Speaker Asylum

RE: Biamping KEF 107/2s

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SgreenP@MSN.com

In Reply to: RE: Biamping KEF 107/2s posted by dbphd on August 04, 2012 at 18:18:56

I found bi-wiring with a better amp rather than more but lesser amps results in better sound.

Follow Ups:

RE: Biamping KEF 107/2s - ahendler 15:02:58 08/05/12 (2)
I agree. If you are going to stay with passive bi-amping and spend money for additional amps you would be better in getting a new single amp and biwire. I have tried both passive bi-amping and a better single amp and always prefer a single amp. If you want to actively bi-amp then that is another story all together
Alan
- I absolutely disagree and note that Kef did too in their manual for the spkrs. - Timbo in Oz 20:36:38 08/05/12 (1)
  In the case of the KEFs in question in this thread, the passive crossover also equalises flattens the load presented to the speakers (conjugate loading IIRC), also s in many high-end passive spkrs Eq's the drivers raw responses, before applying (or as well as applying) suitable electrical slopes which will give the (often different order) desired acoustic slopes.
  In fact by the time this model came out KEF were using computing and measurement to do all three jobs, trying to minimise parts count, and maximise quality.
  Please both of you, do tell us, and the OP, where to go to find a tame and cheap techie with i) equivalent measuring gear and chamber to KEFs and ii) equivalent judgement to iii)design an active crossover to replace the existing passive circuits. So that your active bi-amping mantra - will - be an improvement.
  IMO if you wish to comment on a proposal by an OP you should find out what the actual particular case is, before simply repeating a mantra that may not be applicable. Neither of you bothered to do any of that.
  Very few high-end full-range speakers have the same crossover in each serial number let alone across each pair. Yes?
  Did both of you try both kinds of passive bi-amping? In each case clearly distinguished please, what differences did you note?
  And when you both went active on an existing high-end Mfd spkr, at least one I hope for each of you, how did you both match the Mfrs original crossover slopes, FR Eq and inductance eq?
  And how much did it all end up costing?
  EMWTKnow.
  
  Note that a post in response is preferred.
  
  Warmest
  
  Timothy Bailey
  
  The Skyptical Mensurer and Audio Scrounger
  
  And gladly would he learn and gladly teach - Chaucer. ;-)!
  
  'Still not saluting.'
  
  Edits: 08/05/12
  - RE: I absolutely disagree and note that Kef did too in their manual for the spkrs. - Presto 10:36:22 08/09/12 (0)
    Forget equalization and impedance compensation for a second... how about basic things like filter Q? Yes, some guys will pull their LR24 PA crossover out of the closet and bi-amp a speaker because they know the crossover point and relative levels of the drivers involved. But this creates a whole new speaker.
    
    Yes, you need a guy who can measure (and properly interpret measurements) to do a passive to active conversion. As far as how close you'd need to match the existing response curve, some would say +/- 0.1 db but I think this is to associate much higher sensitivity to changes in SPL than the human ear is capable of. Some people can't tell when a tweeter is wired antiphase with a significant null!
    
    In any case, you're right. Many say that passive bi-amping is a waste of time but I don't think this is necessarily the case. I think many advocates of active crossovers think passive crossovers in general are a waste of time, so bi-wiring/bi-amping makes no sense to them in the passive domain at all.
    
    There are obvious benefits to manipulating which currents the amps see, and separating bass current from high frequency current, and doing it in different ways (horizontal, vertical, and even quad monoblocks).
    
    Cheers,
    Presto
    
    Cheers,
    Presto
Did you try horizontal as well as vertical? - Timbo in Oz 08:03:58 08/05/12 (0)
? see below.
If you did, did they sound different? IME they always do, with horizontal sounding much better, like it should. That's with matching amps each with a single shared power transformer.
And, how much more powerful was/were the bigger amps - in dbw - than the two matching amps totals in dbw? Twice as powerful is 3dbw extra.
e.g. two 100wpc amps as against one 400watt amp which should have 3dbw more headroom into the same spkr.
How many bi-amping 'cases' were involved?

Note that a post in response is preferred.

Warmest

Timothy Bailey

The Skyptical Mensurer and Audio Scrounger

And gladly would he learn and gladly teach - Chaucer. ;-)!

'Still not saluting.'

Edits: 08/05/12

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