# One channel cuts out at low volumes but is normal volume at high volumes.



## voltij (Feb 15, 2011)

Hi.

I have a weird problem and would like to know what you think it could be.

My left front midrange speaker will occasionally not make any sound at low volumes, but as soon as I turn the volume to probably about 75% or higher (relatively speaking) it cuts on and plays at equal volume to the other side.

*What is the likely culprit?*

Note: It is not loose speaker leads. I have inspected visually and checked continuity with a DMM as well as a "battery test" (hook battery up to leads and listen for pop from speaker)

Could this be:
- Damaged voice coil (speaker is old)
- Problem somewhere within amplifier (i.e. loose connector within amp)
- Bad RCA cables (i made my own, but continuity checks out)


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## voltij (Feb 15, 2011)

Is this sort of thing caused by miniscule gaps in an RCA cable or other internal signal connector? (aka something loose inside of the amp)

I'm 100% sure this occurs between my signal processor and the amplifier's ... uh, amplifier section.


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## UNBROKEN (Sep 25, 2009)

Input stage on the amp taking a dump?


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## dragonrage (Feb 14, 2007)

I'm wondering about maybe the bias on the amp being too low so that the transistors are not conducting until a certain voltage is reached... But, anyway, try a different channel on the amplifier?


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## sqshoestring (Jun 19, 2007)

Every time I had that it was the speaker wiring, a bad connection. Could also be a bad tinsel in the speaker I suppose. Usually only high power to the speaker has the power to jump a bad connection, unlike RCA/etc. Another tell was it would be worse with rain or humid weather.


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## voltij (Feb 15, 2011)

UNBROKEN said:


> Input stage on the amp taking a dump?


Possible. The RCA's and crossover / gain settings are on a separate sub-board inside of the amp. They connect to the mainboard by way of a ~24 pin breadboard connector. This could be loose is what I'm thinking about.

Side note: This happened to my STEG K2.01 (smaller version) for my horns, and it was happening almost daily for at least 2 months. Turning the volume up didn't *fix* it, but the horns are super sensitive and super low power. I took the amp apart and put it back together and it hasn't happened at all since. Probably the same issue i'm thinking.



dragonrage said:


> I'm wondering about maybe the bias on the amp being too low so that the transistors are not conducting until a certain voltage is reached... But, anyway, try a different channel on the amplifier?


Amp has two channels - right channel doesn't do it, left channel does. Nonetheless i will do a bit of swapping around to see where in the chain the problem is caused. AKA before or after the amplifier outputs.



sqshoestring said:


> Every time I had that it was the speaker wiring, a bad connection. Could also be a bad tinsel in the speaker I suppose. Usually only high power to the speaker has the power to jump a bad connection, unlike RCA/etc. Another tell was it would be worse with rain or humid weather.


I double checked the speaker terminals (using appropriately sized female disconnects and they are solidly clipped on. And I'm using the 5-row barrier terminal with correctly sized and securely attached fork terminals. And at no place is there fraying or a loose connection.


_______

Oh yeah, another thing I found out yesterday is that if I press random XOVER buttons on the side of the amp, the speaker often picks back up even at low volume. The XOVER is disabled. The XOVER buttons are on the same side as the RCA terminals.... so this is what makes me think it might be a loose connector inside of the amp and associated with that circuitry sub-panel.


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## sqshoestring (Jun 19, 2007)

Is entirely possible for amp controls to do that, just not as often as speaker connections. I take the female and crush it slightly on every door speaker because sometimes even a snug fit they still do it. So I make them hard to get on, have to be careful you don't break the terminal on the speaker I get them that tight if I can.

For the amp you can try to move all the controls all over a few times, you can get to them and spray them all with contact cleaner, you can investigate for lose solders and resolder the posts of the switches/plugs/gain pots/etc. Most cards and plugs in good condition just reseating them will take care of those, providing they fit tight at the terminals/pins/slots.


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## voltij (Feb 15, 2011)

Thanks for the post. This morning when I got out to my car it was about 55 degrees and dry and the left channel was out.

To test a theory I went back and just wiggled the input RCA cable around. The channel came back on almost instantly and was fine for the entire 45 minute drive to work.

So yeah, I'll just take the amp apart and re-seat the internal connectors and see if it'd be easy to just head up the RCA solder points (to maybe fix a cold solder spot)


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## trojan fan (Nov 4, 2007)

intermittent problems can be hard to diagnose sometimes, could just be a bad RCA...good luck


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## sqshoestring (Jun 19, 2007)

Sounds like you found it. Some bad solders are hard to see you may have to test it.


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