1970 Fender Silverface Twin Reverb

[frankeg]

Hello Everyone,
I have a 1970 Silverface twin reverb which was found in a garage and is in very poor cosmetic shape - needs new tolex, grillcloth and cab hardware. The chassic is clean though and the amp works. It's loaded with RCA tubes and sounds very nice although I did not crank it. One of the RCA 6l6's (closest to the PT) glows red in the bottom of the tube but it is not redplating. I am confused with the bias scheme and am hoping you can clear it up for me. There is a pot on the back of the amp placed between the 820 ohm resistor connected to the phase inverter input and the output speaker jacks. It isn't on any schematic I can find. Looks like adjustable feed-back? The bias pot has the Silverface modifications which I read is not a bias adjustment but a hum balance? How do you bias this amp? I'll get pics up as soon as I can. I'd appreciate some learning here. I have never messed with a twin before. Thanks

[frankeg]

pics



This is the pot in question.

[frankeg]

Other pics.

[52 Bill]

The feedback control was added at some point. The bias control as well as the phase inverter section appears to have been changed to black face values. To bias the amp turn the bias pot up or down.

[popoahi]

I just have a question...
about your 1970 silverface..... does this mean all 70's twin reverbs are silverface?
69' and earlier would be blackface?

I was told that a bit after 1970 they released some blackface ones and they were not called reissues?

aloha, popoahi

[Jazz P Bass]

The 'Silverface' amps where introduced in 1968.
Fender Amplifiers - Wikipedia, the free encyclopedia

[Justin Thomas]

Hi popoahi,

This is an old thread, but don't worry about it - we all do it occasionally.

In answer to your questions about Blackface/Silverface,

What we call "blackface" amps came out in 1963. These amps had a black faceplate with the numbered round knobs, and the amp mames were in script. They were made until 1967. These amps had certain circuit features that were loved by players, and when we say a "Blackface Fender," it is these 1963-1967 amps we're talking about. Early 1968 saw the first silverface amps, aluminum with round knobs and block logos in blue ink. These were made until about 1980. In 1980, Fender offered the option of "blackface" cosmetics or silverface. But the important point is, the circuits were the same, no matter the faceplate color. You have one of these amps - a very late silverface twin reverb in blackface cosmetics. All of these amps were discontinued in 1983, when the "II" series amps came out: twin reverb II, Champ II, etc.

In the mid 70s, there were several amps issued with black faceplates, but are unlike Fenders before or since. The ones that pop into my head are the Super Twin, Super Twin Reverb, 400PS, 300PS. There may be others... In spite of cosmetics, these are not "Blackface" amps.

So basically, all Fenders from 1968-1982 were Silverface CIRCUITS, no matter what they looked like, except for the few from the mid-late 70s.

The Blackface Reissues are closely copying the blackface CIRCUITS and cosmetics from the mid 60s.

Regarding the sound and reputation of Silverface amps, if it sounds good to you, it sounds good. I personally don't buy the whole "silverface are dogs/blackface are great" thing. Evaluate every amp on its own. My personal favorite amp is my 1967 Blackface Bassman. The worst Fender I ever heard? A blackface Bassman. Prolly had problems, but the owner didn't want to fix it, because "it's a Blackface! Don't mess with it!"

Hope that helped!

Justin

[JoeM]

I just have a question...
about your 1970 silverface..... does this mean all 70's twin reverbs are silverface?
69' and earlier would be blackface?

I was told that a bit after 1970 they released some blackface ones and they were not called reissues?

aloha, popoahi

Here's a quote from Teagle and Sprungs book "FENDER AMPS: the first fifty years" (This is regarding the Twin Reverb)

"The blackface look was offered as an option beginning in 1980 and became standard issue for 1982, the last year of the traditional Twin Reverb."

[popoahi]

aloha justin,

thanks very much for the great info!
it answers a lot of my questions, you did see the numbers of the transformers I listed then? the last I saw was from tom who said it was a 1970 possibly a silver face in back trim? so the consensus is it's definitely what you say?
So you're saying I have a late 70's up to a 83' silverface with BF trim? And this Fact is derived from the numbers I posted??
I truly need to know honestly what to call it. a late

one last thing so far no one has told me what the push/pull feature of the master volume knob does??? I don't know if I missed a post on this?? someone pls tell me.

thanks again, popoahi

[Tom Phillips]

...the last I saw was from tom who said it was a 1970 possibly a silver face in back trim? ...

popoahi,
Please review that other thread at http://music-electronics-forum.com/t35129/#post329979 . After all was said and done we all agreed that you probably have a 1981 or 1982 Twin Reverb. It's all explained in that thread so I won't repeat here.
Cheers,
Tom