Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Speakz on February 12, 2016, 09:52:11 pm

Title: MM 5E3 OT Ground wire?
Post by: Speakz on February 12, 2016, 09:52:11 pm

I am building a 5E3 for a family member who bought the MM 59 clone OT and I was wondering how I should wire the speaker jacks given the OT from MM has the wire grounded to the OT housing?


Thanks for any help you guys can offer.

Title: Re: MM 5E3 OT Ground wire?
Post by: Fresh_Start on February 12, 2016, 10:06:36 pm

You might want to search for this topic on the music-electronics forum. I think there was a recent discussion in the 5E3 sub-forum. Recent or not, there was a lively debate about whether or not it was better to detach the ground from the OT housing and run the ground to wherever you think best.

Chip

Title: Re: MM 5E3 OT Ground wire?
Post by: sluckey on February 12, 2016, 10:15:30 pm

You mean something like this?

     http://sluckeyamps.com/harvard/h02.jpg (http://sluckeyamps.com/harvard/h02.jpg)

It's electrically grounded to chassis thru the frame and bolts. So as long as the speaker jack is also securely grounded it should be OK. My personal preference would be to remove the wire connection from the frame and connect the wire directly to the speaker jack ground lug. This eliminates a couple mechanical connections and also prevents the speaker current from having to flow thru the chassis

Title: Re: MM 5E3 OT Ground wire?
Post by: Speakz on February 13, 2016, 12:06:33 am

You got it thanks guys.  I will check out that forum out of curiosity but I believe I will detach it and then follow Doug's schematic for grounding.  I just wanted to validate that it made sense to detach it.  I imagine people don't wire it like they did back then for various reasons. It will fun to have it kicking a round here ot play for a few weeks.   

Title: Re: MM 5E3 OT Ground wire?
Post by: jojokeo on February 13, 2016, 06:28:47 am

I have this OT and questioned it a while back with the MM crew. Unsolder it and proceed as you normally would going to the speaker jack as sluckey also said. (just another confirming voice)

Title: Re: MM 5E3 OT Ground wire?
Post by: Speakz on February 13, 2016, 05:00:41 pm

Thank you jojokeo, appreciate it.