Super twin Reverb's "distortion"

[drewl]

Lord, who designed this mess of an amp?

Anyway, what were they trying to do with this distortion circuit anyway?
Did it ever sound good?




http://www.webphix.com/schematic%20h...180w_schem.pdf

[Enzo]

No, I hate it. But then I can't think of any Fender amp with a distortion/overdrive channel that sounded worth a damn.

[drewl]

Well Enzo, I figured you have seen at least one of these with all your experience.

The same owner has a Silver Princeton here with the pull boost coming from the reverb driver, and it doesn't sound too bad in that amp.

[Enzo]

I am not so sure a pull boost is the same thing as a "distortion channel." Many Fenders can be pleasingly distorted or overdriven. COntrast that with a channel designed to be some sort of overdrive channel. Take a Hot Rod DeVille. In my mind, a nice sounding amp...on the clean channel. Press the overdrive channel button and ...BLECH.

[Chuck H]

But then I can't think of any Fender amp with a distortion/overdrive channel that sounded worth a damn.

Easy now. Are you including the Prosonic? The Zinky stuff sounds pretty good to me. If you look at much of the post Zinky stuff it seems like Fender tried to cut and paste pieces of his circuits into totally different amps, and it didn't work. I don't care who they have designing and building prototypes for new stuff. But who's listening and giving it a thumbs up???

[Alan0354]

Super twin belong to the early 70s and the distortion sound of all the Fender sounded lousy at the time!!! I tested the super twin before, don't remember that much......but that's the problem, it did not stand out even I had the 74 twin to compare with, that's a very low standard to beat!!!!

The new Fender Hot Rod Deville, Deluxe, Prosonic are a different world from those old days. I was temped buy the new Fenders those days, but the JCM900 won me over when I ran across one in perfect condition for $499 in 97 or 98. The JCM900 have much better clean sound than the Plexi I had before......not measuring up to the Fender though. But when come to distortion, Marshall define the distortion sound.

To me, the most important thing against the Super Twin is the 180W!!! Who in the right mind in these days want a 180W amp?..........To break you back?!!! Vibrolux is about as big as you want for gigging. From my experience, the Deluxe is just a touch under power in big venue.My JCM900 only have 2 tubes installed ever, never want the full power. And I decrease the bias to make it more towards class A side.............And I have a THD power plate........as if I ever want to go out and gig!!!

[teemuk]

Lord, who designed this mess of an amp?

Ed Jahns.

Anyway, what were they trying to do with this distortion circuit anyway?

Short answer: Imitate what some very popular amps taking Fender's marketplace (namely Mesa/Boogie) were doing at the times, distort.
Longer answer: They are blending the hard, asymmetric clipping of an overdriven cathode follower to the clean signal. Ed Jahns's patent also describes a similar system using transistors but I don't know if they ever used it in practice.

Did it ever sound good?

I've seen Ted Nugent rock the [beep] out of those amps so I'd guess I have to say, in proper hands and context, yes. But I have to agree, as a distortion tone and compared to classic distortion tones of other amps it's rather hideous.

[Steve Conner]

Didn't all guitar amps of the 70s have a dreadful sounding distortion circuit? The distorted guitar sound was getting popular and the design engineers were probably handed a Hendrix album by the boss and told to "make it sound like that".

Ed Jahns also designed the 400PS. I wonder if he included the distortion circuit?

[teemuk]

Ed Jahns also designed the 400PS. I wonder if he included the distortion circuit?

Nope, it's a tad older design. ...But it was featured in the "baby brother" of that amp, 300PS, for example. All in all, you can easily see a pattern here: First and foremost, the traditional Silverface styling was abandoned and Fender went more in line with the old blackface styling, or even completely redesigned the looks (like in the cases of 300PS, 400PS, the "Super" series, 30, 75, 140, etc.), Old-fashioned features such as tremolo were stripped, the power amps were revised to gain more output power and linearity (this design choice was even reflecting in the Silverface amps that were still produced), active tone controls were included, crude effects loops were added, the aformentioned distortion circuit appeared, soon followed by crude channel switching schemes of 75 140 amps, etc. A lot of this stuff is commonly credited to Rivera (early 1980's) but in reality Ed Jahns started it already in mid 1970's.