1978 fender twin reverb problems...please help

[GIBSON&FENDER]

I have a 1978 Twin Reverb Silverface with new tubes and new Legends 12"s when
I bought it, it worked perfectly but one night i was not home a few friends came over and not only hooked a guitar through the one channel but a bass through the other.
Now im no tech expert but after that night it hasn't been the same, it no longer has that clean sound through either channel now it seems to play as if it the guitar had been down tuned or just out of tune and sounds really minor. It also sounds really electronic if that makes any sense and this is an amp problem i've tried several different guitars. any power chords or barre chords sound close but not right on but single notes have that sound i described...Please if any one has any ideas let me know i would be grateful

[Jazz P Bass]

Is there any chance that could you try other speakers? (you only need one to try it)
Or disconnect the Twin's speakers one at a time (don't overdo it on the volume)
They just may have toasted a speaker or two

[Krwkka]

I agree. Playing bass through those speakers is a BAD idea.

Those are great amps, by the way. That's one of the 135 watt jobbers, isn't it?

[GIBSON&FENDER]

Hey thanks for responding, I was just wondering if the speakers were fried could I still play through them? because I can now...
I just found a pair of 1974 fender blue twin reverb speakers on cl for 100 bucks just not two days ago...lucky me. I hope thats the
problem...

[GIBSON&FENDER]

Its not the speakers I installed 1974 twin reverb speakers and im still getting that really distorted electronic sounds like a fuzz...soo now im freakin clueless! thank you by the way!

[Krwkka]

I think most folks around here would agree that the first suspect in this case would be the tubes.

An experiment you might try:

There are four output tubes on this amp. They are the big ones on the left side as you're looking at the back of the amp. With the amp off, remove the inner two tubes. Now turn on the amp and play.

Still sound bad? If so, turn off the amp, put those tubes back in and remove the outer pair.

How does that sound? If either of those setups works, your problem is most likely the output tubes.

[GIBSON&FENDER]

Well I tried you experiment, thank you btw, i removed two of the output tubes...turned it on and just got feedback a louder hum the usual...so i put them back in and took the other two out and turned it on the amp got alot louder and hum got so loud eventually it just shut itself off and now it wont even turn on...
ahhh now im really lost

[Enzo]

It just sounds to me like when you lent the amp out, a tube failed. Didn't fail outright all of a sudden. Like it had a heart attck and still breathing for the ambulance medics. You gave it some medicine, but niot enough so now it sits there.

I don't think you are any worse off. The tube failure has completed itself.

[Krwkka]

Ha! Nice prose, Enzo.

Just so you know, it wasn't necessarily the fault of the people who used it. Tubes get old. Next they die. Like people, ya know?

[GIBSON&FENDER]

soo..it not turning on seems like a tube problem? i thought they could still turn on without tubes...? this is all very new to me..thank you for you patience

[Krwkka]

Very likely that a fuse is blown. This happens when the tubes short out.

Check the fuse in back of the amp. If it's blown replace it BUT DON'T TURN THE AMP ON AGAIN UNTIL YOU'VE REPLACED THE FOUR OUTPUT TUBES OR THE FUSE WILL JUST BLOW AGAIN (or worse).

I'm hoping it's just the fuse and tubes.

[Krwkka]

I suggest that you order a "matched set" of tubes for this amp. Somebody correct me if there's a better choice, but I believe the Sovtek 5881 tubes will work in this amp. If not those, the JJ 6L6 should work.

It might be a good idea to take the amp to a good repair tech since you're not familiar with these things. He/she can check things out and give you a good diagnosis of the problem(s).

[GIBSON&FENDER]

so finally i replaced the two speakers with 74" original twin speakers I replaced the fOUR OUTPUT TUBES WHICH were JJ 6L6s with Mesa 6L6s and the fuse which I replaced also I replaced five of the six preamp tubes...
so i guess I have to take it to have it looked at because I guess I exhausted all I can think of...

[überfuzz]

Still not breathing..? Looking at the backside faceplate, what tube did you not replace?

[GIBSON&FENDER]

it turns on now after I replaced the fuse but and I replaced the four output tubes with mesa boogie 6l6s and five out of the six of the preamp tubes...I didn't replace the one all the way on the opposite site of the output tubes...
it turns on but im getting the same really electronic sound when i play through it doesn't very natural...