IMO, since room correction remains one of the highest priorities of the flagship Meridian processor, I will continue to keep this thread going periodically. I am continually frustrated by the lack of digital room correction in the Flagship Meridian 861 as well as lack of definitive plans to implement digital room correction as soon as possible.
do you know how many filter coefficients are required to implement a notch at 10Hz with a width of 1Hz at a sample rate of 96kHz? Remember that the DSP has to do one multiply-accumulate for each coefficient in the filter on EVERY SINGLE SAMPLE of EVERY CHANNEL in REAL TIME.
That could well be why Meridian haven't offered room correction.
Simon.
[This message has been edited by Simon the Whale (edited 03-13-2002).]
> Neither of these options will work. I asked TaCT sometime ago about allowing 8 channels of digital inputs, but they are not interested.
They are possibly changing their mind. Have a look at the TacT Audio users group on groups.yahoo.com, there was discussions about it and they seem to be looking at a future product that could do that.
I have the TacT RCS 2.2x and it's an amaising product (and compatible with 24/192).
It's time for the regular reminder that Digital Equalization/Room correction should be of single highest priority for the 800 series. This point cannot be stressed enough.
What should the target price for the room correction board be?
Should it be modular so you have the option of only buying enough correction for the number of channels you currently have (say 5.1) with the option of upgrading it if you add side and height channels?
I can easily see the board running more than the 861 iteslf.
I assume it will support 8-channels. You get a limited # of notches, where you use them is up to you. You want to take care of the front speakers first. Then you can use what is left over on the rears.
I estitmate between $2k-$5k for such a card. That is just a number I pulled out of thin air, so take it as a grain of salt.
Again, It is probably going to be a V4 option. (based on CES info 2 years ago. (or was that Cedia? I don't recall.)
the room correction is absolutly the most important upgrade beyound DVD-A. BUT-what Iam expect from Meridian-- is not the simple thing what is already done. My expection are: 0)Mic on the sweet spot-- 1)Automatic measure the distance of the speaker-including height channels 2)Generally equalize the frequency response(amplitude to frequency) 3)Measure the phase from EACH speaker chassis -that means high, mid and bass chassis AT THE SWEEP SPOT ---NOT AT ONE METER DISTANCE AS IT SPECIFIED TO MEASURE AND COMPARE LOUDSPEAKER-------THATS BULLSHIT!!!!!!! 4)Measure the amplitude of SHORT bursts at the sweet spot -- the room influence--reflections from the wall are NOT MESURED as descriped at point 2---the generall praxis 5)SAMPLE more measurement(5-10) at the sweet spot-or better at a certain radius from the sweetspot-store it...and the call back the measurement via the remote control to select the best hearing compensation and also a default without any compensation. 6)Why only stupid change of low frequency response-only amplitude..not phase..and why restricted to bass only??????? For "hearing" an instrument ONLY the first milliseconds are necesarry--not a FLAT frequency response based on a LONG time measuring --thts ONLY show ALL the amplitudes from the music AND reflections-- BUt not from the speaker itself!!!!!!!!!!!!!
Surly, what you hear, is just a sample of ALL the amplitudes..BUT also the "timing" or better the "phase" or "first" "wavefronts" what reaching your ears. I mean--the big deal is to compensate the first wavefront(the "amplitde at the "right " time of each chassis and speaker
Meridian can do it VERY easy, because the have a LOT EXPERIENCE with "calculating" musical informations(different (MODES) and therefore it a SHAME only to make a "simple" variable filter in the bass range. More later
The last post got me thinking. What do all the forum members want/expect from room correction? I have faithfully read the forum and the postings from everyone on this topic tend to be all over the map. I will give my input on what I expect.
First off, I side with those that say the room has an enormous impact on the sound. I have felt that way for many years and it is why I have extensively treated my room with acoustical treatments from ASC. My room is treated in much the same fashion as Peter Moncreif suggested in his writings some years ago (these articles can be read on the ASC web site at asc-hifi.com).
Tube traps are primarily thought of as low frequency control. Used correctly, however, they do a great job of diffusing as well as absorbing higher frequencies. This controls the frequencies that lie above 200hz quite well. The frequencies that lie below 200 hz are the hardest to control. My room treatments greatly aid in that area but room correction would add that last bit of control over that critical region.
Where I have a problem is with trying to do more with your room than the above. One of my most interesting auditions was with a Sigtech. The Sigtech allows many of the correction abilities that Robert mentioned in his posting above. I was quite anxious to hear the improvement from this piece as it appeared to be the holy grail of correction. Reality was different for me.
The phase and time correction did work as advertised at the seated postion where the measurements were taken. I did hear more precision of soundstaging. Move a foot to the side or back and it all collapsed, sounding worse than it did with no correction. Detuning the correction to widen the sweet spot did not widen the sweet spot that much, certainly not wide enough for a typical home theater seating enviornment. Detuning also reduced the improved imaging to the point that I preferred it uncorrected. Now if you are a solitary user of your system and sit in the same spot as measured, phase correction may be for you.
As to correcting frequencies above 200hz, the Sigtech allows the ability to correct all the way to 20khz. I found that listening to music in this manner was way too bright and unmusical, no matter what I did to adjust the rest of my system. Sigtech recognized this and allows for a user defined rolloff of higher frequencies to suit your tastes. No matter the curve I tried, I ended up preferring no correction. My take on this is that the original source material is always mastered without the use of a product such as the Sigtech. Instead the mastering is done with speakers similar to what you would use in your home. Correcting with a product like the Sigtech above 200hz simply does not match what the recording engineer heard when they mastered the recording. The sound through the Sigtech was definitely different, it simply was not better.
In my opinion, Meridian is attacking room correction in the proper manner. The room modes below 200 hz have the greatest impact on the sound and are the hardest to correct. Once they are corrected, room treatment becomes the best way to handle the frequencies above 200hz. You have an excellent sweet spot that multiple listeners can enjoy and you are not introducing frequency corrections that were not part of the original mastering of the recording. My room treatments also do a good job of reducing room modes below 200hz, the room correction card would simply get you all the way there on the worst of them. I personally feel it is a mistake to rely on electronic room correction to cure all of your rooms ills without first addressing treating your room with conventional treatment means first. You will get better results in that manner.
I agree that the focus should be on frequencies 200Hz and below. What we are after is room correction, not speaker correction.
I saw the TacT units at CEDIA and concluded that if I bought one, I'd never listen to music. I'd simply futz with the settings to see if a .25db boost at 827Hz or a .50db cut a 2.256Khz sounded better. I don't want to design speakers, I want to listen to music.
I've got a couple of room anomolies that all the ASC and similar products simply can't fix. They are a funtion of the room dimensions. This is what we need help with.
There is software out there which will tell you where to place your speakers to minimize the effect of standing waves. Unfortunately, the resulting suggested locations usually don't correspond to the best location for soundstaging, etc., not to mention practical consideration which mitigate against putting your sub in the doorway or you main speakers 3/4s of the way out in the room.
Besides, keeping it simpler keeps the cost down and makes it and easier to use - not to mention getting it to market quicker.
Since I don't have an 861, I wonder if it could be sold as an outboard 500 series component as well, perhaps as an alternative to a 562V.2.
I've got a couple of room anomolies that all the ASC and similar products simply can't fix. They are a funtion of the room dimensions. This is what we need help with.
Definitely. Some of these peaks can be quite terrible! Personally, I am concerned with the 200 Hz and below, although as I get more sophisticated, I can't say for sure my needs won't grow.
I am concerned about the ability to be able to control the bass output as low as possible. I would have the option to control all down to 5 Hz. If that is not possible, I absolutely require control to at least 10 Hz (5 Hz is not essential and I am not concerned, but control to 10 Hz is *mandatory* for me). Life does not end at 20 Hz. The 800 series (especially) is supposed to represent a custom installers dream for the highest performance possible. Control to 10 Hz would be absolutely essential to me, to the point that the room correction card would not be appealing without control to 10 Hz. I would need to control the subwoofer response-- this might be achieved simply by adjusting a few regions in the 10-60 Hz range in the main channels, with the digital crossover simply taking care of which frequencies go to the main channels and to the subwoofers, but what about the LFE channel? I continue to despise the LFE channel, but if I am stuck with it, I need to tailor the output of the subwoofer whether it be from just adjusting the main channels in the 10-60 Hz range, or from adjusting the subwoofer channels directly.
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Tube traps are primarily thought of as low frequency control. Used correctly, however, they do a great job of diffusing as well as absorbing higher frequencies. This controls the frequencies that lie above 200hz quite well
Tube traps are Helmholtz resonators which simply produce opposite phase within a fairly narrow region (for the purpose of canceling a certain dB at a certain narrow frequency range). Tube traps are difficult to work with and can only produce mild effects before requiring lots of physical room if the peak you are trying to cancel is excessive. Tube traps work on the same principle of a port in a speaker. Helmoholtz resonators (tube traps) have to be picked for which frequency you want to cancel and have a relatively narrow effect. The process relies on the resonance frequncy of the tube and provides maximal cancelation at that frequency with a fairly steep rolloff aabove and below the resonant frequency. Tube trabs/helmoholtz resonators can be efective, but the concept can be tricky to implement properly. Certainly, the combination of 'physical' tools such as 'diffusers' for upper frequencies and Helmholtz resonators for lower frequencies are essential tools for proper room response. Digital EQ is of course the single most powerful and eloquent tool for controlling room response.
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the room correction card would simply get you all the way there on the worst of them. I personally feel it is a mistake to rely on electronic room correction to cure all of your rooms ills without first addressing treating your room with conventional treatment means first. You will get better results in that manner.
Definitely, I agree wholehertedly. However, 'the worst of them' can be very bad, something no conventional treatment can do anything about. Digital EQ is desperatly needed to tailor the low end. I've heard of many custom installers wanting to tailor the entire curve, but the 'real' problems lie in the 10-200 Hz range.
There is a lot more to room response, FFT, etc... Many custom Meridian installers are well versed on physics/acoustics. Meridian needs to release digital EQ/room correction ASAP.
[This message has been edited by Health Nut (edited 05-15-2002).]
I have a TacT 2.0, and the impact via a pair of DSP5000s in a highly irregular room, with lots of hard surfaces, is nothing short of astounding. I thought about getting the parametric eq upgrade, but decided against it. I have 9 "curves" set on the TacT, from absolutely flat, to ones that do a great job fixing old recordings that were mixed for bad car stereos.
I just wanted to add again that control point should be selectable down to 10 Hz, not just 15 Hz as is currently provided. If Meridian can make the room correction selectable down to 10 Hz, that would be very important. Please keep me advised on the ability to have room correction control down to 10 Hz selectability.
I'm currently (slowly but surely) designing a 20'W x 30'L x 12' H custom room which will have a huge custom Infinite baffle. I will at some point be organizing a large group purchase for a run of 75-100 subwoofer drivers which as designed from the ground up to be ideal for infinite baffle. There are three-four driver manufacturing companies are willing take on this custom driver project, but would require a run of 75-100 drivers minimum.
Infinite baffles are one of the most amazing subwoofer designs available. A custom driver designed exclusively for IB use means a large Vas, Qts of 0.5, Fs of around 14 Hz. This will not take place until the 'near' future, but certainly around the time Meridian 4.0 upgrade will be available (2 years?).
In any case, please include control to 10 Hz and keep me advised of any updates on the development of the room correction software.
Sincerely,
Chris
[This message has been edited by Health Nut (edited 06-08-2002).]
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