[Brian Cheney]

The live vs recorded CES demo at the Zeus Ballroom taught me many things and reinforced other convictions about good sound which I have held for some time.

I'll just touch on a few subjects:

1. Room Treatment.  Even with a perfect source (live sound) it was necessary to treat the playback venue and in truth, we did not go far enough in our CES demo.  I brought eight 4x8' sheets of 3" Sonex mounted on panels.   That's 256 square feet of absorption.  I could have used more in the 28x38x17' ballroom.  In particular I would have liked to damp all four upper corners to prevent the slap echo which degraded both our live and reproduced sound.  If your listening room is live enough so that you hear a buzz or echo when you clap hands sharply over your head, treat at least the room corners (all of them) with absorption.

2. Listening position.  Our playback sound changed considerably depending on where you sat.  For that matter, the same is true of the live music.  Best seats in our demo were not close to the source, but further back and off to one side.  The "equilateral triangle" rule does not apply.  There are good seats and better seats and you should look for the better seats where you listen.

3. Dipole bass.  By far the best bass quality we obtained for true to live sound reproduction came with the dipole subwoofer configuration we ended up with.  This means four low-Q woofers facing opposite directions, the top one in the stack wired electrically out of phase with the other.  The resulting figure 8 dispersion pattern made it much easier to integrate bass with the rest of the spectrum vs. standard omnidirectional bass. 

4. Room and speaker correction via active parametric equalization.  We could not have approached credible live sound playback without the seven bands of parametric EQ available from  our woofer amps and the modded DCX2496.  Small changes in EQ settings on a Hertz-by-Hertz pole frequency selection basis gave us the ability to match our live sources to a very convincing degree.  No un-EQed speaker regardless of price or design would have done this.  A "flat" speaker such as those that measure well with conventional technques would not have done the job. In fact, all would have fallen far short.

5. Don't "Trust your ears"--"Train your ears!"  Audiophiles need to learn where problem areas of reproduction are located by their frequency bands.  You should be able to identify to at least within a half-octave where a peak or trough is located.  A little study of music and voices and their respective ranges will yield great benefits.

6. Speaker quality counts.  I chose the V60 for our demo because of its flexibility.  It can be configured as a dipole or monopole, or somewhere inbetween.  In the large ballroom full dipole gave the least coloration.  You can't EQ away box sounds and resonances, so it's best if the speaker not have them to begin with.  With the V60, subbass is outboard, which made dealing with problems in that one area easier to deal with.  We could move, invert polarity, EQ and cross over the outboard subs quickly and easily, not true in a fullrange system where the woofers cross over above 80Hz or so.
The planar magnetic, push pull mids and true ribbon trebles also proved to reproduce live music with greater fidelity than cone and dome dynamic I have heard regardless of quality or price tag. 

There are probably a dozen speakers out there which could have performed well in our demo, but their prices are all a large multiple of the V60 ($8900pr, plus $1650 per powered sub).  If what you want is good, pleasant sound, there are hundreds of speakers out there you can buy.  If you want great, accurate, faithful to source sound, you'll need a speaker as good as the V60.

7. DSD is better.  Having listened to reproduction from unadulterated DSD 2 channel masters  for five days, in A/B comparison with the unimpeachable live music source, I'll say without reservation that DSD is capable of completely natural and faithful music reproduction.  It's difficult to edit, mix, and EQ DSD, but still, technology for near perfect music playback is here, now. A single stereo mic feeding a DSD recorder gives great sound once you move your musicians around to balance out their sound.

Your comments on the above are welcome.

[seadogs1]

Dipole Bass, how is it done with two VSS subs? Right now I took off the bases tuned one on it's side with the cloth facing the front. The second sub I also tipped on end and turned upside down on top of the first sub. Both cloth sides facing out and one bottom woofer facing left and the other facing right. I still have them wired right channel, left channel in phase.

Did any of the press write up your system?

[Brian Cheney]

With two VSS, you can set them up for dipole bass by placing them back to back in the middle of the room, between the main speakers.

Wire the rear firing sub in inverted polarity to the front sub.

With the V60's I suggest a 65Hz crossover and slightly higher bass level than before.  Also, be sure to set the parametric EQ for the floor to ceiling mode, 565 divided by ceiling height in feet.  I suggest 4 to 5 dB of cut and a Q =.25.

[Manowar]

7. DSD is better.  Having listened to reproduction from unadulterated DSD 2 channel masters  for five days, in A/B comparison with the unimpeachable live music source, I'll say without reservation that DSD is capable of completely natural and faithful music reproduction.  It's difficult to edit, mix, and EQ DSD, but still, technology for near perfect music playback is here, now. A single stereo mic feeding a DSD recorder gives great sound once you move your musicians around to balance out their sound.

Your comments on the above are welcome.

What does DSD stand for???

Thanks,
John

[thegage]

What does DSD stand for???

Thanks,
John

Direct Stream Digital

http://en.wikipedia.org/wiki/Direct_Stream_Digital

John K.

[tbrooke]

Sounds like a success - I hope there is some good press coverage. In my limited perspective it seems that VMPS is one of the few that puts an emphasis on reproducing an accurate representation of the live experience and it seem that it takes a good sized speaker or speakers to do this. I was intrigued with using 4 subwoofers for what was basically a small acoustic combo. Good job.

I am interested in the dipole subs will we see a new VMPS dipole sub?

I have the RM30-M's and two original subs and the article has renewed my experimenting with the interaction between the 30M's side woofer and the subs. It seems there are a lot of timing, phase and directionality issues with multiple subs especially in a large room.

Keep up the good work.

Tom Brooke 

[John Casler]

Dipole Bass, how is it done with two VSS subs? Right now I took off the bases tuned one on it's side with the cloth facing the front. The second sub I also tipped on end and turned upside down on top of the first sub. Both cloth sides facing out and one bottom woofer facing left and the other facing right. I still have them wired right channel, left channel in phase.

Did any of the press write up your system?

Hi Chuck,

You don't need to remove the "bases" to make a Dipole, but there are actually "several" orientations.  In fact, you don't even need to "stack" them like we did.

All that effectively needs to happen is that they need be in the same area, and are "firing" in OPPOSITE directions.  They also need to have a specific "cone" movement.  That is, as the FRONT FACING woofer is moving TOWARDS you, the REAR FACING woofer is moving in the SAME direction.  In this case the front would be PUSHING Air, while the rear would be refracting or "pulling air".

It is as if they are the SAME Woofer of an "open baffle".  This is Dipole.

How can you set them up?

1) Stack them on top of each other (as we did)
2) Place one sub directly behind the other, but on the floor also in a normal orientation
3) Place them on their ends with one in front and the other behind
4) Place them "side by side" with one facing front and the other rear
5) other (I'm sure there are other possible placements)

I have often placed one Sub in front facing me, and the other behind me (either reverse phase or facing away from the listener) which actually puts you "IN" the middle of the dipole. and is quite interesting, and I find the most accurate, but was not an easy option at the show.

[John Casler]

Sounds like a success - I hope there is some good press coverage. In my limited perspective it seems that VMPS is one of the few that puts an emphasis on reproducing an accurate representation of the live experience and it seem that it takes a good sized speaker or speakers to do this. I was intrigued with using 4 subwoofers for what was basically a small acoustic combo. Good job.

I am interested in the dipole subs will we see a new VMPS dipole sub?

I have the RM30-M's and two original subs and the article has renewed my experimenting with the interaction between the 30M's side woofer and the subs. It seems there are a lot of timing, phase and directionality issues with multiple subs especially in a large room.

Keep up the good work.

Tom Brooke 

Hi Tom,

Only B, would know if he is interested in "dipole" bass to the point of actually building such a device.  However it seems less than likely with the present SUB design.

That is, it would be a difficult task to use a Passive Radiator in a Dipolar single enclosure.

It is easy enough to simply use the two sub approach.

As many know, I have used some very "strange" and interesting multiple sub approaches including dipolar, bipolar, monopole, quadratic, push/pull. and even placing one sub down the hall and at least 30' from the listening position.

I have stacked, re-oriented, corner-loaded, and tried many strange and different phase relationships, and putty adjustments.

The Dipole we used at the show was beneficial to "that" application because of the enormous wave lengths we were dealing with, and some of the "subsonic" sounds both from the system and the environment.

Brian mentioned the Air Conditioner, but there was also McCarron Airport close by with the St Tropez and Alexis Park very close to both the airport "and" the flight path.

Quite often a Jet would be warming up sending us SUBSONIC information which was at such a low level you didn't notice it, but the mikes picked it up (it was very similar to the same frequencies of the Air Conditioner.

However, the sensitive mikes picked it up and it was VERY evident during play back and the dipole sub config was the best at NOT amplifying it beyond its original level.

So anyone who wishes to experiment with DIPOLE bass need only TWO subs (preferably VMPS) and the wherewithal to place them and wire them in the dipolar in one of the DIPOLE configs I mentioned.

If anyone needs an extra sub, let me know 

[Brian Cheney]

We were fortunate an unlucky accident prevented us from using two VLA as planned.  We could have set them up in a dipole configuration, but that would have required center placement and our performers were already occupying that space.