Are these amps able to be Bridged?

Timothy Reason · « **on:** 18 Jan 2005, 06:58 am »

I am looking to use a single amp and Bridge it Mono to a VMPS sub, however I can not find Bridge Mono stats on a few amps and am wondering if they can not be bridged. If you could tell me yes or no, and happen to know the watt rate if they are that would be great! tyvm! They are...

B&K st1400
Adcom GFA-545 and or GFA-5400
Hafler DH-200

The others I am considering I have seen the bridged numbers so have no worry.

I will add to this... If the Bridged power is in the 200 watt range I will stick with the VMPS Original sub, If the Mono Watt power is 350, should I stick with the Original with Mega Woofers or go to the Larger Sub? Of what I am considering I think the Rotel 980BX is most powerful in Mono mode around 350 watts. Thanks all!

jeffreybehr · « **Reply #1 on:** 18 Jan 2005, 07:28 am »

I have no idea if those amps have bridging circuitry in them, but I know this--in a solidstate amp, when the channels are bridged, theoretically, the total power quadruples. SAW, a 100WPC/8 stereo amp turns into a 400-Watt/8 amp. However, and it's an important however, virtually no bridgeable SS amps have a bridged-power rating into 4 Ohms. That's because they're somewhat current-limited in bridged mode because, effectively, each channel drives only half the load, so each channel already is driving only 4 Ohms when those 2 channels are driving an 8-Ohm load.

What's the impedance of the VMPS woofer?

Timothy Reason · « **Reply #2 on:** 18 Jan 2005, 07:56 am »

Good Call, The Impedance load on the Original sub is 8ohm, the Larger Sub is 4 Ohm/Or 8ohm if the right channel goes to one woofer and left goes to the other. I think I am going to go with a Rotel RB-980BX which is around 100X2 in 8 ohm, 200X2 4 Ohm and 360 Bridge Mono. Since the Larger Sub is a 4ohm load, I assume I can not run this amp Bridged, so now I have to ask..... Is the Rotel too strong for a VMPS Original with Mega Woofers? I think the Mega's are rated at 300 watts, so will the 360 from a Rotel amp be too much? Not that I will ever play the amp at its max, but as a precaution. Thanks!

warnerwh · « **Reply #3 on:** 19 Jan 2005, 01:32 am »

You will not have to worry about the fact your amp is rated slightly higher than the VMPS subs. The megawoofers I believe are designed to not bottom out. I've owned two pair of VMPS speakers and never had a problem with amps running major power. The Rotel is a good choice and will work well. Also you'll find the VMPS subs to do very well and are a very good choice. They are a bargain and Brian rates his speakers honestly, you will have bass POWER in the twenties no problemo.

Timothy Reason · « **Reply #4 on:** 19 Jan 2005, 03:27 am »

Thanks all, turns out I found a Used Original in Piano Black with every upgrade option available! Was worth it to me! I will be using the Rotel amp on it, as everyone said the mega woofers will be fine! So for once in my life I can say I have plenety of power for this particular application! lol Thanks everyone for the help!

bubba966 · « **Reply #5 on:** 19 Jan 2005, 07:09 am »

Don't worry about having a bit too much power. Too much power doesn't really kill subs/speakers, too little power kills 'em. Yes, you can melt down voice coils if you feed a speaker waaay too much power. but you need to do that for extended periods of time at absolutely insane volumes to do that.

If it makes you feel any better, I've only heard one VMPS sub. It was a new larger being fed by a QSC 3402 (I think that's the right model #). And, if I'm recalling properly, it was running bridged and putting out 3,400W!

And while I'm not sure how long that subs been in use like that. But I'd guess at least two years.

Now I've no clue what the rated continous power handling of the new larger is, but I know it's nowhere near 3,400W. But it doesn't matter as it's never getting fed 3,400W continous (if ever).

Don't worry about using an amp rated at 360W for a sub that's rated for 300W.