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Disabled Distortion Pedals Muffle Amp Sound

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Hi all,

 

I tried searching for this but couldn't find anything, so was hoping for some help. I am running 2.91 and never noticed this before so think it might be a bug? There are several distortion pedals that if they are in the chain before an amp, they muffle the amp sound really bad when they are disabled. Deleting the distortion pedal brings the clear/chimey sound of an amp back. I also noticed if I changed the input impedance from auto to 1M, the effect was reduced a little but not enough. Is this an impedance issue? Or is it a bug? I've never noticed such a muffled sound from an amp before on Helix. I noticed it with quite a few pedals and quite a few amps. Has anyone else experienced this?

 

Thanks

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Update to v2.92.

The attached file lists the Input Impedances for all of the effects.

When using an effect whose Input Impedance is <1M, assign the same bypass pedal that you use for the effect to the Input Impedance parameter in the Input Block.

Set the MIN (effect OFF) to AUTO. Set the MAX (effect ON) to the correct Input impedance.

Be aware that this only matters if you are using a cable (not wireless), and only if there are no external effects between the guitar and Helix.

 

Helix 2.90 Amp Cabs Effects Impedance List.xlsx

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Thank you @rd2rk. This is very helpful. It dawned on me to search for input impedance and found all the information I could ever need on the topic. I see you've commented quite a bit on it.

 

I understand that if I leave the input impedance to Auto it will match the first effect on input/path 1A, whether it's enabled or disabled. I get that and I've played with input impedance before and understood that certain pedals, especially fuzzes, had lower impedances. This is why I set the input impedance to 1M as I described, to compare disabled and deleted states. I would have expected that to sound the same with the effect disabled as well as deleted. But they are very different. Unless there's another explanation, I still think this may be a bug in 2.91/2.92. I am wired straight into the helix with a cable and guitar only, btw.

 

Am I wrong assuming the 1M setting should make disabled-effect and deleted-effect sound the same?

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23 minutes ago, obscurehifi said:

Am I wrong assuming the 1M setting should make disabled-effect and deleted-effect sound the same?

 

I'm not sure what you mean. A deleted effect is, well, deleted. It has no effect whatsoever.

I think you mean active vs bypassed, ON vs OFF.

No, this is not a "bug". The problem you seem to be having (muffled sound) is not normal, and the difference made by mis-matched impedance settings is not radical. 

All that's happening with impedance is the way that the pickups are "loaded". If anything, lower impedance attenuates (slightly) the high frequencies.

The main advantage to accurate impedance matching is in the "authenticity" of the effects' tone.

If I switch between cable and wireless on a preset with a Tube Screamer properly impedance matched, with cable the pickups are loaded at 230k. The sound is slightly smoother than if I go wireless where the pickups are loaded at 1M. At 1M the sound is slightly "raspier" (to my ears). In neither case is the sound muffled, just different.

This is consistent even with the Deranged Master (Dallas Rangemaster), which has 10k impedance. At 1M the sound is just plain nasty. 

Again, muffled sound is not normal. I would look at updating to the latest version (2.92) and, if you've already done that, a full system reset.

Failing that, open a support ticket. 

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No, I literaly mean comparing these two scenarios, the second having the fuzz deleted.

 

Scenario 1)

Guitar-->Cable-->1M input Imp -->bypassed fuzz or distortion -->Amp

 

Scenario 2)

Guitar-->Cable-->1M input Imp --------------------------->Amp

 

Scenario 2 sounds bright and chimey. Scenario 1 sounds muffled even with 1M input impedance. Sorry to not have explained what I meant by deleted effect, but I literally meant deleting the effect for comparison's sake.

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Also, I updated to 2.92 right after I submitted my first post. Same thing happens.

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I have nonesuch problems, on either Floor or Stomp.

You should open a support ticket.

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2 minutes ago, rd2rk said:

I have nonesuch problems, on either Floor or Stomp.

You should open a support ticket.

Thanks for your help and comparison with your own equipment. I'll do that.

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Anybody know the specifics about the input buffer? It's not the fuzz that makes the tone muffled, it's having a buffer on somewhere in front of the fuzz. I know AFX3 has a buffer you can't turn off, fuzzes suffer for it. With input impedance set on auto, I'd think L6 would know that a fuzz ain't gonna fuzz with a buffer on, I bet 'auto' would switch it off. Keeping it set on 1M, I bet the default buffer state, if it's got switchable states, would just be 'stay on'. That still wouldn't explain why the block in bypass is still killing the high end, unless they modeled the pedals bypass characteristics too. Fuzzes don't like buffers, they like to be plugged in straight to a pickup. 

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2 minutes ago, bypassvalve said:

Anybody know the specifics about the input buffer? It's not the fuzz that makes the tone muffled, it's having a buffer on somewhere in front of the fuzz. I know AFX3 has a buffer you can't turn off, fuzzes suffer for it. With input impedance set on auto, I'd think L6 would know that a fuzz ain't gonna fuzz with a buffer on, I bet 'auto' would switch it off. Keeping it set on 1M, I bet the default buffer state, if it's got switchable states, would just be 'stay on'. That still wouldn't explain why the block in bypass is still killing the high end, unless they modeled the pedals bypass characteristics too. Fuzzes don't like buffers, they like to be plugged in straight to a pickup. 

 

I can't think of any reason why there would be a buffer anywhere in the internal signal chain, since there are no wires to add the capacitance that buffers are implemented to overcome.

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19 minutes ago, rd2rk said:

 

I can't think of any reason why there would be a buffer anywhere in the internal signal chain

 

Me either, other than I know AFX3 has a fixed buffer on the input. And the described loss of high end, if it's not from impedance, sounds just like running a buffer in front of a fuzz

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I did find a solution to my problem even though maybe it's just a way around an actual issue.

 

Using the impedance switching advice from Rd2rk, I then created a second input path that includes non-distortion pedals and the main input path that only has the fuzz (or low impedance effect) and the Mixer is controlled by the snapshot too, blending in only the path with the path that I want on.

 

The Non-Fuzz snapshot has the input set to 1M input impedance. When I bypass the Dhyana drive, the path sounds exactly as if there's nothing in front of the amp, like a true bypass should with a 1M impedance.

image.png.2bd45cf1fd9a0004fa82151087954d91.png

image.png.314c4158583e339113bd7a3d84b36c5d.png

image.png.a3cd35a9598187a7491ff9bbeaf6a128.png

 

The fuzz path is just the opposite.

image.png.d71776e16c36c0bae159f8acb8ea3845.png

image.png.3c2757de8dd73e74fc04e322dccb6893.png

image.png.5fa8f4f030cc99a5caa29612e9d2c9b6.png

 

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That's certainly a creative workaround, but seems kind of a waste of both Snapshots and a Split.

Doesn't the attached do the same?

obscurehifi.hlx

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BTW - I finally see what you're talking about when using AUTO. I can't speak to previous versions, since I never use any of those effects, but messing with the preset that I just sent, if I change the MIN value to AUTO and put the Arbitrator in front of the Dhyana, there's a definite volume drop when the Arbitrator is bypassed that results in a muffled effect.

 

I couldn't really hear it because I was using the TS for testing which, at 230k, isn't as noticeable. The Arbitrator at 10k is another story, and now that I've heard it, I can hear it with the TS too, albeit not nearly as noticeable.

 

Again, not a bug, as it's been known for a long time, but a definite shortcoming that L6 should address. If you haven't already, go on Ideascale and search for Impedance. Be sure to vote for all of the requests (nobody searches before posting "new" ideas).

 

 

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Thanks for creating the attached comparison. Well, I'm glad it's not just me hearing the muffled sound. The list of impedances of pedals that you attached really helped me understand what was going on. Before I posted my first post, I randomly selected several distortions and must have picked a bunch that were low by chance, thinking it was more widespread. I'm surprised I didn't notice this as much before but my presets must have been a bit different, so I didn't notice as much.

 

Now that I created the preset that I made pictures of, I'm getting one of the best fuzz setups that I've ever had on the helix. I've set the imp. to 10hz before in front of fuzzes before but I just happened to combine the Arb Fuzz, the Madarin 80, and the OH DVRB+VVRB (r)evolution IR. The fuzz distortion knob has to be turned down to near zero. I was going to post the file here but I can't get a stock cab to sound the same, so not sure it's worth posting.

 

As a side note, those Ownhammer (r)evolution impulses are incredible. I just downloaded them the other day and it finally got rid of this artificial "buzzy" sound (always at a different frequency based on speaker) I always noticed with most cabs and free impulses I've tried.

 

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Yo I can't get over this HX stomp, with a arbitrator fuzz 1st in the chain, with input set on auto it's fuzzy and spitty like it's supposed to be. If you put it on 1M, you can hear it get a lot more high end through, but because it's a fuzz it stops fuzzing the same, just like a fuzz does if it has a buffer before it, I swear there's a switchable buffer in there, where auto knows to turn it off and 1M keeps it on. I haven't been this thoroughly satisfied with piece of gear since the OP-1, cheers to the L6 team, this little thing is so much fun

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On 5/27/2020 at 4:16 PM, bypassvalve said:

Yo I can't get over this HX stomp, with a arbitrator fuzz 1st in the chain, with input set on auto it's fuzzy and spitty like it's supposed to be. If you put it on 1M, you can hear it get a lot more high end through, but because it's a fuzz it stops fuzzing the same, just like a fuzz does if it has a buffer before it, I swear there's a switchable buffer in there, where auto knows to turn it off and 1M keeps it on. I haven't been this thoroughly satisfied with piece of gear since the OP-1, cheers to the L6 team, this little thing is so much fun

 

I found the arb fuzz works well set to 10k. I'll give it another shot set to auto.

 

Mind if I ask what settings you use on the fuzz, what amp you use, and amp settings?

 

Have you tried the industrial fuzz with all the knobs set to zero other than drive and level? I find it also sounds pretty great that way too. You can add in a little of the other knobs to get some good spittiness too.

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On 5/24/2020 at 8:43 AM, obscurehifi said:

No, I literaly mean comparing these two scenarios, the second having the fuzz deleted.

 

Scenario 1)

Guitar-->Cable-->1M input Imp -->bypassed fuzz or distortion -->Amp

 

Scenario 2)

Guitar-->Cable-->1M input Imp --------------------------->Amp

 

Scenario 2 sounds bright and chimey. Scenario 1 sounds muffled even with 1M input impedance. Sorry to not have explained what I meant by deleted effect, but I literally meant deleting the effect for comparison's sake.

FWIW, I tried exactly this and can't hear any difference in the treble freqs. I made two identical presets, one with a fuzz bypassed and one with the fuzz deleted completely. I set the input impedance to 1M on both. If you're still having this issue, can you share a preset that you're sure shows it?

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L6 modeled bypass characteristics of the pedals... regardless of input Z setting, if a pedal is in the chain, it has inherent bypass characteristics that will effect subsequent blocks, just like the real device would. Some are subtle, some have a lot of color, it's mix and match till you find what you need. Or route them all on parallel paths and snapshot a mixer dot to roll your own switcher. 

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On 5/27/2020 at 4:16 PM, bypassvalve said:

Yo I can't get over this HX stomp, with a arbitrator fuzz 1st in the chain, with input set on auto it's fuzzy and spitty like it's supposed to be. If you put it on 1M, you can hear it get a lot more high end through, but because it's a fuzz it stops fuzzing the same, just like a fuzz does if it has a buffer before it, I swear there's a switchable buffer in there, where auto knows to turn it off and 1M keeps it on. I haven't been this thoroughly satisfied with piece of gear since the OP-1, cheers to the L6 team, this little thing is so much fun

I'm kinda confused by what you're implying... the input impedance is an analog circuit inside the Stomp/Helix, which changes the actual impedance at the input jack. In other words, it's changing the way the pickups are loaded. The lower the input impedance, the more treble gets cut. That's not a buffer phenomenon, that's simply what happens with a low impedance input in circuit with the pickups--it creates a low-pass filter.

On 'Auto', the input impedance is set to the value of your first block (it's baked into the model--it won't tell you anywhere what it actually is). For fuzzes, 'Auto' sets it to a pretty low impedance, because the real pedals also have low input impedances. That's where the treble loss comes from; that's what makes a fuzz sound the way it does. If you override the input impedance to 1MOhm, you've now changed the fuzz model itself because fuzz pedals in real-life don't have high input impedances. Thus you end up passing way more treble frequencies into the fuzz. It doesn't have anything to do with a buffer vs. no buffer in the Helix/Stomp, but this same thing is essentially what happens if you put a buffer before a fuzz in the real world.

TL;DR: you're not hearing a switchable buffer; you're just hearing the difference between a low-impedance and high-impedance input on the same fuzz pedal. Real fuzzes have low input impedance which filters treble.

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18 minutes ago, bypassvalve said:

L6 modeled bypass characteristics of the pedals... regardless of input Z setting, if a pedal is in the chain, it has inherent bypass characteristics that will effect subsequent blocks, just like the real device would. Some are subtle, some have a lot of color, it's mix and match till you find what you need. Or route them all on parallel paths and snapshot a mixer dot to roll your own switcher. 

Are you certain of this? If so, what's the source? I've never read this anywhere before -- everything I've seen previously said bypassed vs. not bypassed retains the same input impedance values and only turns the model on or off.

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My source is having input Z on auto, with a drive block in front of the amp in bypass, playing, then deleting the drive, and gaining some top end after removing the bypassed drive block

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47 minutes ago, bypassvalve said:

My source is having input Z on auto, with a drive block in front of the amp in bypass, playing, then deleting the drive, and gaining some top end after removing the bypassed drive block

 

 

Oop's... Yea that's a good source alrighty... 

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5 hours ago, bypassvalve said:

My source is having input Z on auto, with a drive block in front of the amp in bypass, playing, then deleting the drive, and gaining some top end after removing the bypassed drive block

You're misunderstanding. Each model in Helix has an input impedance value included with it. Whether the block is bypassed or active, that input impedance still applies, and it is actually switching an analog circuit inside Helix at the instrument input. I'm going to explain with an example to make it clearer:

  • The '70s Chorus' pedal has a 22kOhm input impedance. This is a built-in property of the model.
  • You have the signal input's path Input Impedance set to 'Auto'. You put the 70s Chorus as the first block in your path, after the input.
  • The input impedance (set by the switchable circuit inside Helix) will now be 22kOhm, because of the 70s Chorus pedal and the 'Auto' setting
    • It doesn't matter if the pedal is active or bypassed. As long as it's there and the Auto option is selected, it will have the same input impedance with the corresponding load on the guitar's pickups in the circuit.
  • If you delete the pedal with 'Auto' still chosen, then the next block in the path will set the new input impedance. If it's an amp, it'll probably be a much higher input impedance.
  • If you override the input impedance value instead of using 'Auto', the override value applies no matter what. It no longer matters which models are in your chain.

Lastly, just to really make this clear, the input impedance is a switchable circuit on the instrument input of Helix. The lower the chosen value, the lower the impedance in circuit with the pickups, which creates a low-pass filter that chops off treble. You can set this value to whatever you want to hear the difference.

 

If you're still confused, this has been discussed endlessly on this forum -- you can search and there are LOTS of old posts that explain it ad nauseam.
 

  

17 hours ago, bypassvalve said:

L6 modeled bypass characteristics of the pedals... regardless of input Z setting, if a pedal is in the chain, it has inherent bypass characteristics that will effect subsequent blocks, just like the real device would.

This is the point I'm making: that statement is not correct. There are no modeled bypass characteristics except the impedance (Z), and it absolutely matters what the setting of it is. With 'Auto', it gets assigned by the first pedal in the path, regardless of bypass state. With a fixed value, it ignores anything in the path and just sets it to whatever you choose. If you have anything that proves otherwise, please share it, because nothing any of the Line 6 staff have ever said that I've seen disagrees with what I've just stated.

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31 minutes ago, spikey said:

 

 

Oop's... Yea that's a good source alrighty... 

No it's not, because it's still being misunderstood how it works and what is actually happening.

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13 hours ago, qwerty42 said:
On 5/24/2020 at 8:43 AM, obscurehifi said:

No, I literaly mean comparing these two scenarios, the second having the fuzz deleted.

 

Scenario 1)

Guitar-->Cable-->1M input Imp -->bypassed fuzz or distortion -->Amp

 

Scenario 2)

Guitar-->Cable-->1M input Imp --------------------------->Amp

 

Scenario 2 sounds bright and chimey. Scenario 1 sounds muffled even with 1M input impedance. Sorry to not have explained what I meant by deleted effect, but I literally meant deleting the effect for comparison's sake.

FWIW, I tried exactly this and can't hear any difference in the treble freqs. I made two identical presets, one with a fuzz bypassed and one with the fuzz deleted completely. I set the input impedance to 1M on both. If you're still having this issue, can you share a preset that you're sure shows it?

 

To bring this back on topic with the original problem, what the original poster described in this diagram above should *not* sound any different. Scenario 1 should be no different in tone than Scenario 2, if the input impedance is indeed manually set to a fixed value. Duplicating the above on my Helix as a test, I hear no difference. If the OP is still hearing a difference, their problem isn't solved, and more troubleshooting is needed.

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On 6/1/2020 at 3:31 PM, qwerty42 said:

No it's not, because it's still being misunderstood how it works and what is actually happening.

 

 

Normally (for us old schoolers) If I have a Tube screamer in front of a 1 meg Impedance Fender Twin input and its in true bypass, the tone of that Fender amp should sound the same as if its not there. Thats how I understand it. And, if that Tube Screamer is set tone wise not to add any treble or bass (via your own ear's) and just to add gain to the front end of the twin , when I remove that pedal and plug straight into the Twin again, my tone and Impedance (not the gain), should not change, but just be cleaner sounding. That is what he is saying, I think, that his IS changing. It should sound just as it did with the pedal bypassed (if it's true bypass). If his setup is changing under those rules I just laid out, then impedance "should not" be causing his issue. And Yes, I can see with all the different impedance's used in pedals these days this norm is "not" a "norm" any longer and all this go's out the window. ; )

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5 hours ago, spikey said:

Normally (for us old schoolers) If I have a Tube screamer in front of a 1 meg Impedance Fender Twin input and its in true bypass, the tone of that Fender amp should sound the same as if its not there.

Correct.

 

5 hours ago, spikey said:

nd, if that Tube Screamer is set tone wise not to add any treble or bass (via your own ear's) and just to add gain to the front end of the twin , when I remove that pedal and plug straight into the Twin again, my tone and Impedance (not the gain), should not change, but just be cleaner sounding.

This is a confusing statement. You're saying with the TubeScreamer on (NOT bypassed), your 'tone and impedance should not change' if you remove it. Input impedance is a property of a circuit. The TubeScreamer has its own input impedance. Your amp has its own input impedance. It affects the tone of your guitar because of how it interacts with your pickups, and every device you plug into has its own input impedance that doesn't necessarily match anything else.

The rest of your statement is just further confusing the original poster's problem. We're not talking about real pedals. We're talking about behavior of Helix under 2 very specific conditions, which should give identical tone. Re-read my post just above yours where I distilled it back down to exactly his issue. The more I address what you're saying, the more confused it's going to get again.
 

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10 hours ago, qwerty42 said:

The TubeScreamer has its own input impedance.

 

Engaged yes it does. Yea I was assuming that the TS had 1 meg ohm input impedance "while engaged", which I was wrong on when engaged- (a TS-9 engaged its "according to the net"- a is around 500K)... Now, I dont know "when off" if its in "true bypass" or not. And I "assume" true bypass of the pedal (real or virtual) means it tonewise is invisible to the rest of the chain. I assume that the amp's input see's only the guitar pickups for a load at this point. Lots of assumptions here I know. ; )

10 hours ago, qwerty42 said:

The rest of your statement is just further confusing the original poster's problem.

Well it's not confusing to me any more than flying the space shuttle would be but as always YMMV and thats ok. ; ) I'm just saying that whether or not the pedal is in the chain and "true-bypassed", or not there at all, it should NOT affect the tone of the amp given that all Impedances are set to say..., "1 meg ohm". I.E., the amp see's a 1 meg ohm impedance on the input no matter what is connected. He is saying if I read this right, it is. Could be that the pedal that was modeled "has" a buffered circuit inside it and while "off" versus when removed from the chain, this is why the tone is changing?

 

Here is an article I found about "buffered vs true bypass"...  http://www.gilmourish.com/?p=1611

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Wow, this is all new to me as I've primarily giggled with my Variaxes or used a wireless so I've never run into this until tonight.

 

Just now I put an Arbitrator in front of an Essex 30, and to me the bypassed sound is just unusable. I don't remember ever encountering this before but likely because maybe it's just possible I never used a regular pickup guitar cabled into the guitar input and wanted a patch where I could kick fuzz on/off. I literally thought this was a bug and was about to file a bug report when I did a search and found this thread. Maybe in 37 years of playing, I just never ran a real tone-sucking impedance pedal. This is crazy! I feel like my world just got turned upside down and like "How the hell have I been a professional guitar player for 33 years and never had to deal with this?" My guess because I used wirelesses a lot, and likely pedals that just didn't have as drastic an effect as a Fuzz Face, I'd guess. And then I switched to Line 6 stuff from their first product (the AxSys 212) and Variaxes as soon as they came out. 

 

For now I set up a whole separate second path now which seems unnecessarily complicated for just wanting to toggle a fuzz on/off with no gain/tone loss, or setting Input Z manually and I'm guessing compromising the fuzz tone. 

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21 hours ago, Nos402 said:

I'm so confused by all this. Is this a new "problem/feature" in 2.9x? I don't remember ever having this problem before. Now maybe I just somehow never noticed it or used a scenario in which it was relevant, but I feel pretty positive I've put a fuzz (like the arbitrator) in front of an amp and not noticed the HUGE change in tone when it's bypassed vs. when it's deleted. 

 

Just now I put an Arbitrator in front of an Essex 30, and to me the bypassed sound is just unusable. I don't remember ever encountering this before. Good to know I can use an A/B split block or something to work around it but I was about to file a bug report before I read this.


Nope, it's not new, and it's only confusing because whenever a post gets made about it, people who don't quite get it muddy the waters by talking in philosophical circles instead of taking 10 quiet minutes to understand how it works.

For posterity, here is what's going on, again, from top to bottom. If you have questions after this, please read it again.


First, let's talk about real-world analog pedals and amps:

(1) First, we need to understand that input impedance (represented by Z) is a property of a circuit. Everything you plug your guitar cable into has a certain input impedance. Every pedal you've ever used has a certain input impedance.
 

(2) Some pedals like fuzzes have LOW input impedances (e.g. 10 000 Ohms aka 10 kOhm). Some other pedals have HIGH input impedances (e.g., 1 000 000 Ohms aka 1 MOhm)

(3) The input impedance of whatever your guitar is directly plugged into affects the sound of your guitar's pickups. This is because your pickups become part of the circuit, and the input impedance interacts with your guitar pickups to create what is essentially an analog low-pass filter.

(4) If your guitar is connected to something with very HIGH input impedance, it will have no noticeable filtering, and will sound bright with all of the treble frequencies passing through. If you connect your guitar to something with LOW input impedance, the combined circuit acts as a low-pass filter, which attenuates treble frequencies. The lower the input impedance, the more the treble gets attenuated.

(5) Ok, given #4, why would we ever want a low input impedance for something you plug your guitar into? Well, many old-school effects like fuzzes don't sound or feel 'right' without their low input impedance chopping the treble frequencies out of the input signal. Low input impedance is generally an undesirable thing for a guitar input, but at the same time it's essential to making some pedals/amps sound the way we expect them to in the real-world.
 

(6) The interaction of guitar pickups + input impedance applies to the first thing your guitar is directly plugged into. If you have a pedal with 1MOhm input impedance first in your chain, and then a low-impedance fuzz after that, the fuzz won't sound right because your guitar is 'seeing' the 1MOhm impedance, not the lower impedance of the fuzz. Likewise, if you have a buffered pedal first in the chain, this will also behave as if your guitar is plugged into a high input impedance.
 

(7) If you have a true-bypass pedal, and it's in the bypass state, then the input impedance of the NEXT pedal in the chain is what your guitar 'sees.' This is because a true bypass is basically like adding some extra length to your guitar cord and connecting it directly to the next pedal.

Ok, now let's talk about how the Helix models input impedance:
(A) The Helix/LT/Stomp have a variable input impedance circuit on the guitar input. This means there is an analog circuit on the input which can be switched through many different values of input impedance. It can go from 1 MOhm all the way down to 10 kOhm. This isn't a digitally-modeled effect -- it is an actual analog circuit that loads the pickups.

(B) If your guitar is plugged DIRECTLY into Helix's guitar input, then your pickups are loaded by this analog input impedance circuit. If you have things in between your guitar and Helix, then those things determine the input impedance seen by your guitar as described earlier.

(C) Every model within Helix (amps, pedals, etc.) has an input impedance value internally coded into it. No, you can't look at the value anywhere, but just understand that a 70s Chorus pedal has a 22 kOhm input impedance, and a Scream 808 has a 230 kOhm input impedance, and so on. These internally-stored values are based on the input impedances of the real-life pedals.

(D) The internally-coded input impedance of the first block in your signal path sets the Helix's input impedance value by default. In other words, if the first pedal in your signal path is a 70s Chorus, the adjustable input impedance circuit will be set to 22 kOhm. This input impedance still applies whether that effect is bypassed or not. This behavior is realistic for pedals that aren't true-bypass, but is unrealistic for pedals that ARE true-bypass. Like it or not, that's how it currently works.


(E) You can override the auto-adjusted input impedance by choosing a fixed value for it in the input block of your signal path. The parameter to adjust this is named "Guitar In-Z." The default value is AUTO which behaves as I described above. You can manually set it to any value you want, and that will be the new input impedance of the guitar input circuit no matter what is in your patch, and no matter their bypass states.

(F) The outcome of the default Auto behavior is that if you have a pedal with low input impedance (e.g. Industrial Fuzz) first in your chain, and you bypass it, then whatever is next in the chain will sound darker, because it's behaving as if it, too, has a low input impedance. If the next thing in your chain was an amp, it'd sound like the amp's instrument input circuit had a 10 kOhm input impedance, which no amp will likely have in real life. Again, this behavior is how real-life pedals without true-bypass behave. This behavior is not how real-life pedals with true-bypass behave.

 

(G) Line 6 chose to do it this way, and some people disagree with that. If they'd chosen to set the Auto-Z based on the first non-bypassed pedal in the chain, some people would be happier and some would probably not like it that way, either. If this really matters to you and is causing problems, you can either (1) manually set the Guitar In-Z to a fixed value; or (2) link the Guitar In-Z value to snapshots, and then manually set the value you want for each snapshot along with the bypass states of your pedals; or (3) link the Guitar In-Z to be controlled directly by a footswitch rather than snapshots, and then assign that same footswitch to toggle the bypass state of your first pedal. If you have plenty of DSP to spare, you can also split your patch into multiple inputs with different values and mute/unmute them, but that's a pretty brute-force approach IMO.

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BTW, I edited my original post once I realized why I had only *just* encountered this problem.

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And thanks for the extremely detailed lesson, Qwerty. It feels so weird to be 37 years into a guitar career and somehow not knowing this stuff. I've never been a vintage gearhead, or even really that much of a pedal freak so I just never had to deal with any super drastic effects like that.

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What if you are running two parallel paths in the Helix? I'm guessing the impedance would be set by the first block on path 1?

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42 minutes ago, Nos402 said:

What if you are running two parallel paths in the Helix? I'm guessing the impedance would be set by the first block on path 1?


I think that's correct, yes, but I'd have to test it to be sure. That would be a useful bit of info to add for others if you figure it out before I have time to do so :)

Also, I added a 3rd option to my post above to toggle the Guitar In-Z that I'd forgotten: instead of assigning it to be controlled by snapshots, you can also just assign it directly to a footswitch and then choose two values for it that the footswitch toggles. Then, assign your first pedal to that same footswitch for bypass on/off. Doing this will let you use a fuzz with low input impedance, but then when you bypass that fuzz it'll switch to your other chosen value. Using snapshots is of course a good option too, where it just directly recalls whatever value you stored for that particular snapshot. There's a few listings somewhere on these forums of the internally-set input impedance values for each effect if you need it--should be able to find it with a search.

Using a wireless input like you mentioned above will indeed make none of this matter, because the guitar just gets the 1 MOhm impedance of the wireless transmitter. Of course, that also means fuzzes won't sound as they 'should', which is true of their real-life pedal versions too. You need that cable going into them straight from the guitar if you want proper vintage fuzz feel & tone. I'm not sure how the Variax dedicated port handles it, but since the Variax pickups are piezo saddles and it does the sound processing onboard, I'd guess that it also doesn't care what the input impedance is set to on Helix (the Variax electronics probably act like a buffer, but I'm just guessing here).

Many people who use analog pedals intentionally use a buffered pedal first in their chain, which avoids all these tone-suck issues in general, because as far as the guitar is concerned it's like having it connected to your wireless transmitter. But the same caveats about fuzzes not sounding as intended still apply in that case too. Setting the Guitar In-Z to a fixed value of 1 MOhm should be just like using your wireless transmitter, and also just like using a buffered pedal first in a chain of real pedals.

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6 hours ago, qwerty42 said:

Nope, it's not new, and it's only confusing because whenever a post gets made about it, people who don't quite get it muddy the waters by talking in philosophical circles instead of taking 10 quiet minutes to understand how it works.

For posterity, here is what's going on, again, from top to bottom. If you have questions after this, please read it again.

 

Great, all inclusive explanation! This is indeed one of those subjects that gets brought up repeatedly. I've taken to saving my explanations in Notepad files so that I don't have to re-type them over and over. This particular explanation deserves a sticky! Oh, wait, nobody reads the stickies.....

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7 hours ago, qwerty42 said:

(G) Line 6 chose to do it this way, and some people disagree with that. If they'd chosen to set the Auto-Z based on the first non-bypassed pedal in the chain, some people would be happier and some would probably not like it that way, either. If this really matters to you and is causing problems, you can either (1) manually set the Guitar In-Z to a fixed value; or (2) link the Guitar In-Z value to snapshots, and then make it flip between 2 chosen values depending on the bypass state of the first pedal in your chain

 

@qwerty42 Thank you very much for the detailed explanation and write up. It helped me set up a test to confirm what you have said is accurate and also that my Helix appears to be functioning normally. Not sure why my initial test (in my first post) setting the impedance to 1M didn't work. I may have made a mistake or maybe the setting didn't take? Who knows. Anyways, this is the test that confirms everything seems to be working properly:

 

Setup:

Guitar-->Cable-->10k input Imp (or Auto Z if arb 1st in chain) -->arb fuzz -->Amp (Architype Clean)--->dual path of Ownhammer (r)Evolution IR's-->Merged--->delay-->reverb

Result: This sounds wonderful. This may be the perfect fuzz amp, or at least the best on helix I've found so far. Set the gain near 8. Cleans up nice with guitar volume rolled down, just like the real fuzz face is supposed to do. Sounds best with passive low output pickups. Doesn't sound as good with active pickups or high gain pickups.

 

Test 1 Bypassed Arb Fuzz 1st in Chain:

SnapShot1)

Guitar-->Cable-->10k input Imp -->bypassed arb fuzz -->Amp

Result - Sounds muddled and terrible.

 

SnapShot2)

Guitar-->Cable-->1M input Imp -->bypassed arb fuzz -->Amp

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

SnapShot3)

Guitar-->Cable-->Auto input Imp -->bypassed arb fuzz -->Amp

Result - Sounds muddled and terrible. Auto must be staying at 10k.

 

Test 2 Deleted Arb Fuzz:

SnapShot1)

Guitar-->Cable-->10k input Imp --->Amp

Result - Sounds muddled and terrible.

 

SnapShot2)

Guitar-->Cable-->1M input Imp --->Amp

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

SnapShot3)

Guitar-->Cable-->Auto input Imp --->Amp

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

Test 3 Moved Bypassed Arb Fuzz after Amp:

SnapShot1)

Guitar-->Cable-->10k input Imp --->Amp-->bypassed arb fuzz

Result - Sounds muddled and terrible.

 

SnapShot2)

Guitar-->Cable-->1M input Imp --->Amp-->bypassed arb fuzz

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

SnapShot3)

Guitar-->Cable-->Auto input Imp --->Amp-->bypassed arb fuzz

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

Test 4 Simple EQ (no adjustments) 1st in Chain, Bypassed Arb Fuzz 2nd in Chain

SnapShot1)

Guitar-->Cable-->10k input Imp -->Simple EQ-->bypassed arb fuzz -->Amp

Result - Sounds muddled and terrible.

 

SnapShot2)

Guitar-->Cable-->1M input Imp -->Simple EQ-->bypassed arb fuzz -->Amp

Result - Sounds fantastic. All highs back. Lot's of shimmer. Makes me smile.

 

SnapShot3)

Guitar-->Cable-->Auto input Imp -->Simple EQ-->bypassed arb fuzz -->Amp

Result - Sounds muddled and terrible. Auto must be staying at 10k.

 

It's clear to me now that the first effect in the chain does in fact set the Auto impedance value. I think the tests also show that the bypassed fuzz when not first in chain doesn't affect the signal. It's unclear to me why this didn't work when I first tested.

 

The only thing I did notice in this series of testing is that the Auto Z setting doesn't not automatically change sometimes, for example, if I have the bypassed-arb-fuzz and move it after an effect with a higher impedance, the Auto Z doesn't change automatically to match the newly positioned first in the chain, until something else is changed, such as switching the snapshot to another then back or actually adding an effect before the arb-fuzz. Those force it to change but it could be perceived as a sound quality issue if someone doesn't recognize the Auto Z wasn't forced to change. I think this only happens if the chain content isn't changed, such as just shuffling effects around, until it's forced to change.

 

Anyways, thanks for all the responses everyone! It looks to me the best solution is using snapshots to manually change the impedance between 10k and 1M for the effect I used.

 

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8 hours ago, obscurehifi said:

The only thing I did notice in this series of testing is that the Auto Z setting doesn't not automatically change sometimes, for example, if I have the bypassed-arb-fuzz and move it after an effect with a higher impedance, the Auto Z doesn't change automatically to match the newly positioned first in the chain, until something else is changed, such as switching the snapshot to another then back or actually adding an effect before the arb-fuzz. Those force it to change but it could be perceived as a sound quality issue if someone doesn't recognize the Auto Z wasn't forced to change. I think this only happens if the chain content isn't changed, such as just shuffling effects around, until it's forced to change.


Ah, interesting, thanks for that observation! Maybe this is why it seemed like it wasn't working correctly at first. Good to know!

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You can also assign the input impedance to the same switch as the fuzz.

When fuzz is switched on, the impedance is set to 10k, when off, it's set to 1M.

Best of both world

 

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