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mixing woofer sizes on mono amp ok?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=126179
Printed Date: May 10, 2024 at 3:26 AM


Topic: mixing woofer sizes on mono amp ok?

Posted By: offthahorseceo
Subject: mixing woofer sizes on mono amp ok?
Date Posted: February 16, 2011 at 11:48 AM

1st question, and the answer to this may answer the rest...when running multiple subs on a mono amp, does power get split evenly, or does it depend on wiring length, speaker condition etc etc?

ok so originally i wanted to use 2, 3, or 4 rockford fosgate p28s8 8" 8ohm svc subs.
These subs are rated to handle 200w rms each
I have an Auiobahn a8000t amp, which is rated 400w rms @4ohm or 800w rms at 2 ohm

if i use two i can create the 4ohm load and run it at 400w rms which means 200 per speaker.
If i use 4 i can create the 2 ohm load which will mean 800w rms according to audiobahn, which will STILL mean 200w RMS per sub. Well, that sounded like a great idea. but it is VERY hard to find 2 more p28s8 speakers now since theyre a few years old. (i already have two)

So then i considered a 10 as well, i could get a different bass freq range and fill more of the space i needed to fill. i found a DVC rockford fosgate p210 which can be wired UP to 4 ohms and can handle 250w rms

that would be look great, a big 10 with two 8's on each side.

The question is, would the amp be able to power two 8's AND a 10? Also, how would i wire the 2 8's and a 10 to create an acceptale load? i figure i can wire the 2 8's down to 4 ohm and the 10 UP to 4 ohm, but how can i wire them together to create 2ohm

also, i plan on using a sealed box with seperate chambers for each driver of course.



Replies:

Posted By: offthahorseceo
Date Posted: February 16, 2011 at 11:49 AM
edit:

or am i better off just running the 2 8's or even continuing my search for 2 more p28s8's




Posted By: DYohn
Date Posted: February 16, 2011 at 4:22 PM

Power output is shared among multiple drivers depending on their impedance.  If all speakers are the same impedance, then the power is equally distributed.  If any have lower impedance, they will utilize more power than ones with higher impedance.

There is nothing inherently wrong with mixing woofer sizes, however your idea that different sizes will produce different bands is incorrect.  Larger cones simply tend to produce lower frequencies at higher output levels (everything else being equal.)  The real problem with using multiple woofers, and especially mixing multiple sizes, is matching efficiency (higher efficiency woofers will be louder) and avoiding phase cancellations due to placement issues,.

Using two tens and two eights per side is fine, as long as you make sure you are not overloading the amp by creating too low a net load, and as long as you don't care about the loudness issues and possible phase issues - or if you can either adjust their position or individual phase and levels by using separate amps that would be much better. 



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Posted By: offthahorseceo
Date Posted: February 16, 2011 at 4:37 PM
thanks for the quick reply


im not necessarily worried about loudness as much as clarity. I want to HEAR as much bass as possible even if it isnt necessarily LOUD.

i actually meant ONE 10 and two 8's, set up kinda like this:
____
|oOo|

i guess i could get a seperate amp but then its almost like a waste of amp...

taking into consideration the power increases claimed by adding a third or fourth amp and wiring the set down to 2ohm. would two more subs theoretically performing with 200 watts each really make a difference.

if different size subs wont make a sound or different bands, how about differently configured sub box, for example, 4 8's 2 sealed 2 ported (same box, 4 chambers, two ported chambers two sealed chambers)




Posted By: offthahorseceo
Date Posted: February 16, 2011 at 4:39 PM
edit i meant power increases claimed by adding a third of fourth subwoofer, NOT amp




Posted By: DYohn
Date Posted: February 18, 2011 at 12:17 AM

If it is clarity and sound quality you're after, a single 12" or set of 12" woofers will likely sound better than anything you've mentioned so far.  Get rid of the Audiobahn and the Rockford ideas and purchase high quality components and you will be much happier for much longer. 



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