Improving SQ decoding

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QuantumGuitar

Active Member
Joined
Mar 18, 2016
Messages
61
Location
Holden, MA
So I've been using a Phase Linear 8000 (4ft low capacitance cable output modified) with a fairly nice CD-4 capable cartridge/stylus (I can get specifics later if necessary) through my QRX-9001 that did a great job with CD-4, but never really impressed me with its SQ decoding. I recently, however, had to bring it in to get some service (more arm drop issues...) and brought out my old Optonica RP3500 from the bedroom system in the meantime. I figured since CD-4 wasn't an option that I might as well throw on an SQ album and boy was I glad I did. I was actually hearing real major separation improvement from vinyl I had even listened to just weeks earlier. So my question is, what can I do to optimize my CD-4 capable rig (when it returns) to decode Matrix encoded vinyl better? Is this something that can see results from applying more weight to the needle? I'm somewhat of a Noob when it comes to the finer points of adjustments for making these processes work, so I'm open to most suggestions.
 
Last edited:
Hi

SQ is very level intolerant, as it really decides rear content within 3 db of level. The real issue is to make sure the L/R output of your set up is well matched or you will get minimal separation.

Regards

Chucky

So I've been using a Phase Linear 8000 (4ft low capacitance cable output modified) with a fairly nice CD-4 capable cartridge/stylus (I can get specifics later if necessary) through my QRX-9001 that did a great job with CD-4, but never really impressed me with its SQ decoding. I recently, however, had to bring it in to get some service (more arm drop issues...) and brought out my old Optonica RP3500 from the bedroom system in the meantime. I figured since CD-4 wasn't an option that I might as well throw on an SQ album and boy was I glad I did. I was actually hearing real major separation improvement from vinyl I had even listened to just weeks earlier. So my question is, what can I do to optimize my CD-4 capable rig (when it returns) to decode Matrix encoded vinyl better? Is this something that can see results from applying more weight to the needle? I'm somewhat of a Noob when it comes to the finer points of adjustments for making these processes work, so I'm open to most suggestions.
 
I got the biggest improvement in SQ and QS performance by adding a separate phono preamp (connected to a 2-channel Line, Auxilliary or Tape input). The phono inputs in vintage quad receivers are now very old and tired, and newer designs just sound better than the built-ins. This ties in with Chucky's channel balance comment because 40+ year-old circuit components do not deteriorate uniformly.

I am using a Graham Slee Gram Amp 2SE with a regulated power supply; but even an entry level NAD PP2 (don't get a PP1), Cambridge Audio (get a 6xxP, not a 5xxP), or ProJect Phono Box would provide a noticeable improvement in matrix decoding ... and you can easily find a decent one used for about $100. Find one with passive (versus active) RIAA equalization.
 
I've had the surround master for a while now and wasn't too thrilled with the sq decoding (specifically the front to back separation). It didn't have the full logic pumping issue my old Lafayette sq w has, but for a while I thought that old unit had better separation. So, I took the advice from this thread and picked up a project phono box. Prior to this it was hooked up to the built in preamp of my LR-4000 receiver.

What a difference!! results are close to some excellent Tate and script conversions I've heard. Some standouts have been deep purple machine head, Jeff beck wired, super session, and others. Yes I know there are discrete sacds of some of those titles but it's fun to spin an sq lp every once in a while. Overall I'm very impressed, even though I still have a few titles that just refuse to decode correctly due to the nature of the mix (Aerosmith toys in the attic comes to mind).

Anyone who is down on involve sq should definitely upgrade their preamp it really helps
 
Several tonearm setup issues can affect SQ decoding more than other matrix systems:

- The vertical angle of the stylus to the record is more critical with SQ than it is with other matrix systems. But it is even more critical with CD-4.

- Any tracking error affects SQ more than other systems. The overhang and offset angle of the stylus are critical for this. Make sure they are set correctly for your arm.

- Many DJ arms do not produce good overhang and offset angles for this. This is done so backcueing and scratching won't throw the stylus out of the groove.

- Make sure your pickup is tracking within the manufacturer's recommended range.

- Make sure the antiskate is set correctly for the type of stylus.

- Make sure the cables and pre-amps on both stereo channels are identical.

- Do not interpose EQ controls between the pre-amps and the decoder.

- The phono pre-amp in the CD demodulator might not do a good job on matrix.
 
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