#1
Hi guys-

I just scored a real-deal 1965 Super Reverb. It sounds awesome with the exception of one small issue. There is a buzz that exists when the vibrato channel is engaged. It's pretty apparent with the volume on 1, gets quieter on about 2-4, then comes back when the volume is turned up higher than that. The problem goes away when pulling V4, but I've swapped with a known working tube and it still persists. I've also swapped V2. In addition, pulling the reverb cables has no effect on the noise. It gets noisier as I turn up the reverb, but it's a different kind of noise (sounds pretty normal to me). Any ideas before I take it to a tech? Tube sockets? Internal components?

It's really not a huge deal...it's just not as quiet as my '65 Bandmaster and '66 Showman. All are plugged into the same outlet. I've used extension cabs so I know it's the head and not the speakers.

Thanks for the help!

EDIT: Also, I should mention that sometimes when I play loud notes, the volume will either drop slightly, sound weak, or the sound will distort. Don't know if that's a related problem or not...

EDIT 2: Also also, when I got it, it came with a bag of large brown caps, so I figure it's had a cap job recently.
Ben
Last edited by muffinman123192 at Dec 15, 2015,
#2
You might have that look at, I am not sure if it is related problem (I don't think it is) but the second one could be worn master channel tubes, caps or something similar. The reverb problem I am not sure, maybe cold solder joint or something failing around it, or I think these amps actually had that problem as part of their "character". I'd be more worried about the second one.
#3
Okay, update after toying with it some more...

With all the tubes in, and the vibrato volume at minimum, the noise gets gradually and significantly louder as the normal channel volume is turned up. However, the noise completely goes away when the normal channel hits max volume. Like, just going from 9-10 makes it disappear entirely. This is with no cables plugged in, btw.

Also, some pots are scratchy, so I may take it in anyway. At this point, I'm more curious than anything. Hoping someone with tech experience can take an educated guess...
Ben
#4
What caps were replaced?

An amp that old really needs to have every cap in it replaced, especially the electrolytics. Electrolytic caps dry out after 25 years or so, that amp is closer to 50.

I have a 73 Super Reverb, when I got it I already knew it needed work, it would play fine for about 10 minutes then the volume would drop as if you pulled a power tube and it got pretty dirty sounding. I talked it over with a local owner of a vintage guitar shop (drool city, wall of vintage guitars and always at least a few blackface Fenders) we were almost convinced it was a bad output transformer.

That's a pretty expensive repair, so while I waited for a good job to come along I started replacing capacitors a few at a time, whatever I could afford. The last 2 "orange drops" I replaced did the trick, one of them was going bad and would get hot and fail after a few minutes.

All the electrolytics were replaced first, I knew they needed it, in an amp over 35 years old they were certainly on their way to dry, especially after being stored in a closet for 15 years.

Then I went to the orange drops, (filter caps had already been replaced) and also replaced all of the higher wattage resistors. Those will cause a sound like bacon frying after they are used for a few years. The larger resistors heat up and cool down and they gradually develop tiny internal cracks, arcing across these almost microscopic cracks causes a sizzling sound.

Check it out, I think this sounds like a cap somewhere is going bad. Even if they have been replaced, a new cap failing in no time is not unheard of. The filter caps are the large electrolytics in a metal pan that hangs underneath the chassis. I think those were originally brown, they are always the first ones that need to be replaced. Then every other electrolytic in the thing, then the others. The only ones that usually don't fail from years of use are the thin brownish orange ceramic caps, and it's a good idea to replace those too.

One thing to consider, if a cap fails while in use, it can create a direct short that can damage a transformer. The one I replaced in my Peavey MX was $125 around 15 years ago. Not a cheap repair, it cost me around $50-60 to replace every cap in the thing. I did the soldering myself, I can do a very good soldering job, taught by a guy who soldered calculators together for Westinghouse many moons ago, so I do a professional soldering job and don't have to pay a tech and take my chances.

Could also be a failing resistor, even if they all test good with a multimeter. The properties of a resistor change when they heat up, it can test good but get weak once it gets hot and starts working hard. Everything expands and contracts from heating and cooling, that's what causes the cracks in resistors I mentioned earlier. Heat can also cause a resistor to simply fail under a load. It's not common, but does happen now and then.

Have it checked out, probably needs a complete cap job and maybe a few resistors replaced. It's worth it, you may have to shell out some bucks to have it fixed up, but a 65 Super Reverb is a valuable vintage amp. I could get around $1500 for my 73 Super Reverb silverface if I wanted to sell it...the blackface amps are worth more any day than silverface amps. If I wanted to wait a while I could get more than that...

You have a gem there. Ever listen to Derek Trucks? A 65 Super Reverb is what he records with most of the time, his parents got him one when it was brand new...I think he uses a reissue onstage and a couple of other amps but the 65 SR is his usual recording amp. Many American rock and rollers started out on that amp too. Joe Walsh, Johnny Winter, Rick Derringer...That was their first amp, in the same year range, 65 to 68. I'll never let my 73 get away...other amps can come and go, the Super Reverb stays right here...