quattroworld

You guys may recall that I recently picked up two Aragon 4004 amplifiers. The model is about 25 years old. I have no idea how many miles are on these actual units. The insides look to be in good shape. The covers are scratched, but nothing that affects performance.

They were not working when I obtained them. But the problem was just a pair of fuses.
I don't know if the blown fuses are indicative of abuse, or if the fuses were doing their job and preventing further damage.

After changing the channel fuses, I have been putting these amps through their paces.
I noticed that one of the units (unfortunately the one in better physical condition) has a slight hum from the power supply. The hum does not come through the speakers. (I already have a slight buzz coming from the speakers -- that's nothing new. I attribute it to the AC circuit. But it's very low and not worth worrying about right now.) I do not remember my older Aragon 2004 having a hum like this. Then again, its power supply was not as large as the 4004's.

I connected up the second amplifier and noticed that it also has a slight hum. Quieter than the other amp, but still present. Both amps seem to work fine, and the hum is low enough that I don't notice it when there is music playing.

Could it be that this is normal operation, and I just never noticed it before?
Maybe I am only noticing it now because the amplifiers are both sitting on a table, inches from my ear, whereas the rest of my gear is stashed away inside a closet.
Or might it be indicative of a potential problem? Afterall, these units are 25 years old, and were not working when I got them. (Blown fuses are indicative of possible abuse.)

I would like to test them out with a lower impedance load to see if they still perform well. All of my speakers are only 8 ohms. These amps are designed to run at 4 ohms, and are supposedly 1ohm stable. Maybe I should hook up 2 pairs of speakers in parallel.

Thanks!
-- Peter