KEF 104/2 biamping / bridging question - AVS Forum
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post #1 of 14 Old 07-27-2013, 02:36 PM - Thread Starter
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I just bought a second pair of KEF 104/2s to use out here in CA. My original ones were not biamp-able, but these are. (At least, they have 4 terminals on the back of each, though I see no indication or labelling that they are Raymond Cooke models. The serial numbers are 5910 A & B.). These are certainly a later version than my originals, as these have the magnetic grille attachments rather than the pegs on my first set.
However, there appears to be no visible / external 'bridge' between the two pairs on the back of each speaker. IIRC, if I want to use these WITHOUT biamping, there should be an external bridge, right?

If that is correct, it may be easier to simply biamp ( which I can do) rather than try to find or jerry-rig bridges.

Sorry if this question reveals my profound ignorance of all matters bi-amp, it's just not something I've ever dealt with before. I searched the forums here and elsewhere, but no luck. TIA for any guidance!
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post #2 of 14 Old 07-27-2013, 03:03 PM
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Quote:
Originally Posted by miami View Post

I just bought a second pair of KEF 104/2s to use out here in CA. My original ones were not biamp-able, but these are. (At least, they have 4 terminals on the back of each, though I see no indication or labelling that they are Raymond Cooke models. The serial numbers are 5910 A & B.). These are certainly a later version than my originals, as these have the magnetic grille attachments rather than the pegs on my first set.
However, there appears to be no visible / external 'bridge' between the two pairs on the back of each speaker. IIRC, if I want to use these WITHOUT biamping, there should be an external bridge, right?

If that is correct, it may be easier to simply biamp ( which I can do) rather than try to find or jerry-rig bridges.

Sorry if this question reveals my profound ignorance of all matters bi-amp, it's just not something I've ever dealt with before. I searched the forums here and elsewhere, but no luck. TIA for any guidance!

 

I have the same speakers and mine do have the bridge so yours were apparently lost somewhere along the way. Just use a short length of speaker wire and bridge the upper and lower posts. That will work just as well as the factory bridges. I wouldn't bother with bi-amping. You'll get no improvement.


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post #3 of 14 Old 07-27-2013, 03:05 PM
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Just use some extra speaker wire from one set of terminals to the other. Jumpers are just pretty pieces of metal that do the same thing. Don't waste your time biwiring or biamping. It's BS. Any speaker with a passive crossover will not benefit from biwiring or passive biamping. The only way to truly biamp would be to rip out the current crossovers and get separate amps with DSP. Not worth the time and effort IMO.

Dumb enough to spend lots of cash on this junk!
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post #4 of 14 Old 07-27-2013, 04:10 PM - Thread Starter
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Thanks for the help - Just from my own curiosity, if bi-amping has no benefit, why did KEF set the later models up for it? They were usually not ones for show vs. go. Also, as everyone seems to agree that these always benefit from more power, why wouldn't bi-amping help? (I have 130 wpc, and a bi-amp option on the power.)

Understand, I am definitely NOT challenging the kind answers, just trying to comprehend!
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post #5 of 14 Old 07-27-2013, 04:13 PM
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Quote:
Originally Posted by miami View Post

Thanks for the help - Just from my own curiosity, if bi-amping has no benefit, why did KEF set the later models up for it? They were usually not ones for show vs. go. Also, as everyone seems to agree that these always benefit from more power, why wouldn't bi-amping help? (I have 130 wpc, and a bi-amp option on the power.)

Understand, I am definitely NOT challenging the kind answers, just trying to comprehend!

 

It helps to sell speakers. If the competition does it you follow along. Sill useful for bi-amping the way flying fool stated. If you bi-amp through the speakers internal crossover you'll get no benefit.


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post #6 of 14 Old 07-27-2013, 05:03 PM
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In those days it was big to use a tube amp for the mids & tweets and SS for the woofers. Still probably a good thing to do.

Main Kef: Reference 205/2 & 202/2c, Surrounds: Kef XQ40, Velodyne Optimum 12, Integra DHC 80.3, Oppo BDP-103, Bryston 4Bsst2, Parasound Halo A31. Second B&W: 685 (3), CCM618, Def Tech Powerfield 1500, Onkyo TX-NR1008, DBP 2010, Samsung BD-C7900, Zone 2 Klipsch AW650. Sitting still CCM616, Kef...
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post #7 of 14 Old 07-27-2013, 05:54 PM
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If you're interested here's a pic of a 104/2 crossover. It'll have to come out if you ever replace the woofer surrounds. It's a PIA compared to other speakers. Those surrounds will need to be replaced sooner or later.

 


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post #8 of 14 Old 07-28-2013, 12:10 AM
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Quote:
Originally Posted by jima4a View Post

In those days it was big to use a tube amp for the mids & tweets and SS for the woofers. Still probably a good thing to do.
No it's not. It won't do anything at all. All you have to do is take a gander at the pic of the crossover. It's all interconnected. How does the power and signal get routed separately if its all interconnected? Also, if you look at the specs of most all receivers in biamp mode, there actually is no more power to be had because a receiver has limited power output. In order to get more power in one place you have to rob it from another.

Test after test has shown there is zero benefit to passive biamping. It's nothing more than a gimmick.

Dumb enough to spend lots of cash on this junk!
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post #9 of 14 Old 07-28-2013, 03:48 PM - Thread Starter
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Thanks for the explanation, much appreciated!

One last question -- I assume that, as I'm using plain 14 gauge to connect, I may as well run the one wire through both terminals (with bare patch for each terminal), rather than have a separate piece as a jumper ... Right?

Logically, it seems like that would be the same, but I have learned that, like taxes, in matters electronic, logic is an uncertain guide.
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post #10 of 14 Old 07-28-2013, 03:59 PM
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Like the photo but bare wire at the ends work just as well. This photo is the back side of my bookshelves. They come from the factory using braided speaker wire.

 


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post #11 of 14 Old 07-28-2013, 04:20 PM - Thread Starter
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Thanks for the quick reply (it's hooked up but I wanna get the OK here before music happens ... )

I understand it, I just need to know is there any problem or difference between
a) using a separate piece of wire as the jumper vs.
b) just running the speaker wire through both terminals instead.
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post #12 of 14 Old 07-28-2013, 04:23 PM
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Quote:
Originally Posted by miami View Post

Thanks for the quick reply (it's hooked up but I wanna get the OK here before music happens ... )

I understand it, I just need to know is there any problem or difference between
a) using a separate piece of wire as the jumper vs.
b) just running the speaker wire through both terminals instead.

 

I'd personally use a separate piece of wire although either way will work.


Denon AVR4311CI
Magnepan 2.7QR's w/ MGCC3 Center
(2) Polk RT15i
(2) Sonotube Subs with 18" Stereo Integrity D4 Drivers
Behringer NU3000 & NU4-6000 Amps
Panasonic DMP-BDP210 - Projector: BenQ W1070
Panamax M5400-PM
60" Samsung TV
WDTV Live & Minix Neo X7
Some audio history: https://skydrive.live.c...
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post #13 of 14 Old 07-28-2013, 06:03 PM - Thread Starter
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OK, thanks for the help ...

First song on a new-to-me pair of 20-year-old speakers, after 3 weeks with no music but a clock radio ... Critical listening can wait, I wanna rattle the sashwork.

"Burning Down the House" will do fine ...

Aaaaahhhhhh -- Thanks again!
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post #14 of 14 Old 07-28-2013, 06:04 PM
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Enjoy, they're some great speakers. smile.gif


Denon AVR4311CI
Magnepan 2.7QR's w/ MGCC3 Center
(2) Polk RT15i
(2) Sonotube Subs with 18" Stereo Integrity D4 Drivers
Behringer NU3000 & NU4-6000 Amps
Panasonic DMP-BDP210 - Projector: BenQ W1070
Panamax M5400-PM
60" Samsung TV
WDTV Live & Minix Neo X7
Some audio history: https://skydrive.live.c...
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