Amp Grounding

[dawsonaudio]

Is there a particular way of deciding which ground connections connect together back at the main power supply ground? I've normally brought things back to a master ground off the negative electrolytic capacitor/s. I am just not particularly sure which grounds should bus together back to the master ground point. Here's the schematic I'm working with? I currently have the main power ground connected to the chassis when it comes in the box. The three 22uf electrolytic capacitors are grounded together and I'm planning on bringing the other grounds back to this point.

Questions:

Since the 1/4 inputs are already self-grounded to the chassis, do I need to run another ground connection back to the master ground?

Should all the grounds connections be taken back with one wire or should they be split into different sections of the amp? This is where I'm not sure.

Thanks,
Nate

[img:800:600]http://www.serviceairsocal.com/amp/ampeg2.png[/img]

[martin manning]

Some reading on ground schemes: http://www.valvewizard.co.uk/Grounding.html

Your amp has a lot of extra lead wire length. Especially on high impedance grid and tone stack wires, this is a very good way to pick up hum.

[ToneMerc]

http://www.aikenamps.com/index.php/grounding


TM

[tubeswell]

The way you've drawn your ground return schematic is less than optimal. It would be more ideal, in terms of avoiding hum, for the respective ground returns from each stage (grid load, cathode, and any other load that is dc-coupled to the plate of the stage) to go back to the same point as the ground return for the filter cap from which that stage takes its power supply node. If you're putting all your returns on the one ground bus wire, the ideal point for attaching the ground bus to the chassis would be at the lowest-return-current (input stage) end. Its all in the Merlin Blencowe article Martin linked above.

[ampdoc1]

I like the Peavey Classics "dual ground returns thru 47 ohm resistors " set up. Used it in a number of amps. It is the same on the Classic 20, 30 and 50 amps.

[bal704]

I'm having trouble deciphering that schematic. There's a ground symbol, a circled ground signal, and a boxed symbol that (I guess) represents ground, all connected by 47 ohm resistors. The three symbols are used at various places in the amp.

Care to walk me through that?

I like the Peavey Classics "dual ground returns thru 47 ohm resistors " set up. Used it in a number of amps. It is the same on the Classic 20, 30 and 50 amps.