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KEF R11 quick measurements single vs bi-amp

gags11

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Just wanted to share some measurements I got from my new KEF R11s.

mic at 1 meter in room with all reflections active.

REW measurements, MacBook to Mytek DAC+ to McIntosh MC462 vs. to Wyred4Sound (W4S) ST1000 (ICE 1000ASP) low (RCA) + MC462 HF (XLR) bi-amp. Using XLR out to the Mc and single ended to W4S. Bi-amp has about 1-1.5 dB more gain in the low end. Using 4 Ohm taps on MC462.

I thought I could here a difference when playing bass heavy pop. However, I did blind testing and it was a wash. Here are the measurements.

Overall, these KEFs are amazing, only give way to my previous active set up at extreme SPLs.

1st Mc462 alone
2nd MC462 + W4S bi-amp
3rd MC462 alone distortion
4th Bi-amp distortion

7820F704-0D93-4B30-BEEC-8CF3FE47C782.jpeg


43AB4791-119E-454C-B486-6CED277C70A7.jpeg


1DC46D71-56DD-435D-9288-22BC96B2F5E6.jpeg


F1006321-0562-479E-BE96-F584D3E289B9.jpeg


PS: compared to KEF R3, the bass distortion is commendable.
Also look at the noise floor, much lower with McIntosh.
 
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gags11

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Another point these measurements address is the skeptics’ claims that McIntosh autoformers are an Achilles heel. These results show that say a 4ohm tap can drive a speaker with impedance ranging from 2.6 to above 15 and barely show any frequency variation.

Specifically, these speakers have a nasty phase of -45 degrees with 2.6-2.8 ohm impedance at 40hz. Compared to a 1000 watt class D amp with 0.005 ohm output impedance at that frequency, I personally do not see much variation or elevated distortion.

also, a few other observations. The ICE 1000ASP module has a SINAD of about 95db around the frequency band it is operating here vs about 105db for Macintosh. In the actual frequency response distortion, both are about the same, limited by the speakers. However, the noise floor difference is a bit more pronounced, 0.18 for Mc and 0.55 for the W4S. Either way, I think it is safe to say, it would be almost impossible to hear a difference between 105db vs 95 dd SINAD amp, at least at the lower frequencies. My brother and I could not tell the difference.
 
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Bjorn

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Do you mind showing a measurement of the speakers separately at a distance of somewhere from 2.5 m and 3 m?
 

steve59

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Kwf usually puts the xover point at 350 hz on their 3 way speakers. should be easy to find tho'.
 

songOVERsound

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When bi-amping these speakers, does the speaker take the crossovers out of the picture? If you are bi-amping into a speaker that has crossovers anyway, it defeats the purpose because the crossovers are still downstream of the amps vs upstream of the amps
 

fpitas

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When bi-amping these speakers, does the speaker take the crossovers out of the picture? If you are bi-amping into a speaker that has crossovers anyway, it defeats the purpose because the crossovers are still downstream of the amps vs upstream of the amps
Yup.

 

songOVERsound

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Yup.


Can you think of speakers that can be truly bi-amped? Divine Alpha comes to mind but not a lot of info on it.

I suppose one could simply remove the crossovers in a speaker and direct wire but there may be warranty issues with that…
 

fpitas

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Can you think of speakers that can be truly bi-amped? Divine Alpha comes to mind but not a lot of info on it.

I suppose one could simply remove the crossovers in a speaker and direct wire but there may be warranty issues with that…
I honestly have little experience tangling with commercial speakers, but you're most likely right. I think the dual binding post approach is simply to allow bi-wiring.
 

Dbassist

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Can you think of speakers that can be truly bi-amped? Divine Alpha comes to mind but not a lot of info on it.

I suppose one could simply remove the crossovers in a speaker and direct wire but there may be warranty issues with that…
That's exactly what Linn's Exakt system was predicated on - removing the crossovers of third party speakers and wiring the individual amps directly to the drivers.
 

fpitas

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That's exactly what Linn's Exakt system was predicated on - removing the crossovers of third party speakers and wiring the individual amps directly to the drivers.
Your warranty is toast after that, unless Linn picks up the responsibility.
 

Dbassist

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Your warranty is toast after that, unless Linn picks up the responsibility.
I'm not entirely sure about that being the case - some loudspeaker brands would actually supply 'Exakt conversion kits.' There weren't many though - B&W, KEF and JBL did them for at least one model apiece.
 

songOVERsound

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That's exactly what Linn's Exakt system was predicated on - removing the crossovers of third party speakers and wiring the individual amps directly to the drivers.
I’m trying to figure out if Trinnov’s Nova will be able to facilitate this. I was told that it will be able to crossover 3-way active systems (6 outputs total) but don’t think it’s worth it if the speakers still have passive electronics downstream of the amps speaker out’s
 
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