Sansui QRX-6001-CD-4 problems

I've been putting together my first quad system over a couple years time and finally hooked everything up. I have a Sansui QRX-6001 and I use a Shure M24H quad cartringe. The receiver works great in the SQ and QS modes and the quad r-to-r works great too. The problem is when I select the CD-4 mode and play a CD-4 record, I get screeching, white noise and lots of pops. I tried more than one record with the same results. When I played these records in the regular stereo mode, they played great. Is this the way CD-4 is or am I not doing something right?

welcome -

this is normally where i jump in and say dump cd-4 - but doug g jumps all over for me for that - so let me say this instead - stick with your qs synth mode until someone finds a fix for you - i think you will find one hundred percent of your stereo LPs will decode into quad beautifully in this mode - and so will your stereo cd's - so will all stereo inputs - so going with that logic - use your cd-4 when you get it up and running - but sparingly - every time the needle hits the record you are closer and closer to the death of that LP - whereas - you can use a cd player - aux. input on the receiver and play that thing in QS synth mode - till we all die.


congratulations on the use of the sansui qrx - X001 receiver - a very well-rounded receiver with the best stereo-to-quad decoding put into a receiver....period.

and with that being said - sounds like the cd-4 mode has not been used that often and something is burned up - do you at least get the cd-4 indicator lamp to light up?

and - lastly - you do see the cd-4 adjustment screws on the receiver - any difference when they are adjusted one way or the other?

there are plenty of cd-4 aficionados on this forum - you'll get some help - but i am a troubleshooter and i want you to use your r2r and or lp and cartridge thru another cd-4 ...what?...decoder or receiver - to narrow down whether it is a receiver issue or input issue.

take care and post the results.

and we always all want to know what youve got - gear - quad lps, 8-tracks and all of that.

william a reid

I think Mr. Reid is on the right track with his idea that you have a toasted CD-4 demodulator. This assumes that you have used a good CD-4 setup record to properly set up your unit for CD-4 decoding. I know Mr. Reid has a low opinion of CD-4 in general, but I have found that CD-4 when played back through a properly set up CD-4 decoder can deliver excellent 4 channel performance.

Good luck on your CD-4 problem, I hope you solve it.

MTGC (Michael)

I am new to both this forum and actually owning quadraphonic equipment. I was around when quad first came out, but pricewise, it was out of my league back then. The closest I got to quad back them was an AT12S cartridge, which I think that I still have either the cartridge or stylus stashed somewhere, but not both.

Thank you for the responses.

Yes, when in the CD-4 mode and I play a CD-4 record, the indicator lights up. Yes, I know about the three adjustment screws for the CD-4 and have tried turning each, without any substantial results. Still the screeches, pops and white noise.

I know about the set-up records, but I'm not sure if I have one for the CD-4. I do have at least an SQ demo set-up record.

For your information, the turntable that I have chosen to use is an old QRK brand radio station model, which like the RUSSCO turntable that it was cloned from, both were made right here in Fresno, California where I live. It is a three-speed rim drive high-torque turntable with a large Bodine motor. These locally made turntables were used all over the world and were very common at one time, unless you were trying to find one over the last 10 years or so. It is made of cast aluminum but is very heavy and precision machined. It has a 12" balanced platter with a recess for 45's. I found my turntable by accident at a recording studio in Eureka. They had three of them, two being new in the box(with moth-eaten felt mats and small motors) and the one that I bought with a new felt mat and a custom made wooden base.

I have a pile of other turntables, but the only two other ones that I use are AudioTechnica AT-PL120's which I use with my home theater system and for transferring vinyl on my computer.

As for speakers on my quad system, I use four JBL2800's.

Thank you again for your input and I hope to hear more!
-Dan

I'm glad William restrained himself. \:^)

Anyway, there is more than one thing that can cause problems with CD-4, one of which is, indeed, a demodulator that has deteriorated with age.

Do you know what condition your M24H stylus is in? This is extremely important for satifactory CD-4 performance because you must have pretty much perfect tracking. Those 30kHz and higher frequencies are more difficult for the stylus to trace.

If the modulator doesn't get a consistently high enough carrier level, forget it. I would get some more cartridges, or at least a known good stylus and see if they make a difference. I have found, though, that almost any of the original CD-4 cartridges give good performance with an unworn stylus.

Also, the turntable is important because the tonearm must allow the cartridge to track the records without any hinderance. The correct anti-skate setting is also important to keep equal tracking on both groove walls. Does your broadcast turntable even have anti-skate? The wiring from the turntable to the demodulator must be low capacitance (100pF or less) to avoid attenuation of the super sonic frequencies.

Once you get the cartridge/tracking squared away, that is when you can judge whether or not to condemn the demodulator.

But it must be stressed that it is most important to get good signals to the demodulator in the first place.

It may seem daunting, at first, but it is really just making sure everything meets original CD-4 specifications developed by JVC to ensure wonderful CD-4 reproduction.

Someday, I just know William will reenter the CD-4 universe and thrill to the perfect (compared to matrix quad, anyway) separation and incredible soundfield of CD-4!

Doug

Again, thank you to everyone who has responded.

The Shure M24H was new in the sealed box. I have a second NIB cartridge plus two NIB genuine Shure replacement styluses.

No. The broadcast turntable does NOT have anti-skate. When I was in broadcast radio in the 70's none of the broadcast turntables did until radio stations started using Japanese turntables like the Techniques. We then had problems with the anti-skate systems. The most serious problems we had with the new turntables was that they started using elliptical styluses instead of the normal conical, which resulted in cue-burned records, as the elliptical styluses were directional and the conicals were omni-directional. A good modern current cartrige that comes with a conical stylus, though of limited frequency, is the Pickering NP/AC.

My QRK turntable has it's own proprietary audio cables, so there's no way to change them. I may try the M24H in one of my AudioTechnica turntables to see if there is a difference this weekend. They also have proprietary attached audio cables. The M24H plays excellent in the stereo, SQ and QS modes.

I do have a Shure stereo system test record that I will try, but I would think that any results can vary depending on the equipment that the cartridge is connected to.

Thank you again!
-Dan

Here's the service manual.
http://www.service-manual.eu/model.php?id=1152

THANK YOU! I downloaded it and will look at it later.
-Dan

Is it possible that the turntable or something else is generating some RF interference that might be picked up by the cartridge? Try turning off the turntable when playing a CD-4 record to see if the noise stops. Also, try moving the turntable to another place. My Grado cartridge starts to generate hum sometimes, but when I touch it, it seems to discharge static electricity and the hum stops. I grounded my system using a long jumper cable to a receptacle box, but that doesn't seem to help. Maybe the cartridge needs grounding.

scifi said:

Here's the service manual.
http://www.service-manual.eu/model.php?id=1152

Click to expand...

hey - thats nice - nothing like a friend with the goods!

w.a.r.

I was working with my quad system last night.

First, I played my Shure "audio obstacle course-era III" record. This is a mostly mono record to test frequency response and tracking. Everything played well as expected until the last track which was a single bass drum. On the 5th and most intense repitition of the drum, the sound distorted. Increasing the tracking force from 1 gram to 11/2 grams solved the problem.

Next, I put the JVC/WEA quad test record on and followed the set-up procedure. Starting with the 3 adjustment screws all the way clockwise, the best sound was about 1 to 2 clicks counterclockwise. The sound output is definitely in four discrete channels. Although not apparent in the louder sections of the tracks, there were a lot of ticks in the quieter or talking sections of the tracks, like a scratched record. I don't hear any ticks in the 2-channel mode.

Of note, as the CD-4 useses a carrier frequency to identify a CD-4 record(being dependant on maintaining the same speed that the record was cut), cutting the power to the turntable motor and putting it in nuetral, would cause the frequency to vary thereby making the CD-4 system drop out. Nice suggestion, thank you!

I understand that grounding and static charges can be a problem with overall sound quality, and possibly the CD-4 demodulator as well. I know that the tone arm on my QRK has a ground wire to the chassis and my AT-PL120's, as the QRK, have no external ground wires.

I may try the cartridge in another turntable this weekend. I played the Shure test record on another turntable that I have which is connected to my home theater system. It had the cartrige that I use to plays 45's on it, a Pickering NP/AC, tracking at 3 grams, and although it didn't reproduce the high frequencies that well, it never distorted in the bass drum track.

Thank you again!

Dan

Of note, as the CD-4 useses a carrier frequency to identify a CD-4 record(being dependant on maintaining the same speed that the record was cut), cutting the power to the turntable motor and putting it in nuetral, would cause the frequency to vary thereby making the CD-4 system drop out.

Click to expand...

I don't know what your turntable is like, but my turntables don't stop right away when unplugged. I usually have to unplug cords, turn them around and plug them back in to minimize hum, especially when using tube amps and tube preamps. Turn it by hand if you're worried about the record stopping too fast.

The QRK is a rim drive and has to be put in nuetral to freewheel. The At-PL120's are direct drive and auto brake when shut down. Both can be hand turned after shutdown, but I don't know about you, but I am not capable of manually turning the platters at a constant proper speed.
Thank you again,
Dan

I'm back. Here are some updates. The Sansui QRX-6001 died and no sound came out of it although it lights up. I replaced it with a Sansui QRX-7500 and had the same problems with CD-4 records as before. One thing that I did discover was, although new, the headshell I was using caused a hum in the system and that hum probably led to the demise of the QRX-6001. I put my Shure quad cart in a new headshell and the hum went away. Being an idler drive and having a huge Bodine motor powering my QRK turntable, there was just too much motor noise coming through. I ended up buying a new AudioTechnica AT-LP120-USB direct drive turntable with all the features you would expect in a good turntable and installed the quad cart in it. I was getting the same ticks, pops and surface noise with the new turntable hooked to my newly acquired QRX-7500 in the CD-4 mode. Although it sounded great, the QS quadralizer wasn't quite as good as the 6001.
The next saga, I acquired a Pioneer QX-949. Although the CD-4 demodulator was noticeably better than the Sansui's, I still get all the same surface and background noise, but not as bad as with the QXR's. As before and with the other two receivers, in the stereo mode, the sound is excellent.

Does anybody out there know if this is just the way CD-4 records are or is there something that I am doing wrong?
-Dan

jukeboxexpress said:

I'm back. Here are some updates. The Sansui QRX-6001 died and no sound came out of it although it lights up. I replaced it with a Sansui QRX-7500 and had the same problems with CD-4 records as before. One thing that I did discover was, although new, the headshell I was using caused a hum in the system and that hum probably led to the demise of the QRX-6001. I put my Shure quad cart in a new headshell and the hum went away. Being an idler drive and having a huge Bodine motor powering my QRK turntable, there was just too much motor noise coming through. I ended up buying a new AudioTechnica AT-LP120-USB direct drive turntable with all the features you would expect in a good turntable and installed the quad cart in it. I was getting the same ticks, pops and surface noise with the new turntable hooked to my newly acquired QRX-7500 in the CD-4 mode. Although it sounded great, the QS quadralizer wasn't quite as good as the 6001.
The next saga, I acquired a Pioneer QX-949. Although the CD-4 demodulator was noticeably better than the Sansui's, I still get all the same surface and background noise, but not as bad as with the QXR's. As before and with the other two receivers, in the stereo mode, the sound is excellent.

Does anybody out there know if this is just the way CD-4 records are or is there something that I am doing wrong?
-Dan

Click to expand...

Some CD-4 discs are noisier than others to be sure, but some of the noise issues may be because of a lack of low-capacitance cables (and tonearm wiring) required by the CD-4 standard. One thing you may try is to back off on the separation controls just a little to see if you can get rid of the noise that way. You'll have less front-to-back separation, but a little better fidelity. I have a Sansui QRX-6001 that I had completely restored last year (with the exception of the CD-4 section, the tech couldn't get a new IC chip for the demodulator, though he did replace all the capacitors in it), and the CD-4 performance is pretty good, most of the time I get great results with no noise, other times it seems like the demodulator can't maintain carrier lock. The problem improves once the unit has been on for a while. I suspect that my biggest problem may be the Technics SL-1200MK2 that I'm using may not meet the low-capacitance spec, even though I had KAB do the Cardas rewire on it, so the carrier might be getting attenuated. I'm going to try hooking up my Dual 1220Q to it and see if it improves. I've used Audio-Technica cartridges for years: I have a AT-14Sa that I bought new in 1975 installed on the Technics, and I'm going to install a NOS AT-12Sa on the Dual.

I don't think you're doing anything wrong, but you probably need to tweak your adjustments for the demodulator to get the best sound. Do you have a CD-4 test record? You may need to get one to check your adjustments. IIRC the Pioneer is a later demodulator design which doesn't require manual adjustment of the 30kHz lock range adjustment, but I believe you have to play the track to get the demodulator to adjust itself to your cartridge. You still have to adjust front-to-back separation. Finally, a dirty or worn disc can cause the sounds (not the screeching) you're hearing; the first you can do something about, the second, not so much.

Any special cable needed for cd4 on a qrx6001? There is a (1) discrete out port next to the phono in ports on the back of the receiver.. All my past quad receivers used external cd4 decoders for cd4..

When I play a cd4 record on phono using the cd4 button, I only get 2 channels.. Is there some cable I need to go from discrete out to the aux ports? Some thing new to me. 1-->4 some 1 to 4 Rica cable?

And what's this cd4 light... I see nothing..

Any of that make sense?

Thanks..

Pat

patwalsh said:

Any special cable needed for cd4 on a qrx6001? There is a (1) discrete out port next to the phono in ports on the back of the receiver.. All my past quad receivers used external cd4 decoders for cd4..

When I play a cd4 record on phono using the cd4 button, I only get 2 channels.. Is there some cable I need to go from discrete out to the aux ports? Some thing new to me. 1-->4 some 1 to 4 Rica cable?

And what's this cd4 light... I see nothing..

Any of that make sense?

Thanks..

Pat

Click to expand...

I haven't ever used any special cables but ones which are of good quality. Specs suggest that any of the wiring be low impedance.
The "Discrete Out" jacks are what you would plug into a quad tape recorder's inputs.

For CD-4, it requires a special cartridge and stylus. The carrier frequency is in the 30khz range, so, the cartridge has to have those upper ends. My Shure M24H has a top end of 50khz. The Shibata stylus was designed for CD-4. In modern terms, I am told that this can be an in-line stylus, but you still need a cart capable of the high carrier frequency.

If you play a CD-4 record, if you are using a CD-4 compatible cartridge/stylus combo, if you are using a high quality turntable, if you have the carrier adjustment adjusted properly, if your CD-4 demodulator is in working order and all four channels in the receiver are working, then you should hear quadraphonic.

The CD-4 light? This is a pilot light just like the one which lights up for an FM stereo station. If the CD-4 light is not burned out but is not coming on when playing a CD-4 record, either the CD-4 demodulator circuitry is bad or it is not receiving the carrier frequency.

On a CD-4 record, the carrier frequency starts before the first song and is continuously present, even in the silent spaces between selections. You can rotate the turntable by hand and hear the carrier frequency. If you turn the turntable too fast, it will disappear to the human ear.

I have a quad cartridge and shibata stylus. I tested it on my QRX-5500a and I get quad when connected to my external JVC CD4 demodulator, but that connects 2 pairs of RCA cables to the AUX ports.

In my new 6001, I think I have a bad quad board. I connect my turntable to the phono ports but only get sound out of 2 channels. I just wanted to eliminate cabling as a possible issue.

Where on the front panel of the 6001 is the CD4 light located? I am not seeing it..

Also - would any CD-4 adjustment record work? as long as it has the L\R seperation and 30kHz carrier adjustment or would I need the Sansui record? I have a Harmon Kardon one, but it doesn't have a 30 khz carrier adjustment track.

appreciate the support!

Well I cleared the first hurdle... I got the CD-4 working.. I bought a Pioneer CD-4 adjustment record off eBay tonight and need to run the calibrations...

My turntable is a Technics SL 1800 MKII, The guy I bought it from was an "engineer" and upgraded the RCA plugs... Guess what he did.. Swapped the red and white... So the whole time I have been having issues, I've had the cables swapped.. I reversed them for shits and giggles and low and behold.... CD-4 works.. Like I said still needs to be calibrated... But I'm a lot more confident it works as it should..

patwalsh said:

Well I cleared the first hurdle... I got the CD-4 working.. I bought a Pioneer CD-4 adjustment record off eBay tonight and need to run the calibrations...

My turntable is a Technics SL 1800 MKII, The guy I bought it from was an "engineer" and upgraded the RCA plugs... Guess what he did.. Swapped the red and white... So the whole time I have been having issues, I've had the cables swapped.. I reversed them for shits and giggles and low and behold.... CD-4 works.. Like I said still needs to be calibrated... But I'm a lot more confident it works as it should..

Click to expand...

That's great! Most of the CD-4 adjustment records I've had all have similar test tracks. My Pioneer CD-4 test record , PQX-1011, is a 7 inch 45 rpm record with the same 4 tracks on each side. My first CD-4 test record was one put out by JVC through Warner, Elektra & Atlantic. It is a 12" 33 rpm Lp which starts out with 5 separate test bands: Left Channel, Right Channel, Channel Balancing Tone, Channel Location Tones & Carrier Level Adjustment Tones. It also has 9 full-length songs in CD-4 like "Rock Steady" by Aretha Franklin and "Diamond Girl" by Seals and Crofts, which were both big hits.