[thewire]

I have four MA-500 monoblock amps that I using to power four 12" Crystal Audio & Video drivers. They drivers are rated 4ohm and up to 400W, but the amp they came with was a 200W RMS. The monoblocks I drive them are 180W into a 4 ohm load. This might be a silly question but do I loose or gain anything by running two of the 12" drivers with two bridged monoblocks? If I could do so I could use the speaker plates in my HT and try and run the amps in my equipment closet which would get my amps off my front stage.

Here are specs for the amp.

http://209.85.173.132/search?q=cache:LDr-U0LrdS0J:www.marantz.com/pdfs/u_amp_ma500_bck.pdf+marantz+MA-500&hl=en&ct=clnk&cd=2&gl=us

I used to know the answer to this and I think last time I asked about this question for my 15" subs that were clicking on and off the answer was that my amps were not powerful enough to handle the 2 ohm load. :doh: I tried running some sweeps and they do work bridged, but this does not mean for certain it will work for movies I think. Thanks.

Photos of my subwoofer drivers.

 

[JCD]

So, I'm answering only based on preconceptions and prejudices -- so don't take this as an end all be all answer..

But I would not bridge the amps for a couple of reasons.

One, I don't think having those extra watts is going to make much of a difference even if everything else stays the same. For the most part, most of what you hear is only using about 10 watts or less.

Two, my understanding is that you add a bunch of unwanted "stuff" into the mix when you bridge an amp. The noise floor goes up, you get some unwanted distortion, etc..

Again, that's just what I've picked up from readings here and there. Now, if I were feeling frisky, would I give it a whirl and see? Probably. That's part of the fun about this hobby/obsession of ours.. you can do a lot of experimentation.

 

[Kal Rubinson]

I would advise against it. Bridging may increase power but it also reduces the ability to put that power into low impedance loads. Bridging two amps, rated at 4ohms, would reduce their ability to handle 4ohms with full power. Moreover, paralleling two 4ohm drivers would give you a net 2ohm load, something that would stress even the unbridged amps. A bridged pair might just go 'poof,' as each of the pair would only see 1ohm!!

Kal

 

[thewire]

I would advise against it. Bridging may increase power but it also reduces the ability to put that power into low impedance loads. Bridging two amps, rated at 4ohms, would reduce their ability to handle 4ohms with full power. Moreover, paralleling two 4ohm drivers would give you a net 2ohm load, something that would stress even the unbridged amps. A bridged pair might just go 'poof,' as each of the pair would only see 1ohm!!

Kal

I completely forgot that paralleling the woofers would make them 2 ohm. I'm certain you have saved me harming the amps or having to replace fuses. I'm glad that I asked about this and thank you.

JCD,

When I had them bridged I was testing the single sweep I tried with my laptop adapter, and I noticed the hiss and pops from the bridged amps and paralell subs was very loud and annoying more so than the ones that were not. Since I might be using some new 4V outputs instead of my current 2V sub output I thought it might not be an issue, but that is worth considering. If I were to listen at a higher level there would be the possibility of adding some noise and espicially since my amps are not designed to run this way as Kal has pointed out. Good points and this is what I think I had forgotten about. Thanks.

I will stick with the way that I have it, or consider running each sub off the wall plates that feature bi-amp (bi-wiring) wiring. I could then run some new wires from equipment closet to the front stage for the left and right speakers using the same access point I have running my sub RCA line and mic line from. I don't have enough wire to do that at the moment, but I will keep that on my list and see what others think of the idea. That way I might still get the amps into the equipment closet.

 

[Andysu]

Hi Mo get one of those affordable large PA amplifiers from Behringer EP2500 this sucker will support 2ohm load along with plenty of headroom support.
http://www.behringer.com/EP2500/index.cfm?lang=ENG

Or it might be wise to run each sub with its own dedicated power amplifier along with DCX2496 to give you easy of mind without blowing the subs into kingdom come.

Merry Christmas