My DR has died, my poor baby...

[Dominus22]

What up, dudes. I had a tragedy occur at practice last night.

Well, first off I gotta say my Dual Rectifier has had a wierd buzzing sound for the last few weeks, in all channels, even when the volume on my guitar is all the way down. I just figured it was some type of interference and blew it off.

So, I show up for practice last night and I plug my guitar in and fire everything up. I take the amp of stand by and instead of the usual instant volume, I get super low volume and it takes about 20 seconds for my amp to get to it's normal volume. Again, I blew it off. After jamming for a while we took a break. After the break I again take my amp off stand by and the same thing - it takes like 20 seconds for the amp to get to full volume, it sounded almost like the tubes were warming up or something.

So by now I figure there's some bad ju ju goin on with the power coming out of the ghetto warehouse I practice in. So, I move my amp to another power outlet. I fire it up and I get - NOTHING! My poor baby is dead! The amp that has been with me through hundreds of shows and countless practices is dead!

If I crank the amp all the way up past three o'clock I can hear myself play, but the volume and gain are low, like I have the volume set to 9 o'clock instead of 3 o'clock. It's like this in all three channels.

Any ideas?

 

[domct203]

How old are the powertubes? Sounds like you have alot of hours on them.

Check V3 and V4 for failure (swap them one at a time with known good tubes):

MESA SERVICE MEMO

SOUND “DROP-OUTS” / INTERMITTENT SIGNAL

One Possible Cause

Most (but not all) Mesa/Boogie amplifiers have one or two “cathode follower” tube
stages in their preamps. Tube selection is CRITICAL in these stages.

Specifically, in a 12AX7 tube used as a “cathode follower”, the voltage difference
between that present at the cathode, as compared with the heater voltage, can be
withstood or tolerated by certain types of tubes, whereas other tubes will fail. The
failure of a “cathode follower“ tube will cause sound dropouts or signal loss.

For the past few years, Mesa has been using two types of 12AX7 tubes: ones
originating in Russia (Sovtek EH), and ones originating in China. The Russian (Sovtek)
tube is NOT reliable as a cathode follower. Of the tubes we are using today (March
2008), ONLY THE CHINESE 12AX7 IS RELIABLE AS A CATHODE FOLLOWER.

In conclusion, if you are troubleshooting for signal dropout in a Mesa/Boogie amp,
suspect a cathode follower tube, and try replacing it with a Mesa 12AX7 that is marked
as “CHINESE” (silk-screened on the tube itself).

Below is a partial list of Mesa amps and cathode follower tube locations:

GUITAR AMPS BASS AMPS

Lone Star & LS Special: V3
M-Pulse: V2
Stiletto: V3 & V4
Venture: V2
Road King I: V3 & V4
Big Block 750: V4
Road King II: V3 & V5
Titan: V4
Roadster: V3 & V5
M2000: V2
Dual & Triple (2ch or 3ch): V3 & V4
Bass 400+: V2
Tremoverb: V3 & V4

ANOTHER POSSIBLE SCENARIO may occur in the “SPONGY” (or on some models,
“TWEED”) power setting: the reduced filament voltage may cause very low output from
a RUSSIAN preamp tube. Again, the recommended fix is to replace the “sagging” tube
with the CHINESE type of Mesa 12AX7 - which are more immune to this type of failure.

Dom

 

[YellowJacket]

Tube amps are like cars in that they require regular maintenance. Swap out the tubes for sure and if there is still a problem, get thee to a tech. Now my DR is making a swishing noise but I know that this isn't interference, it is a bad tube. I just haven't taken the time to figure out which is causing the trouble.