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Comment by bsder | Hacker News Reader

> My perspective, not widely shared, is that JFETs in general have been made obsolete by depletion-mode MOSFETs, at least in audio circuits.

A guitarist friend decided to "test" me once and put this in front of me and ask what it would sound like: http://el34world.com/charts/Schematics/files/randall/Randall...

My immediate response was: "That looks like a really great amp from the mid 1980's--looks like it was designed by someone who actually understands electrical engineering. It should have a pretty clean. But if you overdrive it, the clipping on those JFET's is gonna sound like fscking buzzsaw trash."

He, of course, laughed knowing that Dimebag Darrell used the amp for precisely that buzzsaw sound. You would have to add lots of "clipping" components to get the same sound out of depletion mode MOSFET's.

Now, whether that's a good sound is open to debate. :)

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There definitely are people who want that buzzsaw sound. The Boss HM-2 pedal "chainsaw" sound is also having a moment right now. I'm not really into either, but I do like really saturated high gain sounds with a lot of compression.

HM-2 on bass is really good. If my memory serves, Kevin Shields used the HM-2 on bass on some My Bloody Valentine tracks.

ADC, MCU, DAC, done. Cheaper, too -- I think 50 cent ARMs can do that these days. Any pedal that isn't digital today is just nostalgia (like tube headphone amps and the like.) Digital is the clear better choice even for sound shaping.

Nostalgia sells, yet another 'that digital crap' pedal may not. And many, many guitar players are dead keen on recreating classic tones of the 60's and 70's with period-authentic designs.

Its not really that simple. Does the 50 cent ARM have accelerated floating point (though 32-bit fixed point is usually fine)? Does the analog design have a realizable digital model (not always possible/practical with non-linear systems)? Can a 50 cent ARM run the digital model at a high sample rate (needs to be 4-8x higher than normal audio rates to be able to filter out aliasing)?

A lot of times the "magic" is in the variance... the subtle things like drifting resistance values with temperature. Digital never does that right.

> ADC, MCU, DAC, done. Cheaper, too -- I think 50 cent ARMs can do that these days.

And yet smart engineers keep using Analog Devices SHARC DSP's for effects on audio interfaces.

So SOMETHING must not be quite as simple as your claim.

(The answer is that most of these guitar effects are VERY non-linear and simulating non-linear stuff digitally is very much NOT straightforward in real-time.)

not smart, but old school and embedded in big companies Devkit alone is >$1K and you wont be able to do anything with it without couple of $K in software and maybe even support contract. All that for ~$10 Arm Soc performance.

It's definitely a straightforward and cost-effective circuit to build. The real cost (and test) is in the DSP programming. There's a reason a Fractal Axe-FX or Kemper Profiler is so expensive, and it's not the bill of materials. Electro-Harmonix sells a lot of DSP based pedals like the POGs and the B9/C9/M9 series, but I'd bet it's a small fraction of the number of Big Muffs they move, which they don't seem to be in any hurry to digitize. It's a lot easier to capture the sound of a '70s Big Muff by just building a Big Muff circuit than by programming a simulation of one.

Lest you think I'm some kind of analog purist, I'm actually currently building a batch of pedals for sale that use an AVR MCU an its internal ADC to generate 3 different octaves of square wave output.

Hogwash. There are effects that analogue clearly destroys digital on. And the main one is distortion.

Digital is much more suited to time based effects. Analogue to harmonic distortion based effects.

You can keep your ADC/MCU/DAC distortion pedal. But if you are ever wondering why your guitar distortion sounds crap, this is it. But maybe you think it's fine. Anything sounds great with cotton-ears.

And tube amps only being for nostalgia? I wan't you to take your guitar, your digital distortion pedal and your digital amplifier and go to a rehearsal room with another guitarist who uses analogue distortion and a tube amp. Turn them both up loud. Jam together. Compare the tones. Compare the nature of how your amplifiers respond to your tone.

Sitting in your bedroom playing by yourself will never convince you of the short comings of your digital rig.

I'm more of a recording engineer than a guitarist (member of the AES for many years.)

Shitty digital pedals from 20 years ago sound shitty, I agree!

Well modelled digital effects, however, can these days give you anything an analog pedal can. Most of the time, just run a high accuracy Spice model of the pedal in real time! Modern DSP is so cheap and fast that this is possible and works fine.

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