software without adding latency.
  - jgalentine007 8y ago
    As far as guitar tube amps go - check out a Kemper Profiler or Fractal Audio system, it's pretty much there. That said, I'd take the pure simplicity of a nice tube amp any day.
omershapira 8y ago
> Classic tube guitar amps got a lot of their tone from the phase splitter, power amp tubes, and power amp transformers. Don't expect an all-nutube-amp. Subjectively, the one effect often missing from preamp-only tube amps I've tried is power stage sag[1]. I've seen DSP software with it (or rather, a knob for it). In that respect, I'm not sure the solid state / preamp tube / all-tube segmentation can be justified anymore: modern modelling amps sound terrific (subjectively, to my ears), offer sonic variety (because why not), and have a completely different idea of value (comfort, power and size); With that, the NuTube just feels like it's going after an audience who won't be convinced that electrons flowing through a DSP are made of the same quantum stuff, which is unfortunate. [1] Demo: https://www.youtube.com/watch?v=INi6lepBZt0 https://www.youtube.com/watch?v=INi6lepBZt0
microcolonel 8y ago
Frankly I think the world is (rightly) going the way of DSP + objective (probably class D more and more) power amp. If there is something nice about tubes, it is probably captured in somebody's software by now.
- WalterBright 8y ago
  I don't know about the dynamics of tubes, but I have yet to hear a credible replication of the sound of a trumpet with a synthesizer.
  - Applejinx 8y ago
    Hell, you're not going to get a credible replication of the sound of a trumpet off a CD… not compared to real life. Trumpets are among the few sorts of instruments that produce an overtone sequence going WAY beyond human hearing. It might not take that much more to cover those bases (I personally think 24/96 is more than enough and as such ought to be considered the baseline) and the heavy lifting will definitely be done by the amplification and speakers, but even a compact disc is going to fall short, much less a synthesizer.
    - WalterBright 8y ago
      I well know that any playback of recorded sound is hopelessly inadequate compared to live sound (I don't know why). But listen to any Herb Alpert recording, and then listen to any synthesized trumpet. The gulf is as wide as the Atlantic. (Part of the reason is that Alpert plays with the notes and the transitions, while a synthesizer just emits a note.)
      - microcolonel 8y ago
        > while a synthesizer just emits a note Well, maybe a crap one, or one not designed for that. Trumpets have some convenient physics that are (comparatively) simple to model, the problem you're thinking of may have more to do with the control system (i.e. not based on actuation of valves, but skipping right to the oscillators) than some inherent weakness of synthesis.
ZoomZoomZoom 8y ago
By the way, I totally understand why almost all guitar amps that marketed as hybrid use preamp tube stages and solid-state power amps. However, the reasons are almost all are from the standpoint of engineering, not sound quality. From my experience, overdriven guitar signal formed by ubiquitous FET-based approach driving a saturated tube power amp can sound gorgeous, tight and punchy, and feel very "natural" and responsive. 12AX7s into your ordinary solid-state power amps - not so much.
- jackhack 8y ago
  A FET preamp feeding a tube power section, pushed into clipping is at the heart of the Dumble tube amps. The Overtone Special (OTS) and Steel String Singer (SSS) are among the most desirable and most expensive guitar amplifiers in the world with models selling for $50,000 to $100,000+
  - diydsp 8y ago
    Also the tube pre-amp stage in the Dean Markley RM 80 DR is absolutely gorgeous sounding, as corroborated by its intricate tone-shaping in the schematic. My friend and I use it with keys and synths without even touching the transistor output stage.

jdietrich 8y ago

>Classic tube guitar amps got a lot of their tone from the phase splitter, power amp tubes, and power amp transformers. 100% this. A tube gain stage in isolation isn't especially difficult to imitate using solid-state electronics or DSP, but sounds nothing like a tube amp. >Utility for guitar amps would be for "hybrid" amps with a tube preamp and tone circuit feeding a solid-state power amp. The Vox MV50 amps make a decent attempt at this, pairing a Nutube with a class D power stage. It's tiny, it's reasonably loud and it sounds pretty good. I suspect the lack of interest from other manufacturers is mainly due to cost; for the price of a single Nutube module, you could add a decent DSP chip and gain a whole bunch of extra functionality. An ornamental 12AX7 and an orange LED has better showroom appeal and costs significantly less. Purists will still want real tubes and real transformers, budget-oriented players will want an amp with all the DSP bells and whistles, leaving the Nutube caught in an uncomfortably narrow niche.

WalterBright 8y ago
I don't understand why a tube's profile cannot be emulated with a DSP and so be indistinguishable.
- Filligree 8y ago
  Oh, it absolutely can. The target market for tubes isn't people who do double blind tests, though.
  - ehnto 8y ago
    They want tubes and the tube sound, not just the sound. I can understand, it's a matter if authenticity rather than practicality. Just like a kit car replica versus an original car. The original will always be more authentic, and there will be some who care more than others.
- Applejinx 8y ago
  Indistinguishable is a mighty strong word. We haven't completely mastered digital audio and to think we have is foolish (I do DSP for digital audio for a living, I'm Chris from Airwindows) Also, a tube has absolutely no latency.
  - TimTheTinker 8y ago
    > a tube has absolutely no latency I think that's the primary key here. We can decently emulate a tube amp in software even (and that can improve indefinitely as our knowledge improves), but we'll never create drop-in circuit element emulators either in silicon or software without adding latency.
- jgalentine007 8y ago
  As far as guitar tube amps go - check out a Kemper Profiler or Fractal Audio system, it's pretty much there. That said, I'd take the pure simplicity of a nice tube amp any day.

omershapira 8y ago

> Classic tube guitar amps got a lot of their tone from the phase splitter, power amp tubes, and power amp transformers. Don't expect an all-nutube-amp. Subjectively, the one effect often missing from preamp-only tube amps I've tried is power stage sag[1]. I've seen DSP software with it (or rather, a knob for it). In that respect, I'm not sure the solid state / preamp tube / all-tube segmentation can be justified anymore: modern modelling amps sound terrific (subjectively, to my ears), offer sonic variety (because why not), and have a completely different idea of value (comfort, power and size); With that, the NuTube just feels like it's going after an audience who won't be convinced that electrons flowing through a DSP are made of the same quantum stuff, which is unfortunate. [1] Demo: https://www.youtube.com/watch?v=INi6lepBZt0 https://www.youtube.com/watch?v=INi6lepBZt0

microcolonel 8y ago

Frankly I think the world is (rightly) going the way of DSP + objective (probably class D more and more) power amp. If there is something nice about tubes, it is probably captured in somebody's software by now.

WalterBright 8y ago
I don't know about the dynamics of tubes, but I have yet to hear a credible replication of the sound of a trumpet with a synthesizer.
- Applejinx 8y ago
  Hell, you're not going to get a credible replication of the sound of a trumpet off a CD… not compared to real life. Trumpets are among the few sorts of instruments that produce an overtone sequence going WAY beyond human hearing. It might not take that much more to cover those bases (I personally think 24/96 is more than enough and as such ought to be considered the baseline) and the heavy lifting will definitely be done by the amplification and speakers, but even a compact disc is going to fall short, much less a synthesizer.
  - WalterBright 8y ago
    I well know that any playback of recorded sound is hopelessly inadequate compared to live sound (I don't know why). But listen to any Herb Alpert recording, and then listen to any synthesized trumpet. The gulf is as wide as the Atlantic. (Part of the reason is that Alpert plays with the notes and the transitions, while a synthesizer just emits a note.)
    - microcolonel 8y ago
      > while a synthesizer just emits a note Well, maybe a crap one, or one not designed for that. Trumpets have some convenient physics that are (comparatively) simple to model, the problem you're thinking of may have more to do with the control system (i.e. not based on actuation of valves, but skipping right to the oscillators) than some inherent weakness of synthesis.

ZoomZoomZoom 8y ago

By the way, I totally understand why almost all guitar amps that marketed as hybrid use preamp tube stages and solid-state power amps. However, the reasons are almost all are from the standpoint of engineering, not sound quality. From my experience, overdriven guitar signal formed by ubiquitous FET-based approach driving a saturated tube power amp can sound gorgeous, tight and punchy, and feel very "natural" and responsive. 12AX7s into your ordinary solid-state power amps - not so much.

jackhack 8y ago
A FET preamp feeding a tube power section, pushed into clipping is at the heart of the Dumble tube amps. The Overtone Special (OTS) and Steel String Singer (SSS) are among the most desirable and most expensive guitar amplifiers in the world with models selling for $50,000 to $100,000+
- diydsp 8y ago
  Also the tube pre-amp stage in the Dean Markley RM 80 DR is absolutely gorgeous sounding, as corroborated by its intricate tone-shaping in the schematic. My friend and I use it with keys and synths without even touching the transistor output stage.