I finally upgraded my old amp (an American Legacy, 440 watt 4 channel amp to a 1000w 2 channel Kenwood KAC-929 amp). It is powering a 10" Rockford Fostage Punch Dual Voice coil sub (4 ohms). I'm using 8 guage power/gound wires (not that it should pertain to my problem). Well, today is the first day I hooked it up, and instead of reacting to the bass, the sub was extending and retracting almost like a heart beat. It does this without music playing, however, with the cd player on (Kenwood headunit). What is going on? What should I check? What would cause this problem? The amp turns on...
Lou


And I didn't bridge the amp, it is wired straight.

 

The speaker wires may be crossed somewhere. The polarities reversed will cause it to retract and extend.

 

Also what kind of box do you have? A air tight box with the right space will cause the speaker to go in and come out slow. sounds like you have engine noise that is causing the speaker to react to the sounds. When driving and giving it gas see if yyou hear any rev through the speaker..

 

Sounds like the amp is shorting out. Sometimes they do that causing that heartbeat to happen. That amp may not have a protection circuit to kill the power to the sub and keep it from blowing. So instead of AC output from the amp, you now may have DC output.

 

turn the amplifier gain down. Do you have the sub out on your eq and xover or head unit turned all the way up as well? sounds like your amplifying silence. if you have a hi low converter do the same and turn it down as well and start from there.

 

Speaker wire polarity would not cause this problem. It also doesnt sound like the box. It sounds like the amp to me. I say reinstall the American Legacy to see whether the amp is definitely the problem. And double checking all your gains and eq settings can never hurt.

 

Would a difference in ohm setup create a problem? My amp bridges to a 2 ohm setup, which is how I wired my DVC 4 ohm sub, to be a 2 ohm. Right now, I didn't bridge my setup, so it is running off one channel, which creates a 4 ohm setup, powering a sub wired for a 2 ohm setup. I will double check everything, thanks for the help this far.

 

Turn on the amp and unplug the rca's. My mtx amp would still drive the sub after this. My amp was bad, I ended up replacing it with a better one. Is the kenwood brand new?

 

Nope, bought it on ebay and is supposedly two years old.

 

Here is the ebay auction I won: http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWN%3AIT.
So I disconnected my RCA's, and the sub still did the extend/retract thing. When I hook the sub to be bridged (one channel= pos, one channel= neg.) nothing happens, but only when it is hooked up to the channel 1. When I hook up the sub exclusively to channel two, nothing happens either. I'm using 8 guage power/ground wires w/ a 40 amp inline fuse, not that it should cause this problem (I think). Please help. Oh yeah, my sub is wired like this (Wiring option #1, the 2 ohm setup): http://www.rockfordfosgate.com/rftec...x=19&image.y=9

And another thing: I turned all the controls from my headunit down (+0 dB bass, etc.) and the above still happened.

AAAAnnnnndddddd....I reinstalled the American Legacy POS amp, and the sub still hits, so something's up with the amp.

 

I know how to adjust gain, and know the basic principle behind it, but how do I go about adjusting the equalizer? Is it something in my headunit, or seperate?

 

so you know the rca works on the left, try hooking the working rca to the other side and hook the speaker back up to channel two. It will definitively tell you if your amp just sux, you can get it fixed easily enough. I have a local guy you can contact and i have one form the bay that will fix it.

 

BIG LOU if your looking for audio stuff im located in ORANGE, CT @ Safeandsound (Right Behind Tgi Fridays) . We have a ton of amps Including PPI, PG, Alpine and tons more. If you go down their tell them Rob sent you hell give you a nice deal :]

 

By the way, I never thanked you for the offer, but I'm more interested in getting this amp fixed instead. Once the problem is worked out, I can't see myself wanting anything else. Again, thanks, sorry for bumping such an old damn thread, but maybe someone will see this again.

I still don't know how to adjust the equalizer, is there a website highlighting how to tune an amplifier?

Also, I have an aftermarket headunit (Kenwood), and the audio shop installed a hi/lo converter to tone down the amplifier noise I was getting from running an AM headunit to the BOSE speakers. Do I have to do something with this as well?

 

I agree.

 

Off topic, but I'm suprised you CT guys didn't goto CTMaximas.org meet today in Manchester @ Hooters. Only reason why I didn't go is because I am working on the CustomEnterprise 2006 calendar.

 

I wonder if the seller had the amp ran bridged and couldn't see this problem since there were two channels sort of hiding this issue. Looks like you bought an amp that had problems and now its showing you it's problems in full effect. It needs to be re-built or at least gone over to determine the problem with it at an authorized place.

Does the sub play okay with the music playing wired to the bad channel? Also if you're going to eventually run the amp bridged you want to run the sub at 8 ohms, the way it is wired now will burn up the amp.

 

Try to see what happens if you wire the sub to 8ohms and run the amp bridged. Wouldn't be surprized if the problem doesn't show itself as much wired this way.

 

I will try that, thanks. Out of curiosity, is there a reason why an 8 ohm bridged setup would work better? If I remember correctly, the auction states the bridged wattage at 2 ohms, so I figured that's how I would keep my wiring. I'm not looking for amazing power, definately better than my old POS amp, and hope this works out. I'm going to email the seller to see exactly how he was using the amp, bridged or whatever, and go from there. I hope this works.

 

I would have gone, had I not been 5 hours away in Rochester, NY for college. Believe me, I would have been all over that.

 

When running the amp bridged, it is running itself at 2 ohms which is why the wattage goes from say 150 x 2 to 460x1. Applying that to the sub wired in series at 2 ohms will show the amp a 1 ohm load, this amp is not 1 ohm stable. Bridging it to 8 ohms will allow you to run the amp cooler, safer, and with more power. With your sub I would wire each coil to one channel of the amp. This will provide the greatest output and most power from the amp.

 

The auction shows 460x1 at 4 ohms. The resistance that the amp will run at is determined by the resistance of your speakers.

 

If he has a 4Ohm DVC how are you seeing 1Ohm? It would be either 2Ohm in parallel or 8Ohm in series...

 

If he runs the amp bridged and bridges it to a 2 ohm load that will burn the amp out. Its rated at 2 ohms not 1 ohm stable. Once you run an amp bridged its running itself at 2 ohms. Which is why 2 ohm stable amps can only be bridged to 4 ohms. If thats not right, explain to me why they can't be bridged to 2 ohm loads if they are not 1 ohm stable

 

I get what you mean. The amp won't be seeing a 1 ohm load from the sub, but it will be pushing into a 2 ohm load, althought the amp is not rated/recommended at 2 ohms bridged.

 

The amp is only "bridged" in configuration with the sub. If your giving it a 2Ohm load then it sees a 2Ohm load. It doesnt drop it self more than that.

Being 1Ohm stable and 2Ohm stable are completely different. Because an amp isnt 1Ohm stable, why would that make it not 2Ohm stable? What in the world does one have to do with the other?

 

The kenwood is 2 ohm stable in stereo. So you can't bridge it to a 2 ohm load, it can only bridge it to a 4 ohm load, correct? So my point it is he runs it the way he has it and runs it bridged the amp will eventually overheat/breakdown or go into protection mode.

If they aren't 1 ohm stable and only stable to 2 ohms then you can't bridge a 2 channel amp into a 2 ohm load.

If I have an amp that is 1 ohm stable then I can bridge left and right channels into a 2 ohm sub, but not a 1 ohm sub. This is the principle I'm working with for this situation.

2 ohm stable stereo, 4 ohm stable mono. Thats what this amp is.

 

Correct on the first statement, although on the second sentence..

Not exactly.If theyre "only stable to 2Ohm" is that in stereo or Mono? Or possibly both? Not all amps are the same, so to generalize would be incorrect info.

Not a good principle as I stated, not all amps are the same.

 

Alright, I get it but I was talkin about this amp specifically and other 2 ohm stable in stereo amps.

 

I went by the staement of the "principle" you were using of its one it cant be the other. An example would be the Arc 1500XXK...

Stereo 4Ohm
Stereo 2Ohm
Bridged 4Ohm

AND

Stereo 1Ohm
Bridged 2Ohm

Theres alot of amps out there that are very versatile.

BTW..Kenwood is poopy anywayz.

 

So should I still wire my sub in series to produce an 8 ohm setup, or no?

 

Yes, although itll be less power produced from the amp, it should stay on and working correctly.

 

Well, I'll be sure to try that out when I get home for X-Mas Break next week sometime. Thanks for your help.

 

I think thats the bottom line anyways

 

 

hey man i live in rochester, and i've got some decent experience with systems. Shoot me a PM and depending on where your located I could try and help you out.

 

As others have pointed out:

2 ohm stable (stereo) = 4 ohm mono stable
1 ohm stable (stereo) = 2 ohm mono stable

There are many amps that will run a 2 ohm mono load, but there are many more that will not. Most consumer grade amps are only 4 ohm mono stable (2 ohm stereo).

Sounds like you may not have it hooked up right. An amp that isn't 2 ohm mono stable should still play at 2 ohm mono be it for a long time or a very short time. Your issue seems to be related to a malfunctioning amplifier or mis-wiring if you ask me.