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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'.
 
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