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Amp Issues?
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Author:  DJ Swirl [ Tue Jun 17, 2008 6:29 am ]
Post subject:  Amp Issues?

Lonman (again), I've got one more sound issue, and I believe I saw on your website that you have this exact amp, so I figured I'd ask.

I've got the QSC RMX 1450 running two Yamaha S115Vs. Recently, I've had some sound issues, and I think it's one of the channels on the amp either going bad, or needing a cleaning or something. When I turn the volume on the right channel, it makes a loud fuzzy sound (think the same sound you get when changing channels on an old AM radio). If I turn it all the way up, the sound from that channel drops significantly lower than the other. Sometimes I get no sound out of it at all, and have to wiggle the speak on cable a bit, but I think that may just be the cable going bad (always seems to be on that same channel, though, so I don't know).

So, um, any ideas?

Author:  Lone Wolf [ Tue Jun 17, 2008 6:51 am ]
Post subject:  Re: Amp Issues?

Sounds to me like either the rheostat needs cleaning for that channel or the pot has gone bad. But you said that if you wiggle speaker cable sometimes it works so it might be that the connections where the cable go in are dirty or loose. I don't know if you have phone jack or what kind of connection on the back of the amp but it could be loose on the inside from putting the cable on and taking it off all the time.

If you change cables does it still happen?

You can buy rheostat spray cleaner at a good repair center or rad shack might still carry it.

L.W.

Author:  Lonman [ Tue Jun 17, 2008 11:51 am ]
Post subject:  Re: Amp Issues?

Lone Wolf @ Tue Jun 17, 2008 7:51 am wrote:
Sounds to me like either the rheostat needs cleaning for that channel or the pot has gone bad. But you said that if you wiggle speaker cable sometimes it works so it might be that the connections where the cable go in are dirty or loose. I don't know if you have phone jack or what kind of connection on the back of the amp but it could be loose on the inside from putting the cable on and taking it off all the time.

If you change cables does it still happen?

You can buy rheostat spray cleaner at a good repair center or rad shack might still carry it.

L.W.
I'd agree with this. Dirty pots. But if it is the amp really going bad (which I doubt), upgrade to the RMX2450 - better match for the S115's.

Author:  LondonLive [ Tue Jun 17, 2008 9:10 pm ]
Post subject:  Re: Amp Issues?

My name ain't Lonman, but sounds to me like you have a resistor going out on the preamp of the channel. It is possible you have a pot failing but I'm affraid a resistor is the more likely suspect. I cold solder joint is also a possibility, going by you saying wiggling the output sometimes helps some. I think a trip to the shop is in order unless you have the ability to test circuits.

Author:  DJ Swirl [ Wed Jul 02, 2008 12:16 am ]
Post subject:  Re: Amp Issues?

UPDATE:

I simply pulled the volume knobs off and used compressed air to clean them out. Also cleaned the fan area, etc.

Now it seems to be back to full strength with no (current) issues. I'll keep an eye out, but it really does look like it's fixed.

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