Problems with amp losing volume.

[SignsOfDelirium_bassist]

I played my first gig with my new band yesterday, using an amp I bought off here this past week. It's an Ampeg SVT6 pro. hybrid tube preamp / SS power amp, 750 at 8ohms running into a Genz Benz 1000w cab, although at the gig I was using the house cab, I don't know what it was but the same issue happened on both, so I'm assuming it's the head. Should probably mention that I had the gain turned up pretty far, but there wasn't much, if any, distortion coming from the amp, I also had the tube voltage control turned up to about 2 or 3 o'clock.

Problem is it randomly seems to drop volume significantly. This only happened at the start of the show, but the amp had been on for a good few minutes by that point. At home I noticed it, thought it was a bit weird, so I turned the amp off just in case I was damaging it, at the rehearsal I changed the genz benz cab for my old 400w 410 and 300w 115 laney cabs, it was fine after then. At the gig it happened on the first song only, then it was fine afterwards. Is it just the tubes not warming up? if so, how long should I give them?

Also, it doesn't seem as loud an amp as I was expecting. My old Laney 230w solid state head seems to be able to keep up with it just fine. The ad said it probably needs a service, is there anything that could be making the amp quieter than it should be? I was expecting to be way louder than my old amp!

Granted, I know nothing when it comes to amps, this is my first foray into anything tube. If there's anything you guys could advise me on, that would be awesome!


Cheers
Jack.

[Lozz196]

Service/new valves would be my guess. That should establish if there are any specific issues.