Deluxe Reverb: slight distortion at low volume

[Jonny toetags]

I'm noticing slight distortion a low volume (between 1 and 2) on a Deluxe Reverb. It happens on both channels
What would be the possible culprit: a preamp tube? power tubes?

I should note, it's a Deluxe Reverb Reissue that was fully re-tubed after purchase.
It's a backup amp that doesn't get used a lot. The last time I turned it on was in Dec. and it worked perfectly.

[g1]

Tried another speaker? Light voice coil rub is sometimes only noticeable at low volumes.

[Jonny toetags]

Tried another speaker? Light voice coil rub is sometimes only noticeable at low volumes.

I do have some other speakers. I just find it odd since it's a brand new wgs speaker in there and i never had the problem before.

[pdf64]

Try re-seating all tubes and connectors a time or 2, exercise all controls.
How old is it?

[Jonny toetags]

Try re-seating all tubes and connectors a time or 2, exercise all controls.
How old is it?

I bought it In Dec 2012.
Like I said, the lest time I used it was earlier this winter. I normally don't let amps sit this long without being played a bit.

[Jonny toetags]

One thing i noticed it's doing it never did is with the volume at 0, signal passes a bit and is distorted.
As i raise the volume, it slowly goes away, but by that time the volume is at 2.

[Enzo]

never assume something MUST be good because it isn;t very old. A new speaker could have a little blob of lacquer break free of the voice coil, and get in the gap.

[Jonny toetags]

never assume something MUST be good because it isn;t very old. A new speaker could have a little blob of lacquer break free of the voice coil, and get in the gap.

I just tried a few speakers and it still does the same thing.

[Chuck H]

I've had this happen to me before. In my case it was a bad tube. Since the amp worked last time you used it and has been sitting for months I would say follow the instruction of wiggling the tubes in the sockets and operating all the controls. If that doesn't help try replacing the first preamp tube. If that doesn't help you may have a bad decoupling/filter cap in the preamp. Fender amps of a certain era seem prone to power supply cap fragility. Your amp may be one of them.

[Jonny toetags]

I've had this happen to me before. In my case it was a bad tube. Since the amp worked last time you used it and has been sitting for months I would say follow the instruction of wiggling the tubes in the sockets and operating all the controls. If that doesn't help try replacing the first preamp tube. If that doesn't help you may have a bad decoupling/filter cap in the preamp. Fender amps of a certain era seem prone to power supply cap fragility. Your amp may be one of them.

I went through the amp, changing one tube at a time then trying it and it always did the same thing.
What are the chances 2 tubes are shot?
It's a Dlx Rvb Reissue. Which preamp filter cap would I be looking at?

[Chuck H]

Locate the large can 22uf polarized capacitor that goes from the power supply end of the preamp plate resistors to ground and tack solder an equivalent cap across it. Be sure to observe correct polarity. If this fixes your problem you should probably replace all the filter caps.

[pdf64]

From http://support.fender.com/schematics..._schematic.pdf C35 seems a likely suspect.
It may be a bad ground connection, eg from C35 to P17 to CP19 to main 0V.
Pete

[Chuck H]

Good call. Too much going on to get that cap to the 0V termination. Non soldered connections can form an oxide layer on their surfaces. This is especially true of amps that sit around unused. Unplug and replug the ribbon cables a couple of times and test for continuity.

[Jonny toetags]

... Unplug and replug the ribbon cables a couple of times and test for continuity.

Ugh...this is why I would never use a RI as my main amp. Seeing as I got this amp for nothing, my plan was eventually to gut it and rebuild it PTP.


Thanks for the tips guys. I'll try them when i get home.

[Chuck H]

If they're used regularly the oxides don't seem to cause faults. I don't know why. There are A LOT of guys out playing gigs night after night with HR Deluxe HR Deville, Blues Deville and DR reissues. All use similar construction. The 1x12 Fender combos may be the best tone per dollar value on the market and I think they've proved reasonably reliable. There were a year or two where those amps, and possibly others had filter caps of less than sufficient quality and they tended to go bad after only a few years. You don't hear too much about it anymore. So your trouble is likely oxidized connections or stale filter caps. It's really no biggie and you have a good amp there.