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    running DVC sub on two channels of power amp?

    When I sourced the subs for the Alpine system in my truck, I bought Alpine SWS1043D DVC subs because they were 4 ohm and in the right RMS range for bridged mode on a Alpine PDX-F4 amp.

    I bought two of the PDX-F4's because I wanted the same amp for the door speakers and the subs, in bridged mode (200WX2@4ohms). I realize there are better choices for a sub amp, that is another discussion though.

    The mistake I made when I bought the subs was not knowing that a 200W RMS DVC sub advertised as 4 ohm is actually two 4 ohm voice coils that run in series or parallel. Meaning the load to the amp is actually 2 or 8 ohms. I didn't realize this until 4 months after buying them when I was ready to start the first phase of the install. So, I decided to use them in 8 ohm mode (actually, they measure 6.8 ohms on my meter in series).

    So, last weekend I finished the main install and powered up, set levels, EQ, etc. -- they sound pretty good. But, predictably, don't hit hard enough. I am more interested in SQ than massive thump but I think the kick drum and picked bass guitar needs to punch through with a little more authority. It's not bad, just could be better.

    So, what I am thinking about doing is un-bridging the PDX-F4 amp and running each voice coil on a discrete channel for each side. That is:

    * Left channel, two pairs of outputs, one for each voice coil on the Left sub.
    * Right channel, two pairs of outputs, one for each voice coil on the Right sub.

    That way, my amp sees a 4 ohm load on all channels which is what it is designed for in non-bridged mode and the subs are getting the FULL 200W (as opposed to around 140W now because of the higher impedance, lower current, E=IR, etc.). It is the exact same signal to each coil on each sub so no, it isn't going to cause thrashing between the coils.

    I think they are going to sound a lot better. But, wanted to post about this in case anybody has done this in a similar arrangement and has comments, suggestions, observations, etc.

    Thanks.







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    Re: running DVC sub on two channels of power amp?

    sounds good in theory...and should work. but my advice would be to not do it because it could open the door for a slew of problems down the road if you were to develop a loose connection or something of that nature. Do you have the subs in separate enclosures? Shrugs*....give it a shot and see if the difference would be justifiable. I do have one question..why did you want the exact same amp for the sub stage as the other drivers in your system?


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    Re: running DVC sub on two channels of power amp?

    Good question -- partially for simplicity and cosmetics (they look great side by side), but mainly because the place I ordered them from gave me a SMOKIN deal if I ordered two. I figured, for that price, I could get creative and make it work. Which is, in fact, the way it is working out

    Good point about losing a connection. That would probably NOT fry the sub though, my understanding is you can run a DVC sub on one coil, it's just inefficient and sounds bad. The amp would probably shut down in that case as well. Just have to make sure my conections are solid (learned that the hard way -- long story).

    I'm gonna try it this weekend.




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    Re: running DVC sub on two channels of power amp?

    nothing wrong with a clean install and saving $$...let us know how it works out




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    Re: running DVC sub on two channels of power amp?

    ok, so I did it this weekend, rewired the two 4 ohm DVC subs to run off each of the four channels of my 4 channel Alpine PDX-F4 amp. That about 100W per coil, 200W per sub into 4 ohms, using the right outputs for one sub, the left outputs for the other. Significant improvement over running the amp bridged into the subs with coils in series at 8 ohms. Very low, almost sub-sonic frequencies now apparent. They hit harder -- not a massive difference in that respect but definite and all good. I need to tune my crossover points to give them a little more in the upper range, around 200 - 250'ish. Door speakers roll off at 100; want to raise that a bit but try doubling up with the subs around 225 (with correct phasing).

    Overall, it's a keeper. I would almost say, in my novice naiveté, that running a pair of DVC subs, with identical sub/coil input signals, off a 4 channel amp, designed for the impedance of the individual coils and RMS rating, is a Real Good Thing.




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