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Circuit building: stop using antique parts (2014)

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Re: Circuit building: stop using antique parts (2014)

#111

Post by wyc »

I think the author describes my point of view and defuses many of his own points at the very bottom of the page:

    also, you are likely making one circuit, not planning
    on mass-producing 1,000,000,000 of whatever it is; who
    cares if you spend a buck where a dime might do? you
    want it to work first time every time, right? this is
    art not technology (eg. industrial capitalism); we
    have different design criteria here.
That's exactly right. I'm usually making one circuit, and not mass-producing them. My inefficiencies will likely be limited in scale to no more than cents per month on the electricity bill. If I were mass-producing, then of course I'll reach for the low-power switching FETs.

Re: Circuit building: stop using antique parts (2014)

#112

Post by mb_72 »

jwatte wrote: post #103
bsder wrote: post #31

Earlier quoted context omitted.

> 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 design…

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.

Re: Circuit building: stop using antique parts (2014)

#113

Post by jacquesm »

CamperBob2 wrote: post #102
jacquesm wrote: post #21

Earlier quoted context omitted.

RF grade relays will cost you an arm and a leg though.

To that point, another mistake a lot of amateurs make is that they buy expensive things on DigiKey without looking on eBay first.

Or at the local HAM swapfest.

Re: Circuit building: stop using antique parts (2014)

#117

Post by ssalazar »

jwatte wrote: post #103
bsder wrote: post #31

Earlier quoted context omitted.

> 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 design…

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.

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)?

Re: Circuit building: stop using antique parts (2014)

#119

Post by bsder »

jwatte wrote: post #103
bsder wrote: post #31

Earlier quoted context omitted.

> 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 design…

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.

> 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.)

Re: Circuit building: stop using antique parts (2014)

#120

Post by PeanutNore »

jwatte wrote: post #103
bsder wrote: post #31

Earlier quoted context omitted.

> 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 design…

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.

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.

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