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-   -   Tower Speaker Amp Issue (http://www.wakeworld.com/forum/showthread.php?t=798649)

TNWake 06-17-2013 11:42 AM

Tower Speaker Amp Issue
 
I'm running two XS-650 on a clarion xr2410 (bridged 100W RMSx2). Right now I'm running a HPF with X-over at about 100 hz on the amp and gains only set about 25%. When I turn the head unit to about 60% power the speakers will turn off but the amp's power protect light stays blue when louder/bassy parts of the song come on. When I run a test tone (1 kHz sine wave) the power protect red light will come on if I turn gains past 25% typically, though they don't shut off. I turned head unit bass down but that didn't help. All speaker connections are good (measuring 3.9 ohm) across wires by the amp. I'm sort of lost now--any advice?

Thanks

jonyb 06-17-2013 5:48 PM

The XS-650's are less than 4 ohm. 2 of those on 1 channel, is less than 2 ohm. The Clarion amp is not stable below 2 ohm. The only way around is to upgrade to a better amp, or add another amp and drop down to 2 speakers per amp.

david_e_m 06-17-2013 5:59 PM

You are measuring the speaker DCR which is a little lower than the AC impedance. 3.9-ohms DCR is perfectly normal. Many 4-ohm speakers measure lower than that.
In any case, your amplifier doesn't like a 4-ohm load when bridged....it would appear.
So take the amplifier back to stereo and use only two of the channels. You won't get as much power but on the other hand the amplifier won't go into protection.
If the issue persists then the cause is something else. If it works fine then you have a short term solution until you upgrade the amplifier.
Try one speaker at a time.
Make sure the amplifier is getting adequate supply B+ and ground via the cable and the connections.

David
Earmark Marine

TNWake 06-17-2013 8:15 PM

Thanks, didn't think bridging reduced the impedance, but that would make sense. Looks like I'll have to get another amp.

david_e_m 06-18-2013 6:45 AM

TNWake,
Yes, to the amplifier, bridged into a 4-ohm load is the same as stereo into a 2-ohm load. Or, bridged into a 2-ohm load is the same as stereo into a 1-ohm load.
But four channels bridged into two and driving one pair of 4-ohm speakers isn't unusual if the amplifier is intended for bridging.
Before you purchase a replacement amplifier, convert your amplifier back to stereo and check all channels. If there is a different cause you want to find it now.

David
Earmark Marine

TNWake 06-18-2013 8:06 PM

Okay, so switching it to stereo seemed to work and I can turn the gains up now without power protect coming on. Ground and power connections seem good.

My problem now is that I'm getting some ridiculous interference (even with gains turned down) when I do things like turn on the blower (sounds through the speakers). I think the issue is because I'm grounded directly to the battery, but I'm not sure where else I can ground to (battery and audio equipment are in front compartment, away from engine block). Any advice?

Thanks

david_e_m 06-19-2013 6:41 AM

TNWake,
Excessive input gain sensitivity on the amplifier invites noise. But you still have a core issue. And most often it is a ground or supply loop. Make sure that ALL audio equipment procures its B+ from the same point. ALL audio equipment grounds must share the same point. That means that the source unit will probably have to be removed from the factory harness. The best place for the source unit to get B+ (ign/acc & memory) and ground is closest to the amplifier primary power terminals. Eliminating a resistance difference in supply points eliminates any potential voltage difference and eliminates the noise path.
All grounds are common. The battery is fine. If you have two batteries and a conventional dual battery switch (and no ACR/VSR) then the alternator/starter feed, helm buss and ALL audio equipment should be off the dual battery switch output and not battery-direct.

David
Earmark Marine

TNWake 06-19-2013 7:16 AM

I'll have to double check, but I think everything is getting its power/ground directly from the battery (my two amps for sure, though my head unit might be running to the circuit board by the driver for some reason). My other amp, which runs a sub and two in-boats, gets no noise whatsoever. I measured voltage drops across the ground and power supply--for my noisy amp, ground was .003 V and power was .015 V, which seems to indicate to me that it could be the power supply, particularly across the power distribution block.

Thanks

TNWake 06-19-2013 7:44 PM

I'm still kind of stuck. I checked all the power and grounds, no resistance. I even changed the power and ground wires from the amp that gives me no noise to the amp that's giving me noise, and still got noise (and other amp was still clean). All are running from a single battery. Could the amp be bad?


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