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Expression pedal value range....
by dftpunk on 2011-01-07 08:24:31

Have you ever noticed that when you control some parameter using expression pedal the range changes are not linear comparing the on the way from the heel to the top position?

I mean that if you have for example volume controlled by the EXP so if you pass the way from the heel position up for about X - you get volume increased from 0 % to 10 % and if you pass the same X way from the top position down - you get volume decrease from 100% to 80%. So the same way - and different amount. Is it the way it should work, or it's a bug?



Re: Expression pedal value range....
by Hey_Joe on 2011-01-07 08:50:16

Are talking about EXP 1 or 2 pedal knob in Edit freaking out after the update? When I use the add -on pedal 2 for the presets I get no  more circular movements when going from heel to toe (0-100%)...the knob in the GUI just sort of jerks around from bottom right  to left and somrtimes when the pedal is around 50% it might hop up to about 10:00.



Re: Expression pedal value range....
by dftpunk on 2011-01-07 10:44:31

No, I'm talking about the pedal in action...without HD Edit...this is not about assigning. When you're done assignment (using onboard "editor") just move the pedal and see how the value changing in the right bottom corner(or on the FX edit page). You will see that behaviour I've wrote about.



Re: Expression pedal value range....
by Hey_Joe on 2011-01-07 11:19:28

No  - I'm not seeing that happen with my unit.

You didn't mention which HD you have -- 300, 400 or 500.

I've got the 500 and just tried using just the Pod to edit and used both onboard and add-on pedal 2 and see %s that seem to correlate with the position of my pedal. The bar showing %s seems to follow the heel/toe position up and down for me.

But maybe I don't understand the issue and am not seeing what you are talking about.



Re: Expression pedal value range....
by dftpunk on 2011-01-07 13:21:11

Yeah, I have HD500.

Yes, the bar is working correctly BUT...Steps to feel the problem:

Get a Wah model. Put the pedal to the heel position and whatch to the bar. It's 0%. Ok. Now slowly push the pedal toward the top position. You'll see the bar slowly filled and on the half way the bar is filled only for 30%( but I suppose that on the half way the bar should be 50%). Then continue to push the pedal toward the end and you'll see the bar filles faster - and it's normal as it should fill the last 70% for the same way as it filled up 30%.

Another example: the same wah model. Set it to 15%. Set your finger on the bottom corner of the pedal and push it down to the 0%. Remember the path the pedal passed.

Then set your pedal to 85%. Set your finger to the upper corner of the pedal and push it down to the 100%. Have you noticed that the path the pedal passed now is shorter? That what I meant - the same 15 percents but the different physical path pedal passes.



Re: Expression pedal value range....
by Xsample33 on 2011-01-07 13:45:43

I'm guessing it is due to having an audio pot.

Our ears don't hear volume increases linearly, so the audio pot compensate for this and make a pot increase the amount of signal in a way that we perceive as linear. So in order for us to perceive it as linear, the increment curve has bellied in instead of being a straight line. In another word, it may not feel right to the eyes but should feel right to the ear!

In the attached graph, the green line is a linear pot and the blue line is the audio pot (also called log)

This should illustrate what I mean!



Re: Expression pedal value range....
by dftpunk on 2011-01-07 14:39:52

Yes, You've completely caught my idea! This is what I meant. But this happens not with volume only but with wahs, and whatever parameter we controll by the Expression pedal. If for volume it's a normal behavior as you said but for wah and, for example some parameter as delay time it's not normal because it should change it value linear between its min and max value corresponding with the Exp pedal position.....hm....I guess the line6's sipport only knows what happens



Re: Expression pedal value range....
by Xsample33 on 2011-01-07 14:45:38

If it's an actual pot in there, it probably cannot be converted...

Although the unit being a digital processor, it should be able to switch from one type of pot to another depending on the use.

You can make a request I guess!!!



Re: Expression pedal value range....
by Hey_Joe on 2011-01-07 15:33:46

I read in this thread that the volume pedal uses an optical sensor and I guess that means it's not a pot at all.

read here:

http://line6.com/community/message/219408#219408



Re: Expression pedal value range....
by Xsample33 on 2011-01-07 16:00:30

That means that Line 6 should be able to give us control over the type of pot we want to use or assign a log/audio taper pot to volume and wah and linear taper pot to other parameters!

Make a request if it's of any use to you!



Re: Expression pedal value range....
by dftpunk on 2011-01-08 01:37:11

GOD DAMN IT!!! IT"S OPTICAL!!! WHAT A FAIL!

So now there's a chance that such different ranges is the cause of bright light around the POD......need to apply solution to prevent lights going to the sensor and then recheck.



Re: Expression pedal value range....
by Hey_Joe on 2011-01-08 07:48:49

Calm down man.

Didn't you read what Line6Miller said in that link?

"  . . . Our development team did improve the pedal design and performed extensive testing and ultimately decided it passed our quality standards ..."

It was the FBV an X3L that were failing from sun and stage light.



Re: Expression pedal value range....
by Nick_Mattocks on 2011-01-08 08:02:59

dftpunk wrote:

GOD DAMN IT!!! IT"S OPTICAL!!! WHAT A FAIL!

So now there's a chance that such different ranges is the cause of bright light around the POD......need to apply solution to prevent lights going to the sensor and then recheck.

The expression pedal in the HD500 is definitely an optical device.  Less prone to becoming scratchy like a standard pot could.  Personally I think the lack of a pot is the better option, but I understand that others may disagree. I haven't checked this particular controller in extremely bright sunlight, but there are significant differences between the design of this controller and the ones in the FBV Shortboard and POD X3 Live.    The controller and sensors are much further back under the pedal than the X3L and FBV with less travel available but greater shade from direct sunlight from the steel structure surrounding the hole with the sensor underneath it.  The silver pin on the underside of the pedal nearer the front is actually the pin for pressing on the toe switch.  This will mean that there's less opportunity for light to leak into the unit - OK it's not impossible, but the amount of light leakage will be less.  I don't know for sure, but I strongly suspect the new positioning is part of a design attempt to overcome the issue of light leakage.

Nick



Re: Expression pedal value range....
by dftpunk on 2011-01-08 08:16:15

Calm down man.

Didn't you read what Line6Miller said in that link?

I saw but there was a man below who said that HD still goes crazy under the direct sunlight.

@Nick....Let forget about "optical" part of the issue.. Have you mentioned the behaviour I've wrote above?

Get a Wah model. Put the pedal to the heel position and whatch to the bar. It's 0%. Ok. Now slowly push the pedal toward the top position. You'll see the bar slowly filled and on the half way the bar is filled only for 30%( but I suppose that on the half way the bar should be 50%). Then continue to push the pedal toward the end and you'll see the bar filles faster - and it's normal as it should fill the last 70% for the same way as it filled up 30%.



Another example: the same wah model. Set it to 15%. Set your finger on the bottom corner of the pedal and push it down to the 0%. Remember the path the pedal passed.

Then set your pedal to 85%. Set your finger to the upper corner of the pedal and push it down to the 100%. Have you noticed that the path the pedal passed now is shorter? That what I meant - the same 15 percents but the different physical path pedal passes.



Re: Expression pedal value range....
by Nick_Mattocks on 2011-01-08 08:30:17

No I didn't mention that.  But have tried your recipe.  My HD500's progress bar with the Wah enabled is smooth and there doesn't appear to be aby difference in the reading either way when the pedal is physically in the same position.  What you are experiencing seems to me to possibly be a calibration issue.  Which particular Wah models display this?  All of them or some of them? 

In HD500 Edit under the Controllers tab for the Wah what are your Minimum and Maximum settings showing?  Mine are set by me to 0% and 100% respectively

I have seen similar stuff happen when after an update my expression pedal has needed calibrating.  You should not put additional pressure on the pedal at the toe end when calibrating the pedal as this can lead to whacky behaviour - just move the pedal to 100% without pressure and it should work for you.  I'm not saying that this IS your issue, but more that it might be.

Nick



Re: Expression pedal value range....
by Hey_Joe on 2011-01-08 08:58:13

OK  - I didn't want to ask this before because I didn't want to insult you and your ability to follow directions.

So far nobody has asked you and you haven't mentioned that you have done it. Nick has touched on it in his last reply.

Have you done the pedal calibration procedure to the 500 ?

Just asking, just in case you haven't -- since no one else is chiming in as to having the same problem.

Otherwise maybe you have a defective unit and if it's not too old you can get an exchange from where you purchased it under a 30 day satisfaction guarantee.



Re: Expression pedal value range....
by dftpunk on 2011-01-08 09:52:46

The pedal is well calibrated as it shows 0% at the heel and 100% at the top positions respectively. And min/max values are 0/100.

I think I should post a picture of what I mean.

Concerning the "Actual behavior" picture. The values are something near the real ones.



Re: Expression pedal value range....
by dftpunk on 2011-01-08 09:54:30

Guys I've done a little mistake at the picture... I should use the bottom corner of the pedal, but I hope it's not critical and you've got me.



Re: Expression pedal value range....
by Nick_Mattocks on 2011-01-08 10:00:21

Yes - I understood what you were getting at.  Thanks for the pictures though - it helps.  But still not seeing the same behaviour as you are  - sorry



Re: Expression pedal value range....
by dftpunk on 2011-01-08 11:28:18

Thanks, I will try to re-calibrate the pedal and try one more time in whole darkness



Re: Expression pedal value range....
by MusicalCircuitry on 2011-01-09 15:54:10

The expression pedal on my HD500 appears to have a logarithmic taper. I have successfully done the calibration, both before and after the 1.20 update.

I've used a protractor, taken down some readings, and created a graph from the results (attached). The graph clearly represents the audio / logarithmic style taper (from a math perspective, it looks more like an inverse logarithmic function though). The readings and graph aren't perfect, but I think it's enough to get the general idea.

I understand that our ears perceive changes in volume logarithmically, however, it seems to me that Line 6 has already accounted for that in the volume percentages. When I set the volume to be 50%, my ears perceive roughly 50% of the full volume. With that in mind, when using the expression pedal for volume, I would expect that at 50% of its range of motion, I would get 50% volume. Instead, it's somewhere between 15% and 20% and I can barely hear anything.

When I first tried using the expression pedal, I was disappointed, but figured it was working as intended since audio / logarithmic pots are common in music gear. Now that I've found out other users aren't experiencing the same thing and it's an optical rather than analog pot, I hope this is something that could be fixed - perhaps a setting in expression pedal assignment, a system wide setting, or another "Test Mode" item along with calibration.

Even if this is only an isolated issue, I still think a configurable setting would be handy. Since you can associate the expression pedal with a variety of different settings, it'd be handy to be able to change how the expression pedal reacts.

On a side note, after I press the D footswitch to finish the calibration, I am returned to the "Test Mode" screen and see a "P" after "Pedal Cal" to indicate the calibration was successful. However, after powering off, if I enter the "Test Mode" screen again, the "P" is gone. Is that normal? Also, the section on expression pedal calibration seems to have been dropped from the newest advanced manual (Rev D), whereas it was present in the previous one (Rev B).



Re: Expression pedal value range....
by Xsample33 on 2011-01-09 16:13:50

Thanks for the graph, pretty demonstrative...

Although it is log. and not inverted. The inverted taper shows a bellied up curve and it does the adverse effect.

I think it should be a piece of cake for Line 6 to program the HD500 to choose what type of pot it simulates!

Same thing with some other feature request like inverting the FS5-8 to FS1-4 for patch switching, Keeping XLR out at line level at all times, etc...



Re: Expression pedal value range....
by ozbadman on 2011-01-09 16:43:41

So just to clear things up:

1) yes, it's optical. All good due to the new design masking outside light sources.

2) that also means the input to the DSP world is linear-ish->the optical sensor detects the distance betwen itself and the pedal, thus making it inherently linear-ish (the graph above shows some bend, but my guess is that's due either to the pedal rotating about a pivot point which would introduce some minor non-linearity, or possibly the percentage values displayed on the screen are already processed values). But yes, once it's in DSP land, Line 6 can conform it (process it) to any shape they want (ie:convert it to be a log taper instead).

Looks like Nick's run some tests and he isn't seeing the issues your seeing.

David.



Re: Expression pedal value range....
by MusicalCircuitry on 2011-01-09 16:52:35

We both agree it's an audio taper. I'm curious why it tends to be called logarithmic in musical circles though, because from a math point of view, it's an inverse logarithmic graph. Check out the graphs on this page:

http://www.purplemath.com/modules/graphlog.htm

Is this just a quirky musical use of terminology, or am I missing something here?

As for the original issue, yeah, Line 6 should be able to quite easily allow us to modify the taper. I'll send in a request about it, but I'll hold off a bit to see if it's just an isolated bug with a few units that needs to be handled as a warranty issue. It does seem a bit odd that my expression pedal works, but has a different taper than most other users. Perhaps that's a sign that it is configurable, but the setting is hidden and mine is set wrong?



Re: Expression pedal value range....
by Xsample33 on 2011-01-09 17:27:24

LMAO...

Dude... I will take your word for it... no questions ask!

I'm a pretty good lawyer, an average guitar player, but lord.... am I ever bad at advanced math!!



Re: Expression pedal value range....
by dftpunk on 2011-01-09 23:13:00

Guys it's really nice to see that you can notice such things too.

Maybe such "tape" shape is good for volume pedal, but you have the same tape for wahs and when you control other FX parameters. I think in last cases it SHOULD be linear! So if they will inhance device to choose what pot to use - this feature should be per EXP pedal per Effect. But it sounds utopian.

Guys maybe we all should post this as feature? It would be efficient! Sign mine petition!))))



Re: Expression pedal value range....
by tommasi on 2011-01-10 00:16:08

MusicalCircuitry wrote:

We both agree it's an audio taper. I'm curious why it tends to be called logarithmic in musical circles though, because from a math point of view, it's an inverse logarithmic graph.

I think it's because they are meant to account for a logarithmic perception (as is the ear's of volume). By providing an inverse logarithmic function, they "linearize" the perception wrt to their mechanical position. The Ohm function plotted against rotation is indeed exponential.



Re: Expression pedal value range....
by adhiwisnus on 2011-01-16 19:03:10

Hello guys, I live in Indonesia and recently bought a pod hd300. I also have the same issues with my pod hd... Done calibration many times, but didnt resolve it. This issues is more obvious when were in the calibration mode, in the check parameter page.. the pedal value was moving slow from heel 0 value to a half pedal value around 45...but try push it little forward, the values will jump from 50 to 127 in a small pedal movement. Maybe a hardware failure or programming algorithm, i dont know.  I have try to recalibrate using ''small" pedal movement (i.e i try to kinda shortened the toe travel) and the issues still occures, even in a small travel setting, the pedal value still jump from 50 to 127... I hope line 6 will resolve this issues in the next firmware update. sorry for the bad english.



Re: Expression pedal value range....
by dftpunk on 2011-01-16 23:13:18

I Think we should submit this as a bug so maybe line6 will fix the issue or give us an explanation of such behavior.



Re: Expression pedal value range....
by adhiwisnus on 2011-01-16 23:31:35

i dont know how to submit a complain a bug/ issues to line 6.... through support forum? 



Re: Expression pedal value range....
by dftpunk on 2011-01-17 03:43:43

Hm....Maybe through Contact us -> Product FeedBack -> Dislike?

Maybe line6Miller will tell us how to submit a bug?



RE: Expression pedal value range....
by ricksox on 2011-01-17 15:44:14

Just to clarify, are you saying that when you assign wah or volume to Exp 1 or Exp 2 the taper on the POD itself goes from )% to 100% smoothly but it skips around on the editor?

That's what I'm seeing here but, it's not affecting the tone.

Is this what you are saying?

Line6Miller



Re: RE: Expression pedal value range....
by adhiwisnus on 2011-01-17 15:57:15

The issues is not just occured in the editor, but also in the real playing situation. just like what all the good guys in this thread says, The volume pedal only opens about 30 / 40% when half pedal engaged.... but it quickly turns from 40 to 100 in a small forward pedal movement/ travel. the "logarithmic" theory make sense, because the expresion pedal seems behave like a volume/gain pedal on your guitar....... the issues is more obvious if we see it at the calibration page.... when the value of the pedal move from 0 value to 127 value.  btw tx for the quick response miller.. hope this issues could be resolved. btw, musicalcircuitry explanation is well explained the whole issue.



Re: RE: Expression pedal value range....
by Hey_Joe on 2011-01-17 16:01:26

Line6Miller wrote:

Just to clarify, are you saying that when you assign wah or volume to Exp 1 or Exp 2 the taper on the POD itself goes from )% to 100% smoothly but it skips around on the editor?

  That's what I'm seeing here but, it's not affecting the tone.

  Is this what you are saying?

  Line6Miller

I'm saying that this is happening to me after the 1.20 update.

It's such a small bug and I have brought it up twice in other threads but never started a thread like I did on the last Editor vs. Volume Pedal bug that you  confirmed.

I don't think dftpunk is saying this.



Re: RE: Expression pedal value range....
by dftpunk on 2011-01-18 02:17:56

Hi Miller,

this issue is not about Editor it's about POD unit itself. adhiwisnus  clearly described the issue. You can see page 2 of this topic for attached pictures of what we've faced.



RE: Expression pedal value range....
by ricksox on 2011-01-18 15:16:15

I suppose I can see the pedal values jump a bit here and there in pedal calibration mode but I think this is more of a feature request then it is a true bug in the POD.

This is something we can probably try improving in a future firmware update so please submit your feedback.

Line6Miller



Re: RE: Expression pedal value range....
by adhiwisnus on 2011-01-18 19:42:35

Thx for the quick respone, mr.miller. with ur expalation, maybe i could conclude that the POD HD expression pedal is "actually" design to works logarichmically, so there are no error on our unit. (correct me if im wrong:). But i still think that it was a faulty design, cause minimal pedal travel length is not what lots of user prefer. We like to have a lot of options to control our pods. Personally , i like a linear, long pedal travel range , just like an ordinary volume pedal/ dunlop wah wah,   If i could make a suggestion, in the next update, is it possible to include a choice of expresion pedal behaviour setting, so users could choose linear, logarithmic or anti-log seting. i think zoom already does that in their G.2/7/9u unit. btw, i dont now how exactly i could reach line6 for feedback.....is it in another forum/ via email? thx



Re: RE: Expression pedal value range....
by dftpunk on 2011-01-19 01:47:19

Yes I'd like linear pedal travel too. But I really don't know how to clearly explain this to POD's support because now I see that only few could understand the problem. It's not a calibration issue it's how the pedal works. As I've wrote before you can clearly see the issue following the next steps:

Get a Wah model. Put the pedal to the heel position and whatch to the bar. It's 0%. Ok. Now slowly push the pedal toward the top position. You'll see the bar slowly filled and on the half way the bar is filled only for 30%( but I suppose that on the half way the bar should be 50%). Then continue to push the pedal toward the end and you'll see the bar filles faster - and it's normal as it should fill the last 70% for the same way as it filled up 30%.



Re: RE: Expression pedal value range....
by MusicalCircuitry on 2011-01-20 00:22:56

Since this discussion seems to have gotten a bit confused, here is a very simple way to illustrate the problem:

  1. select a "New Tone" and select an amp
  2. double press the move button while the amp is selected to enter expression pedal assignment
  3. change the parameter to "Output" (ie. channel volume), the controller to be EXP 1, min value to 0% and max value to 100%
  4. press view to get back to the signal chain view, then double press the enter button to get into the AMP:EDIT screen
  5. press the expression pedal all the way forwards (toe position)
  6. turn the physical volume knob (amp volume, not master) to its maximum setting, then look at the AMP:EDIT view, it should reflect the physical setting and show 100%
  7. play your guitar a bit and note how loud it seems
  8. turn the physical volume knob to its halfway point, then look at the AMP:EDIT view, it should reflect the physical setting and show 50%
  9. play your guitar a bit and note how loud it seems - it should seem to be about half of the full volume
  10. return the physical volume knob to its maximum setting
  11. adjust the expression pedal so that it's at about half of its range of motion, then look at the AMP:EDIT view, it will read somewhere around 15% - 25%
  12. play your guitar a bit and note how loud it seems - it will sound significantly less than half of the full volume

The question then is clear - why is it that the volume knob behaves the way I expect, but the expression pedal does not? They are both physical controls that can be used to adjust volume - shouldn't setting each of them to equivalent points of their physical range have the same effect?

I understand the point of the audio / logarithmic taper -  our ears don't respond to volume changes linearly, and the audio taper  accounts  for that. To me, it seems like the scale of values for volume is already accounting for this logarithmic nature. The volume knob has a linear taper, so that at 50% of its range, the volume level reads 50%, which has already been adjusted for the logarithmic volume issues. On the other hand, the expression pedal uses a logarithmic taper, so that in effect the logarithmic adjustment is happening twice.

For a real world example of why this is a problem, say you are playing a song, and want to back off a little bit on the volume. If you have the expression pedal controlling volume, the immediate suggestion would be to ease off a bit on the expression pedal. Unfortunately, with the current taper, even a small movement could drop you to 50 - 60% volume, which is a drastic change.

I contacted Line 6 by phone earlier to ask about this. The guy I spoke to told me that my expression pedal is working as intended, and that there is nothing wrong with my HD500. This might not be affecting all users, but all HD500s should be reacting the same way. He told me that all Line 6 expression pedals have worked this way, and that people haven't seemed to mind. Taking all of that into account along with the lack of communication from Line 6 about firmware updates, it doesn't make sense to wait for a fix.

Is my real world example above a bizarre scenario that most guitarists don't care about? Am I approaching this the wrong way?

Does anyone have any good ideas for working around this? One thought is to have two volume pedal slots in your signal chain, one with min at 0% and max at 100%, and the other with min at say 75% and max at 100%, then switch between the two. There are obvious downsides to this though - first off you're wasting yet another FX slot on a volume pedal, then you either need to use a footswitch to change between them or give up the ability to switch to wah with the toe switch. Even if this works, it seems quite kludgy and not at all user friendly.

Any thoughts or advice would be appreciated!



Re: RE: Expression pedal value range....
by dftpunk on 2011-01-20 04:01:29

Guys we all just need to "post a feature", because every parameter you're controlling with Expression pedal will behave itself  in a "logarithmical way" and it's really not cool. Line6Miller, could you please give us your personal opinion regarding the problem and what chances line6 will fix it?



Re: RE: Expression pedal value range....
by Xsample33 on 2011-01-20 09:36:04

For a real world example of why this is a problem, say you are playing a  song, and want to back off a little bit on the volume. If you have the  expression pedal controlling volume, the immediate suggestion would be  to ease off a bit on the expression pedal. Unfortunately, with the  current taper, even a small movement could drop you to 50 - 60% volume,  which is a drastic change.

To help you with this specific example... you could use the volume pedal in reverse mode. Set the min to 100% and the max to 0%...

That way, you can back off on volume with the bigger sweep part of the pedal, but just in a reverse manner.



Re: RE: Expression pedal value range....
by MusicalCircuitry on 2011-01-20 19:08:51

Xsample33 wrote:

To help you with this specific example... you could use the volume pedal in reverse mode. Set the min to 100% and the max to 0%...

That way, you can back off on volume with the bigger sweep part of the pedal, but just in a reverse manner.

Thanks for the tip, I think that could give me the control I'm looking for. However, do I really want to start using a volume pedal backwards to my previous experience, not to mention other gear that works as expected? I'll give it a try, but I'm not sure that I want to form habits that will mess me up with other gear.

Anyways, I've submitted feedback about this to Line 6. For anyone following this thread, if it's an issue for you too, please submit feedback to Line 6 about it.



Re: RE: Expression pedal value range....
by dftpunk on 2011-01-21 01:26:46

For anyone following this thread, if it's an issue for you too, please submit feedback to Line 6 about it.

+1. I've just submitted too!




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