Impedance & Buffering question

Jon Light · From: Saugerties, NY

I'm messing around with my Fender Volume/Tone pedal and I've got a buffering effect on a loop box so that I can A/B my sound with & without the buffer. Signal chain is steel>buffer-in-a-loop>pedal>amp. Without the buffer, I get the expected doo-wah effect with the swivel of the pedal. But when I switch the buffer in, it alters the effect of the tone pot and reduces its affect on the tone to next to nil.
What's up with that? I'm severely challenged in my understanding of hi-z, lo-z kinda stuff and I expect that the answer will require an understanding. But is there a simple explanation? Does the V/T rule out using something like a black box?

Brad Sarno · From: St. Louis, MO USA

Jon,

the value of a capcitor in a passive tone control like that on a guitar or in that vol/tone pedal is dependent upon the impedance of the circuit at that point. If you buffer before the tone control, then the impedance is lowered and suddenly that tone cap value is way too small to have any effect. The lower the impedance, the larger the cap required.

The trick for those vol/tone pedals is that they need to be first and "see" the pickup unbuffered. With a buffer like a matchbox or black box you'd simply put that vol/tone pedal before the buffer, and it'll work like it should.

Brad

Jon Light · From: Saugerties, NY

Great, Brad. Thanks. The important part of your answer is just the confirmation that I was right in my assumptions about what the problem was. I guess I didn't take it to the next step which involved ditching the iron-clad assumption that the buffer should always be the very first thing the pickup sees.
Cool.

Brad Sarno · From: St. Louis, MO USA

Yea Jon. There are sometimes situations where a buffer should NOT be first. The most common situation is with fuzz pedals like the old Fuzz Face or other similar circuits. Those really like to see the volume pot and/or the pickup directly. Also in your case, a passive tone control like what's in that pedal.

Brad

Garry Vanderlinde · From: CA

That's the best explanation I've heard. This has been driving me nuts for a while Confused

I first experienced it when using a Super Bro in front of a Bigsby V/T pedal and then when using a '80's Ibanez Tube Screamer in front of a Fender V/T.

In both cases the Tone side-side became non-functional.

To get the distortion to work correctly you have to have it before the volume. So what do I do? Is there a distortion pedal that will work in this situation?

Brad Sarno · From: St. Louis, MO USA

Garry,

You're not likely to be able to have any active device before the vol/tone pedal and still have the tone control part of it work right. Your tubescreamer, even when bypassed, is still buffered. I belive Boss pedals will create the same problem. What you'd want is a mechanically switched overdrive pedal, preferrably one with true-bypass. That way, at least when you aren't using the distortion effect, the tone control in the V/T pedal will get to directly see the pickup and act as the tone control you want. If you like the tubescreamer tone, there are lots of other varieties of that pedal out there that use a true, mechanical bypass switch instead of the FET switching like in a real tubescreamer.

Here's a true-bypass tubescreamer.

http://www.maxonfx.com/reissue/od808/

Brad

Garry Vanderlinde · From: CA

Thanks for the tip! I checked out the Maxon and the OD808 is not listed as true by-pass whereas the OD-9 is.

Jon Light · From: Saugerties, NY

Garry--there are so many flavors of Tube Screamer clones. One that I like is the Voodoo Labs Sparkle Drive. Their unique contribution to the field is that in addition to a distortion control you also have a blend control that adds as much or as little of the clean signal back into the output as you want. 100% clean is just that--a clean boost (about 95% uncolored). This is good for pushing tubes and I find that it also adds some...I hate to say 'sparkle' but that's the word that comes to mind...to a solid state rig. And the unit is true bypass. I clip it to the steel leg.
Sparkle Drive
As to your original quest---if you were hoping to feed a distortion device into the v/t pedal, it looks like you (we) are SOL. I am thinking about adding a tone control to my steel, though, lap steel style, pinky activated.

John Groover McDuffie · From: LA California, USA

I second the recommendation of the Sparkle Drive. I bought it for and use it with elec. 6-string, but I like it for steel too, better than any other overdrive/distortion device I have used. FYI I have a Maxon 808 also, and I prefer the Sparkle Drive.

Jay Ganz · From: Out Behind The Barn

I've been using this lately. Best I've ever heard yet Exclamation

Check it out

Jon Light · From: Saugerties, NY

The RC & AC Boosters have been on my items of interest list for a while. Now I've got to add the BB Preamp.

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