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The mid and late 70's preamp schematics have a dashed line indicating that some amps had this 47 nF cathode bypass cap and some didn't. Is there a particular reason when and why it was/wasn't used? What is the tonal affect of adding this?

I was playing bass with my 2-input DR504, plugged into the Normal channel and I happened to have the Bright channel turned up really high. There was a lot of background noise that went away as I turned it down. Out of curiosity, I turned Bright channel back up and turned the Normal channel all the w...

Cool, I like it! I can't believe that is Amplitube.

Dr.HIWATT wrote:And these beauties just for the DR201's

Will these be available separately? My 201 has been patiently waiting for a recap.

teethdream wrote:So I guess I should try to track down a NOS replacement for it and maybe start there

Mine has recently replaced Arrow NOS mains and standby switches from VHR, and it still pops.
Since mine has not had a cap job, I assumed that was the issue?

My '78 DR201 does the exact same thing. Switch wiring looks like yours.

They certainly would, but I would use the end sockets: O x O O x O A proper KT88 installation has those long thin ventilation slots on either side of the tube sockets. --mark Really, wow that opens up the opportunities. Mark, what does this do to the output impedance? Would you have to compensate?

I've been tempted to try the EHX 6CA7 in mine for bass use. I don't hate the Winged C EL34s I have in there now, but I am curious. They are described to be sturdy and have big sound with more headroom than EL34s.
They are not too expensive either.

That sounds just like mine. It is a simple circuit, how can the BYOC clone be so bad?
Dang, I was so close to buying the MJM BritBender before I ordered this kit.
Thanks for the info.

jason

I just built a BYOC ESV Tonebender clone,and it is VERY fuzzy, but the "attack" knob seems to have little effect on the tone or character or anything for that matter? I have no point of reference and can't see any mistakes in the build, so I was wondering if anyone has experience with the ...

Never used them in a Hiwatt, but tried to tame a Fender Hot Rod DeVille with them. What I wanted was bedroom level cranked tone, and Yellow Jackets don't do that. Basically, they will give your amp the character of a lower wattage EL84 amp, which isn't a bad thing if that is what you are after. Neve...

Got it, one 27k resistor and she's idling happily. It sounds awesome, and LOUD!

I need clarification in the values I posted above measured the cathode current, and by measuring plate current through voltage drop the average is ~3-5 milliamps lower, which I understand is screen current. Plate voltage: 675 Bias Voltage: -37 Left: 32.3, 35.1, 32.9 mA (delta V 1.774/20.2 ohms = 84....

No this one has the alternate configuration, still a separate bias winding but fixed. I see your diagram shows -46V, I only measure -37V right now, so you think it will take a large change in resistance to bring it in?

Thanks Mark, that leads me to the next question. The bias resistor is 22k right now. I have values of 24k, 27k, etc in increments of 3k. I would like to avoid solder, test, solder, test, so in your experience can you tell what a good increment would be to get close with the operating parameters above?