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Mono Bridging

Discussion in 'Amps and Cabs [BG]' started by ASR, Apr 11, 2001.


  1. ASR

    ASR

    Apr 2, 2001
    Houston, Texas
    I have an Ampeg B4 amp that I run through an Ampeg 8x10 cab. The back of the amp says that it puts out 1000 watts if it is monobridged. That sounds pretty good, but what would the difference be if I run each channel (500 watts per channel) into a seperate input on the cab? I have tried it, but I don't hear any difference. It may be that I only tried it in our rehearsal space, which isn't the best place to work on good sounds.
     
  2. seamus

    seamus

    Feb 8, 2001
    Jersey
    I'm thinking it's 500x2 @ 2 ohms, but 350x2 @ 4 ohms.

    Bridged, it would be 1000x1 @ 4 ohms.

    Bridged mono would be your highest output to an 8x10, I'm assuming it's a 4 ohm enclosure.

    As a matter of fact, I would think bridged mono would almost *always* be the way to go with an 8x10, to maximize output. :)
     
  3. ASR

    ASR

    Apr 2, 2001
    Houston, Texas
    you are correct! The cab is 4 ohms. Good point that I was not thinking of...electronics is not my thing.

    The other thing I was getting to is this: if I ran each channel seperately into the cab, would that give it a stereo sound, and would the reduction in wattage outweigh any gains from stereo sound?
     
  4. seamus

    seamus

    Feb 8, 2001
    Jersey
    No sweat, electronics are not really my thing either. There are a ton of guys in here that have fogotten more about gear than I will ever know. :)

    Sorry I can't comment on the difference between stereo and mono as far as that goes, I have never had an 8x10. :(

    I only bridge mono to utilize my heads to their fullest output potential, but I haven't considered how it differs in sound compared to running full range stereo.

    Maybe someone else can pick up where I left off...
     
  5. bent23

    bent23 Guest

    Jan 3, 2001
    Memphis, TN
    It is my understanding that it is usually NOT a good idea to run 2 channels into a single cabinet. Your amp should have a switch for bridging its separate channels. You would then run a single cable from one output channel of your amp to you cab.
    Someone please correct me if I'm wrong.

    Brent
     
  6. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    bent23, I believe that the 8x10 cab that ASR is referring to has 2 inputs, and if that is the case, it would be fine to run one channel into each input.
     
  7. ASR

    ASR

    Apr 2, 2001
    Houston, Texas
    embellisher is also correct. The cab has 2 plugs. The cab says on that back that it will handle 1600 watts, and even with mono bridging, I am only putting 1000 into her, so I'm kind of lost on why that is a bad idea. Enlighten me, if you will. Like I said before, an electronics guru I am not...
     
  8. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    The SVT 810E can be used either as a 810 or as 'two 410s in one box' (at least the newer models), BUT I want to warn other readers of this thread:
    if a cab has 2 input plugs, these are usually parallel inputs with the purpose to hook up a second cab.
    You should NEVER run two different amps into the same cab!! (the 2 channels of a stereo amp also work as two different amps unless they are not bridged).

    Back to your rig:
    impedance of the SVT 810 is 4 Ohms if run as 810 and 8Ohms each if run as two 410s
    The power output of an amp also depends on the impedance of the cab(s) hooked up. According to the Ampeg homepage the B4 puts out 1000W into 4Ohms in mono bridged mode but only 200W into 8Ohms per channel! (laws of nature: higher impedance => lower power output...)

    Hope that helps,
    Matthias
     
  9. bent23

    bent23 Guest

    Jan 3, 2001
    Memphis, TN
    Matthias,

    So I wasn't totally incorrect about my statement, with special exception to this case and perhaps others where a cab can be split in 2 halves, each requiring its own amplification. It has been my own experience, limited as it is- that one usually is discouraged from running 2 channels into a single cab, for the reasons you stated in your post- usually the extra input jack is for the connection of an extension speaker running in parallel.
    I own an ADA Bassline VX (2x10 and 2x5)which has an 8 ohm input, a parallel jack, and a series jack. The manual specifies NEVER to plug more than one amplifier output channel into it.
     
  10. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    Brent, both your statements are correct, but to every rule there's an exception ;)
    (That's a rule too, but I don't know if there's an exception to it :D)

    There's another case where you can run two amps into one cab: biampable cabs, e.g. by Gallien-Krueger or Ampeg's 'extreme series' and some years ago I had a Peavey 1516 (1x15" + 2x8") which was biampable, too.

    But usually, yes, never run more than one amp into each cab.

    Matthias
     
  11. ASR

    ASR

    Apr 2, 2001
    Houston, Texas
    Thanks everyone for your help here. I think I have been given a lot to consider. I think. Actually, let me review all this one more time! Thanks again everyone. I really appreciate the help.
     
  12. Okay Matthias, I've never actually heard this one before. Why? What if my 2x10 cab is capable of running in either a 4 ohm 1 channel configuration, or a 2 channel 8 ohm configuration? (The cab is, actually)

    FF
     
  13. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    Well, that's what we've been talking about all the time - the SVT 810 is also capable of running in 1 or 2 channel configuration.
    Sorry, but I can't see the sense of your statement, you maybe better read the whole thread or think before typing...

    But one thing is for sure: If you connect 2 amps into 'the same set of speakers' (to avoid the misleading word cab here) you will fry both amps.

    Matthias
     
  14. seamus

    seamus

    Feb 8, 2001
    Jersey
    I stand by what I originally posted for an 8x10.

    Bridging mono is the way to go, especially if you have 600 watts to spare on the cab's rated power handling. Put all 1000 into that bad boy and stand back! :)
     

  15. I always think before I post. I can see running both amps into the same set of speakers doing damage. I think there was some miscommunication with the "cabinet" term.

    Fair enough. I was just looking for clarification. Don't want to damage my speakers :)

    FF
     
  16. ASR

    ASR

    Apr 2, 2001
    Houston, Texas
    Seamus - That is the way I have it set up now, and yes, it will make your heart skip beats. I play it with the volume on about 2 and the gain around 4. And since I picked up 3 identical rigs (all new except one amp for 3K, if you believe that), I'm not thinking I will need anything else for amplification until Metallica is opening up for us. Yeah, I mean never.
     
  17. seamus

    seamus

    Feb 8, 2001
    Jersey
    ASR:

    Cool man :)

    All that surface area on an 8x10 is a definitely a monster.