Your tube amp at low vs. high settings

[OD-Black_Fire]

I have a B-52 AT212 100watt Combo for a amp and it's all tube. Now, when I have the volume pretty low, similar to what you would listen to music with, the amp sounds fine. Of course it suffers from the usually at-low-volume problems but its smooth.  When I turn it up to about 1/4 way, however, it gets all thrashy. The low end slides away (I have the bass pretty high, and I know how mids/high effect lows, I've gone through all that) and I hear less mids, and thats pretty much normal. But their is so much $%&#ing rough thrashy treble it just burns. Even with the treble low, bass high, and mids somewhere between them with my tone nob on my guitar turned down I still hear this thrashy treble. Like noise. Like an extra layer of treble, but thrashy and uncontrolled. The amount of distortion doesn't help, in fact more distortion seems to help, and the treble knob does have effect.

It sounds like the normal treble frequency is being changed like normal, but there is "another treble" not changing. Sorry if I'm coming across really unclear, its hard to describe. I don't have any recording equipment either. Its not my guitar.

I took it back to where I got it and tested out some other amps and it sounded just like them, but a lot less thrashy. It seemed clearer too. I took it back home and pop, its $%&#ed again.  A employee at the store (Guitar Center) said it might be the walls of my house. My downstairs living room where my amp is at was a basement, and there is a stone wall. This might also explain why when I turn up the amp, it bites, because the walls might be reflecting all the treble and not the bass.  

I took the amp outside and turned it up but I could only get a few measures down before my father and neighborhood stopped me. shite, it was like they were waiting for me to do that.  I'll have to check it again, but I do remember hearing the mids much better and it sounded warmer.

I described this to my guitar teacher and he said it might be microphonic tubes. The symptoms of microphonic tubes match up pretty well. He told me to switch the amp onto a clean channel and tap the tubes with a pencil and if they make some really weird noises, they're $%&#ed. I'll get to this tomorrow.

Now, does anyone else hear the same thing with your amps, when you compare them at low volumes to high?

[Ced777]

A thing I think you should consider is the way your ear "reacts" to high levels.
I think our brain and ear does not analyze the same way a loud sound and a low one.
Did you ever listen music to rock concert?? The volume is very high and you have the feeling that the treble is agressive. Put some earplugs (linear) and the music becomes fine with no harsh spike.
It could be one of the factors.

[indysmith]

play it in a bigger room, standing further away and yu'll realise how much better it sounds. Playing in the wrong room destroys the tone. A hotplate gives yu a good idea of this at lower volumes

[Muttley]

Just something interesting to note:

The human ear is progressively worse at picking up low frequencies the quieter the source is.  This basically means that when playing guitar at bedroom levels, people tend to boost the bass way up to get the sound they like.  When you increase the volume of your amp therefore, you hear more of the bass frequencies that are actually there and this can end up sounding muddy.  So really you shouldn't be using the same settings at gig or rehearsal level that you would be using at bedroom levels.

Have you tried turning the gain down a bit?

Muttley