Add on pseudo stereo enhancement units?

[Diabolical Artificer]

Here you go, ETI article . Took me a while to find it, then had to get it scanned by someone else so took a while. With Keith's circuit's you should be sorted, let us know how you get on.

Andy.

[Heatercathodeshort]

Originally Posted by Techman

The Fidelity AVS2000 all in one TV, radio, record player and tape recorder unit from the early/mid 80s also had this stereo 'wide' and 'spatial' facility.

What a pity the entire thing had not been launched into space. Too many bad memories. John.

[Synchrodyne]

Re-reading the original request and being guided by its content rather than its title, I glean the impression that perhaps what is being sought is a means of “synthesizing” a four channel output from a two-channel stereo input, rather than a means of enhancing/varying the stereo spread.

The existing Kenwood unit unit evidently does this, having some form of matrix circuit that develops a a pair of rear channel outputs as well as the customary pair of front chanel outputs. Whether the matrixing was done at signal level or at speaker level is unknown.

Back in the day, the QS and SQ quadraphonic decoders, both standalone units and those built into amplifiers and receivers usually had a switched position that allowed the synthesis of a four-channel output from a two-channel input, this being done by electronics at signal level. An example circuit is shown here:



As already mentioned, there were also simpler add-on units that derived three or four ouput channels using a Hafler matrix. Some of these operated at signal level, others, such as the NEAL four-channel resolver, operated at speaker level and comprised entirely passive circuitry.



Sugden offered its Q51, intended to work with and be powered from its C51/P51 amplifier combination, and which had Hafler and Scheiber matrices as well as BMX, QS, and SQ matrix decoders.

During the 1970s Wireless World ran a series of articles, many of them constructional, about quadraphonic decoding. Some of the units included four-from-two channel synethesizing capability. I suspect though that some of those circuits were based upon ICs now in the unobtanium class. Anyway, I have attached a partial list of those articles, all of which should be findable at the usual place, http://www.americanradiohistory.com.

WW Surround Sound Articles.xlsx


Cheers,

[dinker11]

Thank you Dr Wobble for the uploads and everyone else that have posted.

The circuit looks pretty straight forward so i will have a go at building it and let you all know how i get on.

All is working o.k at the moment so the low temperature and moist air were probably the ingredients to cause the original malfunction.

It probably is time to give the amp a good service as it must be around 20 years old, if not more but I'm always reluctant to disturb "Sleeping dogs".

[Techman]

Originally Posted by Heatercathodeshort

What a pity the entire thing had not been launched into space. Too many bad memories. John.

Sorry about that, John. I have to admit that it's always a bit 'tongue in cheek' when I mention this set, and I was worried that you might see the post . I'm sure I've got the only working one left!