Bryan McGivney wrote:

I got a Hoffman Stereo Hi-Fi console at the Goodwill because it had a tube
amp in it and I wanted to pirate the amp for a fun project. Well I pulled it
out of the console and fired it up and it hummed badly. It has two multi
part can style caps on the chassis. I found caps at the local supply house
and wired them in below the chassis to the terminals on the original caps.
The amp sounds fine now but I figured I'd ask if there are any issues with
not having removed the original caps from the circuit? I hooked the caps up
with what I think is about 18ga speaker wire, with the copper conductor on
one side and silver conductor on the other. This shouldn't cause any issues
should it?

If the original capacitor decides to short, you may have a problem. I
would disconnect the original capacitor.

How hot might one expect the power transformer to get? I can touch it but
it's hot enough you don't want to hold you finger on it long. My guess is
around 110 - 120 degrees.

Hot is normal. What type of degrees are you talking about?

I have seen reference to adding a modern power socket like a computer would
use and using the 3 prong grounded cord, grounding the chassis to help
reduce hum or noise. Is this usually OK or might I somehow get myself into
trouble doing this?

I don't think it will reduce noise or hum, but it will increase
safety...

I want to make a wooden enclosure for this with a metal screen top or
something like that. It seems that 17" is about the width of most
components?

Most equipment is in the 42-43.5cm range.

Reading the comments along with new tubes it looks like JJ/tesla might be
the winner of not being the cheapest or the most expensive, just inexpensive
yet good sound. I would need 2 x 12AX7 and 2 x 6BQ5. Should these work well
or might I consider others?

Any new tubes should work fine. But the 12AX7 tubes will most likely
work fine for the next 50 years, so I would just leave them. The 6BQ5
may be worn out - just buy a new pair and see if you sound gets better
or worse.

The amp has a switch for off, stereo 1, stereo 2, mono 1, and mono 2. There
are only one set of speaker outputs. Is this maybe a setting for 4 ohm and 8
ohm? I think the volume goes up a bit in the 1 positions.

Are there voltages I should be checking or stuff like that?

Check the voltage on grid 1 of the 6BQ5 tubes. It should be either 0V or
negative. If it's positive you have bad coupling caps that should be
replaced. Do you have a schematic?

There is a little pot on the back marked HUM what should I do with this
adjustment?

Turn up the volume with no signal and adjust for minimum hum.

Best regards,

Mikkel C. Simonsen