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nanoAVR DL bass management issue 7 years 11 months ago #17932

  • markus
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No, volume would not be wrong. Dirac Live corrects each speaker individually and adjusts the level so each speaker will sound as loud as the other one. This is also true for the subwoofer channel.

Dirac will correct the subwoofer, but only with respect to the pre-mixed LFE channel being fed to it. The crossed over component and LFE component cannot be varied independently as it should be. It will make the total output of the subwoofer sound as loud as the other channels, when actually only the LFE component should be as loud as the rest. The total output should actually be louder since the crossed over frequencies are also added.

LFE isn't a "pre-mixed" channel and it shouldn't be "as loud as the rest". It should be 10dB louder. This is what bass management does. Please see diagram above.

This might also interest you: www.genelec.com/faq/multichannel/102-in-...up-or-down-by-10-db/

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Last edit: by markus.

nanoAVR DL bass management issue 6 years 9 months ago #24992

  • kathampy
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The Dirac FAQ has been updated with this:

While crossovers should be applied downstream of (after) Dirac, bass management or any mixing of source signals into speaker channels should be applied upstream of (before) Dirac. The main rule of thumb to follow is that one should not mix together two separately Dirac Live-processed channels into a common speaker channel.

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nanoAVR DL bass management issue 4 years 2 months ago #39396

  • rhollan
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Sigh. I know this is an incredibly old thread, but as someone who considered a DDRC-88DD (with BM) to do bass management BEFORE Dirac EQ, but finds himself with a nanoAVR HD and nanoAVR DL instead, this is of renewed interest to me, espescially since I read the nanoAVR DL manual which recommends that that AVR downstream of the nanoAVR DL have levels trimmed, delay set, and bass management active, and that ALL THREE ARE RELATED.

I don't think this is because it is presumed bass management can't be done before the nanoAVR DL (just buy an nanoAVR HD as well), but rather WHEN it is done AFTER Dirac (which, admittedly, might be the most common scenario since most people would buy just one nanoAVR DL), that is the best way.

Dirac is designed to measure and optimize room response, one speaker at a time, yes? It can perform gain and delay compensation, yes? So a simultaneous signal sent to two speakers (bass management BEFORE Dirac) will still arrive at the listener simultaneously (at least at the sweet spot). Ah! but this presumes the bass management does not "mess things up" and change the effective system response (which it probably will, to some degree, as the filters introduce phase shifts). Dirac would be unable to correct this, not having "seen it".

When we do bass management AFTER Dirac equalization, Dirac does not see one speaker. It sees the speaker of interest AND the subwoofer. While it can smooth out the frequency response, it can ONLY TIGHTEN THE IMPULSE RESPONSE IF IT DEALS WITH A SINGLE SOUND SOURCE, i.e. a single speaker. Therefore, the COMBINATION of sub and target speaker must, as much as possible, act as one.

This same problem exists WITHIN a traditional speaker, whether two-way, three-way, or more: there are MULTIPLE drivers. However, the speaker designer has (hopefully) designed the speaker to try to, as much as possible, time align the signals from all drivers. WITH GAIN/DELAY ADJUSTMENT DOWNSTREAM of Dirac equalization, we can effectively DO THE SAME THING with disparate speakers, making their signals arrive at the measurement point simultaneously.

So, the rule appears to be, if you do bass management downstream of Dirac EQ, SET THE GAIN/DELAY CORRECTLY DOWNSTREAM FIRST. Indeed, this is what the nanoAVR DL manual advises. The downside is if your AVR can't do it WELL ENOUGH, so the Dirac measurement step has to tweak it. Ah, but if that AVR is a nanoAVR HD, it probably can. :-) The advantage here is that bass management is now INTEGRATED with gain and delay, to avoid subwoofer signal combing when low frequencies are on channels initially directed to two or more speakers and managed away. The disadvantage is if you do bass management downstream of Dirac EQ, and DON'T set the gain/delay downstream AS WELL, but rely on Dirac measurement of individual speakers, and get different delays for channels that might have simultaneous low frequencies to be managed away, you will get the dreaded low frequency combing problem.

So, if you do bass management downstream, DO IT RIGHT.

The other advantage here is that Dirac EQ will "see" any artefacts introduced by downstream BM/delay processing and correct them as if they were part of the "speaker" (in quotes here since this may involve multiple drivers in DIFFERENT speaker enclosures acting as one after BM).

Doing bass management downstream has an additional advantage as well: you can equalize for "speakers" (albeit virtual ones since sub and others are combined), and room response (Dirac) separately. You are not using Dirac to compensate for gross speaker issues, but rather more of the room, and less of the speaker (except, perhaps speaker impulse response).

O.K. I'm all ears. And, I've put on my flameproof suit, so flame away. In any case, I'll soon be in a position to try it both ways, with two pieces of equipment presumably equal in calibre (nanoAVR HD and DL).

On edit; multiple physical speakers DO make impulse response optimization across them for multiple locations impossible and only optimizable for a circular sweet "ring" (always the same distance from each speaker producing part of the signal) and this is a strong argument for bass management before Dirac.

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Last edit: by rhollan.
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