Dik Ellis
Tele-Afflicted
Just curious, are there any distinct circuitry differences between Blackface and Silverface amps? Had a '63 blackface Super Reverb and a '74 silverface Twin.
Blackface vs Silverface circuitry, any difference?
- Thread starter Dik Ellis
- Start date
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985plowboy
Poster Extraordinaire
As I understand it, BF and SF Champs use the same circuit.
That’s all I got.
And may even be wrong.
That’s all I got.
And may even be wrong.
Cjteleforum
Tele-Meister
According to Dave Funk's book, yes the Twin had changes--different biasing set up, some caps changed, then addition of a master volume in '70 and "terrible distortion push-pull switch" in '73.
The Super Reverb went from a GZ34 rectifier in '63, to a 5U4GB for the Silverface.
Some of the circuits stayed almost identical, like the Princeton, which can be modded to '60s specs pretty easily.
Also the cabinets went from solid pine to particle board in the '70s, which I think is big downgrade, although there are probably weirdos out there who prefer them.
The Super Reverb went from a GZ34 rectifier in '63, to a 5U4GB for the Silverface.
Some of the circuits stayed almost identical, like the Princeton, which can be modded to '60s specs pretty easily.
Also the cabinets went from solid pine to particle board in the '70s, which I think is big downgrade, although there are probably weirdos out there who prefer them.
corliss1
Poster Extraordinaire
The search feature is your friend 
electroman
Tele-Meister
Some models changed very little; Champ, Princeton, and maybe a couple others. Certainly by around 1979 most models had changed quite a bit. Speaking in broad, general terms, the biggest difference between SF and BF amps, is that SF circuits had more negative feedback. This gave them a little more clean head room. That could be a good thing or a bad thing, depending on what the player is after. When people refer to 'blackfacing' a SF amp, again, in general terms, they are talking about reducing the amount of negative feedback. Less NF allows the amp to be a little more responsive and hit the sweet spot at a slightly lower volume. Others can point out more detailed changes.
msalama
Poster Extraordinaire
Most amps got the same(ish) CBS generic circuit changes during the 70s, did they not? But at least the Vibrolux Reverb was spared the master volume / pull boost / ultralinear thingies the bigger amps got, and luckily so...
If you are not a reader like me I recommend 5 Watt World (fun, historical information and Psionic Audio (fun, opinionated (knowledgeable) technical information. You should find something close to what you are asking. I've been around since the tweeds but never understood, didn't care about what did what. The main issue during those years is what I could afford either cash or trade. There were not a lot of choices, youtube and no option paralysis. There were some fine amps made during the 50s, 60s and 70s that you learned about if your friends had them or you experienced them at a concert. This "vintage" craze can get a person f**ked up quickly. I stated in other posts my take on that is used is used. I am not going to try and gig with an amp that is near my age and they're way to expensive to sit in a room for a few oohs and ahhs. I love to look at them though. Just like classic cars, there are those that enjoy those things, willing to pay for the maintenance and I have nothing against them. As far as your question, yes there are differences but I don't readily have the technical info to answer that. Youtube will give you as many opinions and you find in forums. Can most folks hear the difference? Probably not. The important thing is do you enjoy the both? If so, have fun and explore.
homesick345
Poster Extraordinaire
I have had a couple SF Supers blackfaced
Barely any difference at all...... Maaaaaybe a tad warmer after blackfacing
Barely any difference at all...... Maaaaaybe a tad warmer after blackfacing
SnidelyWhiplash
Poster Extraordinaire
There were changes to some of the amps. Some subtle, some not. Bias balance as opposed to adjustable. Different rectifiers. Plastic coated wiring instead of the cloth push back. Said wiring became sloppier. CBS engineers seemed to want more power & clean headroom in the bigger amps as the 70s progressed. I can't imagine Leo coming up with the solid state series or even the Super Six or Quad Reverb. 
The Champ/Vibro Champ/Bronco family as well as the Princeton/Princeton Reverb and the Deluxe/Deluxe Reverb amps did not
receive big changes. The only 6L6 amp that did not receive major changes was the Vibrolux Reverb. All of the others received more extensive changes from 1963 through the last year of production, which was 1981.
receive big changes. The only 6L6 amp that did not receive major changes was the Vibrolux Reverb. All of the others received more extensive changes from 1963 through the last year of production, which was 1981.
radiocaster
Doctor of Teleocity
I think the black faceplate also reappeared in 1979-1980.
The BF cosmetics returned for the last two years…1980 and 1981….of the ‘classic’ BF/SF circuits. These BF cosmetics were continued during the ‘Rivera era’ from 1982 through 1985, which were the last years for regular production handwired eyelet board construction.
Paul G.
Friend of Leo's
The 6V6 models did not change very much, the 6L6 models did. That being said, most of the changes were made to give more headroom, competing against powerful Hiwatt and Marshall models which gave gobs of clean volume. Personally, among my favorite amps ever are the post 1974 Bandmaster Reverb/Pro Reverb/Super Reverb (which were identical except for the output transformers) amps. They just sound huge and deep and, well, punchy. Much better to my ears than the blackface versions.
The only 6L6 Fender that did not receive the major changes….MV, pull boost, Ultralinear…was the Vibrolux Reverb.
abcdefghijklmnop
Tele-Holic
I blackfaced my 69 Super Reverb back to AB763 specs and it sounds amazing. Im playing it right now. I also have a 67 BF Super Reverb and even though they are now the same "circuit", they sound a bit different. Both are amazing amps. I also have a BF Pro Reverb, a couple BF Bassman and a BF Bandmaster and a Silverface BM 10. All great amps.
Psionic has a video on youtube where he talks about "de CBSin'g" a silverface amp.
This is also a good video which shows most of the process of "blackfacing" an AA1069SR to an AB763:
Psionic has a video on youtube where he talks about "de CBSin'g" a silverface amp.
This is also a good video which shows most of the process of "blackfacing" an AA1069SR to an AB763:
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Not much difference in the BF and SF circuits in general for the basic design.
-There are some oddballs like the 67-69 time frame where they added big ceramic cathode resistors to some of the bigger amps like the Twin, Super etc. But those were short lived experiments.
-And of course the later 70's Ultralinear amps were different.
-The bias changed from an "adjustable fixed bias" in the BF to a "balance bias" in the SF.
-There are some oddballs like the 67-69 time frame where they added big ceramic cathode resistors to some of the bigger amps like the Twin, Super etc. But those were short lived experiments.
-And of course the later 70's Ultralinear amps were different.
-The bias changed from an "adjustable fixed bias" in the BF to a "balance bias" in the SF.
The first changes in the CBS era….. which began in January, 1965…occurred in the summer of 1968. That change was with the AB568 schematic for the Super Reverb…May, 1968.
Yes, there are three amps that carry 1965 dates on their schematics…AA165 Bassman, AB165 Bassman, and the AA165 Pro Reverb. Being that ‘165’ indicates the AA165 circuits were drawn in January of 1965, I posit that those circuits were in the planning at the end of Leo’s ownership and not part of any CBS influence. The AB165 Bassman was the first use of the bias balancing circuit. I do not know when that schematic was draw. All I know is that the AB165 indicates that it was the first revision of the AA165. The rarity of an actual AA165 amps in the wild indicates to me that the revision came relatively quickly.
Yes, there are three amps that carry 1965 dates on their schematics…AA165 Bassman, AB165 Bassman, and the AA165 Pro Reverb. Being that ‘165’ indicates the AA165 circuits were drawn in January of 1965, I posit that those circuits were in the planning at the end of Leo’s ownership and not part of any CBS influence. The AB165 Bassman was the first use of the bias balancing circuit. I do not know when that schematic was draw. All I know is that the AB165 indicates that it was the first revision of the AA165. The rarity of an actual AA165 amps in the wild indicates to me that the revision came relatively quickly.
I h
I had a 73 SF Twin back in the day with the horrible push pull master volume for that nifty keen distortion sound. I never used it. It had the orange JBLs and it was one of the best sounding amps I’ve ever owned. Back then I was **** strong and could snatch it over my head easily and I used to throw it into the back seat of my 75 TransAm on the weekends because I played a lot back then. My band mate had a 64 BF Twin and he agreed that mine just sounded better, and at 130 watts vs. his 80 watts, it was wayyyy ballsier!
A ‘73 TR would be a 100 watt amp. The UL 135 watter came into being in 1977. I tip my hat to you on being able to wrestle TR with JBLs into the backseat of a Trans Am.
39martind18
Poster Extraordinaire
My 1979 Silverface Vibrolux Reverb has the pull-boost, but that's all. If you don't engage it, it doesn't matter!
