Tube Amp Problem

[mgargac]

I recently received an Epiphone Galaxie 10 tube amp that was purchased on Ebay. This is a class A 10 watt amp with one 12AX7 and one 6L6. The volume of this amp is not very loud. I am new to tube amps but I think it should be much louder. I turned the volume to 10 and the gain up and it is not loud at all. I noticed a rattling noise coming from the larger tube, which I believe to be the 12AX7. Does this indicate that I need new tubes? Could something else be causing this? Do I just change the preamp tube to see if it corrects it or should I change both?

[Don Symes]

The bigger tube is the 6L6 - that's the power amp tube. The 12AX7 is the smaller one - a dual triode - that gives you 2 stages of preamp.

If you have another amp handy - preferably of about the same power, try using that amp's speaker with this amplifier and that amplifier with this amp's speaker - it may just be a bum (or really inefficient) speaker.

That rattle may be the tube clamp, the socket or the guts of the tube. Swapping in a known-good tube should answer that third question.

RGKeen's Tube Amp Debug page is really thorough and useful for this sort of thing.

DO read the safety information before proceeding.

HTH!

[mgargac]

Don,
Thanks for the information. I do have a 25 ss amp with the same size speaker. The speaker in the amp is a Celestion tube 10 speaker. Probably not the best but others I've talked to said it's not bad. I will get some alligator clips and wire up a jumper to connect the two. The sound is like the rattling of burned out light bulb and only happens when I strike a chord. I read the safety information but am not real clear on the draining the voltage part. From my understanding it's the caps that hold the charge. If this is correct then how long is it held? It's been 24 hours since I last used it. Is that long enough?

[Amp Kat]

A one 6L6 amp is not very loud at all and some of the silvertones that fit into the case are like this. Nice tone but just not very loud. The output transformers are not very stout either so be careful on using higher wattage tubes. The voltage can remain on the caps for months if it doesn't have discharge resistors on them and draining them is a matter of connecting a resistor to the positive side thru about a 10k ohm resistor to ground will discharge them at a pretty fast rate. The larger the resistor the longer it will take but you don't want to discharge them to quick. Be extremely careful and if your not comfortable with it dont' risk it because there can be up to 300 to 400 on those caps.

[Enzo]

If you plan to connect speaker A to amp B with clip leads, make sure to disconnect the other amplifier from its speaker first. DO NOT just clip the two speakers together still wired to their own amps. That will connect the outputs of the two amps together.

[R ski]

A 6L6 single tube could push 5 - 1o watts. If the tube isn't bias enough
it would result in whimpy volume. A bench technician could clarrify that.

Moreover, the speaker being old doesn't help. I pick up some
old alco magnet speaker from pawn shops and notice they
suck in terms of volume delivery.

A good speaker helps. I recently set up an ampag rocket
from the 60's.

It inputs were guitar, mike, accordian

Once I repaired the dead combo electroncs its circuitry
combined with a 40 something speaker sounded horrible.

Reconfigured the electronics combined with a eminace
entry 10 inch made the combo roar like a rocket.

[mgargac]

I replaced the preamp tube and now the noise is gone and the volume does seem to be louder. Also, I put the amp up on a stand and that seems to have made a big difference in the volume. Next step is to change the power tube. Thanks to all those who responded.