Hey folks, after looking at countless posts of using buffers here, and using buffers there, I thought, how about I use a circuit not specifically for volume pedals, but use the output pot as the volume control (DUH! That's what it's for), so right now I'm looking at the LPB-1 schematic.
(http://www.beavisaudio.com/schematics/Images/Electro-Harmonix-LPB-1-Booster-Schematic.png)
My problem is, a boost actually BOOSTS, and I want the signal to be the same dBs as bypassed. From what I understand, I can insert a potentiometer before the Volume pot to "attenuate" the signal, effectively making a MAX VOLUME control. Another circuit I was looking at had a resistor going from lug 1 of the volume pot (or 3, whichever one went to ground) to ground, and someone on DIYSB suggested that I could replace that with a pot for a MIN VOLUME control. Is this right or am I dreaming too hard? Also, does this mean if I max out the MIN VOLUME knob, I can guarantee zero signal at heel down position?
I'm not sure if I understand completely. You want a boost, but you also want the same volume?
Quote from: mattlee0037 on February 14, 2014, 06:46:40 AM
I'm not sure if I understand completely. You want a boost, but you also want the same volume?
Okay, so I don't want to use it as a boost. I just know I need some sort of circuitry for my volume pedal. I don't want it to just be a passive VP with one pot. Instead of worrying about which buffer to use and where to put em, and how much buffers to use, I thought I'd just use a boost circuit (since they're the most easily accessible to me) and attenuate the output so it matches my clean signal, and then use the output (or "boost") potentiometer as the volume control. Hope that clarifies it up.
Simply take one of these http://www.muzique.com/lab/buffers.htm and add your volume pot at the end...
Quote from: kothoma on February 14, 2014, 07:10:17 AM
Simply take one of these http://www.muzique.com/lab/buffers.htm and add your volume pot at the end...
Oh shoot, is it really that simple? Man, he has a lot of variations for biasing the transistor. Is that all for input impedance?
Yep, the two variations with the NPN transistors mainly differ in the possible input impedance.
I'd use the second one, the one from the TS:
(http://www.muzique.com/images/buff1.gif) (http://www.muzique.com/images/buff6.gif)
Quote from: kothoma on February 14, 2014, 09:22:56 AM
Yep, the two variations with the NPN transistors mainly differ in the possible input impedance.
I'd use the second one, the one from the TS:
(http://www.muzique.com/images/buff1.gif) (http://www.muzique.com/images/buff6.gif)
What's the difference between those two transistors? One has it's legs straight, and another slanted... Do they refer to different types of tranny?
The straight one is a jfet and the slanted one is a bjt.
Functional difference, from what little I understand of it, is quite well presented in the article.
Thanks! I will refer to the article! In a volume pedal, do I need to put a buffer both before and after the pot?