Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ncusack on May 10, 2013, 10:57:22 am

Title: LARMAR grounding question?
Post by: ncusack on May 10, 2013, 10:57:22 am

Hello Everyone,

I'm currently building a 6V6 18watt with a cascaded preamp. It will have a tweed volume and tone section with a LARMAR master volume. I'm wondering about grounding the back of the control pots and where the grounds for the LARMAR should be routed. I know typically you try to separate the preamp ground from the power grounds and since the LARMAR comes after the PI it would make sense to me to ground the LARMAR with the power section but im not sure if that really makes sense. I have included a schematic and a current picture of where the build stands. I just want to know if I should run a ground buss back to the input jack from the master to the tone and volume or just run it from the volume and tone and ground the master separately.

Here is a link to a picture of the build as it stands now and the schematic is attached.
http://imageshack.us/photo/my-images/43/imag0075vs.jpg/ (http://imageshack.us/photo/my-images/43/imag0075vs.jpg/)

Please let me know what you think.

Cheers,

Neill

Title: Re: LARMAR grounding question?
Post by: sluckey on May 10, 2013, 11:05:12 am

Ground the pot lugs at the same place as the 250Ω cathode resistor is grounded, which should be the first filter cap. I wouldn't bother grounding the back of the pots.

Title: Re: LARMAR grounding question?
Post by: ncusack on May 10, 2013, 12:04:05 pm

When you say ground the pot lugs to that point do you mean only on the LARMAR or for all the pots?

Title: Re: LARMAR grounding question?
Post by: sluckey on May 10, 2013, 12:07:01 pm

only on the LARMAR