My bass amp is too loud!


2013-04-30 1:16 am
I'm working on fixing up a small bass combo amp (a Peavey Minx), and have run into an odd problem - it seems way too loud. Even when the volume is turned completely down, my cheap Squire P-Bass can still be clearly heard. At 1/4 up, it is almost unbearable.
The other problem it has is an annoying hiss that, again, is audible with the volume all the way down - even with nothing plugged in.
At this point, I'm not sure where to start looking - any help would be very appreciated!
Which Minx do you have? What exactly does it say on the serial number plate? There was the Minx, the Minx2, the Minx 110, the Minx 110 '91, the Minx 110 '95. Does it say "transtube" anywhere on the amp? Is there two input jacks or just one? Is there a separate preamp out jack between the controls? Or is there a preamp out/power amp in jack near the end? Inside are the output transistors TO3 types or little TO126 or maybe TO220?

When you say all the way down you can still clearly hear it, tell me this: is it overly loud even on zero? I mean is the lower limit too loud? Or is it at a low volume, but you notice it is there? A lot of amps will not go all the way to silent, just from crosstalk. But it isnl;t an issue, since no one plats all the way down. On the other hand if all the way down sounds like other amps on 3, that isn't right.

Are your op amps in sockets? Makes it easy to sub on in going down the row. Noisy op amps are probably the most common source of excess hiss in a solid state amp.

There is only one gain pot, and it is in the first stage. Verify it has integrity - not open at either end.

Plug a dummy TRS plug into the phones jack to silence the speaker. Now run a line from the preamp out to some other amp. Is that signal all hissy too? This determines if the noise is preamp or power amp related.
The peavy minx ... ah, how many hours have I wasted with that little ... minx?

Three things come to mind: ONE - that some internal trim has been set so that the darn thing has way-too-high gain. TWO - that your Squier ... you got the knobs turned down on the bass too? Remember - gain is a 2 way street - there's the input pot on the Minx, and there's the output pot on the bass. trim 'em both. THIRD - is this a direct-connect from bass to amp? Or are there any consarned "boxes" inbetween?

There you are ... stuff to think about.



2013-04-30 1:16 am
Thanks for all the replies!
I email Peavey for the schematic - I imagine I'll have it in the next day or so.
It is the first version of the Minx, before it was called the Minx 110 or anything; no TransTube label on it.
I'm not gonna have time to mess with it until tomorrow evening, but you guys have given me a lot of starting points - thanks!

As far as playing with a drummer, I have many times! But this is a smaller room, and damnit, I'm older than I used to be :)


2012-10-09 11:25 am
You could solder pickup to the jack like that I'm just saying you already think its loud 1/4 way up with the volume control/pot on your guitar right? well even with the control wide open it would be loud as you say but if bypassed it and went straight to the jack it would be even louder, as well as the tone control and switching if you have it lol
Could you answer Enzo's first questions:

How loud is it with the volume all the way down? It should be pretty quiet, or check the volume pot. If hiss is really loud, jack between and figure out whether the noise is from the power amp or preamp. If preamp, consider checking for a noisy op-amp. Is the power amp noisy with no preamp connected?

One thing I'll add: if it's still clean but too loud for intended practice, consider getting or making a switchable 10:1 or even 100:1 power soak and/or power L-PAD or T-PAD.

BTW ENZO is the real expert on most things Peavey!