Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: phsyconoodler on June 11, 2012, 05:18:46 pm

Title: 70's ac 30 woes
Post by: phsyconoodler on June 11, 2012, 05:18:46 pm

I have a seventies AC 30 on the bench and someone modded the trem into a master volume.I need to get the trem working but there are no readable schematics for this year and no pictures that I can find to show the wiring of the trem select rotary control or the trem volume control.
  Anyone have one of those amps that would be kind enough to send some high resolution pictures?
The Weber layout is quite different and of no use in this case.
  Other layouts may exist but I can't find them.
 Help! :dontknow:

Title: Re: 70's ac 30 woes
Post by: stratele52 on June 11, 2012, 06:16:29 pm

IMO , they are readable schematics there ;

http://www.drtube.com/guitamp.htm#Vox (http://www.drtube.com/guitamp.htm#Vox)

or

same there;  www.voxamps.com/support/circuits/ (http://www.voxamps.com/support/circuits/)

Title: Re: 70's ac 30 woes
Post by: phsyconoodler on June 11, 2012, 06:35:00 pm

None of those match my amp. This one has printed boards on the underside.
  It has a 2.2meg speed pot not a speed dial.
The 78 reverb model is close but it again doesn't show the speed pot.

Title: Re: 70's ac 30 woes
Post by: phsyconoodler on June 12, 2012, 02:37:32 pm

Got it working! Grafted an 80's circuit diagram onto this amp and it works perfectly.Much easier to read!

This amp sounds great! I just popped in some new filter caps and away we go.I tried three sets of power tubes,EH,JJ and the Chinese Psvane EL84's. The Psvane's are wayyyyy nicer sounding than either of the other two by a huge margin.They are much clearer note to note at high volumes and chimier when clean.
  Nice tubes,nice amp! G12-30 Rola Celestions sound yummy.

Title: Re: 70's ac 30 woes
Post by: kagliostro on June 12, 2012, 03:06:24 pm

Quote

Got it working! Grafted an 80's circuit diagram onto this amp and it works perfectly

I think you refer to this schematic

http://www.voxamps.com/downloads/circuits/ac301989.jpg (http://www.voxamps.com/downloads/circuits/ac301989.jpg)

does your amp has the reverb circuit ?

if so, please, can you post some photo of the inside, as to see the layout ?

Thanks

K

Title: Re: 70's ac 30 woes
Post by: thelonious on June 12, 2012, 03:25:55 pm

Nice! Would love to hear that thing.
Phsyconoodler, out of curiosity, have you ever compared a Genelex Gold Lion EL84 to any of the others you mentioned (Psvane, JJ, EH)? They seem like a good midpoint price between JJ and Psvane, and I was curious how they compared.

Title: Re: 70's ac 30 woes
Post by: stratele52 on June 12, 2012, 05:09:36 pm

Quote from: phsyconoodler on June 12, 2012, 02:37:32 pm

Got it working! Grafted an 80's circuit diagram onto this amp and it works perfectly.Much easier to read!

Congratulation phsyconoodler