Low output on an TB MKII. Bias pot to large?

Started by PurpleStrat, August 02, 2008, 04:57:09 PM

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PurpleStrat

So I have a second Tone Bender MKII build I am messing around with. The volume seems to be way to low. Unity is all the way up. The only difference in this and another MKII I have is the bias pot. This one has a 100K and I don't have anything closer to use at the moment. Can the higher bias pot effect the out put?

BTW I swaped the transistors from my "good" MKII and the problem is still their.

kurtlives

100K seems to large. I always replace the 8K2 with a 10K trim pot to bias.

QuoteThe only difference in this and another MKII I have is the bias pot.
You sure about that..?
My DIY site:
www.pdfelectronics.com

petemoore

  100k will make it much hard [if not impossible] to locate a resistance which biases the circuit.
 20k spreads the range of useful resistances across a wider portion of the wafer, making it easier to set up proper bias.
 
Convention creates following, following creates convention.

PurpleStrat

Quote from: kurtlives on August 02, 2008, 05:01:21 PM
100K seems to large. I always replace the 8K2 with a 10K trim pot to bias.

QuoteThe only difference in this and another MKII I have is the bias pot.
You sure about that..?

Yep I went at them both with a DMM and everything is the same.

PurpleStrat

Quote from: petemoore on August 02, 2008, 05:02:25 PM
 100k will make it much hard [if not impossible] to locate a resistance which biases the circuit.
 20k spreads the range of useful resistances across a wider portion of the wafer, making it easier to set up proper bias.
 

It is hard but I can get close enough by ear that it sounds good. Problem is I have to raise it higher to compensate for the low output. Then it does not sound so good.

PurpleStrat

Sorry I do have one other difference!  :icon_redface: From what I understad though it should not lower the output.