70s Fender twin ID

skippy76

Evening all,

I picked up this old Fender Twin today which has been heavily modded, I’m looking for some help dating it and figuring out what the mods are. Looks like a toggle switch to bypass the master volume and a foot switchable boost.

The guy selling it mentioned the mods were done by Dave Peterson, I’ve not heard of him.

ill open it up tomorrow and get some shots of the chassis etc

gringopig

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skippy76

Thanks gringo, I had a guess at mid 70s

jdgm

Hello

Just to say that Dave Peterson was/is an excellent amp tech who wrote a book on Vox amps, occasionally worked for Chandlers in Kew, and had a business in Woking called Re-Tech, during the 80s - early 90s.  He modded or repaired at least 3 of my valve amps including a silverface Dual Showman and a Park MV. All still working very well. 

A top bloke who really knew about valve amps and specialized in Vox.

skippy76

Thanks @jdgm thats really good to know, I’ll give him a call later today, the amp sounds great and besides the master volume bypass also has some kind of attenuation mod.

There is a switch on the back with High, medium and low positions. I’ll get some more pics up later.

skippy76

It’s missing a valve.... maybe to tame the output?

Jalfrezi

Nice score, I have a 1970 that's remarkably versatile.  It's a keeper for me, but too heavy too leave the house.

gringopig

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ICBM

The smaller valve appears to be a rectifier.

I would certainly want to see inside to make sure what has been done is reliable and safe. From the outside it looks like a real mess.

skippy76

Thanks both, I’ll get some more pictures up shortly as well as all of the valves.

i should have mentioned it’s runs smoothly and sounds awesome, the attenuation also works.

gringopig

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ICBM

No, it didn’t. It’s clearly been heavily modded - I suspect to basically a Pro Reverb output section. The valve is definitely a rectifier, you can see the gap between the two plates in the pic. It looks like a JJ GZ34.

It will have needed a small extra transformer fitting to drive the 5V filament since there isn’t a winding on a Twin PT.

skippy76

Sorry for the delay guys

gringopig

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ICBM

Good grief!

Massive, massive amounts of bodgery and bad workmanship. There's so much wrong it's difficult to know where to start.

It's not easy to see if it's actually definitely safe. Personally, I wouldn't even turn it on until it's been properly assessed by someone who knows what they're doing.

Sorry to be the bearer of bad news .

skippy76

Yeah, who knows what’s going in there! Sounds good though?!

gringopig

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skippy76

 No worries, I appreciate the honest assessment

It was a bit of a gamble, but sounded good when I went to pick it up and still sounds good. 

I’ll get someone to give it a safety once over and leave it as is. So long as it’s safe and sounds good I’m happy  

Amp tach recommendations in the Croydon/Redhill area?

bandmaster188

When I bought my second bandmaster it sounded great but the internals were so badly bodged, it was laughable. I had the circuit board completely re-done as it seemed like the most sensible option. Cost £250 but was worth every penny. That was done by Steve’s Amps near Guildford but I believe he’s relocated.
Henk Phillipson in Horsham is worth a shout or Dickinson’s in Crystal Palace.

skippy76

Thanks @bandmaster188 appreciated 

ICBM

In all honesty I would want to strip out everything that isn't original in that and start again, even if you wanted to end up with something more like what it is now than a stock Twin. It really is a total basket case.

I'd maybe leave what's on the stripboards, they don't look too bad - although I would want to see what's under that tape - but most of the rest needs to be redone far better. The PT could stay too, and that certainly does explain the valve rectifier! Interestingly it's been done like a Mesa Dual Rec in that both of the end sockets are wired for rectifiers, so you could actually fit two 5Y3s if you want it really saggy...

I suppose I should have noticed the randomly-angled OT and choke in the first pics, I can't believe I didn't spot that now .