Digital Simulation Pedals

[Fael]

This may be a really stupid or obvious question but I sincerely do not know the answer. With the current technology, is it possible to make a low cost digital simulation pedal?

I know that there already are some like Line 6 stuff. And high cost like MUSE Receptor and Axe-FX. But as far as I know, all those existing solutions are based around DSP, not actual schematic simulation.

Is it possible to build a pedal with better simulations (compared to DSP) like some VST plugins? Evidently, using VST's would not be an optimal choice. Using direct code (e.g. C++) would be faster and royalty free. However, VST simulations are quite CPU heavy. Do you guys think that a DSP or other kind of processor could handle real-time, 24 bit, 44KHz sampling rate quality simulation? If so, are there any low cost chips that you know of?

Another question that's been bugging me is: does that kind of solution require ADCs and DACs? This is the stupid question I was talking about. I mean, could you use a processor like you would use a 4558RC IC on a Tube Screamer (i.e., without any ADCs and DACs)?

So, to sum up:
1) is there a cheap (<$150) way to implement an accurate circuit simulation (non-DSP) on a pedal? I'm thinking about a schematically correct TubeScreamer simulation;
2) if it is possible, how many simultaneous pedals could a single chip run?
3) would ADCs and DACs be needed? (other than to change the simulation's parameters)

[potul]

wow..... there are some concepts you don't have clear around digital electronics...

First of all:

-Any digital device will need ADC/DAC and some ort of DSP. For sure.
-VST plugins are in the same family here. They use the signal (alrady in digital format) and use DSP algorithms. The signal needs to go through an ADC and DAC anyway (the one in the PC soundcard)

But, the question is a good question: Would we get better emulations by using real time circuit simulation instead of the currect techniques? I had the impression Axe-Fx was doing something in this direction, but I'm not sure.

If you wanna stick in the analog world, the closest you can get are the Tech21 pedals, like que GT2. All analog and try to emulate some different amps. But this is not what you had in mind.

Potul

[cloudscapes]

#1 is impossible to not be DSP. you would build a TS "schematic" in DSP code.

as for your #2 question, the best answer anyone can give you is 0 pedals, or 100 pedals, or 8 pedals, or 76, etc..

it depends on the complexity of your simulations, what you're trying to simulate, code efficiency, and the actual DSP chip which vary greatly in performance.

also is to what extent you're willing to "fake" bits and pieces of hardware as software. if you were to do actual electron simulation (is this what you're asking?) through virtual wires, resistors, caps and transistors, then I doubt any DSP in the world, or even desktop computer would have enough horsepower to run it in realtime. I don't think even university supercomputers are powerful enough!

this is why faking is important.

ADCs and DACs are what bridge DSP to the analog world. your guitar signal, being analog, has no way to influence or be influenced by a DSP without that sort of bridge. there will always be a DAC and an ADC between the DPS and your sounds.

[Fael]

Ok, so the ADC DAC stupid question is resolved, thank you.

Now, I think I wasn't clear enough. What I meant was making a simulation truer to its analog counterpart. Some DSP effects rely on simple waveshapers. What I'd like to do is, as cloudscapes said, "fake" bits and pieces of hardware as software as much as possible to stay closer to the real hardware.

Would you please recommend a chip, ADCs and DACs (or an evaluation board with this features) that might be suitable for this endeavor?

Thank you all for replying.

[Hides-His-Eyes]

You'd have to write the modelling software for each component yourself. there is no DSP chip which will allow you to design a digital effect using components.

LT spice will allow the effect of an electronics circuit on a wav file to be heard; this takes a desktop computer many seconds or even minutes to model a single second of audio.

What you want will not be possible in a chip for years or decades.

[Fael]

You'd have to write the modelling software for each component yourself. there is no DSP chip which will allow you to design a digital effect using components.

LT spice will allow the effect of an electronics circuit on a wav file to be heard; this takes a desktop computer many seconds or even minutes to model a single second of audio.

What you want will not be possible in a chip for years or decades.

Yes, that was exactly my intention, model everything in whatever language (e.g., C++).

And yes, it is possible. There are VSTs coded this way.

[Fael]

Hides-His-Eyes, I just reread your reply. I'm sorry I got confused. Thanks for clearing that out. I guess this settles it, I'll have to wait. Frak.

[potul]

You'd have to write the modelling software for each component yourself. there is no DSP chip which will allow you to design a digital effect using components.

LT spice will allow the effect of an electronics circuit on a wav file to be heard; this takes a desktop computer many seconds or even minutes to model a single second of audio.

What you want will not be possible in a chip for years or decades.

Yes, that was exactly my intention, model everything in whatever language (e.g., C++).

And yes, it is possible. There are VSTs coded this way.

Really? Could you point us to a VST using this approach. I would like to take a look at it. If this is the case, you could use one of the existing  hardware platforms that can use VST. They are not cheap though.

[potul]

I was thinking.... what about an FPAA? Could it be configured to act as a series of analog circuits for guitar usage? I guess most of the devices based on opamps and passive elements could be done using an FPAA. Although I have to say I have no experience with this... so I might be really wrong.

This would not be a digital simulation but really the analog circuit itself, but programmable.

Anyone knowledgeable?

Potul

[anchovie]

What you want will not be possible in a chip for years or decades.

This is a good thing. I don't think I'm ready to witness internet discussions on "mojo code" and how much better the original JRC4558 module written by p3d4lh4xx0r was.