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In the Forum: Playback Listening
In the Thread: The “Dead Points of Live Sound”
Post Subject: The DPoLS in the new room: new thoughts.Posted by Romy the Cat on: 11/28/2010

Since my new room is set and the playback is installed and configures I name an interesting observation:

Continue to think in this direction I come to very promising hypothesis that I would like to try if my Macondo would not be so huge and heavy. To make practical experiment on it I would need to device a mechanism to move Macondo’s right with very high precision but considering the size and the mass of the thing I do not have this option for now. If someone would devise foe me such a mechanism then I would appreciate it.

Anyhow, back to the inspiration/ hypothesis that I have. The inspiration suggests that time alignment is the key for DPoLS setting. However, here the time alignment needs to be understood a bit differently. Usually time alignment implies the arrival of the sound from all channels of the same loudspeaker at the very same fraction of phase. The DPoLS Time Alignment ™ is a different animal. It implies a Triple Time Alignment:

1)      Alignment  of the Channels of the same loudspeaker
2)      Alignment  of BOTH loudspeaker in the room
3)      First major reflections of the room for both loudspeakers.

This is in a way a revolutionist thinking about Time Alignment as it does not imply the Time Alignment itself but a combination of Time Alignment with benefits of Time Alignment. Let me to explain as it might be a bit confusing die to my careless use of definitions. I will explain it on examples how I feel the DPoLS might be found (if my theory is right) fully predictable, methodologically and without even listening the loudspeaker.

So, you get a pair of loudspeakers and a room with comfortable foe you reflection pattern. You set up left loudspeaker (left for you) where I need to be. I always suggest starting from left loudspeaker as it cares the fist violins, sopranos of choruses and generally in western culture is associated with HF lead. You take RTA or TEF pulse analyzer and perfects align each channel of the loudspeaker to your listening position. Then you take a right loudspeaker and do the same. They the fun begins. You need to align the right and left loudspeakers to each other in respect to this position in the room. We are not taking here about arrival time and it will be skewed and hardly measurable as we will not be able to subtract the modulations from reflections. So you take pulse analyzer away and using just TRA we are trying to setup R and L loudspeakers to have max amplitude of each other impact.  Here is where you deal with true DPoLS.

Here is where you deal with true DPoLS: a single mm of moving or angle of right loudspeaker does impact sound but it also impacts the RTA summation if you use a high resolution (let say .25dB and higher). I need to warn you that the operation at 0.1dB level non-anechoicly from let say 10 feet is very tricky and generally might be considered idiotic. But the whole point is that you want all live reflections of your room to be inclusive.  You might use cancelation after a few ms to deal only with fist reflections. Anyhow, you objective is to setup your R loudspeaker with as low conflict to your L loudspeaker and to your room. The microscopic movement and angling of your R loudspeaker acts as a lubrication that put your R loudspeaker in micro-phase conflict-less operation. This is in my theory is a condition for a proper DPoLS operation.

Now, SOME aspects of the theory above I have tested and was able to get very substantial gain of performance. I did not apply the success to the whole Macondo, I will but to do it I need a full house of strong hoodlums with tools what would very precisely moive my speakers according to my instructions. I very much willing to do it sometimes but the Macondo frame is not friendly for this task.

A note I need to make. The above method is a method with using of tools of objective control. The very identical result might be accomplished by specific targeted listening if a person knows what and how to listen.  However, I do not think that those skills might be delegated in article and I will refer you to measurement tools. If you are not deaf and have some listening intelligence then you will very soon discover what changes happen with sound while it become less self-conflicting and how to look and find those changes in  new sound. The most important is that the theory above gives (I hope) you a tool how to navigate sound objectively, by measurement and predictably toward to the DPoLS operation.

Rgs, Romy the Cat

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