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Thread: 4 channel decoder.

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    Junior Member Zeit's Avatar
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    Talking 4 channel decoder.

    Hello to everyone. I have just joined this site. My name is Jon, I am from England. I hope you are all ok.
    I have recently acquired TWO quadraphonic receivers, and I am now looking for a 4 channel decoder, but ebay doesn't really have any, and I've been looking daily for a few weeks now. I get no results in the UK at all. Where can I get hold of one? Thanks in advance.
    Also, one other quick question... On my Rotel RX-154A, if I have the SQ Matrix button pressed in, to activate all four speakers, but I'm playing a standard stereo LP, the resultant playback is dual stereo, is this right?
    Oh yes, and I'm waiting for some SQ LPs in the mail, which I'll be able to play in 4 channel, of course, but there's an LP I may be bidding on which is a Quadradisc. Do I definitely need a 4 channel decoder to get 4 channel sound with that one if I win it? And what happens if I use the SQ Matrix button in with a Quadradisc LP playing?
    I'm looking forward to acquiring quadraphonic knowledge on here.


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    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: 4 channel decoder.

    Welcome to QQ, Jon!

    In spite of your not finding any decoders on eBay, it is still the place you're most likely to find one. Are you looking world-wide or just the UK? I haven't looked a lot lately in the US but they used to appear very frequently using "SQ decoder" or "QS decoder" as a search.

    When you play a regular stereo record through an SQ decoder, the decoder will "synthesize" quad from the available information on the disc. Any out-of-phase signals will be routed to different speakers depending on the phase and vector relationships. So, no, it is not just dual stereo. It is enhanced.

    A Quadradisc needs a demodulator (as distinguished from a decoder) to enjoy in quad. Also a cartridge and turntable that are CD-4 capable. If you play a Quadradisc through an SQ decoder, it is just like playing a regular stereo record through it. It will synthesize quad from the record. This is because the super-sonic signals on the quadradisc do not come into play (so to speak) without a CD-4 capable turntable or demodulator.

    You state there is an SQ button on your Rotel. Are there any other settings indicating any other formats on either of your receivers?

    Doug

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    LaserVision Landmarks Disclord's Avatar
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    Default Re: 4 channel decoder.

    If it's non-logic SQ, which is likely, then it will most likely sound like dual-stereo, since non-logic SQ has only 3db separation between Lf/Lb and Rf/Rb and 0db separation between Cf/Cb. It's also phasey and unpleasant to listen to. If it's an SQ decoder with 10/40 blend, and most non-logic decoders were, then there will be around 8db separation between Cf/Cb and only 8db between Lb/Rb, giving more 'front-to-back' effect but less 'quad' type sound. In any case, it doesn't sound good.

    For eBay searches, look for a Fosgate Tate 101A or the Audionics Space & Image Composer - those are the only two decoders that decode SQ correctly. Others, like the Sony SQD-2020 or 2010 or the Lafayette SQ-W, use gain-riding logic and while not entirely correct in either directionality or lack of audible side-effects, are better than a non-logic decoder.

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    Junior Member Zeit's Avatar
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    Default Re: 4 channel decoder.

    Thanks for the welcome, and the help and info.
    My other receiver is a vintage Harman Kardon 50+. It doesn't work at the moment, but I am getting it repaired. It's going into the shop tomorrow.
    It features a SQ Matrix button for when using the stereo phono inputs, and also on the back panel, there are discrete audio phono/aux inputs.
    I'm sure this is the same with my Rotel receiver, discrete phono/aux also. I have my turntable plugged into the stereo phono inputs on the Rotel at the moment.
    The LP I may be bidding on is the quadraphonic edition of Paranoid by Black Sabbath. This is the LP that I said was a Quadradisc, that is correct isn't it? I've never seen a copy for real, so I've just tried to identify from the ebay image.
    I love this whole vintage quadraphonic stuff already! Haha.


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    Senior Member ingresman's Avatar
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    Default Re: 4 channel decoder.

    Hi Jon,
    Nice to see more UK people here !
    You might want to check out the Adobe Audition scripts on here that will decode SQ and QS really nicely (as always Kudos to the authors). Audition is quite expensive so you may want to have a look for pre-done decodes which I won't talk of further.
    If your really into hardware, just keep looking on ebay. The Tate do pop up but go for 600+ !
    Again welcome
    Waiting for the Moe Szyslak experience featuring Homer Simpson in SQ

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    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: 4 channel decoder.

    Yes, the Black Sabbath album is a Quadradisc.

    Although the Tate is supposedly the ideal SQ decoder, I think we have to be realistic here. Even though they do appear on eBay now and then, you would probably be in for a long wait and, even then, if one does show up, there is the matter of winning the auction. And that's no small matter when it comes to a Tate. As ingresman indicated, the price of those things reach stratospheric levels.

    The Sonys mentioned actually create a very nice soundfield with a minimum of pumping or other artifacts. My SQD-2050 is also good in that aspect. Most anomalies are caused by variations in production methods during SQ mixing and encoding.

    I do agree that non-logic decoders should generally be avoided but even they can give you a taste of what a quadraphonic soundfield is all about. Just don't expect a whole lot.

    Doug

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    Default Re: 4 channel decoder.

    I everyone I am a newbee as well, I come from a recent love of old CRT projector technology and refurbish them to be able to display 1080p.

    So i have begun looking into old Hifi equipment to play with and an employee of mine gave me for free an old Fisher Quadraphonic receiver. Actually its labled as a ARS 747 which i found out is a Allied Radio Shack rebadge of the Fisher 601.

    So once i get this cleaned up and properly working what would I need/look at for quad playback.
    What is needed in turntable? I have a custom made table with a rega RB300 arm and a sumiko EVO III blue point cartridge.

    Just trying to see what I might be getting into.

    Athanasios

  8. #8
    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: 4 channel decoder.

    Welcome to QQ!

    To begin with, is there a selector switch with markings like "SQ", "QS", etc.?

    If so, you at least have the beginnings of matrix decoding abilities.

    You may want to acquire external decoders for matrix records that would probably be superior to the internal ones in your receiver. It all depends on what's in there though.

    Your turntable will be fine for matrix quad records. Any good stereo turntable can be used for that.

    If you decide you want to be able to listen to CD-4 (Quadradiscs) records in quad, you will need a cartridge/stylus capable of tracking up to 45kHz to retrieve the ultrasonic frequencies necessary for CD-4. I don't know the capabilities of the Blue Point. And, unless the Fisher has an internal CD-4 demodulator, you will need to get one of those too.

    Of course, you will need four speakers! \:^)

    Doug

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    400 Club - QQ All Star w.a.reid's Avatar
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    Default Re: 4 channel decoder.

    welcome - and let me give you my obligatory - buy a sansui qrx -X001 receiver - statement - it will cover all of the basics and - c'mon doug, it does have a decent cd-4 demodulator...or is it a decoder? anywho - i just sent chris ready a qrx-6001 - it was a "demo" model on the shelf at a high fidelity shop back in the day - extremely low hours on it when i bought it - and just now decided to have it rebuilt and made to sell to qq members - ONLY.

    when i search for a decoder - i search "decoder" in title and description - in vintage electronics - and then again....title only in 'electronics' - you may have to dig through a lot of stuff to find a listing that is what you want - but it is fool-proof....and then "save" the search - you will get emails letting you know when another hit on the search term is listed.

    thats how i roll - my brutha
    Sansui Qrx9001 "These go to 11....Its one louder"

  10. #10
    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: 4 channel decoder.

    William, I would never, ever discourage anybody from buying a Sansui QRX-X001 receiver.

    The first time I was really impressed with Sansui stuff was in 1976 when my wife and I stopped at my brother's place in Minneapolis before a David Bowie concert.

    His room mate had a huge rack system with those big, black, bad ass Sansui components driving some ESS Heils. It wasn't quad but, let's just say I was bowled over.

    Doug
    Last edited by Doug G.; 11-20-2010 at 11:38 PM.

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    Default Re: 4 channel decoder.

    i know what you mean - i know you favor lafayette for cd-4...thats all.

    ahhh man - david bowie - now were talking!

    i have to see all those folks on reunion tours - going to see roger waters this sunday - saw jimmy paige - solo - twice - and robert plant solo twice - but as we speak i am missing the jason bonham led zeppelin show - with very special guest - mr paige himself. if i may - i would like to suggest - "it might get loud" dvd - i am big fan of the white stripes - my first concert ever was U2's the joshua tree and there was a point when i ONLY listened to led zeppelin - and i mean O N L Y . this dvd puts all three guitarists together to chat about what they know about guitar stuff - some great footage - but i cant play guitar.

    hijacked! sorry.

    wallace alexander reid
    Sansui Qrx9001 "These go to 11....Its one louder"

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    Default Re: 4 channel decoder.

    Quote Originally Posted by Nashou66 View Post
    I everyone I am a newbee as well, I come from a recent love of old CRT projector technology and refurbish them to be able to display 1080p.

    So i have begun looking into old Hifi equipment to play with and an employee of mine gave me for free an old Fisher Quadraphonic receiver. Actually its labled as a ARS 747 which i found out is a Allied Radio Shack rebadge of the Fisher 601.

    So once i get this cleaned up and properly working what would I need/look at for quad playback.
    What is needed in turntable? I have a custom made table with a rega RB300 arm and a sumiko EVO III blue point cartridge.

    Just trying to see what I might be getting into.

    Athanasios
    a man - secretive - lets call him Nick, said this about what ttables he uses - " I only use JVC QL-Y5F & QL-Y7F and Denon DP-47F & DP-59L "

    but every one ive found has been is in the 300 smacker range - which is fine - what ttable do you use Doug G.?
    Sansui Qrx9001 "These go to 11....Its one louder"

  13. #13
    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: 4 channel decoder.

    Actually, I favor a Panasonic SE-405 or a Technics SH-400 for a demodulator.

    I use a BIC 980 turntable for CD-4. It works very well.

    Doug

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