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ghost in the tube
Old 29th October 2006
Gear Head

ghost in the tube


I have something strange going on with the guitar amp I am using, and I'm wondering if it's common or if someone else has experienced it. I'm using a marshall combo, valvestate 8240. It's a hybrid-amp, with one tube placed in the overdrive channel, and none in the clean channel. Up until now, I've been using only the clean channel by running a boss metal zone through it, but I recently started running it through the OD1-channel with medium gain to get a fatter sound. What's strange, is that after some time of playing/recording, the volume seems to increase all by itself. Not suddenly or jumping up and down, the only way I notice, is that I get unwanted distortion, especially in the lower frequencies, and the recordings are clipping. I compensate by turning down mixer gain and amp volume and everything is fine until I come back from a break, and then the recordings are suddenly too low again. Is this normal tube behavior? It could seem like the tube is producing more gain when really warm, and then backing off a bit when it cools down.

It's not a big issue at all, it just puzzles me, and this seemed like an appropriate place to ask

I'm recording with a large membrane condenser mic - ADK Hamburg Edition (by the way a fantastic mic in its price range for metal guitars. My SM57 captures only bits and pieces of the ADK's sonic spectre and fullness). I hope this is not the guilty component.. I'm rather inexperienced with condensers, just as I am with all tube-stuff.

Old 29th October 2006
Lives for gear

one of the things i noticed is you didn't say anything about the amp going up-down just the recording... are ya sure it's the amp??? are you in the room with it?? or is it in an iso booth??
Old 29th October 2006
Gear Head

I'm pretty sure it's the amp. I think I can feel it, but I'm not 100% sure since the change is rather subtle and I also keep my headset on throughout the recording session, thus making it harder to get a real impression of the amp volume. Perhaps I should have tested more before posting... It's not a big problem, so I guess my approach was more to find out "something interesting" than solving a big issue. And no, there are no dogs knocking mics around, or kids and other evil bastards tweaking the mixer when I look the other way
Old 22nd November 2006
Lives for gear

One of my Event ASP8's was being odd like that too...mine was bass ackwards from what you're talking about though. My monitor would go raging loud when it had been freshly fired up, then get quieter as it warmed up. It turned out to be the main gain pot on it's way out.

Suppose it could be the same thing with your amp though, if you just build the pot it gets better contact when warm than when cold. It's just a thought..

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