Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: john_t on November 10, 2014, 08:33:26 am
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I am pretty much ready to wire up my 5f1 build. The ground bus coming off the board from 1,5 r to the input jacks and volume control. I am using high low jacks. Will the jacks be a sufficiant ground point or should I ground to the transformer bolt. I am grounding the the main buss, center tap and artificial heater taps to the tranny. as well as the ac ground to a tranny bolt by itself.
thanks John t
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That sounds like a good plan. I personally like to put a ground lug bolted to the chassis right next to the input jacks and connect the board preamp ground, input jacks, and pot buss to that ground lug, but the input jacks are sufficient as long as they are tight. Don't forget that the speaker jack must be grounded too. Here's Hoffman's layout...
http://el34world.com/Hoffman/files/Hoffman_5F1.pdf (http://el34world.com/Hoffman/files/Hoffman_5F1.pdf)
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I know this is an old thread, but why duplicate data . . . :
I just want to confirm that in the above schematic for the 5F1 the ground seems to come off of the input jacks, and pot as a wire that is then grounded to the chassis. Is it Doug's ( @EL34 ) intention to ground it to the chassis, or just rely on the grounding from the input jack? Is one generally quieter or less potentially problematic? i.e. will grounding to the chassis be better, or would that introduce the possibility of a ground loop?
Thank you in advance.
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I just want to confirm that in the above schematic for the 5F1 the ground seems to come off of the input jacks, and pot as a wire that is then grounded to the chassis. Is it Doug's intention to ground it to the chassis, or just rely on the grounding from the input jack? Is one generally quieter or less potentially problematic? i.e. will grounding to the chassis be better, or would that introduce the possibility of a ground loop?
Only Doug knows his intentions. :wink: But I believe he is relying on the input jacks to provide the ground and is simply showing a ground symbol to show that the pot and jacks are grounded. He's not actually using a separate ground wire.
This works fine as long as the input jacks are securely tightened. But if the jacks become loose and lose the ground connection you will probably be shocked. I personally do not rely on the input jacks to provide a ground. I install a dedicated ground lug to the chassis located very close to the input jacks. All my preamp ground connections (board, input jacks, and pot grounds are connected to this dedicated ground lug. When using this system if the input jacks become loose all that happens is a buzz. Yes, the input jack ground is parallel to the dedicated ground lug, but it is not a problem.