need some stereo help please

[dorschman]

I just installed a Becker cdr220. The car already had an old ADS pq-10 amp in it that I was using to run the 4 car stereo speakers. The system also has a Kenwood ksc-sw1 powered amp.

Before the install I had no problems with anything (running a panasonic head unit from Best Buy a year ago).

Now I have the system running, no problems with the head unit functioning and reading, but when I turn the volum above about 30 (of 40 I think) on the head unit the speakers cut off. The head unit stays on and keeps on working but no sound. There is no light in the amp (it is old) to indicate whether it is on or not. There is a 30 amp fuse on the amp that has not blown at any time.

I read in the amp manual that it will cut out internally if it is trying to push power beyond its limits or there could be a bad speaker somewhere.

The current head unit (Becker cdr-220) lists power output 4x18 watt. The old panasonic head unit listed max output at 50 watts and rms 18 wattsx 4 channels.

I have to admit the Becker sounds a hell of a lot more powerful than the Panasonic just listening to it.

I do not think the sub-woofer is the problem- it has stayed on throughout.

My question is could the head unit be overpowering the amp or should I potentially look for a faulty speaker now? The fronts are 6 inch MB quartz with satellites- likely old- maybe installed just after the car was bought. The rear plates are infinity from Circuit City last year- listed max 150 watts I think.

Any ideas would be appreciated. By the way I think the speakers could probably handle more power than when the system cuts out.


thanks for any ideas.

erik

[randywebb]

sounds like you are triggering a protection mode

[dorschman]

where or how would I try to determine why? The head units appear (on paper) to have the same power output. I guess I could have something wired improperly but I cannot think what off hand. I was considering just driving the 4 car speakers with the head unit and not using the amp and seeing how it sounds. That means a lot of work sideways in the passenger seat with a headlamp but maybe it would still sound good?

[imcarthur]

If it was a blown speaker it would trigger the amp's protection on turn on. And you wouldn't have sound at low volumes. It sounds like the output voltage of the Becker is overloading the amp at a certain volume (voltage gain). Does the amp have adjustable gain? If yes, crank it down.

Ian

[dorschman]

the amp has input level controls (two screws that I can turn to affect the power sent to the front and rear speakers). I can try to turn these to their lowest settings and see if it helps. I will try that soon. thanks.

[dorschman]

decreased them both to lowest level and speakers still cut out around 30 out of 40 max volume- all speakers loud and do not sound distorted before cut off. I guess maybe the amp is so old it can only handle so much power? No fuses blown at all. One strange thing is the battery would not start the car after all my messing around and trying the stereo. So I just jumped it and started the engine and let it run for a few minutes.

So I just went out there and turned down the gain and thought I would be smart and start the engine again- one turn and no start. I checked the wiring from the battery to the amp and to the head unit and the sub- they appear correct. Do you think I maybe just needed to drive around the block to recharge the battery or could this be part of my problem?

thanks for any help

[imcarthur]

Yep. Those screws are your gain. Turn down (counter-clockwise) to their lowest. If it's not enough gain, turn them up a bit gradually. Remember: more gain=more distortion, so lowest is best.

Ian

[dorschman]

I turned down the gain to minimum and still have speaker cut-off.

Jumped the battery and drove it to work and started just fine for lunch.

I am going to try unplugging the sub connection (the front output of the head unit is split into the amp and to the sub) and see if that makes any difference. I would assume the amp knows the sub has its own power (never had trouble before) but I am interested to see anyway.

So if the head unit is overpowering the amp should I just ditch the amp and use the head unit to power the four stereo speakers?

[favrok01]

Did you run the stereo's speaker wires to the amp or RCA's?
if you did the the latter there would never be problem unless faulty amp.
If you used the speaker wires the low power input is blown and is supplying to much input to the amp.

[favrok01]

and no, the stereo doesn't have enough power to run the speakers.
At high volume they will be under powered and blow them.
Buy another 4 channel amp on ebay for 200. i have 3 extra myself

[Gogar]

I very much agree with favrok. If your head unit has RCA jacks out and your amp has RCA in, by all means use them. You will be much happier. The whole speaker-level input thing has always been a compromise made by manufactures before RCAs were common in car audio. The RCAs will be much much cleaner and allow your amp to work the right way.

If not, sorry about the paragraph telling you what you can't do.

[disfin]

I agree that it sounds like a protection mode. I had that problem and it turned out to be two speaker wires were crossed. Check your connections.

[RANDY P]

dorschman, check your PM

[dorschman]

So to finish the saga a friend of mine suggested a line converter since the head unit has speaker wire outs and the amp has rca ins. I bought one from Circuit City and installed it tonight. Early results are I think it is going to work and the speakers have not cut out so far. I need to do some tweaking with the amp outputs but so far so good.

thanks for all the advice so far.

I may have it set soon but we will see.