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Greetings from Cajah’s Mt. …
I have just gotten my Red Special finished and it seems to be working fine. The only thing that seems off is that when I pick or strum heavily with the guitar volume turned all the way up, I get a heavily distorted sound (kinda like a blown speaker or amp). The note does smooth out after the initial spike, and if I dial back the guitar volume or pick lightly the “blatt” doesn’t happen. (I am using a guitar with a fairly healthy humbucker, btw.)
I don’t have a B5k pot for the Sag control yet, so I placed a jumper between pins 1 and 2 as described in the build instructions.
I did have an issue with biasing Q3. I couldn’t get the voltage below 7 volts. I tried all four of the 2N5457s that I have on hand, but, no joy. ( I had the same problem with biasing the 2N5457s on another build, so they may be the problem).
If they are the problem, is there a substitution or other workaround available?
Also, why is there a place for a diode (D2) on the pcb that isn’t shown on the build instructions? Jus’ wonderin’ ????…
Thanx????
I would absolutely be using the Sag pot.
In retrospect I am not sure why removing it was ever mentioned as an option.
You can put a 1N4001 in the D2 slot.
Adding the SAG pot will allow you to reduce the gain of Q1 by reducing the voltage going to Q1. It will also reduce the voltage going to the BIAS pot. This may allow you to achieve a bias voltage at the Drain of Q3 that is within the desired limits.
These changes may solve your issue of overloading Q1. If not you may wish to either reduce the input level at the guitar or add an additional resistance at the input jack. Maybe 50-100K would do. I hope this helps.
Hey Barry…
I plan on installing the Sag pot when I get one in. I was going to use a 5k trimpot in place of the b5k until then, but, when the “blatt” showed up, I went with the jumper in case that might be an issue. Ya just never know…
So, neither the “blatt” (I used to play trombone in high school and when the director wanted a short, sharp, loud, distorted sound from us, he said he wanted to hear a “blatt”, and that’s what it reminds me of…), nor the over-biased 2N5457’s are an issue? Or, would the Sag pot fix the situation. I can stick a 5k trimpot in if that’s the case. Just lemme know…
Thanx again ????
Thanx again, guys ????
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