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RCVR: Onkyo TS-500

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JonUrban

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Please post comments and and photos of this quadraphonic receiver in this thread.
We'd love to hear from those who own or have owned this receiver.

ONKYO TS-500

Rarity: UNKNOWN

Average Sale Price: UNKNOWN


Onkyo TS-500.jpg
 

doity

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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.
 

furui_suterioo

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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.
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.
 

Jim the Oldbie

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...How did a ‘computer’ figure out whether a recording was in SQ, CD4, or QS way back in 1974?
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.
 

doity

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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.
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.
 

doity

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Well the advert says that it has built in SQ, QS, and EV decoders. I think it would be easy to indentify a CD-4 carrier signal, but to differentiate between the other three would be hard to do effectively you would think. Maybe the signals of the other three have some kind of defining characteristics before being demodulated that would make it work correctly. But knowing as little as I actually do about the subject you would think that even today it would be hard to do this with all of the fancy digital processing stuff available.
 

Soundfield

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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.
 

surround.sound.enthusiast

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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.
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.
 

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doity

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Some ‘computer’. Well at least it “sounds” like a good idea in theory, people would had just as well selected the appropriate decoder. Which I am sure that is what the more discriminating listeners did. The only way something like this was necessary is if you used a record changer and had various Quad and non-quad LP’s and then just let it rip. It makes sense because even I had a hard time figuring out how to use Dolby correctly. I used to record with Dolby and then not engage the switch for playback because it sounded better. Well, maybe for the Dolby B recordings but with C it sounds like garbage. I was blissfully stupid and probably too stoned to even notice a difference as I did it like that for close to 10 years before I realized the error of my ways.
 

Soundfield

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I didn’t keep a copy of the service manual when I had a quick look at on line it a few days ago so haven’t got I in front of me at the moment. I’ll download it later if I get the chance. But as I remember the input signal is sent to both the CD-4 Demodulator and the Matrix Decoder. If a CD-4 carrier is present it sends the output of the Demodulator to the power amp. If there’s no carrier present the output from the Matrix Decoder is sent to the power amp. That is all Auto Mode does. The Matrix Decoder does not distinguish between SQ and RM when in Auto Mode. If you select RM manually I seem to recall all it did was disable the F/B logic. If you select 2Ch manually (Auto mode cannot select it) then the input signal is still passed through the Matrix Decoder but its rear channel outputs to the power amp are earthed. It’s actually pretty crude and the Auto Mode is completely useless if you haven’t got any CD-4 records. The advertising is more clever though – if you read it carefully it doesn’t actually say there are separate matrix decoders for different formats or that it can distinguish between matrix formats - but it clearly invites you to come to the conclusion that it can!!
 
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