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Hi Gents,
Here is my Stones 69 build pic. Kit sourced from Die Muzik Ding. How do you set bias with multimeter? Ive only done it by ear!
Very well done.
Put your DMM on V and measure with a Red probe on the Drain Lead of J113 (Q5) and put the Black Probe on any Ground.
Adjust the trimmer till it reads between 4.5v and 6v whatever sounds best to you.
Cheers, thanks!
so this is weird..i built another and the difference in sounds between the two is like chalk and cheese!? this new one has way more volume headroom and had gain even when the gain is at zero? the first one was a little disappointing, didnt really have much grunt but this one is almost,like a Rat! what could have caused the difference? And i have biassed t5 correctly! Im baffled!
The two circuits by schematic would be identical so the difference is either an error (most likely) or just the differences in tolerance of components.
A faulty component (anything)
Possibly a heat damaged component (transistor)
It really cannot be much else to describe that much of a difference.
I guess it is good to know that one of them sounds like you would expect.
Michael – what Barry said is quite true. In all my years working with audio electronics and specifically pedals, no two sound exactly alike. When they do sound very close, it’s a fluke or there is enough distortion built-in to the circuit, that any differences in the result are aurally indiscernible.
Michael, since you have all the transistors socketed, you could always see what happens when you swap the transistor sets between the two builds. You will then at least know if your issue is with the transistor tolerances/biasing. While I don’t have nearly the expertise as these other gentlemen, I have noticed that even when using the same type of transistors in two builds of the same circuit, I may need to bias each differently to attain a passably equal sound. Good luck!
thanks for the feedback. I will try swapping the Transistors, in the second one I actually didn’t trim the legs, maybe thats the difference?
I also slightly singed the 100n and 1n capacitors, would that cause the difference?
Fixed it! Very simple solution..look carefully at v1..Q4 is actually in the wrong way around, flipped it and I got my ya ya’s out!
Pedal gets very noisy why you crank the gain!
Cheers and thanks!
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