How do I turn a volume pedal into a pan pedal?

[axg20202]

I'm hoping it can be done with a single-gang pot (possibly the existing pot) to allow a mono in, left and right outs configuration, with the pedal acting as a balance control for the left and right outputs. Not sure how to wire it up though.

Thanks.

[R.G.]

Input connects to two 50K resistors. The free end of each resistor then goes to one of the outside terminals of POT. POT is 100K linear. Outer terminals of POT also go to output jacks. Wiper of POT is grounded.

[DougH]

A little off-topic but the pan idea reminded me of this, a "morph" pedal for morphing from one pedal/amp/etc to another: http://home3.netcarrier.com/~lxh2/morph.html

I thought this was a pretty cool idea, and similar to R.G.'s pan pedal solution- only backwards (reverse the ins and outs).

[joegagan]

i used to get all bent trying to make passive blend pedals work (100%wet/dry at each end), and not suck tone.

then i realized that probably over 90% of guitarists have some kind of buffer in line that is on all the time.

if the blender is after the 1st buffer, the signal is suitably conditioned for whatever you wanna do to it, blendwise.

sounds obvious to some of you guys, but i was a true bypass player.

[DougH]

Yeah, buffering the inputs of the morph pedal is probably not a bad idea for general use. It was designed for the LXH2 preamps though which already have buffered outputs IIRC.

[axg20202]

Input connects to two 50K resistors. The free end of each resistor then goes to one of the outside terminals of POT. POT is 100K linear. Outer terminals of POT also go to output jacks. Wiper of POT is grounded.

Excellent. Thanks RG.

Do you think a 250K pot would be OK to use? FWIW, I'm actually modding a reissue Fender Volume/Tone pedal. The tone part of the pedal is a side-to-side movement of the pedal, which will lend itself well to the pan control. I need to check the tone pot value, but it will probably be 250K.

As for Joe's buffer comments, I'll be using this pedal directly before my stereo delay pedal, which is the last in my chain, so hopefully tonesucking wont be a problem given that I do have buffered pedals in my chain.

[ayayay!]

My goodness, this takes me back a ways.  There was a store in SE Kansas City that used to sell an amp that they generically called a "Fender Blender."  It was two discrete amps built into one cabinet, and you "blended" between the two amps with this same type of foot pedal.  I'm wanting to say circa 1993.   Ring a bell with anyone?  

It was awesome by the way!  

[joegagan]

ahh 93. the boutique amp names that come to mind are torres, weber/kendrick, dumble, bedrock, groove tubes sovtek (wow, bassman circuit built by russians , whodo thunk it?)matchless.

there was a really cool amp shootout in guitar player mag around 90, this was the article that literally launched matchless, as they were not quite in production at press time but won the shootout.

[joegagan]

oops , went OT again

my specialty , sorry

[DougH]

Jono, there was a boutique amp that came out a few years ago with a pedal for blending between sounds. I don't remember what it was called. I 'think' Joe Bonamassa uses one but I don't remember for sure.

Anyway, it was kind of hyped as this big "ooh! ahh!" technical achievement at the time. But I think the blend pedal is a very cool idea. There are all kinds of possibilities esp when you start plugging different effects into it.

[A.S.P.]

every FX pedal oughtta have a blend-between-sounds expression jack!

[joegagan]

doug , was it gerlitz?
http://www.gerlitzampsac.com/



didn't it have a twister foot control?

[joegagan]

twister:
http://www.gerlitzamps.com/html/features.html

scroll down

[ayayay!]

ahh 93. the boutique amp names that come to mind are torres, weber/kendrick, dumble, bedrock, groove tubes sovtek (wow, bassman circuit built by russians , whodo thunk it?)matchless.

there was a really cool amp shootout in guitar player mag around 90, this was the article that literally launched matchless, as they were not quite in production at press time but won the shootout

What a great time.  Yes, it was this same time at this same shop on the same trip to the store when I saw and played my first Matchless.  Never seen one (in person) since. 

Back on topic... I don't remember what kind of amp it was.  It was... Heh, it was too long ago to be honest.  Nice tweed looks, but the pedal was just a simple volume-looking pedal.  Chrome with rubber treadle if I recall.  I like this topic.  Brings back great memories. 

agx20202, let us know how it turns out. 

[axg20202]

Input connects to two 50K resistors. The free end of each resistor then goes to one of the outside terminals of POT. POT is 100K linear. Outer terminals of POT also go to output jacks. Wiper of POT is grounded.

Excellent. Thanks RG.

Do you think a 250K pot would be OK to use? FWIW, I'm actually modding a reissue Fender Volume/Tone pedal. The tone part of the pedal is a side-to-side movement of the pedal, which will lend itself well to the pan control. I need to check the tone pot value, but it will probably be 250K.

BUMP 

[joegagan]

ya axg, 250k will probably be ok, you will want to check to see if the taper works for your application. every rig is different.

if you would like to try different tapers , i imagine that fender used a CTS pot in that pedal, should be easy to find something of different value that will still physically fit.

[DougH]

Joe, Gerlitz sounds familiar but I don't remember the "twister" part. I thought it was just a regular pedal like a wah. But it's been a few years, they may have changed the pedal design.

[axg20202]

ya axg, 250k will probably be ok, you will want to check to see if the taper works for your application. every rig is different.

if you would like to try different tapers , i imagine that fender used a CTS pot in that pedal, should be easy to find something of different value that will still physically fit.

Could be CTS, but on inspection it's not one of the usual CTS pots as used in Fender guitars, for example. It is a more typical volume/wah pedal type pot with a domed black casing on the back. (You should see inside this pedal - very neat design based on two sprung cord pullies). I guess I'll have to measure the pot value and taper, because it doesn't have any obvious markings. The shaft has an additional fitting screwed to it which acts as a guide dolly for the pully cord. I'd rather not mess with this if I don't have to.

[joegagan]

doug, the gerlitz has had the rotary twist foot control going back to when i first heard of them around '01 iirc it was part of their big marketing thing, pretty flashy!

axg, i have seen the inside of one of those pedals but it has been a while. a buddy of mine was buying all the weirdest stuff off ebay for a while. if it had a footpedal and was cheap enough, he would buy it.

if you don't want to mess with the pot mechanism, good luck , and hoping the taper will work well for your app.

you can always use the davisson taper resistor calculator to mess with tapers using trimming resistors, easy to do without messing with the mechanicals. provided you want to try a smaller value pot than 250k

[Mark Hammer]

The circuit type that RG suggested (linear pot, wiper to ground) IS the very thing that stereo amps have used with considerable client satisfaction for well over half a century now.  The missing detail is that while stereo balance controls are normally intended to be a set-and-forget control, the intended use here - as a morph pedal - is a more dynamic control.  As a result, the transition over time (and time really means a matter of moments here) is an important aspect of the circuit.  And for that transition to be palatable to the ears, it needs to be logarithmic.

Getting a pot that has a log transition from midpoint to outer lug, and a log transition from midpoint to the other outer lug is a near impossibility.  Getting a dual-ganged pot that is log for one half and anti-log for the other half (where they would be wired up as opposite-direction volume pots), is only slightly more likely.  Consequently, what you need to do is use a parallel fixed resistor between wiper and each outside lug to nudge the taper of the pot a little more in the direction of that.

What THAT suggests is that you start out with a higher value linear pot to begin with, such that you have a wider range of parallel tapering resistors to choose from.

Just as a thought, the fading in and fading out of a signal is more noticeable if there is an accompanying change in the bandwidth.  That helps one signal to psychoacoustically fade into the background even before the overall level has been significantly affected.  So, if the treble is cut at the same time as the level is cut, it can seem like a smoother transition.  The way to possibly accomplish that would be to have a linear dual-ganged pot.  One half is wired up exactly as RG describes.  The second half is wired up more or less the same way, except that there would be a cap between the outside lug and its connection to the 50k/47k series resistor.  As you move the pot shaft, in one direction, you decrease the resistance to ground of the attenuation portion, but you also decrease the resistance to ground for the cap on that side, rolling off treble, exactly as you do with a guitar treble-cut "Tone" control.

Actually, now that I think of it, do it this way:

1) Buffered signal goes to the input of the "pot" formed by the 47k series resistor and the leg of the half of the pot with the wiper to ground.
2) As it does on a guitar, a cap goes from the input side of the 47k resistor to one outside lug on the other half of the dual-ganged pot.
3) The wiper of each pot half goes to ground.

What you end up with is essentially the same thing as a guitar tone and volume pot, except you turn them both up at the same time, while turning the tone and volume down for the other side at the same time.  That, and the use of well-chosen parallel tapering resistors for the level-adjusting pot should yield a pretty convincing and comfortable morph.