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digital eq/room correction trade-offs

I am very confused about digital room correction.

For many years, it seemed the common wisdom was to have as clean a signal path as possible, with as little processing and as few conversions as possible: use a high quality DAC to get the signal to analog and then a pure pre-amp/amp to speakers.

But it now seems that many would argue that the benefits of digital eq are such that even an extra analog-digital-analog step is worth it for the benefits of digital room eq.

So, for example, I enjoy listening to CDs and SACDs using my Bel Canto PL-1A. I go analog out to my pre-amp. Is it worth it to contemplate the extra step of analog to digital for room EQ and then back to analog to the pre? I find it hard to believe that any benefits of the room EQ won't be substantially offset by the additional conversions.

Your thoughts most appreciated. Let's assume for the sake of this discussion that my room is imperfect but not horribly so (which I think is accurate).
dgaylin
samujohn's avatar
samujohn
291 posts
 
TacT versus Lyngdorf. Good question, especially as they were recently partners in the same company (Tact).
My tech says that Tact (Baz) tries to accomplish more correction parameters than Lyngdorf with the result that the Tact system is more difficult to understand and apply. I would love to hear the specifics from someone more knowledgeable than myself.
lewinskih01
911 posts
 
On the Tact, is the volume control analog or digital? Either way I guess it's good as your feedback from it as a preamp is very good.

If it's on the analog side (which is usually recommended) and I wanted to use an external DAC, then it would need to be one with volume control so to drive an amp directly. Correct?

Thank you!
martykl
3,578 posts
 
I'll offer a slightly different take.

Room effects are almost always most pernicious below app 150hz. Room correction in this range - IMHO - will far outweigh any benefits you get from maintaining a purist signal path. As you go upward in frequency, different rooms will make the cost/benefit equation of DRC vary enormously.

My solution is a Velodyne SMS-1 sub controller (room analysis + PEq below 200hz - coupled with a versatile x-over) and a pair of subs. You can keep the SMS out of the signal path above the x-over point, if you so choose. In my book, this as close to a "have your cake and eat it, too" approach as you are likely to find.

Caveat: In some rooms full range DRC may well be worthwhile.

Also, my understanding of the TACT/Lyngdorf approaches is.

TACT: Goal is flat response at the mic position (i.e. corrects for anomalies in the speaker frequency response and room induced frequency effects.

LYNGDORF: Goal is to preserve the speaker's frequency response & remove only room effects. You measure the drivers up close and then at the listening position. The software filters the difference between predicted (anechoic?) response at the listening position and actual measured response.

This explanation came from the folks at Lyngdorf.
shadorne's avatar
shadorne
7,477 posts
 
I'd suggest to

Step 1: find a good mains positioning and listening position so that you can run mains full range and untouched - the straight wire and gain approach.

Step 2: find a good spot for your subwoofer that gives you again the least suckouts in room response when combined with your main speakers - run the sub up to 80 or 90 Hz.

It is important to worry about the suckouts because ultimately you don't mind the bumps so much as you can EQ these down. Whilst the suckouts are gonners and may create "holes" in what you hear - a bass note nearly disappears for example.

Step 3: Apply precise narrowband notch filtering (with any device of your choice) to the signal going to the subwoofer.

If you have paid careful attention to the 100 to 300 Hz range when setting up speakers and sub position then your notch filters on the sub (20 to 90 Hz)should get you pretty close to flat.

Although this process can take days it is worth doing.

=> Be psychologically prepared to be slightly disappointed when your previoulsy favorite demo track with that absolutely awesome devastating pounding earthmoving bass note - that jumps out at you and your neighbours every second or third bar - suddenly sounds tamed and controlled and musical (instead of a gong show).

==> be psychologically preapred to hear more ambience cues and more details in the lower midrange that you did not hear before.

====> be psychologically prepared to discover that you can easily follow bass player notes cleanly, evenly and clearly

FWIW: A precise sound is NOT as impressive in terms of "sound" unless you retrain yourself to focus on the musical details (a musician's careful accenting on particular beats in the bar) rather than the odd musically unrelated kaboom emphasis as a the note happens to hit a room mode.
shadorne's avatar
shadorne
7,477 posts
 
As a corollary to what I said above - part of the reason people change gear so much and like re-mixes/re-masters by clever musically trained sound engineers is that they get a different accent on the musical experience - it changes where emphasis was made. The room does this too. In a sense, the new equipment or the same equipment in a new room creates a new version of what is heard with sometimes hugely wrong (but pleasing to some listeners) differences in emphasis.

Nothing can completely control all this - but measurements and careful attention to gear selection can get you, on average, much closer to what was intended or heard by the persons producing your recorded music. Whether this is worthwhile to you or not is debatable as there can be pleasure in creating new interesting sounds or changing emphasis to make old sound new (even if it isn;t close to what was originally produced)
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