Other Amps

Possible Mod Fender Evil Twin.??


(sorry, top pic is incorrect)

Hi There TwangMeisters..

this is my amp, and not the original pic I posted.

Can anyone advise me if it's possible to mod the pre or power amps (or both) of a Fender Evil Twin (Paul Rivera design) to make it a lot less EVIL? (option 1)

( Even on the 25 watt setting, it's scary loud, but if I turn the gain-stages down to 'bearable', the tone gets quite weedy and thin, and the bottom end is non-existent.)

(option 2) Is it sensible to put a good high-powered power soak across it, as it is? I've never used a power-soak and know nothing about them.

option 3) If I pull the inner pair of tubes out, should the new impedance be set to 8 ohms on the rear impedance selector?.

If so, presently the two 8 ohm speakers are wired in series, so presenting 16 ohms to the amp / or 4 ohms, if re-wired in parallel.....

Do I just leave the speakers set at 16 Ohms? Is it still safe and won't burn out the tubes?

any answers to any above gratefully received.

ritchie bg


Wasn't the Evil Twin a post - Rivera model?


By "less evil" are you saying "less loud"?

Swapping out 12AX7 tubes for lower gain 12A_7 family tubes will help . 12AX7's gain is rated at 100; 12AY7 is 45 and 12AU7 is 20.


Yes, FAR less loud.

Maybe 12AU/ would work...



some of that sounds just fine to me...

ritchie bg


No, Rivera, and it's a myth that the red knob is the evil.

From Wikepedia;

"Red Knob" Twin The Twin Reverb II was replaced by The Twin, commonly referred to, though incorrectly as, the "Evil Twin" (Fender has only referred to the "TWIN AMP" or the '94 Twin Amp as being the "Evil Twin", not the red knob Twin) due to the addition of both a separate gain channel and a switchable overdrive on the clean, in 1987. It featured a dual output switch, allowing the user to select either 25 watts or 100 watts of output. The Twin was designed for maximum versatility for live or studio use with features like speaker jacks with selectable impedance, Low-z/XLR output, a "Power Amp Thru" feature that bypassed the preamp circuit and a buffered effects loop. Both clean and overdrive channels could be activated simultaneously and reverb could be turned on/off for each channel. Earlier Twin Reverb amps were known among musicians to be best suited for loud, "clean" tones. The "Red Knob Twin" was made until 1994; During 1994 it was slightly modified and the knobs were changed from red to black, keeping the same shape. It has since been succeeded by the first version "Twin Amps" of Fender's Protube line in 1995. This was the first in the series to use PCB (printed circuit boards) instead of PTP (point to point) wiring. All subsequent models and reissues have used PCBs.


I may be wrong but I don't think the amp in the OP is a Rivera-era Twin. I had a Rivera Twin, and it was called the "Twin Reverb II" which was screened onto the faceplate. It also had (at first) two toggle switches on the front, but mine had two rocker switches like a Marshall, orange and red, on the right hand end of the control plate on the front.

It also had the Rivera array of pull-pot switches for various functions like mid-boost etc and an FX loop on the back with adjustable send and return levels. It came with castors you could plug in which was just as well because it weighed the same as a Ford F150 Truck.

Despite the multitude of controls it was difficult to find a decent tone and it sounded rather thin. This seems to be a theme for Rivera designed amps - I tried quite a few of his Rivera branded amps in stores but always found myself going around in circles adjusting things. They always nearly sounded fabulous.

The Rivera Twins were still hand-wired on tag boards. The next Twins were the red-knob version which I believe were PCB but can't be certain. The amp in the OP came along after the red-knob Twin if memory serves.


Sorry Jimmy & all.
The above is my amp. THE TWIN. (made post-'87.) My apologies, I stupidly posted the wrong pic.

It has push-pull knobs and three rocker panel switches, 25 watt switch, XLR out, insert fx jack loop, bias setup, speaker impedance selector. etc.

It seems as Jimmy R and DC Birdman say above, that it is not Rivera, but later, as Rivera left Fender in '86. (Although mightn't Fender have still retained production rights of Rivera?) It certainly has a similar distortion channel (a Fender first?) which is maybe not too far from the Red knob amps, and also Rivera's earlier Valley Arts mods...

(A post on Gearslutz;)

Ok, lots of confusion here but understandably so..."The Twin" is "red knob" amp but NOT designed by Paul Rivera in any way. The Rivera era was 82'-86' and "The Twin" was issued in 87'. "The Twin" is very distant in design and sound to its Grandfather, the Blackface/Silverface "Twin Reverb" from the 60's-70's and worlds apart from its Tweed "Twin" Great-Grandfather from the 50's. "The Twin" is more of a modern, feature-rich amp with a much heavier sound more kin to a Marshall or similar but with usable tones nonetheless.

Although arguably a very misunderstood combo, I really love it... But it needs severely taming, somehow.. I read that with the input level at '2' , the volume it puts out on the 25 watt setting won't be much different audibly, ( more than half as loud ) as on the 100 watt setting.

And then David Lindley (who's work with Jackson Browne never fails to impress) and Robben Ford, have both used these combos live..
I think it can't be bad.

ritchie bg


Volume, at least as the human ear perceives it, is deceptive. A 50W Marshall is not half as loud as a 100W - they are almost identical in volume. But the 100W will have more low end punch. It takes 100w to be twice as loud as 10w - but it's sooo subjective and depends on so many other factors that the point is moot.

I'm sure your amp is capable of some great sounds - the main reasons they are not so popular is that (a) they are very heavy!, and (b) most players are incredibly conservative - "the old ones are the best!". Plus Fender don't have a great reputation for dirt channels, rightly or wrongly.

I had a Fender Prosonic for a while. The dirt channel actually sounded pretty good. But the best sound was found by just turning up the clean channel! That was an amazing sound but as usual, too loud for the gig these days.


Thanks Jimmy.. Your comments much appreciated.

ritchie bg


I had a red knob The Twin. You're not going to tame that, at all, swapping tubes around. Look at maybe an attenuator or speaker emulator like a Palmer. Or, look at another amp. It's like having a Marshall JCM800 and expecting it to sound good on '2'. Not gonna happen.

Register Sign in to join the conversation