Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Madison on June 09, 2013, 07:53:58 am
-
Recycled SS reverb unit gutted.
Decided to try my hand at point to point off the Hoffman 3 tube reverb idea.
It was a lot prettier inside before I ran into troubles but oh well.
Only ONE problem.
I have the thing dead silent and sounding fantastic.
When I put the top cover on it, I get a slight buzzing sound .Not a hum but a buzz. Seems like the opposite of what I would expect!
Might just go with a piece of plex glass or thin wood on top if all else fails.
Peace.
-
rear
-
guts
-
That's really cool! Thanks for sharing the photos of it.
I am wondering if it is possible that someway or another that the top in it messes with the orientation of the tank and flipping the tank another direction OR upside down might work to make it silent again? You could use some tall plastic standoffs possibly to flip it upside down?
That's totally a wild guess on my part & may be a useless suggestion. :dontknow: :icon_biggrin:
With respect, Tubenit
-
Just a drive-by idea: Maybe you need a good "strap" type ground connection between the top and the chassis. Just contacting it...anodized metal does not make an especially great connection even with multiple screws through it. Need to scrape off a section of the anodizing on both the top and the "tub" and make a relatively heavyish stout ground connection using through-screws and some heavy stranded wire. Another way might be to just tickle the countersinks in the top flat plate (if they are countersunk) with a countersink bit and carve off the anodizing inside the taper of the countersinks. In operation, do you have tube shields installed on the three tubes? If everything is anodized, including the countersinks in the top, AND you are using painted or anodized screws, your gnd connection between the top plate and the tub could be less than ideal. I would go for this "tickle the countersinks" first as if it did not work, the results would be invisible, and, you could test the result with only one or two screws. Try unpainted/ananodized screws as well.
Drive-by idea #2: Disconnect the 2-wire accessory outlet. (long shot) << no, forget that.
Drive-by idea #3: synthetic center tap on the fil winding?
-
I don't see shields for reverb cables connected to anything? In a real Fender both shields are connected to the amp chassis.
-
Good eye Sluckey! You need to ground the shield on one side of the reverb cables.
-
I take it this is the 3 tube verb you where having a problem with?
How did you get it working right?
Brad :think1:
-
Sorry guys for no reply.
I have been seriously delayed with a broken pinky.
Wrench slipped and POW!.
Now I have two, 1mm pins inserted into it for the next 6 weeks to try to heal the tendon.
Thank goodness it was the right hand; rarely use the digit for geetar
Anyways........
Just plugged the unit in today and I am back to square one!
With a funky pot. grrrrrrrrr!
In this thread.
http://www.el34world.com/Forum/index.php?topic=15633.0 (http://www.el34world.com/Forum/index.php?topic=15633.0)
Sorry to bug.
It's got to be something stupid simple.
Great unit when it works though! :laugh: