Do we need a better portable aftermarket IR solution?

[NoodleFingers]

I'm a big fan of the ToneDexter, and I've always imagined that if it got enough traction, Audio Sprockets would likely come out with much smaller versions that could use existing IR response curves (which they call "WaveMaps) but not train them.

I don't think a narrow-format pedal or a barndoor on a guitar is big enough to do training of WaveMaps, but if those maps were saved on an SD card (for example), I suspect the deconvolution hardware would fit nicely in those smaller formats.

Such an approach would require you to have a full-featured ToneDexter for training (or be able to borrow one). But I imagine there are plenty of people who would be happy to do that. For most people, I don't think the size of ToneDexter is a problem, but it won't fit in most guitar cases.

James May, one of the inventors of ToneDexter, tend to pop into TD threads. So, James, have you had any thoughts along these lines?

[martingitdave]

Originally Posted by NoodleFingers

I'm a big fan of the ToneDexter, and I've always imagined that if it got enough traction, Audio Sprockets would likely come out with much smaller versions that could use existing IR response curves (which they call "WaveMaps) but not train them.

I don't think a narrow-format pedal or a barndoor on a guitar is big enough to do training of WaveMaps, but if those maps were saved on an SD card (for example), I suspect the deconvolution hardware would fit nicely in those smaller formats.

Such an approach would require you to have a full-featured ToneDexter for training (or be able to borrow one). But I imagine there are plenty of people who would be happy to do that. For most people, I don't think the size of ToneDexter is a problem, but it won't fit in most guitar cases.

James May, one of the inventors of ToneDexter, tend to pop into TD threads. So, James, have you had any thoughts along these lines?

You’re thinking exactly like me! I was hoping James would read this. I’d be happy to buy the TD if I could move the wave map to a smaller on-guitar preamp system like the new Fishman.

[NoodleFingers]

If they sold an onboard preamp, I would think it should include a pickup to be a complete system. If only there was a pickup they could use.....

Maybe they should take a look at the James May Engineering Ultra Tonic pickup. I've heard it plays nicely with ToneDexter.

[AndyC]

Originally Posted by troggg

Didn't say that was its sole purpose. I said that was one of the reasons. I don't have an IR based system and I feel my guitar is reproduced faithfully with plenty of nuance. If you'd like to argue that introducing IR does not complicate reproducing amplified acoustic guitars, go right ahead.

And I don't want to put words in your mouth, but it seems as if you are suggesting that using IR is always superior to not using it. That would be a personal opinion as opposed to a universally accepted fact.

Well, you may not have wanted to put words into my mouth, but that is exactly what you have done. I have made no comment regarding the ease or complication of the use of IR in reproducing amplified sound, neither have I stated that an IR system is intrinsically superior to any other.

Notwithstanding the above, this is a forum and as such is full of individuals expressing their opinions - usually in a friendly and non confrontational manner.

[AeroUSA]

As a Tone Dexter user what I will say is that sometimes I have to alter the Wavemap, notch, phase, treble and blend (mainly the later two).

For that reason it makes sense to have the pedal. I’d like to see the technology licensed to someone like TC Helicon so I could have a Play acoustic pedal that does it all. I find their body rez technology useless.

[jonfields45]

What a challenge! Nobody is going to read this. Hopefully in simplifying my crimes against math are forgivable. And any misunderstandings I’ve developed during, or subsequent to, the class I took on this 42 years ago will be attributable to simplification.

I think it might be easy to imagine sampling a signal and feeding back some of the delayed signal into the live signal. This could be called a delay pedal. If you program the delay pedal to feedback the delayed signal into the delay line, you've got the possibility for something that could make a signal last forever. The first of these two possibilities, no feedback of the delay output into the delay input, is an example of a Finite Impulse Response (FIR) filter (a very simple one with a single non-zero tap). The other is an example of an Infinite Impulse Response (IIR) Filter. For this discussion we are only interested in the finite (FIR) version.

All these samples going into delay lines are examples of things you can do in what is called the Time Domain. But, you are very familiar with the tone controls on your gear and they are examples of things where the controls we use to manipulate them are labeled in the Frequency Domain (bass, treble, etc.). It turns out that a French mathematician, Fourier, figured out an interesting transform which can be used to move mathematical formulas (representations of something you are interested in) between these two domains (his actual goal, like how a slide rule uses logarithms to turn multiplication into addition, was to simplify all sorts of hard stuff)

So what's all this concern about "impulses" (seems I've had them at least since puberty...). In this case an impulse is a signal infinitely high in magnitude and infinitely short in duration. Of course, something like this is impossible in the real world, but close enough is usually good enough. The Fourier transform of an impulse in the time domain becomes "1" in the frequency domain (very cool and simplifying). If you put something like an impulse into your amp and sample the speaker output, what comes out is the impulse response. Transform that IR to the frequency domain and you’ve got something like the tone control settings (imagine you are multiplying by the tone control settings) to duplicate that amp’s frequency response (more meaningful to electric guitarists where the amp is really an integrated part of the instrument). It turns out that multiplication in the frequency domain becomes something called convolution in the time domain which is something you can do easily with a FIR filter (a FIR filter is really a convolution machine). But how to program that filter? It can be easily mathematically derived from that impulse response and it is almost as simple as the impulse response is (are?) the coefficients (oops bad word?) of that FIR filter. Thus IR (convolution coefficients) and FIR coefficients have become interchangeable ways to refer to the same thing in the music industry's lexicon.

So you sample your pickup and your mic and you have the two time domain responses to your playing. You grab the digital version of the Fourier transform (usually referred to as an FFT, or fast Fourier transform) and transform them to frequency domain, divide the mic by the pickup, reverse the transformation, and voila, you’ve got the parameters for your convolution (FIR/IR) pedal. For systems like that electric guitar amp modeler, that FIR filter would be programmed with the IR and hardware sold for that purpose can also be used to implement the slightly more complex problem of turning your acoustic guitar pickup output into something that sounds more like a mic. You can’t use an equalizer, or IR pedal, to create something that is not in the source signal at all, and that is one of the reasons (along with the fact you don’t have a different IR for every combination of notes on the guitar struck every possible way you could strike them -- this is some of the Tonedexter magic) you want to start with a relatively nice sounding pickup.

Since I’m the only one who's read this far, I can say I’m glad it's over....

[guitaniac]

Originally Posted by AndyC

The use of IR based systems goes beyond simply eliminating quack - there are many other (predominantly SBT systems) that eliminate quack very successfully. IR based systems move things to another level, and actually seek to faithfully deliver the nuances of a specific guitar at amplified volumes.

Good point. The original purpose of both the Aura and ToneDexter technologies was to make direct-from-pickup amplified (or recorded) sound more like the acoustic sound of the guitar. Its been shown that both technologies can be used for modeling (as in Aura IC for "image casting"), but the original intent and most common application is to get the direct-from-pickup amplified sound to be more like the guitar's acoustic sound.

Whether or not a good facsimile of the guitar's acoustic sound is ideal for high volume amplification is another debate.

[troggg]

Originally Posted by AndyC

Well, you may not have wanted to put words into my mouth, but that is exactly what you have done. I have made no comment regarding the ease or complication of the use of IR in reproducing amplified sound, neither have I stated that an IR system is intrinsically superior to any other.

Notwithstanding the above, this is a forum and as such is full of individuals expressing their opinions - usually in a friendly and non confrontational manner.

"IR based systems move things to another level" would be your quote. And I don't think you were referring to another level down. I'm not here for confrontation. Neither am I here to be told something someone else is using is definitely better than something I'm using. I'm glad IR works for you. I don't feel I need to explore IR. Let's leave it at that.

[martingitdave]

Originally Posted by jonfields45

What a challenge! Nobody is going to read this. Hopefully in simplifying my crimes against math are forgivable. And any misunderstandings I’ve developed during, or subsequent to, the class I took on this 42 years ago will be attributable to simplification.

I think it might be easy to imagine sampling a signal and feeding back some of the delayed signal into the live signal. This could be called a delay pedal. If you program the delay pedal to feedback the delayed signal into the delay line, you've got the possibility for something that could make a signal last forever. The first of these two possibilities, no feedback of the delay output into the delay input, is an example of a Finite Impulse Response (FIR) filter (a very simple one with a single non-zero tap). The other is an example of an Infinite Impulse Response (IIR) Filter. For this discussion we are only interested in the finite (FIR) version.

All these samples going into delay lines are example of things you can do in what is called the Time Domain. But, you are very familiar with the tone controls on your gear and they are examples of things where the controls we use to manipulate them are labeled in the Frequency Domain (bass, treble, etc.). It turns out that a French mathematician, Fourier, figured out an interesting transform which can be used to move mathematical formulas (representations of something you are interested in) between these two domains (his actual goal, like how a slide rule uses logarithms to turn multiplication into addition, was to simply all sorts of hard stuff)

So what's all this concern about "impulses" (seems I've had them at least since puberty...). In this case an impulse is a signal infinitely high in magnitude and infinitely short in duration. Of course, something like this is impossible in the real world, but close enough is usually good enough. The Fourier transform of an impulse in the time domain becomes "1" in the frequency domain (very cool and simplifying). If you put something like an impulse into your amp and sample the speaker output, what comes out is the impulse response. Transform that IR to the frequency domain and you’ve got something like the tone control settings (imagine your are multiplying by the tone control settings) to duplicate that amp’s frequency response (more meaningful to electric guitarists where the amp is really an integrated part of the instrument). It turns out that multiplication in the frequency domain becomes something called convolution in the time domain which is something you can do easily with a FIR filter (a FIR filter is really a convolution machine). But how to program that filter? It can be easily mathematically derived from that impulse response and it is almost as simple as the impulse response is (are?) the coefficients (oops bad word?) of that FIR filter. Thus IR (convolution coefficients) and FIR coefficients have become interchangeable ways to refer to the same thing in the music industry's lexicon.

So you sample you your pickup and your mic and you have the two time domain responses to your playing. You grab the digital version of the Fourier transform (usually referred to an FFT, or fast Fourier transform) and transform them to frequency domain, divide the mic by the pickup, reverse the transformation, and voila, you’ve got the parameters for your convolution (FIR /IR) pedal. For systems like that electric guitar amp modeler, that FIR filter would be programmed with the IR and hardware sold for that purpose can also be used to implement the slightly more complex problem of turning your acoustic guitar pickup output into something that sounds more like a mic. You can’t use an equalizer, or IR pedal, to create something that is not in the source signal at all, and that is one of the reasons (along with the fact you don’t have a different IR for every combination of notes on the guitar struck every possible way you could strike them -- this is some of the Tonedexter magic) you want to start with a relatively nice sounding pickup.

Since I’m the only one whose read this far, I can say I’m glad its over....

I read it Jon. And, I appreciated you taking the time to delve deeper into the details. Though, you had much more courage to describe FFT than I. Before Mathlab, that stuff gave me nightmares in college. LOL

[gfirob]

I’m a Tonedexter user and major fan. I know that the Tonedexter as it is now is a simplified and reduced version of the original (which sold for $900) in order to get the price point down to a range affordable by most musicians. I don’t think a miniaturized version is immediately down the road, but I could imagine something like that some day.

This device does much more than reduce quack and the ability to make custom wavemaps for different guitars is very useful. If you are performing in situations where you are bringing in hardware anyway (pedals, mixers etc) then the Tonedexter is just another box, cable and power supply to add. I don’t find it a problem. It is about the size of TC Helicon’s Play Acoustic, for instance, a very popular voice processor.

Here is an example intercutting two audio files of the same guitar with a K&K mini (a rosewood Martin OM), first with the unprocessed K&K signal, then with the Tonedexter wavemap made with an Ear Trumpet Edwina, back and forth three times. This is a riff on John Hurt’s “Creole Belle” played with metal fingerpicks. I think this shows how the difference is much more than reducing quack. Best to use headsets to listen to this.

[AndyC]

Originally Posted by troggg

"IR based systems move things to another level" would be your quote. And I don't think you were referring to another level down. I'm not here for confrontation. Neither am I here to be told something someone else is using is definitely better than something I'm using. I'm glad IR works for you. I don't feel I need to explore IR. Let's leave it at that.

I don't use IR now - moving things to another level might work for some, it might not work for others. I still don't appreciate being told by you that I am making sweeping pronunciations - I'm sharing my views, not adding to the 10 commandments. Let's leave it at that.

[ManyMartinMan]

Originally Posted by Methos1979

Huh... sounds convoluted.

Yep. Too much Yadda, yadda, not enough play. Even on a cloudy day outside the studio window, play is better than..... not.

[troggg]

Originally Posted by AndyC

I still don't appreciate being told by you that I am making sweeping pronunciations

Another possible reaction would be to ask yourself if maybe the words you chose could actually be interpreted as a sweeping pronouncement from on high -- but that would mean entertaining the possibility that you actually had something to do with creating the animosity.

Apologies to MartinDave; just because I'm not presently attracted to IR doesn't mean it's not a worthy discussion.

[martingitdave]

Hi guys:

The discussion is good. But, I fear we are beginning to detour off topic.

Cheers!

[AndyC]

Originally Posted by troggg

Another possible reaction would be to ask yourself if maybe the words you chose could actually be interpreted as a sweeping pronouncement from on high -- but that would mean entertaining the possibility that you actually had something to do with creating the animosity.
.

Clearly you have not been antagonistic in any way, shape or form in any of your retorts or responses throughout this thread, and equally clearly my opinions and experiences from actually using this technology and expressing my view of it are worthless. I hope that makes you feel better.