These recent posts raise an interesting question: To those with experience measuring in-room FR, where do you find the most significant anomalies? I have experience with 4 rooms, and in all cases the issues below about 150hz to 175hz just dwarfed those above that frequency in my "normal", passively treated rooms. I've usually found significant elevation somewhere in the octave above 75ish cycles and a few severe suckouts scattered below app. 100hz. In any given room, these low end deviations have typically been 3 to 5 times as severe as anything I've encountered above 150hz to 175hz. Sure but our sensitivity to sounds below 100Hz is progressively and markedly reduced. Also, there are fewer sounds down there. Kal notes that passive room treatments are effective for issues higher up in frequency. I wouldn't say 'effective." (If I did, it was a slip.) I would say efficient or practical. Passive room treatments can be effective although cumbersome way down into the bass. If you extend "passive" to include Hemholtz devices, I have found that these treatments can be effective in addressing that octave below 150hz. Below that, DRC (or possibly distributed bass generation with multiple subs...or maybe both) seems to be the best answer. Agreed. Even allowing for the ear's increased sensitivity to deviations in/near the mid-band, I find the deep bass issues much more vexing than those higher up.
Has your experience been different? Yes but this is subjective and depends on one's predelictions. Kal |
These recent posts raise an interesting question: To those with experience measuring in-room FR, where do you find the most significant anomalies? I have experience with 4 rooms, and in all cases the issues below about 150hz to 175hz just dwarfed those above that frequency in my "normal", passively treated rooms. I've usually found significant elevation somewhere in the octave above 75ish cycles and a few severe suckouts scattered below app. 100hz. In any given room, these low end deviations have typically been 3 to 5 times as severe as anything I've encountered above 150hz to 175hz.
Kal notes that passive room treatments are effective for issues higher up in frequency. If you extend "passive" to include Hemholtz devices, I have found that these treatments can be effective in addressing that octave below 150hz. Below that, DRC (or possibly distributed bass generation with multiple subs...or maybe both) seems to be the best answer.
Even allowing for the ear's increased sensitivity to deviations in/near the mid-band, I find the deep bass issues much more vexing than those higher up.
Has your experience been different?
Marty
As an aside, I also stuck a bassbuster in the corner behind the piano in my living room and that now sounds a lot better, too. However, the piano sound would be most dramatically improved by advances in my operation of that exasperating user interface :<( |
Kal, I may not have been clear enough or I oversimplified things too much but I can confirm we are in complete agreement.
It is only below the critical frequency that spatial issues dominate. I very much agree with that and for the sake of a "critical frequency" Meridian's choice of 300 Hz is fair enough as a ball park number. Here is an article which is based on Olsen's work that shows how a mere "baffle" can have some interesting effects. From this is follows that the effect of baffles and therefore room boundary surfaces can actually affect response over a "range" of critical frequencies - depending on the specific situation - leading to suckouts or peaks in what are sometimes broad frequency ranges. |
"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). " I do not think this is true as stated. As the frequencies rise and pass through multiple reflections, their interaction becomes evenly distributed in space and their latency allows the listener to distinguish them from the direct sound. However, they still affect the soundfield and the decay of sounds but, fortunately, they are relatively easy to deal with. Acoustical treatments, absorption and diffusion, will do. It is only below the critical frequency that spatial issues dominate. 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 phenomenonnobody 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 |
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 |
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: |
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. :) |
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. |
Don't let the prices scare you but do keep an open mind. Times (and technology) do change.
Kal |
Kal,
Yikes! I just googled the MSRPs of the models you mentioned.
Just to be clear - Over the past couple of years I have found your posts to these threads invaluable. Along with Drew E., Bob Reynolds and Shadorne, these comments have completely changed the way I configure my system which now reflects a lot of things I picked up from you guys (i.e. DRC, albeit in the bass region only). I suspect that, going forward, you will drag me (possibly kicking and screaming) completely over to your side (AKA the dark side).
Thanks again. If this has wandered a bit OT, I'll bring it back full circle for the OP:
You would be well advised to heed Kal's comments re: room issues as I (mostly) did.
Marty |
That's not exactly what I was suggesting but an Anthem D2v or Denon AVP-A1HDCI or Meridian 861 (all of which have analog outputs much superior to the Integra) might be competitive with digital sources and not encumber any "purism" issues when using EQ. Just a thought.
Kal |
Kal,
The head says "Yessir! Couldn't agree more!", but it's the soul -or possibly nether regions- that begs to disagree. Since this hobby is (purportedly) for fun, I use an approach that tries to satisfy both pleasure centers. I know that "splitting the baby in half" is not necessarily the wisest approach to solving every dilemna, but in this case, it works for me.
Granted, I'm pretty sure that substituting an Integra pre-pro with full range Audyssey for my ARC preamp, NHT x-over and Velodyne PEq would reduce the cost, simplify the operation, and improve the accuracy of my current set-up. I'd only add that this incremental improvement would likely not be dispositive in determining my enjoyment of listening to my system and that it would be at the cost of a certain "right brain" sense of satisfaction.
This argument may not be entirely rational, but at least I'm no Party-Pooper!
Marty |
Such notions of "purity" are grounded in analog considerations. With today's digital media, a more coherent reconsideration of the principle is necessary. ;-)
Kal |
Shauns,
Yes!
Marty
PS The biggest problem with Tact/Lyngdorf/Audyssey etc digital room correction is that is philosphically incompatible with the audiophile notion of "purity". 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. |
In my experience, the Lyngdorf gear can dramatically improve how the room affects the sound.
I had never been able to get smooth bass response in any listening room. I have never had the luxury of a dedicated room speaker placement and listening position have always had wife-based and room-sharing based constraints.
My new system is a Lyndorf TDA2200i, Focal BE1007s, Perraux 3150 amp and Lyngdorf W210 corner woofers. The TDA2200i has a crossover and time delay in the digital domain to integrate the two speaker systems. It also has a room correction module that claims to minimize room effects.
I am very, very happy with the result. Out-of-the-box, after the 30 minute setup process, I got bass flat to about 30Hz and really nice imaging.
However, like anything else audio, tweaking can yield major improvements.
After reading Jim Smiths book Get Better Sound, I made several changes to the room (mostly WAF-friendly tricks for shared-use rooms). Then I ran through the Lyngdorf setup again. Huge, huge improvement. Its as if the Lyngdorf can make certain improvements based on the starting point. So the better the starting point, the better the result
..
So, in my opinion, the room is no longer the limiting factor that it has been. |
One can use large loudspeakers in small rooms with very good results. Depends on the design. Some large speakers need space to intergate. Some dont. |
may want to add the music matters as well. I can easily make my system sound like about any adjective you care to mention by careful music selection. Not just Kb/s or mp3 vs. wav/flac either. been listening carefully to my new setup for 5 months and I'm just now getting to have a good understanding of the characteristics of it "on average". course I could be slow as I am a new hifi enthusiast. |
soooo, then room correction like the technology from Tact/Lyngdorf should be able to have a positive affect on most systems? |
Agreed - the room is the elephant in the room - possibly why many of the regular contributing experts here will not even share a few pix. Nevertheless there are differences in speakers that are significant too. |
No, the room is everything. No piece of gear can overcome it. Check out the room of the TAS editor that is up on the TAS site under his blog. |
