Amp/Bandpass possible connections?

Hello there!

I finnaly went ahead and took my SUV to get everything installed and it's working, but ...(there's always a but...).  What I got is the following:  It's a Montero Sport, with the "Infinity" system (Which has 8 speakers if you count the tweeters, and its amplifier).  I bought some special cables that allowed me to keep the factoy radio, and the factory amp, to install a pre-amp (autotek 7004b) b4 the factory amp.  I needed the preamp for the aux input, but since it came with a sub out I decided to add a bandpass (ABP10 from audiobahn has 2 10" single 4ohm coils).  The bandpass is rated at 600 RMS (300RMS each), and for that I bought a Kenwood amplifier the KAC929 'cause if I could bridge it it will give me 460W X 1.  Here is the "problem" ... The people that did the installation (A pretty clean installation), told me that I could not hook up the amp like that since the bandpass won't let me, so they went to the normal 4 ohms 150w X 2.  Somehow I doubt that that it's true, but I really don't know much of that!  I believe that even though it still soungs good and the subs are moving, I still have to play with the sub out vol to more than what I wanted if I want to feel it.  I will give the full specs of the amp and the bandpass so if anyone know a better way to connect them plz let me know...

AMP Kenwood KAC929::::   MAX Out (4ohm) Normal 300W X 2, Bridge 1000W X 1.   RMS 4ohm Normal 150W x 2, Bridge 460W x 1.    RMS 2ohm Normal 230W X 2.

Bandpass ABP10 from Audiobahn:::  Dual 10", Impedance 4ohm (stereo).

Plz help!  Comments, Sugestions....       Opy

The first thing that comes to mind is that your installers hooked your subs up in a series configuration. If this is true one of your subs would be 180' out of phase thus taking the energy of the other sub.

They are cancelling each other out.

I looked up your amp and I see that there is no rating for a 2ohm mono load, so wiring them in mono paralell may be risky. My suggestion would be that: 1)hook the subs up in stereo 2)trade the subs for 2 8ohm subs 3)get an amp capable of doing a 2ohm bridged load.

Anyone out there running this amp with a 2 ohm mono load???

Thanks for your input Tcole...

I believe that they said that they went stereo for the subs...

And about "...cancelling each other...", since they are in a closed bandpass, how can I check that?  They(it), sounds good, but I know the can sound better if I give them more power and not having to go more than half way in volume...

Why couldn't I just do the 4ohm bridge?  (460W x 1)

Oh they are in stereo.     Well maybe you just have high expectations?

The reason you cant do 4ohmsx1 is because you have 2 4ohm subs. When you run 2  and run them in parallel you present your amp with a 2 ohm load. By the specs your amp cannot handle this low of an impedence. If you run them in series you present the amp with a 4 ohm load but heres the klincher, one of the subs will be out of phase and it will cancel the output wave of the other.

Solution a)trade the subs for 8 ohm ones b)get a different amp that is capable of 2ohm mono"usually higher end amps" c)settle with what ya got.

From experience 2 10 in that order of bandpass box has huge output, narrow freq. response but loud. Large companys like k###w##d arent always that honest about there output ratings. Get clean power not nessesarily huge power. I heard when you actually double your power you only gain 3db.

Hope I helped

Hi Tcole:

Thanks for your explanation.  If I understood correctly, and the specs at 2ohms for that amp is 230W x 2 as "Normal" (whatever that means.), well, then I will be able to connect them like that instead of 4ohms 150W x2?

Thanks again, Opy

I work in a store that sells that particular kenwood amp.  The amp is not designed to handle a 2 ohm bridged mono load, which is why the installers hooked it up in 4 ohms stereo. The 230x2 figure is for 2 ohm stereo, which you can't get with your existing speakers. Back to your original post, though some amps are not rated for a 2 ohm mono load, they will do it in practice provided the gain is kept at reasonable levels(i.e. 75% or less).  Keep in mind that running the subs like that will void any warranty on installation from the shop, and if the amp starts going into protection mode, turn the gain down a bunch and gradually increase it.