Funny thing happened at the gig last night?

[Mont]

Right in the middle of playing Trower's Too rolling stoned the volume on my express takes a dive then comes back up, it does it again and then the volume drops out completly. I lookside the amp, the tubes are not burning, nothing smells like it's on fire so i turn it off and use my backup the rest of the night.. Today I turn it on to try and figure out whats wrong and the amp works perfectly. I checked all the voltages and they all checked out just fine... anyone ever have this happen to them?

[rooster]

You lost bias supply or power supply (bad connection), or a signal path disconnect after V1. Whatever caused it, it will happen again until you find it - and then when you do find it, you will say 'Oh, that makes sense'.

I've been there, good hunting..

[Mont]

I'm using F&T caps. do theese have a habit of going out after a couple of years?

[Randy Magee]

I would check the filament circuit...

[NickC]

The above advice is sound and should be followed first and foremost. If, however, that investigation does not reveal the answer ...... there is another (though remote) possibility. Sometimes stage power is on the same circuit as refrigeration compressors (beer coolers, etc). When those compressors kick on they draw a lot of current, possibly starving the stage AC power (which may not be properly wired in the first place). It has happened to me too many times to count, and can do weird things to guitar amps, especially power-hungry tube amps.

[Reeltarded]

THAT is excellent advice.

Sincerely,

Ben There

[Mont]

Filaments are dead on 6.3. Does a express draw more current than a peavey classic 30(my backup). I had no problems with it the rest of the night.

[Reeltarded]

It is possible that the conditions change by the time you go to backup.

My rig goes on it's own 30 amp service that is provided by a tail wired into a local junction box that is tailed from mains service straight off the rails to stop juice battles with a venue. Most clubs were wired by someone's drunk brother-in-law. Balancing a beer is easier than balancing a load, I GUESS.

heh

It may very well be a bad connection that manifests itself after a special condition, ie; a certain temperature and vibration. Maybe it is your heater wiring.. play hard until it happens again so you have another data point.

[Mont]

I have ran it wide open for about 20 minutes just like I do when I play out. no problems so far. I will be playing the same place tonight. should I use my variac?

[Reeltarded]

Nah.. unless you like the sound. I do! Variac won't stop whatever the current reqirements are from moment to moment. A tailed service would.

Plug into another outlet location and watch the house lights for dimming events. This just may be the problem anyhow, it may not.

Umm.. at idle listen to everything on stage. Do you hear odd hums, or background frittering... switching noises?

Play and be well. If it happens again we'll know more.

[Super_Reverb]

Right in the middle of playing Trower's Too rolling stoned the volume on my express takes a dive then comes back up

Bridge of Signs album

BTW, after you get your express back up, I suggest (if you don't have one already) building a Rocket. I had a classic 30, gave it to my son who plays out and had to fix the thing three times -broken wires between boards, mysterios failure that shorted two ckt board traces and finally PT crapped.

I finished a rocket amp recently and it is a much finer sounding beast compared to classic 30. And with RJ's trannies and chassis, it's a tank.


rob

[NickC]

........... should I use my variac?

A variac would not help with a power brown out. That's sort of what it does .... creates a power brown out.

I got a Furman power regulator to solve my issues with bad AC in venues. It is an expensive, and very heavy, solution. I also carry a three-prong circuit tester in the gig bag to suss out dangerous wiring. On many occasions I have done repairs (even worked on live HV straight from the entry service to get some power to the stage breaker box); just a little "value added" service that sometimes is appreciated by bar owners (and keeps me and bandmates alive and unscorched) and has landed some additional gigs I expect.

[M Fowler]

I agree the Furman voltage regulator will keep everything supplied with good clean voltage when the compressors of the coolers kick in and annoying bar lights. I can tell when the kitchen staff shut down too!

Mark

[Mont]

I picked up the furman and last night I did'nt have any problems. I think my amp was a little quieter too. Don't know why I did'nt do this years ago..thanks for the help guy's BTW, how about I strip my classic 30 and build a rocket in that chassis. any comments?

[Reeltarded]

Asking arsonists for a match?

heh