70's Volume Pedal Mod?

Dean Parks · Post by **Dean Parks** » 11 Mar 2015 3:22 pm

In the 70s, Red Rhodes told me about a volume pedal mod that reversed the usual brighter full-volume portion of the volume sweep. The result was a pedal that was bright in the quiet position, and rolled off the extra treble as the volume pedal was made louder.

Does anyone have experience with this, and if so, on what recordings (or in what years) would this have been used?

Stephen Cowell · Post by **Stephen Cowell** » 11 Mar 2015 5:55 pm

Sounds like a simple bypass cap on the pot... same trick used for straight guitar too. Place a small value capacitor between the top contact and the wiper (bottom contact to ground) of the pot... as the pot is turned up the cap is shorted, removing the capacitance from the circuit.

Choice of cap, and optional series resistor (inline with the cap), will determine the amount of effect. I'd buy an assortment of caps and a 50K pot (to use as a variable series resistor) and experiment until I got it right. Change pickup, put a buffer/box in front of the pedal... everything changes, that's why I can't tell you what exact values to use, it all depends on what your system criteria are. Here's a link describing it in detail...

http://www.ratcliffe.co.za/articles/volumepot2.shtml

Hope this helps!

Jim Smith · Post by **Jim Smith** » 11 Mar 2015 8:50 pm

Just reversing the input and output cords will do that, but it might be more of a change than you want.

Jerry Roller · Post by **Jerry Roller** » 11 Mar 2015 8:57 pm

Dean, it seems you are referring to what steel players know as the Weldon Myrick mod. Weldon used a second pot in the guitar. It has been a while since I have seen one so I did a search and found this post that Craig Baker posted. Upon closer reading I'm not sure this is the Weldon mod or not but I'm sure you can easily find it.
Jerry

Stephen Cowell · Post by **Stephen Cowell** » 12 Mar 2015 5:09 am

There's no cap on that diagram... it ties the input to the output via a pot. What this does is load the guitar more when the volume is low... effectively doing what Jim suggested, but in an adjustable manner. I'd think it would tend to lessen the brightness at low volume, not accentuate it... but then, I haven't played with it. It could do that, by bypassing the top resistance of the pot when the wiper is low. There are effects (BB) that rely on loading the pickup more, so this might do what you want. Easy to try!

Craig Baker · Post by **Craig Baker** » 12 Mar 2015 9:20 am

To accomplish the reverse roll off described by Dean, it seems to me that you would require a dual pot. (two pots on one shaft) While the volume pot increased the level going to the amp, the tone pot would increase the capacity from signal to ground, attenuating the highs as the guitar became louder.

Craig

Donny Hinson · Post by **Donny Hinson** » 26 Feb 2023 5:03 pm

As I recall, A "T-pad" circuit uses concentric pots to maintain impedance when volume is lowered. An "L-pad", what is essentially like our pot-volume pedals, keeps the impedance on only one end constant, while a "T-pad" keeps both input and output impedances constant. (It does this without any capacitors.) I suppose we don't see these because 1/2-meg, dual-concentric, log-taper pots are quite rare.

In addition, some players used to install a small bypass cap in their pedals to allow the highest frequencies to bypass the pot, maintaining some of the highs that were lost due to the impedance change when the volume was lowered.

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70's Volume Pedal Mod?

70's Volume Pedal Mod?

Reverse roll off