- Mar 2, 2002
Such a coincidence that you ask, I was literally wondering the same thing yesterday. I suppose it would have to first check for cd-4 carrier, then check for presence of 90 degree OOP modulations for SQ, otherwise just assumes RM, probably can be fooled with certain recordings.Exactly how did this “Automatic Switching” work? I know that some high end tape decks have this for Dolby NR but I think that uses some kind of test tone that you have to insert via the deck at the start of the recording. How did a ‘computer’ figure out whether a recording was in SQ, CD4, or QS way back in 1974? Seems kinda fishy but I could be wrong I guess.
The ad actually mentions "analog" computer circuitry, which was definitely alive and well during that period, and would have been well-suited for the type of detection circuits furui describes above....How did a ‘computer’ figure out whether a recording was in SQ, CD4, or QS way back in 1974?
Probably didn’t work too well as others would had came up with a similar approach you would think. Just would had called it something different. Still it would be interesting to read a review of the thing to find out. I am somewhat familiar with detection circuitry as some high end Shortwave radios used something similar but it didn’t always work that great.The ad actually mentions "analog" computer circuitry, which was definitely alive and well during that period, and would have been well-suited for the type of detection circuits furui describes above.
Interesting approach. Seems like Onkyo had genuine concerns about the level of consumer confusion in the quad market. Would be nice to know how well it worked in practice, teasing out all the details between the various matrix formats.
If the system automatically indicate if a non-quad stereo recording has SQ-like elements, that itself is interesting/useful because it provide a suggestion of which recordings decode more actively in SQ than RM, which is less common than the other way around.Would be nice to know how well it worked in practice
Since I first heard about this automatic switching I was suspicious that it would either identify a signal as CD-4 and pass it to a demodulator, or otherwise route it to a generic matrix decoder. What Soundfield has identified about the schematic backs up that suspicion. I can't find many pictures of this model, so can't see all of the indicators lit, or what the controls say, but did find this on Ebay and the design hints that it may indeed lump all matrix together based on the indicator I see lit. Probably turn a selector between stereo and four channel, and let the receiver "do" the rest... Put on a phasey stereo album while in four channel, and bam! it thinks it's matrix.I had a very quick look at the circuit diagram and surprise, surprise there's no "Analog Computer"! All I could see was a relay that swapped between the outputs of the CD-4 Demodulator and the Matrix Decoder dependent on whether the CD-4 Carrier Pilot lamp was triggered. The Matrix Decoder was based on the Sony CX-050 basic SQ decoder ic with a bunch of transistor based front-back logic stuck on the output. Nothing clever at all.