Ampeg B4R cabinet hook-up: Confusion!!

Discussion in 'Amps and Cabs [BG]' started by spikyhedgehog, Feb 27, 2005.

  1. spikyhedgehog


    Dec 10, 2004
    Can anyone give me a comprehensive overview of how to hook up my cabinet to my B4r to get the 680 watts (8 ohms). At the moment all I think I am getting is the 255 watts from one power amp.

    How can I mono bridge the outputs, I have pushed the mono bridge switch in, and mono bridged the banana connections but it doesn't seem like 680 watts!!!

    Its running into one 4x12 8 ohm cabinet, and another thing thats confusing me is that if i press the mono/stereo switch in or out the same amount of power comes from the amp, surely this shouldn't be the case.

    Please help!

  2. cb56


    Jul 2, 2000
    You're using a banana cable for the amp and speakon for the cab I assume. The reason I ask is because US models don't have the speakon connection on the amp but the import models do.
    Anyway, assuming that is what you are using, push in the mono bridge button. Connect the banana to the two red banana output jacks (make sure + and - are correct) connect the speakon to your cab. That's all.
    btw you are not going to hear a huge difference between 255 watts and 640 watts. but you will have more headroom.
  3. spikyhedgehog


    Dec 10, 2004
    Ok, basically all I have done at the moment is chopped the end off a 1/4' jack cable and put one section of the wire into one banana plug and the other section into the other, then I have put the 1/4' plug on the other end of the cable into the cab.

    Would this make a difference, I will be getting banana plugs soon but I only just got the cab today so havn't got round to it yet.

    Thanks for your help
  4. cb56


    Jul 2, 2000
    That should work, but I have to warn you. You are possibly venturing into dangerous territory here. Do a search on mono bridging an amp. Some of the things you will read will scare you. From what I've read (not being an amp tech that's all I can go by) there is danger of shock causing injury or death if you screw up. Let me repeat do a search. I personally would wait for or make my own banana cable and use caution when plugging them in or touching them. I always have my amp off when I do this. I bridge my b4r at 1000 watts into my 410 and 15 cab (500 watts per cab) . Last night I used my SVPCL into my Yamaha power amp at only 275 watts per cab and was able to get as loud as I needed (too loud for the soundman) and the amp ran very cool compared to my B4r bridged. I guess what I'm saying is be careful with bridging and don't expect tons more volume. If you really need more volume consider a second cab instead.
  5. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    That must be an older one, newer units DO have Speakon for domestic US as well as export.

    Thing is, if you have it wired for "bridge mono" mode, you shouldn't hear anything with it set to "stereo" mode.....

    If you change from Bridge mono to stereo modes with the speaker wired for mono, it should be like switching the signal on and off. Off in Stereo, and On in mono.....because the phase of the channels is reversed in mono...but not in stereo. In stereo they would cancel.

    If you happen to have it set for biamp, then with stereo mode and mono wiring you will hear something, but it should distort and limit early.

    Since you have the older banana plug version, for "bridge mono" mode you should have one wire going to each RED terminal.

    There should be NO WIRES on the BLACK terminals.
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