Bias Ground and Signal Ground

[ChrisM]

Trying to finish up a Deluxe Reverb I have been working on for the past eight months (on and off).

I installed a long ground bus of 14AWG copper wire. All the cathode grounds and other grounds from the eyelet board go to the buss. The grounds from the pots also go to the buss. Seems standard practice.

The buss is bolted to the chassis in two places. One bolt is to near the input jack and it is insulated with a plastic washer. The other end is bolted to the chassis at the PT. It's bolted there along with the heater CT. Good or bad? I could isolate that side and make the ground near the input jacks? I have seen that done before and apparently that's good.

I also have my bias supply ground connected to the grounding buss. Is this good? I was thinking it should maybe have its own separate ground on the an unused PT bolt.

Final question. I decided to go for non isolated input jacks. Is the reason people like isolated better simple because f the jack slowly becomes loose you don't lose your ground connection?

Thanks!

[Structo]

I would ground the buss at one end only, near the input and ground the input to that as well.
It's find to ground the preamp cathodes there but I would not use it for any of the power supply grounds.

The center tap grounds and power supply grounds should go near the power transformer.
The nuts on the transformer make a handy place to use ground lugs.

[stubbyfex]

Hello!
There are many methods of grounding. Great info here:

http://www.aikenamps.com/

Click on the tech info link, then on the "star grounding" link.

I've tried star grounding, bus grounding, and the type Fender used, a brass plate under the pots. I've had good results with each type. The main thing is to try and avoid ground loops, which is addressed in the above article.

[collinsamps]

Ground your buss at one end only and there isn't a better reference ground than your input jack ground. If you ground it there and keep it actually on the pot shells all the way down you can't go wrong. Be careful if grounding shielded input lines anywhere else other than the buss, that will cause crazy loops and issues, all shielded input lines need to go to the buss in the same place.

[ChrisM]

Ok a question about the output jack.

Seems Aiken really stresses using an isolated jack. So do I use a isolated jack then run a wire from the sleeve of the jack back to the PI's ground?

[drz400]

Ok a question about the output jack.

Seems Aiken really stresses using an isolated jack. So do I use a isolated jack then run a wire from the sleeve of the jack back to the PI's ground?

The OT ground goes to the isolated jack ground, the PI ground also goes there, or if the PI ground is going to the front buss then run the Output jack ground there but run the OT ground to the jack first

[Structo]

I know what Aiken says but I've had pretty good luck with standard jacks.

I use a ground buss that grounds to the chassis below the input jack which grounds there too.

I don't isolate the output jack either.
Mainly due to trying to find the isolated jack washers.
I don't really care for the plastic Cliff style jacks.

I just use a good Switchcraft jack and use a star washer and tighten it very good.
Then I ground the OT there.

All power supply grounds go to a transformer bolt.
All preamp grounds go to the buss wire.

I tried star grounding before and ended up with more hum then before.
I might have had something screwed up but I don't think so.

[Cygnus X1]

Interesting.
I followed Randall Aiken's recommendations for a combined star/buss ground on three different builds.
With the cliff jacks (which I don't like either).
The 5E3 Deluxe is the quietest I have ever heard.

Another tool in the box is putting the power supply section in a doghouse on the top of the chassis like Fender.
I built 2 SEL's, one with the doghouse, one without.
I'm staying with the doghouse-much quieter-and I think tighter sounding.

[Andy Le Blanc]

I plan and start a build on the power side, after I bend and fab the chassis.
One of the first things to go in is a GROUNDING BAR. I use it as the star point.
The neutral (green) wire of the AC supply goes here and acts as the current
return for the entire unit and needs to be sufficient to handle the total current
used by the amp. This makes the AC cord larger than most anticipate.
With this grounding established, you have to maintain the star aspect of your
grounding scheme. The chassis should follow the same rules
that apply to the rest of amp's circuit. Don't use the chassis as a ground plain,
use the star point. Where I live the Ac V is all over, as high as 128V ac.
and the wiring condition of any venue is unpredictable. Using a large gauge
cord and grounding connection reduces resistance to earth preventing EMI
and other interferences associated with poor grounding, the chassis provides
a shield, and if nothing else is attached to it ground loops and other
capacitive effects in the circuit are prevented too.