Room matters

However, every one of these systems that I have auditioned works wonders, particularly in the bass. To reconcile the conflict, I use DRC only for subwoofers - where it makes the biggest improvement - and run a (mostly) "purist" main signal path.

I agree with Kal - in theory there is no "purity" reason that DRC cannot be used throughout, however, from an acoustics perspective the ultra LF frequencies (below about 100 Hz) is the only area where DRC can effectively correct specific frequency related room modal effects. A waveform at 1000 Hz is about a foot long so any specific corrections are not going to apply to a large enough area of the room to be worth doing, and, above the ultra LF freqencies, DRC is really just an EQ adjustment, which can help correct a bright room, for example. In this case, it is always best to get appropriate speakers and acoustic room treatments first rather than make EQ adjustments. The same can be said for the ultra LF - bass traps and an ideal room that needs no correction is likely to sound much better than a system with heavy DRC. However, it is nearly impossible to achieve good acoustics down to 20 Hz so DRC becomes the only "practical" solution.

So in a sense "purity" applies in an acoustic sense - get the room as good as we can (as pure as possible) before doing anything else.

The impure part of DRC is that we are artificially adjusting BOTH the level of the primary AND that reflected signal in order to adjust the COMBINED level to be flat (our ears hear the combined signal but we also have a sense of primary versus reflected as well - although this sense is very poor or weak as you get to low bass frequencies). In reality, in an ideal world, your speakers would have a flat response and therefore you should only want to adjust the level of room reflections/modes (too strong or too weak).

Perhaps, the ultimate solution requires active canceling such as is used on noise-canceling headphones - imagine an array of active woofers with built in microphones that compare the audio in room delayed response and acoustic decay to the original signal (feedback) and which are able to cancel modal peaks and adjust your room acoustics to perform as desired. Designs such as this probably exist already (in labs) - for example Meyer speakers have a microphone in front of the woofer to reduce primary signal distortion already. The only issue is cost - in theory you could re-create the acoustics of any auditorium if you had such a system.

Since when is a four foot tall speaker big? It seems the majority of examples here are not really that big, at least in my world. Now, a six foot tall speaker at about my height - that's getting big! If one drives a compact car every day a full size sedan will seem large. If you drive a sedan an extended cap pickup will seem larger. I tend to "drive" larger speakers, so I was a bit disappointed in the ones mentioned as large speakers. I call a 3' tall floor standing speaker small; much smaller and you may as well get a monitor.

Wafer, some questions: What do you consider to be a small room, and what do you consider a large room? If you're calling these speakers large, then I'm wondering what you consider to be a large room? (Obviously, cultural differences apply, as many places in the world have far more restrictions on space than in North America. If this is the case, then my comments which follow need to be seen in the context of North American concepts of space in a home.)

Have you conducted such tests in order to arrive at your conclusions? I ask because I have conducted such tests and found that a moderate sized room like mine can be fantastic for larger speakers. The critical difference is not so much the room size, but the quality of the room, i.e. construction, whether it has windows, whether it is tuned, etc. In my case though the room looks rather simple, behind the walls are 7.5" of multiple layer construction, under the drop ceiling is another completely solid ceiling, a thick carpet pad is under the plush Berber carpeting, etc. I would prefer a smaller good acoustic environment to a larger and poorer one. The size is not the only, or even the major, factor in securing a good environment. I know one audiophile personally who has a cavernous space with lots of glass; he's fighting sound problems continually.

Have you simply received the "accepted wisdom" of audio which suggests that one must have a larger room in order to enjoy/utilize to their best larger speakers? At times I enjoy breaking such received "laws" of audio. When I was younger and into aquariums I was told that I could not do a smaller saltwater tank, that I needed at least 25-30 gallons to get it done. I didn't like that limitation, so I did my own ten gallon saltwater tank, and it worked. I have to laugh now when I see "micro" saltwater tanks at aquarium stores. What happened to the "law" of size imposed on tanks? It kind of disappeared when enough intelligent people said, "I don't like that limitation, and I think I can get it done!"

All things equal in terms of room construction and room treatment a larger room may be better. But a generalized principle that with quality gear a larger room is better will not do. It is easier to work with a big speaker in a big room, but it certainly is not impossible to do so in a more modest sized room. And I have heard a lot of great gear sound Ho-Hum in bigger rooms, and/or ones with vaulted ceilings. In addition, in a room which has been built for audio and is tuned the most minute distinctions between speakers, both small and great, are easily heard.

When Bill Dudleston of Legacy Audio brought the Helix speaker system for review (it can be seen in my virtual system pics) and set it up in the room, after blasting it at seemingly jet engine levels he turned to me and said, "This room has excellent acoustics. It is like a mastering studio." That was my goal in design and construction - to make an environment where the absolute best experience of the equipment was the reality. I hear huge speakers at their best every time I listen because they are in a quality environment, not simply a big room.

So, Team member Wafer, from my perspective your question (which seems posed more as a declaration) is provocative if you hold to it without exception. :)

More clarification:

If you wander through these threads, you will find a fair bit of evidence that the purist signal path to which I referred in my post is a "primary point" of the hobby for a fair number of 'philes. I understand the rewards of that philosophy, too, even if optimal in-room FR performance isn't among them.

My reference to the "purists" was all by way of responding to the post which posed the question (cynically?) "So room correction technology from TacT/Lyngdorf technology will improve...?"

Note that I answered "Yes!" and then attributed DRC's lack of popularity with the A'gon crowd to the "purist" conflict. I do believe that this is the commercial reality behind (judging by the virtual systems listed here) the low acceptance of DRC among 'gon members. High tech solutions just don't seem to be entirely satisfying to many 'goners.

My current "mix 'n match" approach allows me to put one foot in each camp. I enjoy the benefits of high tech DRC where I find it critical to my enjoyment of music (i.e. the bass range) and use a more typical 'phile approach where I find that those tech solutions are less important. My trend line, however, has been one of (grudging) incremental adaptation. Dark side, here I come...

Whew! Hope that 'splains my position.

Marty

B:

Shadorne wrote: ".......... in theory there is no "purity" reason that DRC cannot be used throughout, however, from an acoustics perspective the ultra LF frequencies (below about 100 Hz) is the only area where DRC can effectively correct specific frequency related room modal effects. "

Agreed except for the frequency. From measurements, the upper limit of useful correction of standing waves and modes was defined by Schroeder as the point where still higher frequencies began to interact on a purely statistical basis. Above this threshold, one can best use a wider band "tone" control if room acoustics are poor. Of course, it is in this upper band that room treatments are practical, both physically and economically, for all serious listeners.

This creates a problem for us since applying correction only to the subwoofer (usually crossed over in the sub-100Hz range) leaves the bottom 2-3 octaves of the main speakers uncorrected and, imho, the problems here are more audible than those in the subwoofer range. Meridian's use of correction in the sub-300Hz range on all channels (optional and modifiable) is a great solution and one that should be an option on all other room EQ systems.

Kal

Meridian's use of correction in the sub-300Hz range on all channels (optional and modifiable) is a great solution and one that should be an option on all other room EQ systems.

My choice of 100 Hz may be a bit low and as you correctly point out - a lot of problems occur between 100 Hz and 300 Hz and, I might add, even further on up as far as about 600 Hz, as the sound goes from omnidirectional (bass) to directional (Lower midrange) and during this transistion the sound is affected at various frequencies by floor and ceiling and side walls until the sound becomes mostly of a forward direction (and the room becomes much less of a problem).

Roy Allison and many others are well aware of this problem with virtualy every free-standing speaker. However, this well known fact is hardly mentioned by the majority of speaker manufacturers these days...despite the fact that professional acousticans continue to take into account these very real acoustical problems in pro studio designs.

I decided to find out what was going on with loudspeakers and room interaction. I'd had a hint of it while doing some papers at AR. There was an unexplained phenomenon—nobody could tell me why it happened: a suckout in the middle bass range in almost every loudspeaker, almost every room transmission curve that we measured. That got my curiosity aroused. I wanted to find out what was causing it.

This transition zone from 100 to 600 Hz is often the most problematic. This is why studios tend to either

1) Use small monitors in near field close to the listener and away from walls/boundaries.
2) Use large main monitors that are built into a wall - a soffit mount