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Fuzz, Input Impedance and why the auto setting "must" be fixed! The ultimate thread!

impedance auto fuzz bug fix tone feel

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#1 victorcastro1

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Posted 05 September 2017 - 09:43 AM

Very sorry for the long post, but I truly feel it's necessary... 

Some might already know me from The Gear Page and it's been pointed out that maybe I should post this here in order to have a bigger impact, I'd reach more people really invested in making Helix better. Recently a couple of threads about Fuzz and Input Impedance came up, it seems a good time to push this idea forward and greatly improve our experience while playing w/ Helix. 

I'm a big fuzz fan. When I started getting heavy into dial in my tones, I found this problem... I dialed my Plexi tone, sounded great, then I added a fuzz face model in front of it, again it sounded great, but when I turned it off, the tone of the amp alone was gone, it sounded muffled. After asking around and some research I found that the culprit was the input impedance, more specifically, the auto setting. 

Input impedance influences tone and feel, it has to do with the interaction of you guitar signal and the first thing it hits on your pedalboard. To make a pedal behave on a modeler like its "real" counterpart, units use analog circuits to mimic the different input impedances you'd find in a regular pedalboard or amp. For example, usually amps have an input impedance of 1M, but if you put a fuzz in front of it, they usually have an input impedance around 10k, and that's what the guitar will see. A lot of people get confused and say that "well, if you bypass the fuzz, the input impedance is the same", but that's not exactly right. We have basically true bypass and buffered bypass, true bypass acts like there's nothing really there, signal goes straight through; buffered bypass makes the signal go through a buffer, and a buffer itself is actually an amp, and in this case the input impedance will be whatever the input bypass of the buffer is. We will ignore the buffered one. A buffer serves the sole purpose of avoiding signal degradation caused by long running cables - and it doesn't come without its own short comings, anyone that has triad a fuzz face after a buffer knows it - but because inside a modeler it doesn't happen, we can think Helix as a kind of paradise where there's no place for Bob Bradshaw, LA Sound Design, Gig Rig, Pete Cornish and a bunch of other companies, whose sole purpose is to make sure your guitar still sounds like your guitar after going through a metric ton of cables and gear. We'll assume everything is true bypass, because, as we don't have to worry about signal loss through cables, that's the best option, no question about it.

Back to input impedance. Everything being true bypass, that means it's going straight through, so the input impedance the guitar sees is of whatever is the first block that's actually on! Going back to my example. In this ideal world, what should happen when I bypassed my fuzz? Signal would go straight through and would see the input impedance of the amp! Turn the Fuzz on and it sees the input impedance of the Fuzz Face! Nice!... Except it's not what happens in Helix. The auto setting doesn't search for the first active block, it goes for the first one, being on OR off. That's why it sounds different! When I turn the Fuzz off, Helix isn't changing the input impedance, so the guitar still sees the low input impedance of the Fuzz Face, making the amp sound just muddy, muffled. 

Tha auto setting as it works right now is doing pretty much nothing useful. Why? Because what it does is fixing the input impedance to whatever effect is first. If you have a compressor first, impedance will be fixed at 1M, as long as you don't change the signal path, specifically the very first effect, impedance won't change. But nobody changes the signal path while playing, so it's not really useful. Takes away the guess work to find the input impedance of the first effect, but by fixing it, makes everything that goes after have the same input impedance, making the models not nearly as accurate as they could be if the input impedance was set properly.

Fixes? Two main ones are usually proposed. After a few FW updates since release the input impedance went from a global preset to the input part of every preset, great! It also can be assigned to footswitches?! GREAT! But it only works for very simple cases. It would for just fuzz-amp. I'd assign the input impedance to the footswitch that turned the fuzz on and off and make it change the input impedance from 10k to 1M. Good! But it doesn't work that great when you put just another pedal in. Let's have Fuzz-Tubescreamer-Amp, all three input impedances are different; when playing the amp it would be 1M, turning the Fuzz on would make it 10k, but now if I turn the Tubescreamer the impedance should not change, but if we assign the input impedance change to its footswitch, it will do just that. But then snapshots came and had to be it, right! Not exactly. By itself it works, but it's extremely limiting and you take in consideration the combinations of pedals I could have using the stomp mode. I'd need 4 snapshots to deal with the fuzz-ts-amp case and set the impedance accordingly, that's not really practical - and the stomp mode is still crippled. 

Isn't there a definitive fix? You guessed, fix the auto setting of the input impedance. If after everything I said you don't believe me, here's what the competition has to say about this: 

From http://community.avi...out-true-z.aspx (and a great read if you want to understand what input impedance actually does. Spoiler, it's not about bypass)

"Typical guitar modeling processors have a fixed input impedance, which can limit the accuracy of the modeling. Eleven Rack's True-Z circuitry is designed to solve this problem by automatically changing the input impedance to closely match the impedance of the first active effect in the Eleven Rack signal chain."

From http://www.fractalau...ners-Manual.pdf

"The Axe-Fx II recreates this effect by switching various (real) resistors and a capacitor in and out of the signal path. In Auto mode, the impedance is automatically set based on the first active effect the input "sees." Normally you will want to leave this on AUTO..."

 

 

Here's the link to the ideascale where I proposed the auto setting fix:
https://line6.ideasc.../idea-v2/862873

Vote up! 


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#2 HonestOpinion

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Posted 05 September 2017 - 11:16 AM

I agree with you and this is not the first time this issue has been brought up. I remember being involved in a topic discussing this about a year ago and am glad to see the subject being approached again. Thanks for posting up the Idea, voted!


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#3 Joepeggio

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Posted 06 September 2017 - 03:23 AM

Thumbs up to the OP. After reading about the Fuzz Face, I can see how impractle it is to have on a board used for a variety of tones.

It would be nice to have an "authentic" or "true bypass" option for each effect. Have it as the last parameter.
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#4 Thurston9

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Posted 06 September 2017 - 05:52 AM

Nice write-up, was going to skip it due to length but glad I didn't.

 

 

Voted!


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#5 victorcastro1

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Posted 06 September 2017 - 06:40 AM

I agree with you and this is not the first time this issue has been brought up. I remember being involved in a topic discussing this about a year ago and am glad to see the subject being approached again. Thanks for posting up the Idea, voted!

I'd not be surprised if I was the one who made this thread back then lol Thanks! 

 

Thumbs up to the OP. After reading about the Fuzz Face, I can see how impractle it is to have on a board used for a variety of tones.

It would be nice to have an "authentic" or "true bypass" option for each effect. Have it as the last parameter.

 

Technically it's not really about bypass, but I get what you're saying. IMO this is not the best solution, but I think the idea is get greater flexibility, and if that's what you want, there's a better way. The auto setting should work as I propose, but instead of adding the a "true or non true bypass" parameter, the new parameter should be the input impedance itself. It would not be global, not per preset, but should be set for each effect block. I've thought a lot about this and I really think it would be ultimate way to handle this is maximum flexibility is the goal. 

 

Nice write-up, was going to skip it due to length but glad I didn't.

 

 

Voted!

 

Thanks! :) 


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#6 phil_m

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Posted 06 September 2017 - 06:44 AM

Thumbs up to the OP. After reading about the Fuzz Face, I can see how impractle it is to have on a board used for a variety of tones.

It would be nice to have an "authentic" or "true bypass" option for each effect. Have it as the last parameter.

 

I actually think it be better to just change it across the board and make work differently. Adding that sort of parameter to every effect block would just confuse too many people, imo. I also think that adding a global setting for every little thing starts to get confusing as well. I'd rather just see the current behavior of the "auto" setting be changed and be done with it.


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#7 Thurston9

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Posted 06 September 2017 - 06:52 AM

I actually think it be better to just change it across the board and make work differently. Adding that sort of parameter to every effect block would just confuse too many people, imo. I also think that adding a global setting for every little thing starts to get confusing as well. I'd rather just see the current behavior of the "auto" setting be changed and be done with it.

I totally agree with this.  The desire for a true vs buffered bypass option should be addressed completely separately, and would not be very useful in my opinion.  


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#8 JN99

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Posted 06 September 2017 - 08:21 AM

Can't up vote the idea because I can't get registered at ideascale  :angry:   Oh well, will try again later.  Interesting read and although I don't use fuzz I wonder where else this might be affecting tone and find it curious that this (auto setting based on the first active block) is done on both 11r and Axe FX but not on the Helix.  That would seem to indicate this is a somewhat glaring oversight, no?


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#9 phil_m

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Posted 06 September 2017 - 08:38 AM

Can't up vote the idea because I can't get registered at ideascale  :angry:   Oh well, will try again later.  Interesting read and although I don't use fuzz I wonder where else this might be affecting tone and find it curious that this (auto setting based on the first active block) is done on both 11r and Axe FX but not on the Helix.  That would seem to indicate this is a somewhat glaring oversight, no?

 

Well the way it's done on the Helix is the same way it's done on the POD HD series... And, actually, Line 6 offered it there before Fractal offered it on the Axe FX (the Axe FX Standard and Ultra didn't have variable input Z, and the Axe FX II was released a year after the HD series). It just comes down to different design decisions from different companies.


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#10 victorcastro1

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Posted 06 September 2017 - 12:21 PM

Well the way it's done on the Helix is the same way it's done on the POD HD series... And, actually, Line 6 offered it there before Fractal offered it on the Axe FX (the Axe FX Standard and Ultra didn't have variable input Z, and the Axe FX II was released a year after the HD series). It just comes down to different design decisions from different companies.

 

The fact is the same tells me nothing. Eleven Rack offered it before both Line 6 and Fractal, so? Different decisions, yes, but it doesn't mean one can't be better than the other. 

You see, I'm not mocking Helix or Line6, there's no need to be this defensive. I could get anything else, still keeping Helix. I like it better as a product - but it doesn't mean I have to think it's perfect. I have my criticisms, but I make a distinction in my head, like: there's things I'd like it better if they were different, like the list of amp and pedals modeled; there's things I "know" they would be better if they were different, and the input impedance is one of those I just know, and every reason I have is explained in the OP. 


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#11 phil_m

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Posted 06 September 2017 - 12:30 PM

The fact is the same tells me nothing. Eleven Rack offered it before both Line 6 and Fractal, so? Different decisions, yes, but it doesn't mean one can't be better than the other. 

You see, I'm not mocking Helix or Line6, there's no need to be this defensive. I could get anything else, still keeping Helix. I like it better as a product - but it doesn't mean I have to think it's perfect. I have my criticisms, but I make a distinction in my head, like: there's things I'd like it better if they were different, like the list of amp and pedals modeled; there's things I "know" they would be better if they were different, and the input impedance is one of those I just know, and every reason I have is explained in the OP. 

 

I wasn't replying to you... I was replying to the poster I quoted, mainly to the "glaring oversight" comment. And because I work in the design field myself, I suppose I do want to give people the benefit of a doubt before calling a design decision something as extreme as a "glaring oversight". The fact is we don't know all the facts that influence every decision.

 

FWIW, I voted your idea up... I'm not against it in any way. Just trying to keep the level of discourse elevated...  :)


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#12 Rocco_Crocco

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Posted 06 September 2017 - 02:04 PM

Voted up! Well written argument, OP. 


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#13 victorcastro1

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Posted 06 September 2017 - 03:29 PM

I wasn't replying to you... I was replying to the poster I quoted, mainly to the "glaring oversight" comment. And because I work in the design field myself, I suppose I do want to give people the benefit of a doubt before calling a design decision something as extreme as a "glaring oversight". The fact is we don't know all the facts that influence every decision.

 

FWIW, I voted your idea up... I'm not against it in any way. Just trying to keep the level of discourse elevated...  :)

 

I still think you're being a bit defensive by saying that this was a design decision, like it's just a "difference of opinion", and I can't look at it like this.  I think nobody here is crucifying anyone, I'm not saying anyone is a bad designer or product is s#it because of it.

 

I'd very much would like to know how this decision came to be. I've tried again and again to find a post from Sean Healey when he still was with Line6 where he answered a post I made on Facebook a while ago saying that he thought Helix tracked the input impedance and that he was puzzled by what I was saying. Every thing I know and every piece of inside information I could get points to a mistake. But mistakes do happen, it's ok. Just fix it :)

 

Voted up! Well written argument, OP. 

Thanks! :) 

Posted video and audio on TGP showing the fuzz into amp situation, here it is to further illustrate the problem: 
 

 
Better quality recording using the very same presets I used in the video:
 

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#14 FlyingsCool

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Posted 06 September 2017 - 05:37 PM

Can't up vote the idea because I can't get registered at ideascale  :angry:   Oh well, will try again later.  Interesting read and although I don't use fuzz I wonder where else this might be affecting tone and find it curious that this (auto setting based on the first active block) is done on both 11r and Axe FX but not on the Helix.  That would seem to indicate this is a somewhat glaring oversight, no?

 

1. It depends on how you look at it.  If this were a real pedal board, most if not all pedals that have an input impedance less than 1M would affect the chain whether they were on or off.  So, design decision... "Should the product act like real life, or should we (them) idealize the situation since we can?"  Not to mention the fact that us peons don't really know ALL the ramifications of adding such a feature on the current Helix architecture.

 

As a little test, I assigned the input z to an expression pedal, and I'm getting interesting results.  Lots of glitches as I move it, though I imagine that goes away if I were to use snapshots instead. 

 

But in my own testing of changing it, I definitely am getting interesting tone changes.  For instance, I have a patch with an Arbitrator and a kwb and a valve driver into the archetype clean.  Arby likes lower z values, KWB and Valvy like the higher values through 1M the best, and the amp without any effect in front sounds really nice to me with values from 90 to 230, and now sounds too bright with 1M as I play around with it.  Lower values softens the pick attack and makes it feel warmer and bloomier on pick attack.  My guitar is a Les Paul copy with hottish unpotted humbuckers btw.

 

Having done this test, I think I agree I'd like to have an input z parameter on every effect, last in the list.  Just because it's there doesn't mean you have to care about it.  But I can't use it if it's not there.  That combined with having z input be set by the first active pedal would be just what the doctor ordered.  They could all be auto by default, or I can set each item how I want.  Yeah, it could be kind of a pain to have to go through and set them if you care.  But I think it could be worth it.  Would be even betterer if we could set a default configuration for each block, so we can set once, save that config and keep using it.


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#15 HonestOpinion

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Posted 06 September 2017 - 07:55 PM

I actually think it be better to just change it across the board and make work differently. Adding that sort of parameter to every effect block would just confuse too many people, imo. I also think that adding a global setting for every little thing starts to get confusing as well. I'd rather just see the current behavior of the "auto" setting be changed and be done with it.

 

Strongly agree with this!


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#16 victorcastro1

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Posted 07 September 2017 - 02:38 AM

So, design decision... "Should the product act like real life, or should we (them) idealize the situation since we can?"  

If you read the whole message, you'll get that that's exactly what I'm asking. Every circuit will have an input impedance, bypass has nothing to do with it. To ask an amp to have the input impedance of a Tube Screamer is as unreal as a winged unicorn. You still seem confused abou this , but the auto setting to search for the first active block is the closest option to real life. 

What you then ask, to make the auto setting to search for the first active block and add the option to change the input impedance of each effect, this would be interesting I think. But for now I'd be very much happy if just the auto setting behavior just got corrected. 


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#17 snipedoguk

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Posted 07 September 2017 - 02:59 AM

Very interesting topic, has anyone actually measured whether the input impedance of the Helix changes under these circumstances ? This will obviously have a very significant effect on tone if you're using high impedance hum buckers, and should have very little impact if you're using active pickups. Im not sure if we are talking about an "actual" change in the input impedance of the Helix, or a modelled change in the software, in which case it will be a change in the frequency response and dynamics of the signal, regardless of what kind of pickups you are using?


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#18 victorcastro1

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Posted 07 September 2017 - 08:15 AM

Very interesting topic, has anyone actually measured whether the input impedance of the Helix changes under these circumstances ? This will obviously have a very significant effect on tone if you're using high impedance hum buckers, and should have very little impact if you're using active pickups. Im not sure if we are talking about an "actual" change in the input impedance of the Helix, or a modelled change in the software, in which case it will be a change in the frequency response and dynamics of the signal, regardless of what kind of pickups you are using?

 

As I understand there's actually an analog circuit that's digitally controlled, the input impedance isn't modeled.  


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#19 zooey

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Posted 07 September 2017 - 10:02 AM

If you read the whole message, you'll get that that's exactly what I'm asking. Every circuit will have an input impedance, bypass has nothing to do with it. To ask an amp to have the input impedance of a Tube Screamer is as unreal as a winged unicorn. You still seem confused abou this , but the auto setting to search for the first active block is the closest option to real life.

What you then ask, to make the auto setting to search for the first active block and add the option to change the input impedance of each effect, this would be interesting I think. But for now I'd be very much happy if just the auto setting behavior just got corrected.

That assumes every effect is true bypass, even ancient ones that predate the concept.

However, I still think a global option to find the first active block and use its real-world impedence or ignore activeness (current behavior I think) would be best.

Options on each effect to set their impedence and/or make them true bypass or not would be too much.
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#20 CraigGT

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Posted 07 September 2017 - 10:32 AM

That assumes every effect is true bypass, even ancient ones that predate the concept.

However, I still think a global option to find the first active block and use its real-world impedence or ignore activeness (current behavior I think) would be best.

Options on each effect to set their impedence and/or make them true bypass or not would be too much.

 

I've got to agree, I don't see anything wrong with making all effects simulate true bypass, after-all who ever bought a pedal cos of the way it sounds when it was off?

 

I believe that the impedance circuit is a bunch of resistors switched in and out to suit so giving every pedal it's own impedance would require hardware mods so won't happen. So I agree that reflecting the impedance of the first active block would seem to be the best solution.

 

Craig


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#21 Joepeggio

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Posted 07 September 2017 - 11:47 AM

I generally agree with having the first active block set the impedance, and in 90% of users, that would be best.

But, as FlyingsCool stated, some (and it seems Line 6), may want the impedance to act like in the real world. If you put a classic Fuzz Face on your board, your guitar would see the input buffer, even when the pedal is off.

With that, there should be an option. Default it to the way some posters want (first active in the chain), or choose in each block to act "authentic". It could be a buffer setting, "When Active" or "Authentic"

With a unit with such versatility, it would be bad to not have a simple choice.
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#22 victorcastro1

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Posted 08 September 2017 - 04:56 AM

You guys are still too caught up with the concept of true bypass vs non true bypass and it's not about that. Every piece of gear has an input impedance that makes it interact with the signal from the guitar, passive pickups are a lot more susceptible to this. Input impedance of a circuit is measured when the signal goes through the actual circuit, it has nothing to do with a piece of gear that's turned off.


 


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#23 CraigGT

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Posted 08 September 2017 - 05:31 AM

You guys are still too caught up with the concept of true bypass vs non true bypass and it's not about that. Every piece of gear has an input impedance that makes it interact with the signal from the guitar, passive pickups are a lot more susceptible to this. Input impedance of a circuit is measured when the signal goes through the actual circuit, it has nothing to do with a piece of gear that's turned off.
 

 

Exactly, that's the whole point of wanting to reflect the impedance of the next device in the chain (as long as it's active)

 

Craig


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#24 victorcastro1

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Posted 08 September 2017 - 05:35 AM

Exactly, that's the whole point of wanting to reflect the impedance of the next device in the chain (as long as it's active)

 

Craig

Please explain a single case where this would be beneficial in anyway, and I think it would even makes things even more confusing. Yes, it would solve my problem, great, but it would be a a bad way to do it IMO. Want flexibility? Add the actual input impedance as a parameter and make the auto setting as I suggested, now you'll have maximum flexibility, because each effect could have whatever input impedance you want. 


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#25 CraigGT

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Posted 08 September 2017 - 07:01 AM

Please explain a single case where this would be beneficial in anyway, and I think it would even makes things even more confusing. Yes, it would solve my problem, great, but it would be a a bad way to do it IMO. Want flexibility? Add the actual input impedance as a parameter and make the auto setting as I suggested, now you'll have maximum flexibility, because each effect could have whatever input impedance you want. 

 

Well your fuzzface - amp example for one  :)


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#26 victorcastro1

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Posted 08 September 2017 - 07:13 AM

Well your fuzzface - amp example for one  :)

As I said, yes, it would solve my problem, but it would only make everything more confusing by adding another parameter while adding no extra functionality. Fix the auto setting and add the input impedance as a new parameter, that would indeed create more options for tweaking. 


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#27 Joepeggio

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Posted 09 September 2017 - 03:38 PM

As I said, yes, it would solve my problem, but it would only make everything more confusing by adding another parameter while adding no extra functionality. Fix the auto setting and add the input impedance as a new parameter, that would indeed create more options for tweaking.


This would solve the problem for half of us, but create a problem for the other half (those who like the authentic experience, how the Helix currently acts)

Therefore, it needs to be a choice. Make Helix better not just different.
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#28 zooey

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Posted 09 September 2017 - 06:26 PM

This would solve the problem for half of us, but create a problem for the other half (those who like the authentic experience, how the Helix currently acts)

Therefore, it needs to be a choice. Make Helix better not just different.

Don't agree with the bolded part. Helix doesn't have the concept of a true bypass pedal, or one that loads the guitar differently when it's on vs off.

 

Option 1: Two additional parameters for each block:

- Input impedance when off

- Input impedance when on

 

Setting them both the same would be like Helix is today, loads the guitar the same on or off. Setting the Off value to 1M and On to a lower one would be like true bypass.

 

Option 2: All blocks have their real-world impedances built in, and we'd get only a setting for whether it should act like true bypass or not, i.e., not load the guitar when it's off, or load it always.

 

Option 3: A single global setting to turn true bypass behavior on or off for all pedals at once.

 

Option 4: Don't add any new parameters, but use true bypass behavior (no loading when off) for pedals that do that in the real world.

 

 

None of this is "authentic" though, because Helix can only change the initial input impedance the guitar sees. In reality all devices have both input and output impedance, which interact in some fashion all the way down the chain. That would need to be implemented in software, no way it's worth the effort IMO.

 

I vote for option 3, a single global "true bypass" setting.


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#29 victorcastro1

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Posted 10 September 2017 - 04:18 AM

This would solve the problem for half of us, but create a problem for the other half (those who like the authentic experience, how the Helix currently acts)

Therefore, it needs to be a choice. Make Helix better not just different.

Except there's nothing authentic about it, I'm sorry, can we get past this? But fine, you like the way it is, that's ok, all you'll have to do is to fix the impedance value to whatever you like. It will be "exactly" the same, and won't mess things up for the rest of us :)
 

 

Don't agree with the bolded part. Helix doesn't have the concept of a true bypass pedal, or one that loads the guitar differently when it's on vs off.

 

Option 1: Two additional parameters for each block:

- Input impedance when off

- Input impedance when on

 

Setting them both the same would be like Helix is today, loads the guitar the same on or off. Setting the Off value to 1M and On to a lower one would be like true bypass.

 

Option 2: All blocks have their real-world impedances built in, and we'd get only a setting for whether it should act like true bypass or not, i.e., not load the guitar when it's off, or load it always.

 

Option 3: A single global setting to turn true bypass behavior on or off for all pedals at once.

 

Option 4: Don't add any new parameters, but use true bypass behavior (no loading when off) for pedals that do that in the real world.

 

 

None of this is "authentic" though, because Helix can only change the initial input impedance the guitar sees. In reality all devices have both input and output impedance, which interact in some fashion all the way down the chain. That would need to be implemented in software, no way it's worth the effort IMO.

 

I vote for option 3, a single global "true bypass" setting.

Why make it so confusing? o.O Why people make a big deal about bypass when it's not about bypass? 

Every piece of gear has its own input impedance that interacts with you guitar signal. Read the AVID article. Let's consider the video example, when I turn off the Fuzz Face, it's not that the Fuzz Face isn't in true bypass mode or whatever, it's the case the the AMP has the input impedance that supposed to be for the Fuzz Face. Every block was modeled with it's respective input impedance in mind, that's the only way for it to work like it's real counterpart. Do you understand that this is not about bypass? The analogy works to an extent, but suddenly people are asking for TBP option in each block and that only makes everything even more confusing. Now all of a sudden what you set in block A will make block B affect the rest of the signal path. Do you get that? 

The simplest way is to "fix the auto setting". Like the way it is right now? Fix to whatever value you feel sounds best, it will work the very same exact way. 


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#30 Joepeggio

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Posted 10 September 2017 - 05:32 AM

I will retract my statement on line 6's accuracy in current handling of impedance.

Side note, after further reading, the original fuzz face IS true bypass (for lack of better term). In so, line 6 does need to fix this issue. I think support tickets may be in order.
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#31 zooey

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Posted 10 September 2017 - 06:49 AM

Victor, apologies if I'm being stupid, but how is this NOT about true bypass?

 

A real-world pedal's circuitry has a given input impedance. It clearly affects the response of the guitar when the effect is on, but if it's true bypass and turned off, its circuitry isn't connected to the guitar at all, so its impedance is totally irrelevant.

 

I completely agree that the current behavior is wrong, and as I said, I don't think the fancier options I detailed are worth Line 6 building, or us users having to deal with them, but the fact remains that those do seem to me like the available choices.


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#32 uburoibob

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Posted 10 September 2017 - 08:15 AM

Strymon pedals, and others, give you the choice of using true-bypass or buffered operation. If we are to try and actually simulate the real world in the Helix, then the idea of giving the option of true-bypass vs buffered on pedals is reflective of many pedals in the real world. 


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#33 victorcastro1

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Posted 10 September 2017 - 12:56 PM

Victor, apologies if I'm being stupid, but how is this NOT about true bypass?

 

A real-world pedal's circuitry has a given input impedance. It clearly affects the response of the guitar when the effect is on, but if it's true bypass and turned off, its circuitry isn't connected to the guitar at all, so its impedance is totally irrelevant.

 

I completely agree that the current behavior is wrong, and as I said, I don't think the fancier options I detailed are worth Line 6 building, or us users having to deal with them, but the fact remains that those do seem to me like the available choices.

Input impedance is one thing, bypass is another. When turned off, even on a buffered bypass, the input impedance is not (or at least not necessarily) the same as the pedal when on. The buffer and the actual effects are two different things that get switched. 

 

Strymon pedals, and others, give you the choice of using true-bypass or buffered operation. If we are to try and actually simulate the real world in the Helix, then the idea of giving the option of true-bypass vs buffered on pedals is reflective of many pedals in the real world. 

Again, input impedance is not the same as a buffer. A buffer is an amp. The important part is the low impedance signal that comes out of it, making it less prone to be affected down the line by cabe length for example. Even if it was the case Helix was simulating a buffer, which it isn't, buffers exist to avoid signal degradation, but they do not come without their own short comings. Why anyone in their right mind would simulate buffers to such a degree that they would replicate the same issues buffers create in the real world while trying to solve a problem that simply does not exist inside a modeler? It's not about bypass. 


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#34 zooey

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Posted 10 September 2017 - 01:17 PM

Back in the day, "true bypass" just meant using a double pole double throw switch to directly connect the input to the output, and at the same time disconnect the guitar from the circuit input, so it didn't get loaded down when you weren't using the pedal. Not rocket science, just doing the extra work so the pedal's guts are completely out of the picture, like it wasn't there at all.

 

That's the fundamental question here: Does a pedal that's off still load the guitar, or does it pass the loading question on to the next block in the chain.

 

"Buffered bypass" may be a thing in the real world, to actively prevent downstream pedals from loading the guitar, even when this one pedal is off, but nobody's proposing modeling that behavior.


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#35 victorcastro1

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Posted 11 September 2017 - 04:51 AM

That's the fundamental question here: Does a pedal that's off still load the guitar, or does it pass the loading question on to the next block in the chain.

It doesn't. As far as I understand, two things can happen when you bypass an effect: the signal is hardwired through, so it's like a cable: or it goes through a buffer to avoid signal loss. There's the input impedance of the actual effect (which is what we get in Helix) and the buffer, which effectively is just another circuit that's processing the signal from the input. The input impedance on Heliix related to the actual effect, the bypass is part is not related. If you read the Strymon manual you'll see they specify the input impedance of the "buffer" when the pedal is bypassed, it has no direct relation with the input impedance of the actual effect. (Technically I guess you could make a true bypass after the buffer, making it so the part of the circuit that is actually responsible for the effect is fed by the signal coming from the buffer, making it so that the input impedance is the same when the effect is turned on or off, but when the pedal is off the buffer is useless in a scenario where signal loss is a nonissue.)


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#36 cclement

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Posted 11 September 2017 - 11:07 AM

No dog in this fight.. but a good read.. The Case Against "True-Bypass"

 

http://www.petecorni...rue_bypass.html


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#37 victorcastro1

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Posted 11 September 2017 - 01:59 PM

No dog in this fight.. but a good read.. The Case Against "True-Bypass"

 

http://www.petecorni...rue_bypass.html

From the very first post: 

"A buffer serves the sole purpose of avoiding signal degradation caused by long running cables(...) inside a modeler it doesn't happen, we can think Helix as a kind of paradise where there's no place for Bob Bradshaw, LA Sound Design, Gig Rig, Pete Cornish and a bunch of other companies, whose sole purpose is to make sure your guitar still sounds like your guitar after going through a metric ton of cables and gear."

 

 

 

 

 

And... It's not about bypass. 


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#38 tommasoferrarese

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Posted 12 September 2017 - 02:15 AM

That's an interesting read, but quite off topic here: we don't have cables degrading our signals in Helix, and some fuzz pedals don't work correctly if preceded by a buffer or by an high impedance device. So a 'true bypass like' implementation is the only way to have the realistic input load on fuzz emulations without the dull sound of a low impedance setting when the fuzz is bypassed.
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#39 zooey

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Posted 12 September 2017 - 03:03 AM

^^^ This.
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#40 mileskb

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Posted 12 September 2017 - 03:19 AM

I have been holding off on saying anything.... as I don't think referencing "impedance" is the issue.  

However... especially in a digital world, the video is very clearly unexpected behavior.   This could be a real issue with complex snapshots and likely is.

 

Bottom line... I agree...  If you have a preset setup... with an amp, and another preset setup with an effect and an amp...  if the effect is bypassed, both presets should sound the same.   That's simple logic.

An option for Bypass (True or Buffered) on the appropriate pedals might be a good solution, as well as many others suggested.  I find the Line 6 folks are pretty smart, so at this point I assume they see the problem  (if they see it as a problem) and will address it in some clever way none of us thought of.


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