Bridging for dummies...

Discussion in 'Amps and Cabs [BG]' started by HeavyDuty, Dec 23, 2001.

  1. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    I'm trying to logically research what I want and need in a new power amp (my first), and I'm getting confused.

    I will (eventually) be driving a pair of 8 Ohm Bag End S-15D cabs, which have a rated power handling capacity of 200W continuous / 400W peak. I figure 300W per cab would be enough for me in any situation, and would give me the SPLs I want with lots 'o headroom.

    I’m considering Carvin amps due to price, availibility, price, reputation, price, features, and - of course - price. Other possibilites include a Mackie M1400 and/or a Stewart World 1.2 . I was originally looking at picking up a small head like a WT400 or Mesa Walkabout, but was lead astray into preamp/power amp/big headroom country.

    As an example, Carvin's DCM1000 is rated at:

    Bridged 1000W @ 4 Ohms / 700W @ 8 Ohms

    Both channels (I assume this means stereo) 350W + 350W @ 4 Ohms / 225W + 225W @ 8 Ohms

    OK, it seems obvious that if I run bridged, I’d be seeing 1000W, which is 500W per cab. And that if I run in stereo mode with parallel input, I’d be seeing 225W per cab, because each channel has only an 8 Ohm load.

    What are the advantages and disadvantages of running bridged vs. stereo in my situation, where I will have two identical cabs? Is one mode more reliable or less demanding than the other? Will the amp run cooler in stereo mode with parallel input than it would in bridged mode? It would seem the amp would be running flat-out all the time in bridged mode, rather than loping along in stereo.

    I couldn’t find definitive answers after a two hour archive search, so I’m probably not searching on the right keywords - I got close a few times, but nothing monosyllabic enough for my antihistamine-addled brain to fully comprehend. I’m sure this has been covered before - can anyone help show me the way to enlightenment?
  2. BigBohn


    Sep 29, 2001
    WPB, Florida
    Just stop your sissy blabbering and buy the damn poweramp, and while you're at it, upgrade to the DCM2000, like I did.

    :p :D
  3. lo-end


    Jun 15, 2001
    Dont listen to bigbohner, he doesnt know that QSC PLX amps kick carvin's butt :p
  4. BigBohn


    Sep 29, 2001
    WPB, Florida
    Hey lo-end, what do YOU know about the QSC?? You're just an Ampeg-er. BOO!!!!!

    :D ;)
  5. The keyword here is "bridging".

    Make sure your combined impedance of both cabs (4 ohms) is supported by the amp when running in bridge mode. Reason is, in bridge mode each amp channel only sees half the impedance. In this case, 2 ohms is probably too low.

    The amp is also working its very hardest in bridge mode and putting out 2x more voltage. This can kill you if you get across it. Personally, I would not bridge anything less than 8 ohms, but I'm conservative. Check your amp manufacturer first.
  6. BigBohn


    Sep 29, 2001
    WPB, Florida
    The Carvins can handle 2 ohms on each channel. I'm positive, because if it couldn't, I wouldn't have bought one, because I'll be doing nearly the same thing as him eventually, just with 2 410XLTs (or a 1x15/18, whatever).

    Don't worry about the Carvin not being able to take all that power, HeavyDuty. The beast is made to last, nuff said.
  7. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    If running it bridged all the time is OK, I'll probably go with the DCM600 or, at most, the DCM1000. My back would appreciate it! I'm within specs bridged with 2 X 8 Ohm cabs - the Carvin will do down to 2 Ohms per channel in stereo mode and 4 Ohms bridged, and they claim it's designed to do so.

    I don't need super-high power levels - I don't slap or pop. And, a DCM600 or DCM1000 is way cheap, too...

    Thanks for the comments!
  8. The manual for the 600 head states that 4 ohms total load is the minimum for bridging.
  9. The way to run your speakers with the Carvin amp would be in the bridged mode.I've run my R 1000 in bridged mode,4 and 8ohms,most of the time I've had it with no problems.It has the same power section as the DCM 1000.I can really hear and feel a difference between running in bridged mode and running on each side of the amp.Get the DCM 1000.It has a little better damping factor and 400 more watts for only a few dollars more.The 1000 wouldn't have to work as hard as the 600 and I think you could hear and feel the difference even at lower volumes.
  10. Forgot to mention Carvins power amps are on sale now,another plus.
  11. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Crap! You mean $369 isn't the normal price for a DCM1000?
  12. bizzaro


    Aug 21, 2000
    The R600 is a weakling :eek: Go for the 1000!!;)