[Samurai7595]

Several manufacturers built & sell Room Correction Systems like: McIntosh, DEQX, Trinnov, TacT, etc.

I'm thinking of getting the DSPeaker Anti-Mode 2.0.  Anyone try this one or any of the other ones?

DSPeaker Anti-Mode 2.0:
http://www.dspeaker.com/en/products/20-dual-core.shtml

DSPeaker Anti-Mode 2.0 review:
http://www.theabsolutesound.com/articles/dspeaker-anti-mode-20-dualcore-digital-signal-processor/

[James Tanner]

Several manufacturers built & sell Room Correction Systems like: McIntosh, DEQX, Trinnov, TacT, etc.

I'm thinking of getting the DSPeaker Anti-Mode 2.0.  Anyone try this one or any of the other ones?

DSPeaker Anti-Mode 2.0:
http://www.dspeaker.com/en/products/20-dual-core.shtml

DSPeaker Anti-Mode 2.0 review:
http://www.theabsolutesound.com/articles/dspeaker-anti-mode-20-dualcore-digital-signal-processor/

if you are using Bryston speakers please don't!

james

[Pneumonic]

James, it would be helpful if you offered up a reason, or reasons, not to do so.

[SoCalWJS]

If you haven't done so already, try to get the best sound and results possible based upon speaker placement and room treatments. If you've done that and still don't like the results, you might look into these types of equipment, but try to do so in a manner that makes them work less hard - that is to say, that they are only trying make small adjustments rather than large ones.

I had a recent chance to listen to the AntiMode and it helped the end result. The issue is room/Speaker interaction. Unless you have some sort of "magic" room that has zero issues, you have to do something to try to minimize the negative interaction between the Speakers and the Room.

[johzel]

James, it would be helpful if you offered up a reason, or reasons, not to do so.

+1

[David Cutler]

The problem that I see is that you are trying to apply a correction to a system at the wrong point in the reproduction chain.

If your listening environment is typical then there will be nulls at particular frequencies, and a peaks at frequencies, a correction system will adjust the gain of the these various frequencies to give a flat response at the measuring/listening position – all good.  However, if you now move your listening position a few inches, the distances to walls, floor etc will change and a different set of frequencies will be at null along with other frequencies being boosted by the room.  The correction system can't compensate for both cases.

The typical size of room peaks and nulls in an untreated room is in the order of tens of dBs, so your system could be being severely stressed in order to produce enough power in order to overcome the room's nulls.  Meantime, at other points in the room, the same frequencies are now tens of dBs too loud, causing nuisance to people outside the listening area.

Not as sexy, but acoustically treat the room.  I don't mean to cover the room in glassfibre, but a few scientifically placed pieces of room treatment can bring the room under control and let you hear the music, not the room.  Additionally, you can have a wide listening area and not annoy the neighbours.

Here on audiocircle, there is a whole discussion area (Industry Circles => GIK Acoustics) that cover such treatment.

I hope this helps,

David

[James Tanner]

The problem that I see is that you are trying to apply a correction to a system at the wrong point in the reproduction chain.

If your listening environment is typical then there will be nulls at particular frequencies, and a peaks at frequencies, a correction system will adjust the gain of the these various frequencies to give a flat response at the measuring/listening position – all good.  However, if you now move your listening position a few inches, the distances to walls, floor etc will change and a different set of frequencies will be at null along with other frequencies being boosted by the room.  The correction system can't compensate for both cases.

The typical size of room peaks and nulls in an untreated room is in the order of tens of dBs, so your system could be being severely stressed in order to produce enough power in order to overcome the room's nulls.  Meantime, at other points in the room, the same frequencies are now tens of dBs too loud, causing nuisance to people outside the listening area.

Not as sexy, but acoustically treat the room.  I don't mean to cover the room in glassfibre, but a few scientifically placed pieces of room treatment can bring the room under control and let you hear the music, not the room.  Additionally, you can have a wide listening area and not annoy the neighbours.

Here on audiocircle, there is a whole discussion area (Industry Circles => GIK Acoustics) that cover such treatment.

I hope this helps,

David

Well said David and I will add some inout later as well.

james

[James Tanner]

DIGITAL ROOM CORRECTION ISSUES

The problem with Digital room correction through ‘EQ’ is that it totally screws up the direct sound vs. the reflected sound coming from the speaker.

When you listen to a speaker in a room you are listening to what we call the ‘POWER RESPONSE’ and you hear all the direct sound as well as the reflected sound mixed together.  So the listening experience is a combination of all the direct and reflected sound waves in a given room with a given speaker. When you alter the ‘direct sound’ at the speaker using ‘EQ’ it totally changes the relationship between the direct and reflected sound and is a disaster when it comes to ‘time smear’. In other words, the source of the problem is that the reflective time smear characteristics of the room 'issues' remains intact, and the direct radiator sound source is being retarded to compensate for this. Thus the result is a time smeared mess where the issues remain, and the original source is destroyed.

So the speaker designer has spent years attempting to get flat frequency and phase response from his speaker and we come along and force the speaker to do anything but accurate signal transfer. Also if you are going to use ‘EQ’ try and only ‘reduce’ the ‘peaks’ in the room and not ‘amplify’ the troughs.  Amplifying the troughs can play havoc with your speaker drivers power handling.

A lot of these newer types of ‘EQ’ products try and average a group of curves taken from many different locations in the room as they are attempting to reduce the negative effects of the single listening chair dilemma. Having a single spot in the room which measures flat but everywhere else in the room measures like crap is not a good result in my opinion. I think you are much better off adjusting the speaker location and using proper room treatments.  If all else fails maybe some ‘EQ’ can be used but I would recommend keeping the correction only for the very low bass frequencies and stay away from upper bass, mids and higher frequency ‘EQ’ where room affects are not an issue due to the shorter wavelengths involved.  I am hopeful that we will see many more Subwoofers with built in room ‘EQ’ which would be the better solution in my opinion if you are forced to use room correction.

James

[redbook]

   Well explained James.

[hawkeye99]

I use the Dspeaker 2.0. I like it.

http://www.audiocircle.com/index.php?topic=110377.0

[Samurai7595]

DIGITAL ROOM CORRECTION ISSUES

The problem with Digital room correction through ‘EQ’ is that it totally screws up the direct sound vs. the reflected sound coming from the speaker.

When you listen to a speaker in a room you are listening to what we call the ‘POWER RESPONSE’ and you hear all the direct sound as well as the reflected sound mixed together.  So the listening experience is a combination of all the direct and reflected sound waves in a given room with a given speaker. When you alter the ‘direct sound’ at the speaker using ‘EQ’ it totally changes the relationship between the direct and reflected sound and is a disaster when it comes to ‘time smear’. In other words, the source of the problem is that the reflective time smear characteristics of the room 'issues' remains intact, and the direct radiator sound source is being retarded to compensate for this. Thus the result is a time smeared mess where the issues remain, and the original source is destroyed.

So the speaker designer has spent years attempting to get flat frequency and phase response from his speaker and we come along and force the speaker to do anything but accurate signal transfer. Also if you are going to use ‘EQ’ try and only ‘reduce’ the ‘peaks’ in the room and not ‘amplify’ the troughs.  Amplifying the troughs can play havoc with your speaker drivers power handling.

A lot of these newer types of ‘EQ’ products try and average a group of curves taken from many different locations in the room as they are attempting to reduce the negative effects of the single listening chair dilemma. Having a single spot in the room which measures flat but everywhere else in the room measures like crap is not a good result in my opinion. I think you are much better off adjusting the speaker location and using proper room treatments.  If all else fails maybe some ‘EQ’ can be used but I would recommend keeping the correction only for the very low bass frequencies and stay away from upper bass, mids and higher frequency ‘EQ’ where room affects are not an issue due to the shorter wavelengths involved.  I am hopeful that we will see many more Subwoofers with built in room ‘EQ’ which would be the better solution in my opinion if you are forced to use room correction.

James

According to a Stereophile review of the DSPeaker product (http://www.stereophile.com/content/music-round-57):
Although the Anti-Mode 2.0 passes a full-range signal through each of its channels, its range of correction is limited to the lower frequencies. By default, it measures and automatically corrects from 16 to 150Hz, but can be configured to work from 16Hz to an upper limit ranging from 80 to 500Hz. However, this is not a really important limitation, for two reasons. First, as I have said many times, the most important acoustical corrections will be in the low frequencies, where room modes—which are determined by room dimensions and speaker placement—impose wide frequency and time-decay variations on your speakers' presumably flat response. Correcting these modes often requires bulky and aesthetically unacceptable physical room treatments, while above the critical or Schroeder frequency (the frequency at which rooms stop resonating and become reflectors/diffusors), the room's acoustical influence becomes stochastic or random, and treatable with furnishings and panels. So using an equalizer only for the bass is an attractive prospect that has been successfully pursued by DSPeaker and others. The second reason the limited range of automatic correction is not critical is that the Anti-Mode 2.0 includes a 16-band, user-configurable parametric equalizer with a center frequency range from 20Hz to 24kHz, each band assignable to the right, left, or both channels.

Is this what you're talking about James?

[James Tanner]

Yes if you have to use it keep it to the very low frequencies and even then I am not personally a fan - but to each his own.

James

[rodge827]

I like my Dual Core 2.0 a lot! I'm using it as a dac, preamp, and room correction device. My room is a dedicated 11x15x8 listening space with a single chair for listening. Speakers are a 2.2 monitor+sub set up.
A couple of features not mentioned are the ability to measure the room from 20hz-200hz, 20hz-500hz, and 20hz-20khz. The measurements can be observed on the front display or transferred to REW for a larger look and smoothing. The measurement tool is very helpful in determining where you might want to target a correction and add room treatments. There are also 4 profiles (ABCD) so that different calibration and eq levels can be applied. This can be helpful in a large room set up where profile A is a single chair listening position calibration, and profile B is a multiple position calibration used for different seating positions.
BTW WAF is off the charts with the Dual Core 2.0

My 2c

       

[Samurai7595]

I like my Dual Core 2.0 a lot! I'm using it as a dac, preamp, and room correction device. My room is a dedicated 11x15x8 listening space with a single chair for listening. Speakers are a 2.2 monitor+sub set up.
A couple of features not mentioned are the ability to measure the room from 20hz-200hz, 20hz-500hz, and 20hz-20khz. The measurements can be observed on the front display or transferred to REW for a larger look and smoothing. The measurement tool is very helpful in determining where you might want to target a correction and add room treatments. There are also 4 profiles (ABCD) so that different calibration and eq levels can be applied. This can be helpful in a large room set up where profile A is a single chair listening position calibration, and profile B is a multiple position calibration used for different seating positions.
BTW WAF is off the charts with the Dual Core 2.0

My 2c

Thanks rodge827 !

[James Tanner]

Hi

The problem is that a microphone does not 'hear' in the same way our ear/brain does.

I think one of the most eloquent comments ever made regarding the dangers of taking microphone measurements as indicative of how people hear was by Dr. Floyd Toole in one of his papers written back when we were doing his speaker research at the NRC;

“A measurement microphone performs a simple transduction of the pressure summation at the diaphragm location, without regard for the direction or timing of the incident sounds. Two ears and a brain, however, are rather more elaborate in their processing”.

james

[Pneumonic]

DIGITAL ROOM CORRECTION ISSUES

The problem with Digital room correction through ‘EQ’ is that it totally screws up the direct sound vs. the reflected sound coming from the speaker.

When you listen to a speaker in a room you are listening to what we call the ‘POWER RESPONSE’ and you hear all the direct sound as well as the reflected sound mixed together.  So the listening experience is a combination of all the direct and reflected sound waves in a given room with a given speaker. When you alter the ‘direct sound’ at the speaker using ‘EQ’ it totally changes the relationship between the direct and reflected sound and is a disaster when it comes to ‘time smear’. In other words, the source of the problem is that the reflective time smear characteristics of the room 'issues' remains intact, and the direct radiator sound source is being retarded to compensate for this. Thus the result is a time smeared mess where the issues remain, and the original source is destroyed.

So the speaker designer has spent years attempting to get flat frequency and phase response from his speaker and we come along and force the speaker to do anything but accurate signal transfer. Also if you are going to use ‘EQ’ try and only ‘reduce’ the ‘peaks’ in the room and not ‘amplify’ the troughs.  Amplifying the troughs can play havoc with your speaker drivers power handling.

A lot of these newer types of ‘EQ’ products try and average a group of curves taken from many different locations in the room as they are attempting to reduce the negative effects of the single listening chair dilemma. Having a single spot in the room which measures flat but everywhere else in the room measures like crap is not a good result in my opinion. I think you are much better off adjusting the speaker location and using proper room treatments.  If all else fails maybe some ‘EQ’ can be used but I would recommend keeping the correction only for the very low bass frequencies and stay away from upper bass, mids and higher frequency ‘EQ’ where room affects are not an issue due to the shorter wavelengths involved.  I am hopeful that we will see many more Subwoofers with built in room ‘EQ’ which would be the better solution in my opinion if you are forced to use room correction.

James

Thanks James for clarifying. I agree, mostly. 
 
I run very directional electrostatic speakers that have very little high frequency dispersion pattern errors to contend with since they aren’t blasting sound all over the side walls.  I also have them out far enough from the back wall that the sound from the rear wave is delayed enough for the precedence effect to be effective. So, I am very good on these two front and really require little to no room damping efforts.

What is challenging, however, is the tendency of the speakers (diploe) to suffer from phase cancellation in the midrange resulting in a thinned out the sound if not compensated for in some way. So, I remedy midrange EQ issues via employment of a digital crossover which, not only does a perfect job on this front, but also allows me to dynamically EQ deep bass to ensure linearity. Not only can ratio, attack and delay thresholds be adjusted to reduce the amount of EQ applied at high levels but it also allows for use of large amounts of EQ at moderate output levels even automatically reducing the amount of EQ used, during really high level condition, to prevent woofer damage/distortion. If that’s not enough, the digital crossover also allows for time alignment of all the drivers involved ….. all done electronically and in real time.

Nevertheless, I still employ diffuser techniques and strategically place my speakers to start in order to get a strong base setup. Then fine tune afterwards.

[Pneumonic]

Hi

The problem is that a microphone does not 'hear' in the same way our ear/brain does.

I think one of the most eloquent comments ever made regarding the dangers of taking microphone measurements as indicative of how people hear was by Dr. Floyd Toole in one of his papers written back when we were doing his speaker research at the NRC;

“A measurement microphone performs a simple transduction of the pressure summation at the diaphragm location, without regard for the direction or timing of the incident sounds. Two ears and a brain, however, are rather more elaborate in their processing”.

james

Gated MLS testing can remove the room and its interactions ... but only for shorter wave lengths (ie mids/highs).  RTA can do bass ..... but room as well.

[James Tanner]

Gated MLS testing can remove the room and its interactions ... but only for shorter wave lengths (ie mids/highs).  RTA can do bass ..... but room as well.

Hi Pneumonic

Yes these MLS measuring devices will measure at about 500Hz and above and gate out the first room reflections and RTA's will measure overall frequency response (but only at one point in space). The point I am making is your ear/brain does not hear in the same way as these measuring devices.  In a real room with a real speaker you are hearing the direct sound from the speakers as well as all the reflected sound mixed in. This is called the Power Response or SOUND POWER of the speaker.

james

[James Tanner]

Hi

Here is an excerpt from my white paper on our speakers and give s a better explanation of my thoughts on speakers and room interactions:

BACKGROUND:
The two most critical parts of any loudspeaker system choice is the listening ‘ROOM’ and the loudspeakers‘POLAR’ response. Recognizing how the room imposes its boundaries (floor, ceiling, walls) on the speaker and how that speaker radiates its energy (polar response) into a specific room is critical to the understanding of the overall performance of any speaker and it is no different for the Bryston Model T loudspeaker.
When you are listening to a loudspeaker in a room you are always listening to a balance between the ‘Direct Sound’ and the ‘Reflected Sound’ from the boundaries of the room – this is called the ‘Power Response or Sound Power.’ It is that balance between direct and reflected energy which changes depending on the frequency radiation pattern (polar response) of the given speaker and the boundaries of the room the speaker is placed in. Dipoles, Bipolar, Omnipoles, Direct Radiators, Horns etc. all behave differently due to their specific radiation patterns and therefore exhibit different power responses in any specific room. Bryston has chosen a direct radiator approach in the design of the Model-T loudspeaker for numerous reasons but one critical reason is because we feel it is currently the best way to accomplish the correct balance between direct and reflected energy in real world listening rooms.

DIRECT and RELECTED SOUND:
The ‘direct sound’ is the sound radiating from the front of the loudspeaker and the ‘reflected sound’ is all the sound your ears perceive after the sound waves have interacted with all the different boundaries in the room. It is important given real world conditions that the on axis response and the off axis frequency response of a loudspeaker be as uniform as possible. This on and off axis characteristic is generally referred to as Polar response. The smoother and more uniform the on and off axis polar response of the speaker the better the tonal balance between the direct sound and the reflected sound will be. In other words, the reflected sound will have the same overall tonal balance and sonic characteristics as the direct sound if ‘on and off’ polar response is smooth and even. This approach also provides the optimum overall 3-dimensional soundstage presentation as well. The Bryston Model-T is a very wide dispersion design so the polar response is very flat on axis and very uniform all the way out to more than 45 degrees off axis in both directions from center to provide a very wide and even listening window.

LISTENING WINDOW and SOUND POWER:
In a loudspeaker the ‘listening window’ is an average of a front set of curves whereas the ‘sound power response’ is an average of all the curves right around the whole speaker. What we actually hear seems heavily weighted to be a balance between these two conditions. The listening windows frequency response should be very linear (flat) across the entire audio band but the sound power should fall off by 8 – 10dB by the time you get to 10kHz (see diagram below) while still remaining linear in its march down from the bass frequencies.
Striking the proper balance between these two is extremely important to the sound of the speaker. Keeping the listening window and the sound power both linear is not an easy task and is where most speakers fall down.




Typical Model-T Passive Anechoic Response

Typically there is a lot of attention paid to the linearity of the direct on-axis frequency response by reviewers and knowledgeable consumers but it is really just one curve in the mix of 64 curves Bryston utilized in the design the Bryston Model T passive loudspeaker.

[Freo-1]

Excellent write-up, James.  Makes a lot of sense.