DC5 Rhythm Channel Problem

[eeviac]

I usually use the pull boost on the rhythym channel for my main distorted chunk.

It usually sounds fine but last night while playing i noticed a sudden drop in the amount of gain on this channel.

It seemed to suddenly sound 'choked' and loose a bit of life. Chords started to decay much quicker and loose sustain - still sounds the same again tonight.

It doesnt seem to be affecting the lead channel though at least not that i can notice.

Im new to tube amps and having having read the manual and done a search here im none the wiser.

I got the amp on ebay recently and was told it had been retubed in the last year. The tubes appear to be stock mesas and look okay. It has started to hum a little recently though on the lead channel for some reason.

Anyone got any ideas?

 

[MJ Slaughter]

I'm no expert but I have both a DC-5 and DC-10. If it were me I'd start by using a known good tube and replace V1, try it, if no change then put old tube back and do the same for V4. Those seem to be the preamp tubes that work with the clean channel.

Whenever I get a new used tube amp I almost always change all the tubes so I have a good base line. Especially if I'm having any trouble with it that may be tube related. The tubes may only be a few months old but if the past owner didn't care for it or turned it on without having it in standby the tubes could already be shot or on their way out.

 

[blacklight_uk]

Could be the tubes, either power or preamp. I'd buy a new set of tubes and try them out. Preamp tubes - replace one tube at a time. Power tubes - stick two new ones in.

I'm sure someone with a bit more knowledge will step in though

 

[Fxrs]

I'm no expert but I have both a DC-5 and DC-10. If it were me I'd start by using a known good tube and replace V1, try it, if no change then put old tube back and do the same for V4. Those seem to be the preamp tubes that work with the clean channel.

Whenever I get a new used tube amp I almost always change all the tubes so I have a good base line. Especially if I'm having any trouble with it that may be tube related. The tubes may only be a few months old but if the past owner didn't care for it or turned it on without having it in standby the tubes could already be shot or on their way out.

I agree, but I would definitely start with V4, as V1 affects both channels.

 

[Alivefor5]

I would pull the amp chassis and carefully use pot cleaner on the rhythm gain pot while turning it and pulling it in and out.

Then I would do the same thing to the loop jacks. Carefully spray pot cleaner in them and run a 1/4 in. phone plug in and out several times.

Be sure the amp is unplugged, then drain the power caps or stay far, far away from them, they can severly injure you.

 

[Monsta-Tone]

It sounds like 1 of 3 things, or a combination:

New tubes
Loop Jack issues
or
Filter caps

If it is starting to hum in channel 2, this is a good sign, but not an absolutely positive sign that you need a cap job.


On all of my amps this old, I make it a point to clean all jacks, pots, replace caps, and on DC models that are Version A, I replace all of the LDR's.

This will ensure another 15 years of flawless performance.