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Axe-Fx Firmware Release Version 17.01 Release Candidate

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Joce

Inspired
The general functionality of the guitar seeing the impedance of the first enabled block is implemented, you're right, and that's great, but that's not what I'm talking about.

The impedance of some of the drive models, Fuzz Face for instance, doesn't match the pedals they emulate. Try it. Choose Auto for importance, make the FF the first block, and enable and disable it, watching the impedance readiut in the input block. It stays at 1M, but the real one is something like 22k, really low.

Since Cliff is going through some or all drive blocks and checking their veracity at low drive levels, I was hoping that project could be expanded to also check if the modeled input impedances are right.

I'm making this up, but it seems like that must just be a value for each model, easy to change. It's not something that needs new modeling tech, just measuring the real pedals, and inputting those values in the right place in the models.

Make sense?
I hear ya that this might not be fully implemented for all the Drives (and potentially other relevant effects early in the chain....).

But I was making reference to this thread here where the question of impedance was discussed at length:

https://forum.fractalaudio.com/thre...lock-does-an-active-mixer-block-count.169836/
 

Dave Merrill

Fractal Fanatic
I hear ya that this might not be fully implemented for all the Drives (and potentially other relevant effects early in the chain....).

But I was making reference to this thread here where the question of impedance was discussed at length:

https://forum.fractalaudio.com/thre...lock-does-an-active-mixer-block-count.169836/
I'm aware. But regardless of the logic used in particular cases, better raw data about the impedance of each block type would be, for lack of a better word, better :)
 

yyz67

Power User
The impedance of some of the drive models, Fuzz Face for instance, doesn't match the pedals they emulate. Try it. Choose Auto for importance, make the FF the first block, and enable and disable it, watching the impedance readiut in the input block. It stays at 1M, but the real one is something like 22k, really low.
Yeah Bender Fuzz shows 22k but Fuzz Face shows 1M.

Probably a bug or fat-finger.
 

RDH

Fractal Fanatic
The general functionality of the guitar seeing the impedance of the first enabled block is implemented, you're right, and that's great, but that's not what I'm talking about.

The impedance of some of the drive models, Fuzz Face for instance, doesn't match the pedals they emulate. Try it. Choose Auto for importance, make the FF the first block, and enable and disable it, watching the impedance readiut in the input block. It stays at 1M, but the real one is something like 22k, really low.

Since Cliff is going through some or all drive blocks and checking their veracity at low drive levels, I was hoping that project could be expanded to also check if the modeled input impedances are right.

I'm making this up, but it seems like that must just be a value for each model, easy to change. It's not something that needs new modeling tech, just measuring the real pedals, and inputting those values in the right place in the models.

Make sense?
It’s the buffered input that messes with the fuzz models.
 

Dave Merrill

Fractal Fanatic
It’s the buffered input that messes with the fuzz models.
Don't think so. There's analog circuitry to do this, in the III at least, not sure about other models.

If what you're saying was true, none of the drive types would show lower impedance, which is demonstrably not the case, as testified to above.

Or I'm misunderstanding what you're saying.
 

RDH

Fractal Fanatic
Don't think so. There's analog circuitry to do this, in the III at least, not sure about other models.

If what you're saying was true, none of the drive types would show lower impedance, which is demonstrably not the case, as testified to above.

Or I'm misunderstanding what you're saying.
I’m not talking about impedance, some model could be incorrect, but it’s been discussed in length before that a fuzz won’t respond the same to a buffered input compared to the passive guitar pickups going directly into a fuzz. I don’t think this can be compensated for
 
I’m not talking about impedance, some model could be incorrect, but it’s been discussed in length before that a fuzz won’t respond the same to a buffered input compared to the passive guitar pickups going directly into a fuzz. I don’t think this can be compensated for

I find the facefuzz model reacts very well to volume control manipulation. I do set my pickups a bit farther from the strings than normal so that may help.
 

unix-guy

Legend!
I’m not talking about impedance, some model could be incorrect, but it’s been discussed in length before that a fuzz won’t respond the same to a buffered input compared to the passive guitar pickups going directly into a fuzz. I don’t think this can be compensated for
But you ARE talking about impedance.

The buffer makes the impedance seen by the pickups high.

The correct auto impedance setting will make the buffer be low(er) impedance.

This will in turn make things work similarly to a guitar directly into a real fuzz pedal.
 

yyz67

Power User
IIRC, the input impedance setting changes the freq response (and volume interaction) of the pickup but the fuzz models then do what they do digitally after ADC from that point. (Anyone confirm?)
 
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FiddlerTheDrum

Inspired
I think you're missing the point... That is what the auto impedance is intended to solve.

It will change the physical input impedance to load the pickups.
It doesn’t work like a fuzz face is supposed to though. I barely have to move my volume knob on a real fuzz face to get real cleanup. I’ve never had the model clean up right and I had to roll the volume way down to get much of an effect.
 

Dave Merrill

Fractal Fanatic
It doesn’t work like a fuzz face is supposed to though. I barely have to move my volume knob on a real fuzz face to get real cleanup. I’ve never had the model clean up right and I had to roll the volume way down to get much of an effect.
Yes. The impedance of the Axe model isn't right. Cliff has also said that the behavior of some of the drive blocks at low gain isn't correctly modeled, which he's working on improving.
 

unix-guy

Legend!
It doesn’t work like a fuzz face is supposed to though. I barely have to move my volume knob on a real fuzz face to get real cleanup. I’ve never had the model clean up right and I had to roll the volume way down to get much of an effect.
And note that above the comments say that the auto impedance for the Fuzz Face doesn't change down from 1M.

This most likely explains the issue.

Have you tried manually setting the impedance to a lower value?
 

FiddlerTheDrum

Inspired
And note that above the comments say that the auto impedance for the Fuzz Face doesn't change down from 1M.

This most likely explains the issue.

Have you tried manually setting the impedance to a lower value?
I've tried some different settings. I remember that some recommended 90k for fuzz faces. If I put the drive on 7 on the pedal and put my Strat volume at 2, I get some decent clean-up. If the drive is on 10 like a real fuzz face, 2 on the guitar still cleans up mostly but not all the way. It still isn't the many shades of clean up that come on quick like a real FF unit
 

Budda

Fractal Fanatic
I've tried some different settings. I remember that some recommended 90k for fuzz faces. If I put the drive on 7 on the pedal and put my Strat volume at 2, I get some decent clean-up. If the drive is on 10 like a real fuzz face, 2 on the guitar still cleans up mostly but not all the way. It still isn't the many shades of clean up that come on quick like a real FF unit

Rotate through all the options til you find the one with the behaviour you want?
 
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