Discrete Quad Record Player?

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JoeE SP9
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Re: Discrete Quad Record Player?

Post by JoeE SP9 » 17 Mar 2019 19:54

CD-4 and QS/SQ are two completely different systems. Both are lumped together as quadrophonic. However, they are very different. A CD-4 decoder and the appropriate LP's are a true discrete four channel (quad) system. SQ and QD are matrix based systems much like Dolby Pro Logic.

AFAIK Sansui receivers did not decode CD-4 LP's. They were made for QS and SQ (matrixed) encoded LP's. Decoding CD-4 LP's was pretty much a JVC thing. It requires a CD-4 decoder to produce the four discrete channels that are on CD-4 LP's.

For those that are interested, a Dolby Pro Logic decoder does a fairly decent job decoding and playing QS and SQ encoded LP's. Many LP's were SQ/QS encoded but don't say so. Give them a listen using Pro Logic. Make up your own mind.

The Sansui Variomatrix QS system was the better of the two matrix systems although there wasn't a great deal of difference between them. Most of the other manufacturers used SQ.
Last edited by JoeE SP9 on 17 Mar 2019 20:08, edited 2 times in total.

dysmike
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Re: Discrete Quad Record Player?

Post by dysmike » 17 Mar 2019 20:02

I think Sansui did a couple that would do CD-4 (actually, I think one of my buddies who is into quad has one), but they were far more into matrixed LPs.

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Re: Discrete Quad Record Player?

Post by wiztom » 17 Mar 2019 23:28

JoeE SP9 wrote:
17 Mar 2019 19:54
CD-4 and QS/SQ are two completely different systems. Both are lumped together as quadrophonic. However, they are very different. A CD-4 decoder and the appropriate LP's are a true discrete four channel (quad) system. SQ and QD are matrix based systems much like Dolby Pro Logic.

AFAIK Sansui receivers did not decode CD-4 LP's. They were made for QS and SQ (matrixed) encoded LP's. Decoding CD-4 LP's was pretty much a JVC thing. It requires a CD-4 decoder to produce the four discrete channels that are on CD-4 LP's.

For those that are interested, a Dolby Pro Logic decoder does a fairly decent job decoding and playing QS and SQ encoded LP's. Many LP's were SQ/QS encoded but don't say so. Give them a listen using Pro Logic. Make up your own mind.

The Sansui Variomatrix QS system was the better of the two matrix systems although there wasn't a great deal of difference between them. Most of the other manufacturers used SQ.
The Sansui QRX-9001 Has QS, Synthesized QS, SQ, and CD-4/4Channel Direct Decoder.
I do not know what AFAIK means.

Thanks

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Re: Discrete Quad Record Player?

Post by Doug G. » 18 Mar 2019 06:49

"AFAIK" - "As Far As I Know".

Yes the later, upper models by Sansui have demodulators for CD-4 in them. That's why they ( the QRX-9001, particularly) have been known as the "everything" receivers

Doug

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Re: Discrete Quad Record Player?

Post by Doug G. » 18 Mar 2019 07:03

wiztom wrote:
17 Mar 2019 19:40
Doug G. wrote:
17 Mar 2019 18:10
A turntable without anti-skating is unlikely to be successful with CD-4. You need to have equal pressure on both groove walls.

Doug
Doug this is good info. I have a couple of questions:
Is the low capacitance wiring actually in the tone arm or just from the solderboard out; ( RCA cables). I cant imagine what low capacitance cabling would be with those small wires in the arm.

Do you have any suggestions on turntables to buy for CD-4 quad usage?

Thanks
Although the specifications mean from the cartridge on, if the wiring in the tonearm is separate small wires, not tightly wound together, they are unlikely to be the cause of any abnormally high capacitance. So, the main consideration IS the cables from the table to the demodulator.

I can only recommend the original BIC upper end 900 series because that's all I have ever used and they work perfectly for CD-4. I'm sure there are others, however. Any quality table with AS and stable arm should work, assuming low capacitance in the total output wiring.

Doug

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Re: Discrete Quad Record Player?

Post by Doug G. » 18 Mar 2019 07:14

The way to identify an 8-Track quad cartridge is the slot-shaped depression on the TOP of the cartridge, not really anything on the bottom. Methods of construction varied fairly widely among the manufacturers. A sensor arm in the player detects whether the cartridge is two or four channel by either staying down when the cartridge is inserted or being raised. Down - quad, up - stereo.

Doug

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Re: Discrete Quad Record Player?

Post by JoeE SP9 » 18 Mar 2019 15:18

Doug G. wrote:
18 Mar 2019 06:49
"AFAIK" - "As Far As I Know".

Yes the later, upper models by Sansui have demodulators for CD-4 in them. That's why they ( the QRX-9001, particularly) have been known as the "everything" receivers

Doug
My lack of knowledge about receivers rears its head. :oops:

I began using separates long before SQ/QS and CD-4 LP's were even thought about. During the heyday of two channel receivers I had no interest in them (still don't). I prefer and still use all separates.

My auditioning of the various "quadrophonic" types of recordings left me underwhelmed. There were never enough CD-4 recordings and most QS/SQ recordings placed the band members in the four corners. Being in the middle of the band while listening has never appealed to me. I got enough of that while playing in a band while I worked my way through college. I did have the old style GI bill for tuition and books. However, I needed some discretionary income beyond what the GI Bill provided.

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Re: Discrete Quad Record Player?

Post by zlartibartfast » 18 Mar 2019 18:59

wiztom wrote:
17 Mar 2019 19:40
...Do you have any suggestions on turntables to buy for CD-4 quad usage?
Any Technics Direct Drive table from the mid-late '70's through the mid-late '80's or similar. Mine is the SL1300 from 1974. Most other decent tables from the same period, or just about any nice table/arm combo that is wired with low-capacitance cabling, will work

They don't market "Quad" any more, but a lot of the better-quality turntable gear today is made with compatible technology. Typically the biggest hurdle for running a CD-4 quad system is getting the decoder.

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Re: Discrete Quad Record Player?

Post by Doug G. » 18 Mar 2019 21:16

I typically like separates too. I have a stereo Heathkit receiver I use in my classic quadraphonic system but it's not really necessary. I can do the same thing with a separate tuner and amp., which I also have.

I do need 4 separate stereo amplifiers because the four speaker systems are Advent stacks and I am of the school that says to use an 8 ohm load with solid state amplifiers because solid state amplifiers work best with 8 ohm loads. I know the general "wisdom" is that four ohms is OK, but it still distresses the amplifier more than an 8 ohm load.

Doug

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Re: Discrete Quad Record Player?

Post by wiztom » 18 Mar 2019 22:09

Thanks all for your input. I have picked up a JVC Nivico SRP-473e from E-Bay for $50. It will need a little TLC and a belt but should be good to go. I have also ordered some discrete LP's and will be recording them to my Tascam 34B.

Thanks Again.

Tom

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Re: Discrete Quad Record Player?

Post by scrapjack+ » 31 Mar 2019 08:46

Doug G. wrote:
18 Mar 2019 07:14
The way to identify an 8-Track quad cartridge is the slot-shaped depression on the TOP of the cartridge, not really anything on the bottom. Methods of construction varied fairly widely among the manufacturers. A sensor arm in the player detects whether the cartridge is two or four channel by either staying down when the cartridge is inserted or being raised. Down - quad, up - stereo.

Doug
This is news to me. My Lafayette RK-84 quad 8-track player has a manual switch on the front that must be used to swap between 2 channel(stereo) and 4 channel(quad). If you could open my photo of a quad 8-track in paint or something and point at which slot depression you mean, that would be of interest to me. You are definitely right about there being many case designs, at least for stereo 8-tracks.

Also in answer to the question posted.
Yes, low capacitance inside the tone arm. Of course those wires often extend out of the player as they are often their own circuit. As I understand this was mostly just an issue for older players from the 60's prior, as cd4 came out in the 70's. Recently I read a thread here that they mentioned a tone arm that came with a capacitor soldered to it, that had to be cut for cd-4 playback, as stated by it's owners manual. I don't recall which brand though.


I seem to recall hearing that most Technics from the 80's had low capacitance tone arm wires by default. I was told my Technics SL-Q2 should be fine for CD-4 as is, If I ever got a hold of a proper demodulator. I however cannot personally confirm this.

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Re: Discrete Quad Record Player?

Post by Pauw » 31 Mar 2019 11:01

The later 12xx Dual tables were marketed as being suitable for quad with low capacitance cables and an arm that could allow a CD4 cartridge to perform well. :D

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Re: Discrete Quad Record Player?

Post by Doug G. » 01 Apr 2019 05:26

scrapjack, I didn't read your first post closely enough the first time and I thought you meant the big hole on the bottom meant a quad tape but I see you meant it means a four track, which is true.

Not all players were automatic in selecting quad or stereo, hence the switch on yours. In a way a selector switch is better because then it doesn't matter which type of case the tape is in.

The quad decks we made for Ford were automatic and would switch between the two, depending on whether the slot was there on the cartridge top at the front.

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Re: Discrete Quad Record Player?

Post by scrapjack+ » 01 Apr 2019 10:12

Doug G. wrote:
01 Apr 2019 05:26
scrapjack, I didn't read your first post closely enough the first time and I thought you meant the big hole on the bottom meant a quad tape but I see you meant it means a four track, which is true.

Not all players were automatic in selecting quad or stereo, hence the switch on yours. In a way a selector switch is better because then it doesn't matter which type of case the tape is in.

The quad decks we made for Ford were automatic and would switch between the two, depending on whether the slot was there on the cartridge top at the front.
Yes, I don't have any of the Ford quad 8-tracks yet, that was the only Q8 I've observed in the wild. Most of my 8-tracks are inaccessible at the moment, however I noticed on the front of the Q8 tape is an oddly machined groove all the others tapes, including the 4-track, lack. I expect the notch marked by the blue arrow is the quad indicator trench you mentioned in a previous post. Reminds me of the notch cut out of the side of 8 tracks that pushes the 4-track roller out of the way for the combination 4-track/8-track car players to play 8-tracks. I found out about those trying to repair and mod a time damaged car unit into a stereo component. As far as I know there was only ever 1 commercially available 4-track player model not designed to be mounted inside a car. These mechanical switches seem to be a running theme with tape decks all the way up to cassettes.
8 tracks 2.jpg
(135.91 KiB) Downloaded 24 times

Coming back to quad stuff, you seemed to suggest that not all quad tapes had the indicator, perhaps due to ford developing it and other companies had their own approaches, I'm spit-balling here. Maybe there was even a quad 8-track recorder at some point whose blanks tapes probably didn't have the notch, I doubt it, but it does seem easily within the possible. With lots of demo tapes from various auto manufacturers, and several Q8's from Ford, It seems the auto industry was really a "driving force" for the 8-tracks at the time, and for keeping quad alive for a another few years. I sense a united front contrasting to when VW backed the PlayTapes with the spectra player while Chrysler decided to invent their own record format with the HiWay HiFi. The rise and fall of 8-tracks(and from what My grandfather tells me they fell fast) was before my time and I don't recall seeing many MiniDisk players either. Anyway, you stated you were involved with Fords production of Quad Q8 players and tapes. you implied that the internal slot based switch might not be 100% reliable. Were you, or are you now, aware of Q8 tapes that could not be played as quad because of a lack of slot, or slot to mechanism interaction? Was that slot devised at the beginning as part of the few requirements for cartridge design, so that all Q8's have it? I didn't think this format had anymore surprises, however if that detail was mentioned before I always overlooked it in the articles I've read.

I suspect if there was any less standardization with 8-tracks they would have been placed in the same chaotic boat as 16rpm records and set adrift.

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Re: Discrete Quad Record Player?

Post by Doug G. » 02 Apr 2019 17:30

Yes, the notch indicated by your blue arrow is the quad notch. Every quad 8-track I have ever seen has the notch although, if quad 8-tracks were made before automatic players, I guess there could have been some made without it.

The tape cartridge (including cassettes) industry relied heavily on various notches/grooves in the cartridges, themselves to operate switches within the player without the user having to manually throw switches on the outside of the player.

The very early 1980's spelled the end of 8-Tracks in cars. We were making players up until 1982 and that was it. Ford wanted us to develop a cassette player for them because they liked our 8-track players so much (we beat Panasonic several time on bids) and our engineers had one started, even up to having the chassis with drive complete but then, they mysteriously quit on it and that was the end of our relationship with Ford. We could have made a lot of money, just like we did with the 8-tracks.

Doug