Room Correction - my new mission in life

nicolasb · « **on:** 10 Dec 2003, 12:01 pm »

I've decided to dedicate my life to persuading James Tanner that electronic room correction is a Good Thing.

Interesting implementations to date include:

Tag McLaren (TMREQ basically comes down to parametric EQ, as far as I can make out)
TacT (corrects in the time as well as frequency domain)
Meridian (featuring on the high-end 861 processor is a rather interesting method that is essentially parametric EQ using notch filters, but with the aim being to flatten decay time in the 15-250Hz range, rather than to flatten the static frequency response curve).
RANE (their PE 17 parametric equaliser, for example, is recommended by the usually-very-good-value subwoofer manufactuer SVSubwoofers, for use with their top-of-the-line B4-Plus and SS models).
Behringer (their Feedback Destroyer Pro is something of a cult hit here in the UK for subwoofer equalisation).[/list:u]Here's another product: the Subwoofer Optimization System by ACEi.

It's been voted "Accessory Of The Year" by the (I understand quite respectable) magazine "Stereophile Guide To Home Theater".

The momentum is building!

James Tanner · « **Reply #1 on:** 11 Dec 2003, 01:37 pm »

Hi Nicolasb,

OK - but I have to warn you every time I have heard these systems they sound very unnatural.

james

thxultra · « **Reply #2 on:** 11 Dec 2003, 09:18 pm »

Does this mean we may see some sort of room correction on the sp1.7 in the future

James Tanner · « **Reply #3 on:** 11 Dec 2003, 09:21 pm »

Not likely as these system do more harm than good. Your ears do not hear a single spot in space - they hear the total power response of the speaker in the room. Correction only works for one spot in the room.

james

thayerg · « **Reply #4 on:** 11 Dec 2003, 10:18 pm »

You might add the Behringer DEQ2496 Ultra-Curve to your list of room eq devices. Digital parametric eq with an automatic eq correction function plus various other features, all at about $300 plus another $40 for the calibrated mic. Not exactly a Tact killer because it doesn't do time correction. Nevertheless it seems to massage bits in several interesting ways.

BTW there is a Tact pre-power combo for sale at echohifi.com

nicolasb · « **Reply #5 on:** 12 Dec 2003, 09:58 am »

(nods)

Yes, the DEQ2496 certainly looks interesting - and, as you say, goes a bit beyond conventional parametric EQ by (for example) allowing different filter slopes above and below the centre frequency, and allowing the filter gain to be dependent on the signal intensity as well as frequency.

What I think is really neat about it (not having actually played with one as yet) is that it can do all of its magic purely in the digital domain. So you can take the digital audio feed from (say) a DVD player or CD transport, feed it into the DEQ2496, and use it as a combination of an EQ device and an outboard stereo DAC; but you can also output the modified signal in digital form, and send it on to your choice of DAC/processor without any spurious D/A or A/D conversion along the way.

Of course its digital capabilities are only useful for PCM streams, not DD or DTS, but it's a start.

Val · « **Reply #6 on:** 12 Dec 2003, 11:51 am »

This is another one, Australian http://www.clarityeq.com/index.html">DEQX.

nicolasb · « **Reply #7 on:** 12 Dec 2003, 03:07 pm »

As a side issue, James T, what are you going to be using all the processing power in the Aureus chip for if you aren't going to be doing room correction?

nicolasb · « **Reply #8 on:** 12 Dec 2003, 03:11 pm »

If we're making a list, I might also mention the QSC Audio DSP-4.

Of course most of these devices (other than the actual home cinema processors listed here) couldn't do as good a job as the SP1.7 could on room EQ, because they'd have to be driven by an AV processor's analogue outputs and there'd be an extra A/D/D/A conversion. So an EQ-capable SP1.7 would take some market share away from the likes of Behringer, Rane, QSC, etc.

thomaspf · « **Reply #9 on:** 12 Dec 2003, 06:12 pm »

Before we get the full room correction thing going I would settle for loudness correction in the meantime (Fletcher-Munson curves).

I tried to convince James on this topic in a previous thread but it did not go anywhere. This is so much more important in day to day listening unless you are only listening at reference levels.

If you look at these curves you will find that even with perfect room correction you are probably 5-10db off in various parts of the frequency bands if you prefer to listen at more moderate levels.

Cheers

Thomas