Help needed with my Denon Universal Matrix Decoder QXU-10 ...

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alaric smith

Active Member
Joined
May 13, 2013
Messages
89
Location
Kent, UK
A couple of years ago, I picked up a "prototype" QS(?), Vario Matrix(?), BMX (?), etc., decoder. It works and gives some weird but excellent results with some stuff (I have a few QS LPs). To be honest, though, I have no idea what it was designed to do, which matrices it was supposed to decode or whether it was ever released into the wild. Mine is marked "Sample 0025" in high-class red and black felt-tip pen on the back and "sample" on the roof.

The board is remarkably simple, with two ICs heatsinked and then shrink wrapped (presumably to hide the ICs from market forces), which seems a little odd to me. Why have a shrink-wrapped heatsink? It would be incredibly simple to come up with a circuit diagram - despite the slightly awkward soldering on the double-throw level pot (the earth seems to wander around the pins like a snake). I daren't take the shrink wrap off, just in case Denon's agents get me :alienrob: ...

I will see if I can add a photo at some point - it is, though, just a little wooden box, with a brushed aluminium front, on which sits a level knob and a on/off toggle switch, and a steel chassis, part of which acts as the rear panel, on which sits stereo-feed rca terminals and quad out rca sockets, a fuse holder and the power cable. The front has "Denon Universal Matrix Decoder / QXU-10" pantographed (screen printed) across the top (from the left had top edge).

I need to clean the pot (it is a bit scratchy) but everything else is fine - no cap crackles or any other pops and whistles.

It does add a little dimensionality to stereo but I wouldn't write home about it (wait a second, I live at home ...). I was hoping that it would have a little ambisonics magic but probably not.

I guess what I am asking is: Has anyone come across this box before? What does it really do? Was it just an UHJ decoder? Is there a manual out there (searches in the www seem to come up with a lot of missed ebay sales of related things but nothing similar)? What are the hidden ICs? Will I be captured by random Denon executives? :yikes So many questions...

Any help would be gratefully received.

Sorry if there is another thread on topic; I searched and searched but might have missed something. Please put me right if I have.
 
I think that I have worked some of this out - clearly nothing to do with CD-4 or QS, which is vaguely annoying. Apparently, there was yet another format called UD-4 which was a hierarchical system starting at mono, then stereo, then 4-2-4, then fully discrete and beyond.

It would appear that LPs encoded in UD- are very rare. So far, a trawl of ebay has turned up one - a Japanese jazz LP by Kaolu Iiyoshi called "feelin' good", which, at the moment, I am not. Does anyone know whether there is enough similarity between UD-4 and other formats to make this useful or has it become a thing to point at and say "that's rare"? :(
 
Check out the QQ UD-4 Page for some info on the format:

www.quadraphonicquad.com/QQ-ud4.htm

QQ Member 'Quad First' is one of the few members I know of that have a lot of UD-4 experience, as well as LPs and decoder/demodulators. You could try sending him a PM and see if he responds. He's not around these parts very often.

He may also know of the box you found. This guy knows just about everything there is to know about '70s quad.
 
Hi, I will have to add a photograph because it looks nothing like any of those (with the partial resemblance to the lower UMX Demodulator). I will give Quad First a go; thank you for the advice. It appears a shame that UD-4 hit the skids. It seems like quite a good system. I am going to guess that mine is a 4-2-4 decoder, not the full hog, discrete one.

Thank you, again for the help.
 
Sorry, I should have added that, according to the chap I bought it from, it had something to do with the BBC - he certainly used to work for their radio department.
 
Here are the photos ...

IMG_0216 01.jpg
IMG_0215 01.jpg
IMG_0217 01.jpg
IMG_0218 01.jpg
 
Hi Alaric, In regard to the QXU-10 you have, it is NOT a UD-4 demodulator, it is a BMX (QX) matrix decoder. There were two levels of Denon's system, the first being a matrix system rather like QS/RM and SQ in the sense that it involved blending 4 channels into 2 for recording in the standard LP bandwidth of roughly 20 to 20,000hz. The higher order, 2nd generation demodulator was the UDA-100, which demodulated UD-4 (Universal Discrete 4 Channel) LPs. UD-4 was a carrier based system somewhat similar to CD-4 (Compatible Discrete 4 Channel). UD-4 added two high frequency carriers above the range of human hearing to the LP, these carriers contained the missing equations for the basic matrix on the LP in BMX-QX format, so that when recombined after demodulating, the result was closer to discrete like on 4 channel tape. Be sure to differentiate between a decoder, used with matrix systems (SQ, QS, RM, QX, EV, etc) and demodulating, which involves ultra sonic FM carriers on the LP above the range of human hearing (CD-4 and UD-4). Matrix systems use a decoder, carrier systems use a demodulator. Denon (Nippon-Columbia) initially released QX matrix LPs in Japan from around 1971 to 1974, then when their UD-4 system was developed enough for commercial release they stopped issuing BMX-QX matrix LPs and switched to UD-4 LP releases, of which there were about 31. I have most of the UD-4's released, and many BMX-QX matrix albums as well. I also have two brand new in the box QXU-10 units like you have. They are a simple matrix decoder, with no logic at all, and the results they produce with a BMX-QX LP are similar to a 1st generation SQ decoder with no logic (3db separation) or a QS/RM decoder prior to the Vario-Matrix system being developed (Sansui QS-1 decoder or QR receivers without the X in the model #). The QXU-10 is a rarity, and interesting for historical purposes, but not particularly good in performance being a very early attempt before the system was fully developed into UD-4. In the Denon brochure for the UD-4 system that also shows the basic, non-carrier decoder style like the QXU-10, they describe the basic decoder as suitable for an "inexpensive" system setup. If you have any further questions, don't hesitate to write again.

Sincerely, Nick
 
Just a note about those shrink-wrapped components. They are actually little circuit boards with transistors and other components mounted on them and then the shrink wrap was added to keep everything in place. They aren't heat sinks and the shrink wrap is not an effort to hide top secrets from anybody. :D

Doug
 
Nice to see Nick on the site. A professor of quad knowledge!
Right or wrong, the quad discography has the QX titles listed as "QS - Matrix Format Vinyl LP (Applies to RM & QX)".
Perhaps I should change this to be more accurate as I do list the discrete titles as UD4.
 
Yes, Nick is the librarian of the Quad era, that's for sure. Some TV station should do a documentary on the guy.
 
Just a note about those shrink-wrapped components. They are actually little circuit boards with transistors and other components mounted on them and then the shrink wrap was added to keep everything in place. They aren't heat sinks and the shrink wrap is not an effort to hide top secrets from anybody. :D

Doug

Brilliant. I would hate to see the Denon ninjas waste their time on me. :)
 
Agreed, Nick's knowledge is amazing. He suggested some albums to look out for in QX. I guess I am going to become a fan of Japanese jazz (not a problem, really; I like Japan and Jazz).
 
I have a question. I am curious about "QX". Is this term interchangeable with "QMX" I have seen "QX" records on ebay too and wondered how to play them if I should buy them. Elsewhere I have seen "BMX" and "QMX" are suppose to be the same thing, if I remember correctly. I currently can play "SQ", "QS", and "CD-4" and am wondering how many more decoders I will want to find to consider my record playing equipment complete for my needs.
 
QX was an early Denon regular matrix under EIAJ standard QM.

UMX is the Denon Uniform Matrix under EIAJ standard UM, incompatible with Regular Matrix.

I don't know if Denon continued to use "QX" fir the UMX decoders.

BMX is the 2-channel matrix version of UMX. UD-4 is the carrier version. Both can be played in either decoder.

You can play BMX or UD-4 on an SQ decoder by placing the LB speaker at center front and the RB speaker at center back, and reversing the phase of the LB speaker wiring.
 
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