Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on November 18, 2011, 04:10:36 pm
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Hi, I need to hook up a fat switch to a JCM800 . A device that doesn't pop when switched, and that doesn't hum either. Any drawing / schem ?
Regards
Colas
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You can put a cap (1uf - 4,7uf - 22uf) bypassing the 820r resistor in the V2A cathode. I have done it several times without problem.
In one of my amps, i activate it via a footswicht (no relay, just close ground connection). You can put a 1M resistor as "anti-pop", but it dont use to be necesary.
Works like a champ
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cool, thanks I'll get back to you when it's done.
Colas
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You can also put a cap across your 470p and 470k resister put a .0022 on one end and 1 meg resister on the other and join them in the middle then put the switch on both ends of the 1 meg which shorts the 1meg resister out of the equation when you flip the switch.
Causing the .0022 to boost the low and upper mids. without any noise. I used it for a solo boost in one of my amps sounds great in a jcm 800.
Thanks Bill
You will have to forgive my odd explination its late and Im tired. :think1:
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Another fat boost is to switch in an 82k resistor in parallel with the 470k resistor in the signal path.
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Just some different examples. There are other ways also. Some of these aren't applicable for the JCM800 but I thought I'd illustrate them anyway
I have used the Dumblish style mid boost and preamp boost on tone stack after a cathode follower and like them. No noise switching
with respect, Tubenit
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cool diagrams, thanx, brotha'
Colas