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(Audyssey) room correction with DSP-based subwoofers like Kef KC62

Blender

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The Kef KC62 uses DSP to offer deeper frequency response at lower volumes or higher volumes with less deep frequency response. Thus, the frequency response of the subwoofer is a function of the volume.

It seems like there’s no way for an AVR’s room correction to account for this with the way room correction currently measures speakers. So does that mean that these subwoofers are effectively incompatible with room correction?
 

Soundstage

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It means that the room correction calibration test should take place at the listening volume, such that the subwoofer is playing lower frequency at the same loudness than the usual listening loudness.
 

Sancus

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Dunno, depends what it's actually doing. First step would be to make/find measurements of the frequency response at different SPLs. If it's just doing compression(probable) then it's not a big deal. Any sub this size would be compressing on HT content anyway.

Considering the KC62 has an LFE mode for the crossover I doubt it's incompatible with a typical AVR setup.
 

HarmonicTHD

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It means that the room correction calibration test should take place at the listening volume, such that the subwoofer is playing lower frequency at the same loudness than the usual listening loudness.
^^^ this ^^^

BTW. I have the KC62 big brother, the KF92. Works perfectly fine with Audyssey. Confirmed with REW.
 
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Blender

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It means that the room correction calibration test should take place at the listening volume, such that the subwoofer is playing lower frequency at the same loudness than the usual listening loudness.
Is there any control over the volume that the listening test is done at? In a Denon AVR?
 

HarmonicTHD

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Is there any control over the volume that the listening test is done at? In a Denon AVR?
No unfortunately not. The measurement sweeps occur at 85dB SPL, if I remember correctly, but I might be wrong - so please double check.
 

Fillius

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The DSP switch on the KC62 and KF92 just attenuates lower frequencies to try to compensate for smaller or more restrictive listening environments. It doesn't do anything based on the actual room measurements like Audessey does:
Screenshot_20220923-224450.png

So your best bet would be leave the switch on the sub on "Room" unless it's too loud below 40Hz when doing the Audessey measurements.

With my KF92 I leave it set to "Room" but I needed a MiniDSP 2x4 to flatten an unavoidable +20dB room mode before running Audessey on my old Denon AVR.

With my NAD AVR I skipped the MiniDSP because Dirac seemed to handle flattening it a little better. But I'm about to add it back in to test the difference.

Edit: I think the DSP in the Kef subs also compensates for the smaller drivers, boosting the power at lower frequencies to achieve a flatter response.
 

HarmonicTHD

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The DSP switch on the KC62 and KF92 just attenuates lower frequencies to try to compensate for smaller or more restrictive listening environments. It doesn't do anything based on the actual room measurements like Audessey does:
View attachment 232899
So your best bet would be leave the switch on the sub on "Room" unless it's too loud below 40Hz when doing the Audessey measurements.

With my KF92 I leave it set to "Room" but I needed a MiniDSP 2x4 to flatten an unavoidable +20dB room mode before running Audessey on my old Denon AVR.

With my NAD AVR I skipped the MiniDSP because Dirac seemed to handle flattening it a little better. But I'm about to add it back in to test the difference.

Edit: I think the DSP in the Kef subs also compensates for the smaller drivers, boosting the power at lower frequencies to achieve a flatter response.
I think the Op didn’t mean the “DSP” switch but the fixed wired internal circuit which limits the low frequency for high SPLs in order to avoid distortion and protect the woofer. I forgot, but KEF also gave it a name.
 

Chrispy

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The Kef KC62 uses DSP to offer deeper frequency response at lower volumes or higher volumes with less deep frequency response. Thus, the frequency response of the subwoofer is a function of the volume.

It seems like there’s no way for an AVR’s room correction to account for this with the way room correction currently measures speakers. So does that mean that these subwoofers are effectively incompatible with room correction?

So it's a limiter to protect the sub from over excursion it sounds like. Why would room correction need to take into account such limitations? Get a more capable sub seems the more logical conclusion....
 

Fillius

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I think the Op didn’t mean the “DSP” switch but the fixed wired internal circuit which limits the low frequency for high SPLs in order to avoid distortion and protect the woofer. I forgot, but KEF also gave it a name.
Yeah re-reading OP's post I had missed that, you're right.

It hadn't occurred to me that the DSP might be intended to limit the performance rather than boost/balance it.

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