Adjustable tapers for expression pedals

    Don‘t expect that a shaping tool with a single parameter could mimic the logarithmic pots of different volume pedals. It is only an approximation especially for the initial slope,

    I was playing the Hammersmith VI piano and they have a nice way of controlling velocity. I'm getting a lot of options with Min, Max and Curve. They also have a Shape option for an S curve.

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    The expression pedal isn’t an analog device and is only controlling the volume or parameters digitally.
    The above example is for midi velocity but the same controls could be used to dial in the response of any expression pedal.

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    I think there are two main ways to use a volume pedal. One is to emulate the volume knob on a guitar by placing it first in the chain before distortion pedals and amp. When the pedal is backed off, the volume decreases but so does the amount of gain since the dirt pedals and amp are being hit less.


    The other way is to place the volume pedal after the distortion and before delays. Wired like this, when the volume pedal is backed off, just the volume gets softer, but the gain and amount of distortion don’t change.


    These are two distinct sounds. The pre pedal sound has a tendency to sound more dramatic and vocal but you lose sustain when volume pedal is lower. The post dirt pedal sound is better for keeping the sustain and tone consistent and it helps to quiet the noise made by the distortion pedals. Most session players seem to run the volume like this, to quiet the rig while recording.


    So, I made some audio examples today testing the range of volume expression pedals using a Boss EV-30 in various Kemper expression volume locations: Input, Pre Stack and Post Stack. Then I compared that to using a Boss Analog Volume FV-500H pre Kemper (between lapsteel and input) then using the effects Loop and placing it Pre and Post stack. So basically two different approaches to accomplish the same thing. One digital and one analog.


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    Edited once, last by Guavadude ().

    I’m basically listening for a few things when using a volume pedal: how smooth, vocal and dynamic is the sweep, how does the tone change when the pedal is backed off...do I lose sustain and amount of distortion.


    What I noticed is that the way the expression pedal reacted completely changed depending on placement. It sounds good on input and pre stack but it sounds terrible post stack. This is where I’ve been using it since post stack would be post all distortion and noise but still pre delay and verb. I didn’t change any settings and I’m playing the pedal consistently. It’s easy to hear the loss of sweep.


    So I think the problem I’ve been having isn’t with the expression pedal range and curve settings, it’s that it just isn’t working well in the post stack location for some reason. The analog pedal sounds much better in the loop placed post stack than the expression pedal.


    I still think it would be good to have some more control over the curve of the expression pedal settings since not all pedals sound and feel alike. One thing I learned is that I should try placing the volume pedal pre distortion more often because it really does have a nice dynamic, vocal sound.

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    Quote from Guavadude

    The expression pedal isn’t an analog device and is only controlling the volume or parameters digitally.
    The above example is for midi velocity but the same controls could be used to dial in the response of any expression pedal.

    Yeah, my bad. The action of a key in a keyboard is the same. Sorry dude!

    No worries. Your comment actually got me wondering if there was much difference in using the expression pedal or an analog pedal in the loop for volume.


    It's hard to tell from the audio samples but long story short: The expression pedal works best in the INPUT location and not so well Post Stack. An analog volume pedal works well in all positions, Input, Pre and Post Stack. It could vary depending on FX and amp used. I only tested it using one amp.


    Like with most effects and guitars, you really have to put the time in and try everything in every possible position to find the best sound.

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    Thanks for describing this so nicely and accurately! I hope it gets changed somewhere down the line to something more authentic feeling.
    I also have a Line6 Helix LT that i use for fly gigs, and the same expression pedal i use with my Kemper now (dunlop the mini-one) connected to the Helix...feels right. So i guess it's possible :)

    Hmm, that's interesting to know. @project_grudge


    I am using a Mission SP-1 RJM which is basically the same as the EP-1 KP except the switch is a TRS instead of TS connection. I have been playing with the wah quite a bit lately and trying to observe the taper. I checked the pedal settings screen and watched the bar move along with the pedal. I don't know if that represents the incoming signal or how the KPA interprets and 'tapers' the incoming signal but on mine there is almost no change in the first part of the pedal sweep then a rapid rise between say 1/8th and 1/2 of the travel followed by greatly slowed movement in the second half of the taper. Other than the real difficulty getting any accuracy in the bottom portion of the travel it seems like the pedal is taking the 10k linear pot's output and making it behave like an audio/log taper pot regardless of the type of pedal function selected. @ckemper is that how it is supposed to work? I understand why players would prefer the log taper for volume pedals as it better reflects how our ears percieve sound. However, I wouldn't expect that to apply to non volume related functions. It would seem sensible for the volume pedal option in settings to have a different taper than wah, morph or pitch. Could you confirm if that is how it should work. I will connect a multi meter to my Mission SP1 tonight (if I remember) and see who the resistance is over the travel to check the pot is functioning properly.

    I don't know really what's right or wrong. For me a linear or almost linear volume pedal feels ok. Haven't used volume pedals enough to say how i like them :)


    But when it comes to wah, yes there is some kind of logarithmics going on with the kemper, but a real wah pedal (or my favourite the dunlop rack cry baby with external pedal) has a steeper logarithmic feel to it. My god this is hard to explain haha.


    A real wah starts out slow from the heel position, and then at the end of it there's a lot happening. It's just a matter of not having to move your foot so much to get the quack, if that makes sense? For up tempo songs it can be almost physically impossible to wah fast enough with all the travel.....


    After some getting used to it can work ok. But it's still more fun to play with a real wah, even if the Kemper makes totally awesome wah sounds in itself!
    Right now i am playing an automated set, where everything (including wah) is controlled over midi so i haven't thought about this in a long time. And yes, when i drew the automation curves to make it sound right, it's pretty darn steep at the ends of each expression!

    I just learned that different guitars can drastically change the feel and response of an expression pedal also.
    Using the expression pedal in Input location for volume, I was getting great sounding swells with my P90 loaded strat. Switched to a Gretsch Falcon and the swell only occurred in the very last part of the pedal throw.


    I tried changing the inout sensitivity but that didn’t help.
    I added a compressor and moved the exp pedal to pre stack. That helped a little but again I really just needed to be able to change the curve of the exp pedal to compensate for the change in pickups.

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    I've just stuck a multi meter on my Mission SP1 and the taper appears pretty much linear as it should be.


    I've also rechecked the taper on Page 5 of the System Menu. When I use it as Type Wah it appears to be pretty linear but very difficult to control - i.e. it doe nothing for the first part of travel then move rapidly through the rest of it's travel until the last portion where it does very little again. However, when I set Type to Volume it appears to move in a Logarithmic taper like a normal volume pedal. That leads me to believe that;


    A - the Kemper is programmed to respond differently to Expression and Volume peal types (as @ckemper said in an earlier post this was a user request for volume and it seems to be performing as you would expect.


    B - either the Mission SP-1 has a crappy taper and too narrow a range to be used for anything that requires precise control or the Kemper isn't responding properly (too sensitive) at the extremes of the range. Although the SP1 tests as "fairly" linear I don't have any way to accurately test whether it is truly linear or a bit off. I suspect that the travel on the SP-1 just isn't long enough to make accurate use for expression control easy.


    Conclusion I think I might be on the look out for a new expression pedal - perhaps a Dunlop DVP1XL?

    I have a DVP1XL. Built like a tank. I haven't really checked to see whether it has a great range or anything, but I like it a fair bit. Only issue imo is the weight and size. The damn thing is huge, and weighs around 2kg. That's about a third of the weight of the Kemper. Add more than one and it adds up fairly quickly.

    I have changed the Volume Pedal towards more logarithmic. The modification will be available in the next firmware update. I opted against an adjustable curve for now, as I think there can be an optimum curve for all purposes, without the need to fiddle around. I am exited to hear what you think.


    Concerning the wah curve: I checked our wah against my analog cry baby. To me both behave the same. The curve is fully logarithmic as well.


    Please check the linearity of your pedals using the bargraph on the respective pedal page. Some pedals, like the Yamaha FC-7, require to set Pedal Type 2, as its connection is reversed.

    Quote from ckemper

    I have changed the Volume Pedal towards more logarithmic. The modification will be available in the next firmware update. I opted against an adjustable curve for now, as I think there can be an optimum curve for all purposes, without the need to fiddle around. I am exited to hear what you think.


    Concerning the wah curve: I checked our wah against my analog cry baby. To me both behave the same. The curve is fully logarithmic as well.


    Please check the linearity of your pedals using the bargraph on the respective pedal page. Some pedals, like the Yamaha FC-7, require to set Pedal Type 2, as its connection is reversed.


    I think that's great, Mr @ckemper! A logarithmic curve for the volume pedal makes a lot of sense.


    May I ask if it would be possible to have the option to have the option to select either the logarithmic curve or the regular linear curve? That would tie in well to any future plans to offer multiple curve shapes such as different log curves, or maybe spline curves or whatever you think would make sense.


    Not that spline curves make sense to me just as a theoretical shape. But it would be great to have the option to select various curves for the volume pedal, which could later perhaps be extended to other expression pedal functions (wah, pitch, morph) as well.


    PS: I can already do this with my Gordius Little Giant foot controller. Just dictate how it sends the values to the Kemper. Works like a charm :)

    Our volume pedal has always been logarithmic, it has never been linear.
    And you wouldnˋt like it to be linear because it would feel awfull.
    I have changed it now to be even more logarithmic.

    Quote from ckemper

    Our volume pedal has always been logarithmic, it has never been linear.
    And you wouldnˋt like it to be linear because it would feel awfull.
    I have changed it now to be even more logarithmic.

    I have to confess to not being an expert on what is happening under the bonnet *hood as the American's say) but the issue of Log V Linear tapers and how they feel seems to be a player preference thing. For Volume I am definitely in the Log camp. It makes perfect sense as that is how our ears work. However, I have friends that switch out the Log Volume pots in their Les Paul's as soon as they get them because they like the way a linear pot works. I know why they do it and understand the playing/feel reasons why it works for them with volumes. It definitely isn't something I like but each to their own.


    Wahs (and expression pedals) seem less clear to me though. If I understand correctly some Wahs have a linear pot others a Log pot but most are Semi Log (a sort of S taper) where there is practically nothing happens at either end of the travel. Again, I understand how this feels in the analogue pedal world. However, I don't know how it translates to the digital world. It does seem to me though that a different taper may be relevant to individual uses (volume, wah, Tremolo Speed etc)