Bi-Amping, need some amps recommendations

Discussion in 'Archived Threads 2001-2004' started by JayM, May 3, 2002.

  1. JayM

    JayM Stunt Coordinator

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    Ok, I have PSB 5T's as my mains and I want to bi-amp them. This is what I know so far.

    I have to disable the internal cross-over in my PSB's. I run a cable from the pre outs of my 777es and run in to an active crossover. The x-over will split into high and low signals, I then run each signal to it's own amp and use the amps to run the high and low of my speakers.

    So I need 4 amps, or 2 stereo amps. 2 lows, 2 highs. I know there are some amps that are better running the lows and some that are better on the high end. What I need from you guys is some recommendations on which amps i should get. I would like to keep the total price reasonable.

    Let me know what you guys think!
     
  2. Wayne A. Pflughaupt

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    Jay,

    What kind of crossover are you using?

    Often if you bypass the manufacturer’s crossover it will change the sound of the speakers. This may or may not be bad - you will have to decide for yourself – but the elements of the passive crossover are sometimes designed to compensate for shortcomings in the drivers.

    In any event, with an outboard crossover - passive or active - you will have to make sure the filter points and slopes are similar to the manufacturer’s.

    Regards,

    Wayne A. Pflughaupt
     
  3. KeithH

    KeithH Lead Actor

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    Jay, it is often said that disabling the crossover in the speakers and using an active crossover component, a technique appropriately called active biamping, is preferred over biamping with the speaker's crossover in place, which is known as passive biamping. That said, I have passive biamp set-up in my main stereo system and love the sound. I have an NAD C 370 stereo integrated amp biamped with an NAD C 270 stereo power amp. The speakers are Totem Arro floorstanders. I added the C 270 in February, and the improvement in the soundstage and bass was immediately obvious. I have chosen not to go with the active biamping route because active crossover components can be expensive and because I don't want to perform surgery on my speakers. So, you could try passive biamping to see if that yields a suitable improvement.
     
  4. SteveRS

    SteveRS Stunt Coordinator

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    PSB Stratus Goldi passive bi-amp with a Aragon 8008x5channel amp sounds good if you like detail and precision with just a touch of warmth.
     
  5. JayM

    JayM Stunt Coordinator

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    "What kind of crossover are you using? "

    Haven't decided yet. Any Suggestions?

    "In any event, with an outboard crossover - passive or active - you will have to make sure the filter points and slopes are similar to the manufacturer’s. "

    I have emailed PSB to see what they recommend, I am waiting for them to reply.

    "So, you could try passive biamping to see if that yields a suitable improvement. "

    I most likely will try it, but i have get some good amps first. I know there are amps better for highs, and amps that are better for lows. That is what I am trying find out with this thread.

    "PSB Stratus Goldi passive bi-amp with a Aragon 8008x5channel amp sounds good if you like detail and precision with just a touch of warmth. "

    How do you have it set up?
     
  6. Dzung Pham

    Dzung Pham Second Unit

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    If you passively biamp, you need to have level-matched amplifiers or at least a way to match the gain. Of course with active crossovers, the crossover itself usually has variable gain so this isn't a problem. There is some good info in a recent AVS thread.
     
  7. KeithH

    KeithH Lead Actor

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    Dzung, absolutely correct. The NAD C 370 integrated amp and NAD C 270 power amp that I use share the same amp section and are gain-matched. They were made to be biamped together, and NAD talks about it on its web site (of course, these amps can be used on their own). The pre-out 2 jacks on the C 370 integrated amp have a gain control, and the owner's manual specifically indicates that the gain control should be set to the maximum level when biamping with the C 270 power amp. It's nice to see a gain control on the C 370 should you want to use a different power amp for biamping. Anyway, many quality manufacturers make matching integrated amps and power amps for biamping, so the gain control issue can be easily put aside.
     
  8. Steve Zimmerman

    Steve Zimmerman Second Unit

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    I think you're SERIOUSLY underestimating how much design work goes into developing a crossover and how much they affect the sound of a speaker.

    I would also challenge anyone who is "passive bi-amping" (also know as "fool's biamping") to have a helper assist them in doing a blind test to see if it actually makes a difference at 80 dB. I've tried it. It didn't make an audible difference.

    If you have a couple of extra amp channels then fool's biamping won't hurt anything. But IMO, the idea of using your own crossover instead of the one designed by the speaker manufacturer pretty much indicates that you think the speaker manufacturer is an idiot.

    Just my opinion.

    --Steve
     
  9. JayM

    JayM Stunt Coordinator

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    Steve,

    so what are you recommending? not to bi-amp at all? your post is a little confusing.
     
  10. Steve Zimmerman

    Steve Zimmerman Second Unit

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    Jay, I'm saying (1) passive (i.e. "fools") bi-amping is an inaudible improvement but if you're dead set on some sort of biamping then it can do no harm if you have the extra amp channels; (2) active bi-amping, in my opinion, has at *least* as good a chance of making your speakers sound worse than it does of making them sound better unless you can reproduce the crossover exactly as the speaker manufacturer intended.

    In short, bi-amping isn't worth the effort. IMO.

    --Steve
     
  11. JohnSC

    JohnSC Stunt Coordinator

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    My experience tells me bi-amping can be beneficial if the individual channels of your amp are underpowered (even slightly) for your speakers. I bi-amped my fronts, using my 5-ch Rotel RMB-1075 (5x120w), recently and found the bi-amping improved the bass noticeably. I feel this is because having a channel dedicated to the bass and one to the mid to high, relieved the amp of the strain. Even more recently, I added the Rotel RB-991 (2x200w)(no bi-amping) to power the fronts and the sound improved again. There are no problems with having enough power, plenty of bass and detailed mid to highs.
     
  12. JayM

    JayM Stunt Coordinator

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    So it seems to bi-amp, or not to bi-amp, that is the question :)
     

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