TOSHIBA 4 channel QM decoder

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No reverberation unit is required to generate them after the fact, they already exist in the recording, which is why no quad decoder I’ve ever come across uses such a thing.

Of course substracting Left from right bring up the differences and reveal a lot of the recorded echoes and stereo effects.
Then you state the effects settings are nothing else than variations of the matrix equations to bring up more or less of these echoes effects.

The mystery of the little box is solved then.
It only contain some matrix circuits in a shielded enclosure.

i'm still puzzled by this diagram and the hard to read content of the first box
 

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Of course substracting Left from right bring up the differences and reveal a lot of the recorded echoes and stereo effects.
Then you state the effects settings are nothing else than variations of the matrix equations to bring up more or less of these echoes effects.

The mystery of the little box is solved then.
It only contain some matrix circuits in a shielded enclosure.

i'm still puzzled by this diagram and the hard to read content of the first box
I turned it, adjusted and blew up- looks like O (or Q) MD unit and - OM (or Q) effect switches.

OMG OMD.jpg
 
What the heck is QM Dolby? QM is neither Dynaco or Dolby matrix. Also from the Midi-Magic Quad Systems page:

If you refer back to that page & section it can be seen that QM involves both encoding of front & rear chs, & matrix decoding of both sets upon playback. The QM/EV4 is has a relatively wide front sound stage, narrow rear left to right, & good separation of front to back. That is neither Dolby or Dynaco.

The earliest Sansui decoders such as the QS-1, QS-500B, and others also had similar modes of operation. The Sansui had not one but two concert hall modes. These were easy tricks back then, various matrix blending, EQ tailoring & all done with out any delay or reverb added. You're right delay is common on modern receivers but that the Toshiba was not one of them. Dolby Matrix with delay had not even been invented then so there's no reason to expect QM would be in compliance with Dolby.

I base my comments on 50+ years involvement with surround sound & audio electronics.

If you read the entire page, you would find that I referred to the Japan Phonograph Record Association (JPRA) and the Electronic Industry Association of Japan (EIAJ). Each produced very similar standards for matrix recordings. These standards are the source of the labels used by many manufacturers:

- RM - Regular Matrix - Equal-separation basic matrix
- QM - Quadraphonic Matrix - Forward-oriented basic matrix
- PM - Phase Matrix - All SQ-related matrix systems
- CD-4 - Compatible Discrete - CD-4
- UX - Uniform Matrix - All UMX-related matrix systems

The title headings on my page are based on these categories, showing which standard applies to which matrix.

Toshiba simply said their decoder conformed to the QM standard. So do EV, Dynaquad, and Dolby Surround.

QX and XM are not standards of either JPRA or EIAJ. They were trademarks of Denon.

I have a Sansui reverb that has a spring box only 4 inches long. And it can be switched to send the output to L-R in the output.
 
Help...
Hi. All

I have finally got the Toshiba SC-410 QM Decoder today I have tested it to see if turns on yes it does I have a step down transformer so that part of it works BUT......

I think I`m thick as a brick .....:bowing:

Can someone tell me how to get a matrix 4 channel output to a 4 channel Aux input of receiver amp from this Toshiba QM Decoder Her is the manual to go by...

Thanks for the photos of the Operator's Manual BBQ! I hadn't found it in my searches previously. Like a number of the other members have mentioned, it looks like this decoder was meant to drive rear channel speakers directly, and not send a decoded signal back to a receiver or outboard power amp. I had my suspicions in the past few weeks, but they seem confirmed now.

It just leads to more creative methods of connecting it into a system...
 
Sounds like a half powered Dynaco/Hafler system for getting quad sound from a stereo recording. I remember having the Dynaco unit and it was incredible with the Who song "Pinball Wizard". Definetly discrete guitar sounds.
I did enjoy the Dynaco unit which was available as a kit back then. I also built the Heathkit quad preamp/tuner, enjoyed it too.
 
I've discovered a few interesting things about this model while following this thread. On the SC-410 the description of the unit is "SOLID STATE QM DECODER" instead of "4 CHANNEL MATRIX DECODER/AMPLIFIER" as seen above. The "4CH INDICATOR" was "QM INDICATOR"; the "MATRIX EFFECT" push buttons were "QM EFFECT"; the "MATRIX" selector position was "QM", and the "MATRIX MODE" push button was "High-Cut" on/off.

I wonder if there are actually any internal differences between the SC-410 and SC-410S, or if it was all a matter of relabeling after pushing the QM system, and then having to back peddle and convince people it was compatible with RM? One thing though, is that the SC-410S appeared to be multi-voltage, so maybe the unit was relabeled for export, where the rest of the world hadn't heard of QM matrix?

I have an SC-410 on my "someday" decoder list for outlier Japanese matrix systems, as well as a Columbia/Denon QXA-1.
 
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