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Question on bridged vs stereo (Ampeg B4R)

Discussion in 'Amps and Cabs [BG]' started by xring, Oct 5, 2003.


  1. xring

    xring

    Sep 16, 2003
    Ohio
    Original topic huh? I will soon be a new owner of the B4R (thanks Chris) and need some advice. The head will do 340w each side at 4ohms, or 1000w bridged 4 ohm. I would prefer to run the 2 channels, but as far as I can tell in the specs, there is no control over the level of each channel - just the master.
    Since I will have different cabs - Avatar 212 and 210, this might be important. So the stereo set up is really only optimized if you have 2 of the same cabs - correct? I have not decided on 4 or 8 ohm cabs yet, thus my question. Is there any advantage (with this head) to run 2 channels? I was going for the 4 ohm, but now think the 8's (1000w bridged) would be wiser. Any opinions? Thanks, Randy
     
  2. cb56

    cb56

    Jul 2, 2000
    Central Illinois
    You are correct. There is no level control between the two power amps unless you are running in biamp mode(Low/Hi). You can also, run in biamp mode (Low/Full range) or (full range/Hi) and have balance control. I personally wouldn't worry about it and run both cabs full range. You could get the 4 ohm cabs and run one off each side of the power amp at 340 watts each or get the 8 ohm cabs and run it bridged at 1000 watts(500 each cab). I don't think you would hear a big difference between the two set ups. If you are sure you only want to run 2 cabs (as opposed to 4 cabs at some time).I would suggest the 4 ohm cabs and run them full range. Just my opinion though.
     
  3. xring

    xring

    Sep 16, 2003
    Ohio
    Thanks for that. Even if I did want 2 more cabs at 4 ohms ea. the head is rated for 2 ohms per side 500w per.:) I don't think that will be necessary.
    One more thing. If you run 2 channels to two cabs with only a master volume, what is the difference really from bridging it? I wonder if Ampeg could have easily added a gain control to ea. channel. Seems logical anyway. Is it easier on the amp to do 2 ch. instead of bridged even if the ohms are the same?
    Too many question I know. I'm still learning at my old age.:D Thanks, r
     
  4. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    The difference is that you will have 1)a combined (lower) impedance 2)the amps run together 3)max output from your amp due to the lowered impedance load. I run a stereo amp with one speaker in bridge mode all the time. I like it better that way! :bassist:
     
  5. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    I had a chance to buy this head last week, but I passed on the offer because I misunderstood how this amp works. Oh well, my loss is your gain. I also had planned on running this head through an Avatar 210 + 212. Anyway, now that I understand how it works, I believe this is what you want to do. Run it bridged and buy two 8 ohm cabs. Daisy chain the cabs (meaning, out from the head, into cab #1, out of cab #1, into cab #2). That will give you a total load of 4 ohms and 500W will go into each cab (1000W total).

    For now I guess I'll just have to be satisified with my little 350 watt head. :meh:
     
  6. xring

    xring

    Sep 16, 2003
    Ohio
    Thanks Brock. Once in a blue moon I get a break.:)
    I'm moving up from a 160w single 15 - no tweeter. I needed it baaad! Randy
     
  7. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    Only one problem with what I mentioned above. The Avatars only take 1/4" plugs. I believe you have to use a Speakon cable to bridge the two sides. May need to buy an adapter or make a slight conversion with one of the cabs. Maybe you can find a cable that's Speakon on one side and 1/4" on the other.
     
  8. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    I believe you have binding posts on that head too? you could get a banana to 1/4" or a speakon to 1/4". The speakon has a locking feature and you can't reverse the polarity when you plug it in. You can buy a speakon wired for bridged going to the 1/4 wired for the cab.
     
  9. xring

    xring

    Sep 16, 2003
    Ohio
    Yeah, I guess the adapter cords are out there. I may have the other jacks installed as the 1/4" may limit the cabs full potential for power so I hear. Thanks for the replies. r

    Brock, Are you using the Avatars now? What do you think of that set up? Got the Delta LF's in the 212??
     
  10. pbd

    pbd Commercial User

    Jul 17, 2003
    Metro Detroit
    owner Procables N Sound
    You can change these out pretty easily yourself. Buy a round panel mount NL4, drill the hole, connect the leads, screw it in and your done. You could keep the 1/4's for future flexibility. I've heard of some speakers getting enough back pressure that they actually pop out the 1/4 plug. The NL4 (speakon's) have faston clips so you won't need to solder if you don't want too. Just tie into the existing wire with a mechanical device (barrier strip, wire nut, etc.)
     
  11. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    If you really need to control the volume of one cabinet relative to the other, you could buy a "volume box" from a guy on eBay. My guess is that it's a box with two jacks, a potentiometer and some wire. You could patch that in the preamp out/poweramp in jacks for the "loud" channel and trim it from there.

    The boxes aren't to expensive and will do what you want.

    FWIW, no commercial interest, etc.
     
  12. xring

    xring

    Sep 16, 2003
    Ohio
    All kinds of good info here! Thanks.
    r