Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: LooseChange on August 18, 2012, 07:41:38 am

Title: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on August 18, 2012, 07:41:38 am

Built a couple more.

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: Boots Deville on August 18, 2012, 08:28:07 am

You use the Par-Metal chassis for these too?

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on August 18, 2012, 09:33:32 am

Yes. The chassis are decent quality and a good price. The front panel is a bit tricky to install.

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: CraigB on August 18, 2012, 09:47:56 am

Beautiful work, Dan!!!  I'd love to see a closer shot of your board and wiring, is there another thread you can link me to that already has those pictures?  Thanks - Craig

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: proaudioguy on August 18, 2012, 12:03:49 pm

This is just beautiful.  I take it they are AB763 preamps.  What are you driving with them, any normal power amp, solid state or tube?  Do you have a schematic?

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on August 18, 2012, 01:12:22 pm

Thanks!
This is an exact copy of the AB763 circuit from a Twin Reverb. I changed some values and brands of some components to be exactly what was changed in Jerry Garcia's post Alembic Twin Reverb he had modified to use only the preamp section into a huge McIntosh 300 watt power amp.
I worked with a musician that plays in a successful Jerry tribute band. He has the entire rig from Guitar to effects to power amp to speakers. We tweaked it together.

The only things that were changed is the grounding scheme so I could add a ground lift to avoid ground loops with the other equipment.

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: proaudioguy on August 18, 2012, 01:28:51 pm

The cool thing here is you can run some line level effects after the preamp, maybe some stereo chorus, etc.  Which brings me to the next question,....Why 2?

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: EL34 on August 20, 2012, 05:56:39 pm

That's awesome!
I love building stuff in rack gear

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on August 20, 2012, 06:21:56 pm

Thanks!
Yes, you can run line level or anything below that. I added an output level on the back.
Two is better than one if you got people who want to buy it. :)

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: plexi50 on August 20, 2012, 06:39:23 pm

They look beautiful Dan. It has been a fun and serious journey hasnt it? Like a fine wine (not crazy about wine) we get better with age :icon_biggrin:

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: DummyLoad on August 21, 2012, 01:14:47 am

excellent work!

dan, you crank out some nice looking stuff.

--DL

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: kagliostro on August 21, 2012, 02:10:41 am

Fine Job :thumbsup:

K

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on August 21, 2012, 06:08:21 am

Thanks Guys... Yes, fine wine says it all.  :icon_biggrin:

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: drumslinger2000 on August 23, 2012, 10:22:07 am

Fine looking Twins, LC!

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: floyd on June 05, 2013, 06:50:42 am

How is the tank suspended from the chassis ?

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: 6G6 on June 05, 2013, 08:04:25 am

Cool!
Twin Twins.
Looks great.

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: Tone Junkie on June 05, 2013, 03:38:16 pm

So were do yo get the par metal chassis my friend. i have been thinking of doing a couple rack mount things for myself.
Thanks Bill

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: Searing on June 06, 2013, 08:40:17 pm

Very nice!  Where were you two weeks ago when I gave up on my twin head (also modded to exact Jerry specs by myself) because of my ailing back, and bought a Jerry Garcia modded SMS preamp from Brad Sarno?  I should have just made it myself, or bought one of yours.  What power transformer did you use? Hell, I would pay you just to help me build one of my own. 

Chris

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: LooseChange on June 10, 2013, 04:41:19 am

Tone Junkie... The chassis comes from Par-metal.com. They burnt down a little while ago and the have no anodizing now.
Searing... See the date of my first post? The question is, where were you? :)
Floyd... Springs man!
Thanks!

Title: Re: Made a pair of Twins!! Jerry would be proud.
Post by: Tone Junkie on June 13, 2013, 03:39:41 pm

Thanks.