Amp refurb

[Autophase]

Hey guys,
I know this isnt specific to our forum but chances are someone in here will have done something like this.

My mum & dad have just sold the family home, and I have aquired by dads VOX AC30 & AC50 amps (im not sure which version they are, possibly 1960's or 1970's)
Anyway, my dad bought some new caps & tubes some years ago but never got round to refurbing them, so lucky me... I get to do it... and keep them FREE OF CHARGE.

I was wondering if anyone here has any experience with them, or knows of a forum similar to groupdiy (similar mind... it could never be as good ;-) )  dedicated to guitar amp repair.

Cheers, I appreciate any feedback.

 

[okgb]

A basic exchange should be straight forward , take your time , not sure if there's anything tricky
about taking them apart , hopefully the caps are the same  physical size , but have fun playing em later !

 

[Autophase]

Cheers,
I dont actually play guitar, but I would like to amp some synths to use in my tracks.

 

[fazer]

They will work for a synth but man they are great guitar amps. 

When you replace caps, just be careful with the polarity.  Also clean and adjust tension of the tube sockets.  You can use a dental pick to do that.  You also should clean pots and sockets.  I have an AC30 and know they can get really hot due to the lack of ventilation in the cabinet.

Also sometimes the new tubes do not sound as good as the mullards that may be in them.  Check a before and after in a tube by tube change out.  Schematics are on the web.  Check duncan amps and others.

Good luck.

 

[Autophase]

Thanks for the advice Fazer.
I just need to get this pesky wedding out of the way in Feb, then my time is free again for DIY.
Looking forward to doing a refurb as opposed to building from scratch.

 

[okgb]

Does it have a bad hum to it now ?

 

[Autophase]

There wasnt any hum when I fired them up a few months back when i was at my parents, I'll have them at my studio in feb when my parents move out, so ill give them a full diagnostic then.
But from what the old man tells me, they just have degraded in overall sound quality (old caps and tubes) and some of the pots are scratchy.

 

[Mr. Snoid]

Go to Doug Hoffman's site and bone up on what you probably need to do... like replace all the old and dried up electrolitic filter caps and cathode caps, any coupling caps that are way out of spec,  and any resistors that have drifted up or down. It has all the info you could ever need.

http://www.el34world.com

Tod

 

[buildafriend]

these guys focus more on dumbles and trainwrecks but its a great community

http://ampgarage.com/forum/

 

[Autophase]

Thanks for all the links guys.
Really looking forward to this post wedding project.

 

[peterc]

One thing I used to do with AC30s was to isolate the transformers from the chassis.

If you take out all the valves and switch on there is a low level hum in the speakers which means that there is hum transmission through the chassis. I found some thick plumbers washers which I inserted between the transformers and the chassis.

Hum gone!

Peter

 

[Autophase]

One thing I used to do with AC30s was to isolate the transformers from the chassis.

If you take out all the valves and switch on there is a low level hum in the speakers which means that there is hum transmission through the chassis. I found some thick plumbers washers which I inserted between the transformers and the chassis.

Hum gone!

Peter

Thanks, great tip, I may as well do this while im in there.

 

[Autophase]

how lucky am i???

I just checked the serial number and the AC30 is a very early one in the low 3000's, so its definately a 1960's model,