68 board layout question
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68 board layout question
Hello all. Had a dumb question about the differences in using the 500/560pf capacitors on the board. I am building a 67/68 100w (haven't finished it quite yet) but I decided along the way to use the '68 board layout in Georges board layout section. I noticed that diagram uses the dual 560pf micas on the board. I have yet to see another original amp using this setup or a replica for that matter. Mabey its not too popular a setup? Most I see use the dual 500pf or the 500/250pf combination. Anyone here use the 560/560pf setup and what are your thoughts vs. the more common setups? I know alot of it will be my personal preference. I'm just looking for personal opinions in what I should expect from this setup vs. other more popular arrangements. I am also using the 33k/470k setup and the (7) .022 mustards if this helps. Thanks in advance.
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Re: 68 board layout question
For the mixer bypass, using 560pF vs. 500pF will lower the high-pass corner frequency slightly so it will pass a little bit more mids (around 600Hz).
560pF in the tone stack will also add mids but higher in frequency, around 1kHz.
Both of these will add a tiny bit of overdrive gain (mainly the tone stack one) but it and the frequency changes will be extremely subtle. You probably won't notice a difference when compared to 500pF.
560pF in the tone stack will also add mids but higher in frequency, around 1kHz.
Both of these will add a tiny bit of overdrive gain (mainly the tone stack one) but it and the frequency changes will be extremely subtle. You probably won't notice a difference when compared to 500pF.
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Re: 68 board layout question
I'm sorry, but what's 33k/470k setup?wrea398 wrote:I am also using the 33k/470k setup and the (7) .022 mustards if this helps. Thanks in advance.
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Re: 68 board layout question
Tone stack resistor is a 33k and the normal and bright channel mix resistors are 470K. I have heard others ask what you had installed when talking about the 500/560pf micas, so I included this info in my question.
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Re: 68 board layout question
Thanks for the quick reply. I just thought it was wierd that NOONE uses this setup as I can find. Thought there might be a better solution for a better reason. I would be interested in a little more mid and gain anyway so mabey I will like this setup. I'm still learning...
toner wrote:For the mixer bypass, using 560pF vs. 500pF will lower the high-pass corner frequency slightly so it will pass a little bit more mids (around 600Hz).
560pF in the tone stack will also add mids but higher in frequency, around 1kHz.
Both of these will add a tiny bit of overdrive gain (mainly the tone stack one) but it and the frequency changes will be extremely subtle. You probably won't notice a difference when compared to 500pF.