Going back to this old theme, something which slipped under my radar but
reappeared when I was re-reading the Integrex decoder articles was
Michael's throw-away statement on page 3 that "...a fully fledged ambisonic
'variable matrix' design is under development for (such) specialist
applications". Does anyone (Geof Barton, Peter Craven, Peter Carbines,
Richard lee...) remember this or know anything about it - certainly nothing
remains in my memory, even if it was there in the first place.
Dave
PS The "specialist applications" alluded to were things like surround
presented drama where good single sound localization is desired, even at
the expense of musicality or listener fatigue.
On 21 October 2015 at 19:32, <tryp...@comcast.net> wrote:
> I have that decoder (Integrex) to which I did some minor updates, mainly
> in the power supply.
> SQ playback is pleasant, with good localization and low phasiness (FWIW,
> IMHO)
> Giovanni Abrate
>
> -----Original Message----- From: Martin Leese
> Sent: Wednesday, October 21, 2015 1:48 PM
> To: sursound@music.vt.edu
> Subject: Re: [Sursound] SQ QUAD
>
> David Pickett wrote:
>
> I dont expect them to ever sound as good as an Ambisonic recording,
>> but I bought some SQ-encoded LPs today. I get pleasant results
>> playing them out of phase with the same on two rear channels at -6 dB.
>>
>> My reason for writing is to ask whether anyone here knows what an SQ
>> decoder actually did. Despite all the BS Ben Bauer spouted when he
>> presented it to the AES in London (or was it the BKSTS?), I seem to
>> recall that it wasnt too sophisticated and perhaps, knowing this, one
>> can synthesize something better than the above in a DAW.
>>
>
> MAG's distaste for SQ is well documented,
> and in December 1977 there was even a fight
> between him and Benjamin Bauer on the
> pages of New Scientist. (This was refereed
> by Barry Fox (writing as Adrian Hope).)
>
> However, in July and August 1977 (refs at end),
> Gerzon published the design of an Ambisonic
> decoder that included an SQ mode (along with
> nine other modes). In Part 1, Gerzon wrote:
> "SQ decoders cannot be designed to give
> full ambisonic results; there is even a
> mathematical theorem to this effect. The
> decoder for SQ provided is, however, less
> phasey in quality than the SQ designs on
> the market, and was designed specifically
> for incorporation into this design. It is not
> in accordance with CBS Laboratories' SQ
> specification, but in the author's opinion, it
> is better than decoders that are."
>
> In Part 2, the equations for decoding SQ are
> given as:
> W'' = 0.73*Sum
> X'' = -0.73*j*Sum
> Y'' = 0.73*Diff - 0.73*j*Diff
> where Sum = Left + Right
> and Diff = Left - Right
>
> As far as I can tell, W'' is the W' signal after
> the shelf filters (and the SQ mode did not use
> shelf filters). Also the W' signal appears to be
> the W signal after removal of the Sqrt(2)
> weighting. Anyone interested in implementing
> this decoder will need to read the refs, which
> will be somewhere in the Ambisonic
> Motherlode.
>
> Regards,
> Martin
>
> Michael Gerzon, "Multi-System Ambisonic
> Decoder":
> Part 1: "Basic Design Philosophy",
> Wireless World, vol. 83 no. 1499,
> pp. 43-47 (1977 July).
> Part 2: "Main Decoder Circuits",
> Wireless World, vol. 83 no. 1500,
> pp. 69-73 (1977 Aug.).
> later parts never written & published.
>
> --
> Martin J Leese
> E-mail: martin.leese stanfordalumni.org
> Web: http://members.tripod.com/martin_leese/
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--
As of 1st October 2012, I have retired from the University.
These are my own views and may or may not be shared by the University
Dave Malham
Honorary Fellow, Department of Music
The University of York
York YO10 5DD
UK
'Ambisonics - Component Imaging for Audio'
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