:: sq quadraphonic ::

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Ragil,

You want comments on your "decoder":

Your phase shifter won't work. It needs to be broadband
which will require multiple sections set to appropriate frequencies
so that there will be reasonable relative 90-degree phase
shifts over the whole audio band. Your second-order single-
section phase shifter will work only over a very small frequency
range. There were papers on SQ in places like the JAES and
one could use them as a basis for a decoder, but they show
the phase shifters as just little boxes indicating a 90-deg
phase shift. (I've not researched enough to know whether
or not the studios' SQ encoders had competent phase shifters.)

Your dismissive response to my previous post where you said:

Hey. we'll find out what we like to listen to when we
evaluate equipment, not words

indicates a lack of understanding of the work involved to
design/build a decoder. I'd suggest (again) exploring
the literature on Ambisonics, if only to glean a reasonable
phase shifter from some of the published decoders. Also,
you'll find designs for Ambisonic decoders with an "SQ"
mode that better decodes SQ than most SQ decoders
did.

With a little thought and web access you can gather
the information you need, though access to a number
of good engineering libraries would be helpful.

Note the following: Most commercial SQ decoders used
application specific IC decoder chips whose audio performance
(disregarding their decoding function) was abysmal by today's
standards. But even the creation of a decoder whose
electronics are more listenable will not negate the fact that
SQ was a poorly conceived and technically incorrect system.

I admire your interest in this project -- I'm on a similar
quest; but the amount of work is not trivial. And before
one can worry about whether the decoder "sounds good"
in the typical audiophile useage of the term, one must
worry about whether the decoder is decoding correctly,
not merely squirting sound out of 4 speakers.
 
BrianL:
Thanks for your comment. I try to create that schematic base from the SQ block diagram and MC1312p SQ chip schematic. OK I will harder to find the information about Quadraphonic. Now I design the QS first, and SQ later if I have enough information about that.

QS -in my mind- is more natural than SQ. QS doesn't need phase shifter in audio line. Just matrix to extract the information from 2 ch to 4 ch . Similar with dolby surround, but with stereo information in the rear channel. Is this correct? :confused:

BrianGT:
That url is about dolby surround ...

Thanks & regards:
ragil.hastomo
Following response doesn't come from me:
Hey. we'll find out what we like to listen to when we
evaluate equipment, not words
 
Sansui QS 800

Looking for info on connecting the QS 800 to a 5000x and RA 500??

rob




QUOTE]Originally posted by roddyama
Hi Ragil,

Sometime next week I'll take it to work and scan it into an 11" X 17" .pdf file. Then I'll have to email it to you.

While taking a better look at the schematic, I realized that there are two boards that are shown as blocks. The schematics for these two blocks are omited. I'm thinking that these are the decoder boards because there is no mention of them in the parts lists or board layouts.:bawling:

I will send the schematic anyway, and you can see what you can see.:bigeyes:

Rodd Yamas***a
[/QUOTE]
 
Interesting that no one actually cares how to do the SQ or QS decoding or posts schematics.

You need two phase shift networks, one -180º and the other -90º. Used together you call them "0º" and "90º", respectively.

Actually you need four phase shift networks (two of each one).

The schematics for such phase shift networks are here:
Analog Wide Band Audio Phase Shift Networks

Actually that schematic has a very good network, one that would be studio-grade and far better than the one on 99% of SQ and QS decoders.

Then you use those networks to implement the matrix equations for QS and SQ, the formula is ubiquitous (just go to wikipedia).

A japanese guy has published full schematic for DIY QS and SQ decoders here:
http://www.hi-ho.ne.jp/odaka/quad/index-e.html

He uses slightly less sophisticated phase shift networks, but he includes "logic" decoding. This is where an analog circuit "steers" the sound, enhancing separation. IMHO this is cheating, but it's what the quaddies prefer.

As somebody mentioned, Ambisonics is a better system, but the point is not to use a better system but to have something to play those SQ and QS records.

If you want to decode CD-4, that's another matter altoghether...
 
OK Quadrafonic WAS and still is 2 channell regular with the other 2 channells at ultrasonic frequency that was demodulated to audible frequency for the back 2 channells, AudioTechnica was the phono cartridge maker I remember that had the bandwidth for that . I still have a turntable that has a Quadrasonic emblem on the front(Akai/Sony)... Beyond that If you want Techie stuff consult sony/etc for stuff.


mE
 
OK Quadrafonic WAS and still is 2 channell regular with the other 2 channells at ultrasonic frequency that was demodulated to audible frequency for the back 2 channells, AudioTechnica was the phono cartridge maker I remember that had the bandwidth for that . I still have a turntable that has a Quadrasonic emblem on the front(Akai/Sony)... Beyond that If you want Techie stuff consult sony/etc for stuff.

You are only describing CD-4 which is one of the quadraphonic delivery formats. BTW Many cartridges are suitable for CD-4, not only Audio-Technica cartridges.
 
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