8.2K + 10K MO Resistors

[GUITARmole]

Can anybody tell me what "the deal" is with the MO resistors to the left of the 10uF bias resistors? I see on the '67 layout that it only uses the 8.2K where the '68 and later use an 8.2k and a 10K resistor in series.

Does it matter which layout I use and if it affects the tone going from 8.2K to 18.2K resistance...how so?

As always any and all help is GREATLY appreciated! Thanks in advance!

[rockstah]

Can anybody tell me what "the deal" is with the MO resistors to the left of the 10uF bias resistors? I see on the '67 layout that it only uses the 8.2K where the '68 and later use an 8.2k and a 10K resistor in series.

Does it matter which layout I use and if it affects the tone going from 8.2K to 18.2K resistance...how so?

As always any and all help is GREATLY appreciated! Thanks in advance!

in general the higher the total resistance here the more preamp gain the amp will to have.( ie metalfaces which had two 10k here) the lower value u mention will give less preamp gain. ( ie the earlier plexi's where u see a single 8.2k here. )

[GUITARmole]

Is it enough of a difference in gain to warrant a toggle switch to bypass the 10K resistor or is it just a subtle gain boost w/ both resistors?

I'm still waiting on that chassis....(didn't arrive in the mail today) but getting the board ready in the meantime.

Thanks for the info!

[Flames1950]

I don't truly hear it as any gain boost, but I hear a difference in the compression of the amp when distorted -- but it kind of depends on if the voltages start off low enough that the extra resistance makes the difference. Start off with 450VDC and the effect may be quite noticeable, but starting with 500VDC it may be very subtle indeed. If the voltages are too low right off, it may suck the life right out of the amp to add the extra resistance -- the '78 50-watter I used to have ran at 402VDC or so, and with both resistors it was one dead fish; removing one was enough to make it liquid-y but lively too.
All of which amounts to try a jumper in place of one, and see if it matters enough to your ears to warrant any more experimenting.