ShortScale.org

Fender Twin Amp ('94 Twin Amp / Evil Twin )
Click here for Service Manual PDF
*This wasn't really a repair, more like some servicing.*

Problem:
Owner wants new ouput tubes installed and says sometimes at his regular settings, there
is a sudden burst of loud distortion at the attack of a note or chord.


Cleaned all jacks, pots, and tube sockets. There was some crackly activity when amp was on, it could be controlled with the first volume control so it had to be either that pot or something before it. I swapped the V1 and V2 tubes and the crackle stopped. Unfortunately I don't have any spare 12ax7's or 12at7's or I would go ahead and put all new preamp tubes in this thing.

There are some AMAZING bias points on the back of this amp so you can have it biased in less than 5 minutes. Suggested is .080V, but the manual even offers some suggested settings for longer tube life with decreased tone, etc. I thought that was very nice to have in the manual.

I had set the bias earlier and after playing a bit set it again just in case, everything seems to be working great and this amp sounds really good. I haven't really played a Fender since being put off by my Hot Rod Deluxe. This is a totally different animal that is worthy of gigging, even the overdrive channel sounds good. It's not gonna get you high gain 80's shit, but for any regular blues to 70's hard rock, it's perfect. The response of the amp feels really good, which is very important to me personally.

I will do some high volume, long time period testing and try to get some sound clips as well.

Sloan wrote:Owner wants new ouput tubes installed and says sometimes at his regular settings, there
is a sudden burst of loud distortion at the attack of a note or chord.

This is DESIGN FEATURE of EVIL Twin

Mike wrote:

Sloan wrote:Owner wants new ouput tubes installed and says sometimes at his regular settings, there
is a sudden burst of loud distortion at the attack of a note or chord.

This is DESIGN FEATURE of EVIL Twin

lol. evli

WTF. 12 tubes. Is 12 louder than 10 ?

[youtube][/youtube]

Audix i5 on left speaker, Shure SM-57 on right speaker, Studio Projects B1 as room mic for more natural sound.

Two rhythm tracks panned hard left and right with an accent track in the middle of the clean sample. Each take is comprised of all three mics.
No eq on individual tracks, but there is master buss compression/eq, i have a saved preset that i slap on tracks to bring them up in my phones and didn't take it off. nothing drastic going on, basically just makes it louder.



CLEAN
http://bestnetworx.com/uploader/files/5 ... nclean.mp3
High Input > Clean Channel > Presence, Low, Mid, and High @ 12:00
Epiphone Goth Les Paul with GFS '59 Vintage bridge humbucker
Accent track: you'll hear it.

DRIVE
http://bestnetworx.com/uploader/files/5 ... crunch.mp3
High Input > Lead Channel > Presence, Low, Mid, and High @ 12:00
Epiphone Goth Les Paul with GFS '59 Vintage bridge humbucker
Accent track: none

So you're signing your work now, are you?



That schematic is Pure Evilness. Bonus points for the right-angle ribbon cable folds though.

Did the attack distortion disappear?

filtercap wrote:So you're signing your work now, are you?



That schematic is Pure Evilness. Bonus points for the right-angle ribbon cable folds though.

Did the attack distortion disappear?

i don't know what that mark is.

when i first played the amp, i didn't really notice any distortion, it was only running on two 5881's at 8ohms into a 16ohm load. Not it has four 6l6's at 16ohms.

I had the amp at about his regular gig volume for the clips and there's nothing there that I can tell.
The v1 12ax7 was making some noise which i suspect was the culprit, i think it's going microphonic. I switched it out with v2, so now it only shows up on the clean channel's overdrive mode. this guy strictly uses this amp for clean and pairs it with dirt pedals. i'll go over it with him to let him know about the preamp tubes, i don't think he knew much about amps in general.

This amp made me want a Fender again. Sounds really good and I was pleasantly surprised with the drive channel. The clips I made have the eq all straight up on '5', so you can hear the midrange emphasis when paired with the gfs humbucker, which is easy to change with the amp eq.

PCB-tastic

Sounds good though.

PCB is not a bad thing. It is impossible to make a complex amplifier without one. And it's a damn sight more cost effective to use than PTP.

I actually prefer working with PCB's because I can find the part I'm looking at on the schematic about 2616 times faster.