Trouble getting an old amp to work

[WoodyT]

This is my first time posting, so I apologize if there are any guidelines I'm not following.

I bought my car used, and happily found an amplifier under the driver seat (a Sony XM-2501) and wires run under the carpet to the trunk and the front dash. I don't have any prior audio experience, but I figured that with so much set up I would buy a subwoofer and see if I could figure it out. The head unit was replaced right before I bought it, so the audio and the turn on wires were disconnected. I connected these myself, and found that the sub had very low output volume. I spent some time debugging (this was about six months ago) and it suddenly started working when I scraped some rust off of the grounding spot for the amp. After it was working I took a drive and about halfway through it stopped working again, and it hasn't worked since (it has the same low output).

I've tried scraping the ground again, replaced the terminals for the sub-amp connection (they were very frayed), checked the battery voltage at the amp (14V), the turn on voltage (also 14), and made sure the amplification was set to the highest setting. It seems like the only thing I haven't eliminated is the audio cable (seems to be in nice condition, Monster brand), but like I said I have very little audio (or car) experience.

What are your suggestions?

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[CSCStang]

Try a new set of rca's. Where is the gain set at on the amp?

 

[WoodyT]

Today I went out and bought new RCAs, hooked it up, and had the same result. Have to say at this point I'm confused and frustrated. The input level control (if that's what you mean by gain) is the only adjustable piece of the amp (shown on page three of the manual). There is little noticable difference when changing between min and max.

 

[CSCStang]

Prolly a good reason why that amp was left behind. What sub is hooked up to it?

 

[WoodyT]

It's hooked up to a Sound Ordnance B12 . What frustrates me is that I had it working, and I'm not sure what changed during the drive when it stopped.

 

[Umbra]

I'd second trying a different RCA cable. If you have a 3.5mm to RCA adapter (a Y that plugs into an MP3 player, but with RCA outs) you can use that directly connected to the amp to bypass the installed RCA cable. The ground should be securely bolted to unpainted (or ground off) chassis. If the connection is "rusty" that's concerning.

 

[mylows10 5,000+ posts]

Sounds like the amps bad. It's not that good anyway. No loss