66 Super Speaker issue vs flub

[fdesalvo]

Hi, all. Hope this message finds you and yours well.

I don’t have much time to troubleshoot this week, so looking for a boost. I have a 66 super that has been fully serviced and sporting known good tubes. I’m experiencing low frequency rumble on low notes around 3 on the volume with bass about midway up. My usual settings on these amps are around 6 on everything.

is there a way to quickly discern if it’s the speakers? Fender replaced one of the ceramic cts speakers with an alnico during a service visit in ‘66. The original owner gave me this amp and said her blown the speaker after getting the amp lol.

[Enzo]

is there a way to quickly discern if it’s the speakers?

Yes, connect the amp to a different speaker.

[Jon Snell]

It will sound nice through a Marshall 4x12.

[g1]

Also, as far as the known good tubes, are the power tubes known to have no low frequency microphonics or rattling? Sometimes they will do this new right out of the box. Or if they work fine in a head, they may rumble in a combo.
From your description of the symptom, power tubes are usually the second thing I suspect, after the speaker.

[Leo_Gnardo]

Also, as far as the known good tubes, are the power tubes known to have no low frequency microphonics or rattling? Sometimes they will do this new right out of the box. Or if they work fine in a head, they may rumble in a combo.
From your description of the symptom, power tubes are usually the second thing I suspect, after the speaker.

^^^ Right there, power tubes would be my first suspect. While the amp's on, give each one a tap with a chop stick or similar item, see if it sets off a rattle/rumble. Also check preamp tubes same way while you're at it. Faulty tube(s) will make themselves evident.

[fdesalvo]

Hey, guys. I was having rumbling in the rectifier and power tubes, so I cleaned and retensioned them and that went away. I can now tap on them and the cabinet and get no rumbling. The low frequency distortion is still present when connected to the original speakers. I connected the amp to a spare 10 I have and only got speaker distortion from the same conditions. Nervous one of these old girls gave up the ghost! I'll have to desolder a lead from each speaker and test next, I suspect. Thanks!

Edit: The power tubes are back to making static sounds when I tap them. I'll try a new set.

Edit 2: New set does the same thing. I'll see if I can borrow a friends amp to run through this cab.

[Leo_Gnardo]

Hey, guys. I was having rumbling in the rectifier and power tubes, so I cleaned and retensioned them and that went away. I can now tap on them and the cabinet and get no rumbling. The low frequency distortion is still present when connected to the original speakers. I connected the amp to a spare 10 I have and only got speaker distortion from the same conditions. Nervous one of these old girls gave up the ghost! I'll have to desolder a lead from each speaker and test next, I suspect..

Good that you cleaned & retensioned output & rectifier sockets. You might have a very close look at all the soldered connections to them. And the condition of attached resistors. Anything loose could result in the clicking noises you describe.

Often enough I find that a speaker that makes buzzing/rattling distortion will "sing along" with its mates in a multi speaker cabinet, even if that defective speaker is disconnected from the amp or has an open voice coil. That makes troubleshooting a bit more difficult. Huge PIA I know to dismount each of 4 speakers for individual testing but know of no other way. In one case I went through the whole remove-examine-replace procedure, and found a very dusty potato chip that had lodged between speaker cone and frame. No replacement was needed for that speaker after all. So be on the lookout for any debris that may have found a home in a similar spot.

[fdesalvo]

... found a very dusty potato chip that had lodged between speaker cone and frame

LOL! Gotta love the random things you find in old amps hehe. I've touched up all the joints around the socket. There's a ghost in the machine.

[fdesalvo]

Guys I got so underwater with the kids that I didn’t give you an update — an embarrassing one! Turns out a sympathetic vibration from a nearby flight case was the culprit!

[Leo_Gnardo]

Guys I got so underwater with the kids that I didn’t give you an update — an embarrassing one! Turns out a sympathetic vibration from a nearby flight case was the culprit!

What a relief!

Couple weeks ago... Got a dreadful hour-plus call from a customer I hadn't seen in 20 years, swore that boo-tique amp he bought for beaucoup bucks so many years ago was giving him the razz tone. This, after not having switched it on since forever.... A couple weeks later, he typed me a phone message - the obnoxious tone was actually from a snare drum nearby.

It pays to find the REAL source of the audio problem. I'm glad you did!

[fdesalvo]

What a relief!

Couple weeks ago... Got a dreadful hour-plus call from a customer I hadn't seen in 20 years, swore that boo-tique amp he bought for beaucoup bucks so many years ago was giving him the razz tone. This, after not having switched it on since forever.... A couple weeks later, he typed me a phone message - the obnoxious tone was actually from a snare drum nearby.

It pays to find the REAL source of the audio problem. I'm glad you did!

The ol' snare drum rattle. That's the worst! My drummer used to get annoyed that he'd come back to the rehearsal room to find I disengaged his springs lol.