Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: steven on January 30, 2011, 02:27:08 pm
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Well, after building about a dozen amps, I built one where I finally _really_ followed Doug's grounding scheme, to the letter.
Whuddya know, quietest amp I've built. The only hum is coming in through the single coil pickups.
"do not try and re-invent the wheel" indeed.
Thanks, Doug. I'll keep this wheel.
steve
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I tried my best to follow Doug's grounding scheme to the letter but I have so much noise the amp is unusable. I don't blame the scheme though, I'm sure I've done something wrong.
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I've used Doug's grounding scheme on every amp I've built. It works great for me!
With respect, Tubenit
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Unable to leave well enough alone, I've never exactly followed Hoffman's grounding scheme. It always is my starting point though. Insulated input jacks with a separate ground lug very close by give me more confidence. Likewise, insulating the speaker jack so I can experiment with its grounding point has worked out well. High current there. Also, advice to ground the PT actually at the negative end of the "reservoir cap" (first in power rail) makes sense in terms of minimizing ground loops.
All that said, Hoffman's approach has worked really well for me. If you study Doug's layouts & grounding scheme closely, it's very close to the "galactic" ground approach Kevin O'Connor advocates.
Indeed a big THANK YOU goes out to Mr. Hoffman.
Cheers,
Chip
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I tried my best to follow Doug's grounding scheme to the letter but I have so much noise the amp is unusable. I don't blame the scheme though, I'm sure I've done something wrong.
My amp is very quiet now and my problem had nothing to do with Doug's scheme. The fact that the amp is quiet now probably has a lot to do with Doug's grounding scheme though, especially considering the challenges with my build - transformers very close to each other, very small chassis, etc.