#### Lynn Olson

##### Active Member

- Joined
- Aug 29, 2010

- Messages
- 96

Here’s a thought: dynamic decoders are usually set up so their static (logic sensing at zero) coefficients are the same as a “classical” static SQ or QS decoder. But it doesn’t have to be that way. The static coefficients can be different ... for SQ, the “tetrahedral” coefficients suggested some years back would be interesting, with 7.7 dB of separation between LF and RF, and 7.7 dB of separation between LB and RB. In a sense, this “primes” the decoder for further shifts in any direction, and should also require less steering overall, since the decoding coefficients are already partway there. (The less steering required, the better ... fewer transient artifacts, less sense of things shuffling around, etc.)

Of course, a QS decoder doesn’t need any changes of this sort, unless to weight it more towards an EV4 set of coefficients. (About 12 to 14 dB in the front, and 3 to 7.7 dB in the back.)

This changes the “resting” set of SQ or QS coefficients to a set that are better optimized for most recordings, and asks less of the logic. This could even be determined experimentally by looking at how much logic activity was demanded on different recordings ... basically, a long-term spectrum analysis of the control signals themselves, and comparing different sets of “resting” decoding coefficients. The coefficients (or default matrix) could be chosen on a basis of requiring the least logic activity over the course of a given recording.

A statistics-based approach to determining the optimum SQ, QS, or stereo-enhancement decoding coefficients would be the smart way to accomplish decoding. I suspect the EV4 set of coefficients would be close to optimum for stereo-enhancement purposes, since they were chosen on a subjective basis many decades ago.

P.S. I agree 100% that many discrete recordings sound unnatural, compared to Shadow Vector at its best. I have not heard any of the TATE units, so can’t comment on their spatial qualities. I think the spatial defects of lesser decoders (including Dolby Pro-Logic II) has given the public, and magazine reviewers, a poor impression of how good decoding can really sound.

Of course, a QS decoder doesn’t need any changes of this sort, unless to weight it more towards an EV4 set of coefficients. (About 12 to 14 dB in the front, and 3 to 7.7 dB in the back.)

This changes the “resting” set of SQ or QS coefficients to a set that are better optimized for most recordings, and asks less of the logic. This could even be determined experimentally by looking at how much logic activity was demanded on different recordings ... basically, a long-term spectrum analysis of the control signals themselves, and comparing different sets of “resting” decoding coefficients. The coefficients (or default matrix) could be chosen on a basis of requiring the least logic activity over the course of a given recording.

A statistics-based approach to determining the optimum SQ, QS, or stereo-enhancement decoding coefficients would be the smart way to accomplish decoding. I suspect the EV4 set of coefficients would be close to optimum for stereo-enhancement purposes, since they were chosen on a subjective basis many decades ago.

P.S. I agree 100% that many discrete recordings sound unnatural, compared to Shadow Vector at its best. I have not heard any of the TATE units, so can’t comment on their spatial qualities. I think the spatial defects of lesser decoders (including Dolby Pro-Logic II) has given the public, and magazine reviewers, a poor impression of how good decoding can really sound.

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