My amplifier goes to 20.

[brooksmoses]

So. My stereo amplifier -- a quite heavy old beast in brushed aluminum and faux rosewood that I got for free when a professor I knew was upgrading his system -- has been having intermittent problems. I recently found the manual for it, and the manual said that these problems can come from problems in the speakers or speaker wires, so I decided to test it for a while with the speakers unplugged.

This, of course, raises a small problem. How does one actually test it without speakers? Well, it's got a headphone jack. And I've got a pair of cheap giveaway airline headphones handy.... So I plugged in the headphones, put a CD of Mannheim Steamroller into the changer, and cranked it up a bit. And it's actually about the right volume to listen to.

The right volume to listen to ... in the room.

So I sat the headphones on the desk, and listened to it for a while, until the tinniness started to drive suzimoses batty. Out of curiousity, I went to go look and see where exactly I had the volume set. It was set on 14. On a scale that goes up to 20.

So, yeah, before I plug the speakers in, I think I'll turn it back down. To eleven.

Comments

[oldsma.livejournal.com]

20? Wow, cool.

So--was it the speaker wires?

MAO

[brooksmoses]

I don't know. Unfortunately, it's being too intermittent to really tell; I thought it was working fine, so I hooked the speakers back up, and it worked fine for quite a while, and then started cutting out, so I disconnected one speaker at a time, and it kept cutting in and out regardless of which one was hooked up.

I'm now starting to suspect that it's overheating for some reason, but I don't know, and unfortunately don't have time to fool with it for another couple of weeks, probably.

[necturus.livejournal.com]

The problem with your test is that unless the headphone jack is directly wired in parallel with the main amplifier output, it's probably possible for the speaker outputs to fail intermittently without affecting the headphones.

How big is the amp? Lacking anything like a pair of 8-ohm power resistors capable of absorbing 100 watts or so, my suggestion would be to try incandescent light bulbs.

[brooksmoses]

In this case, the failure is that something is triggering the main protection circuit in the amp -- the power light is red when you turn it on, and then after a few seconds it turns green and the amp starts working. Normally it then stays green, but what's been happening is that sometimes after a half-hour or so it clicks back over to red for a quarter-minute or so and all of the output stops -- which I'm pretty sure includes the headphone jack.

It's a pretty sizable amp, though, yeah -- rated at 110W, but according to the output meter, I'm usually running it well below 10W or so. Nonetheless, the light-bulb trick sounds useful if I can't figure out what's going wrong some other way. Thanks!