Sansui QRX-3000, anything I should know?

[captainwrong]

Hey, new here. Through some various lucky circumstances I'm back into the quad thing. My last piece of quad gear was a Heathkit reciever/8-track that was pretty lacking in the actual quad department (bargan basement SQ.) So, I've been in the market and to day lucked on to a Sansui QRX-3000. $15 and a replacement fuse and she's up and running.

Well, I'm trying to find some info about this animal and coming up empty handed. I've seen some info on the problems associated with the later, and higher up the line, QRX models, but I haven't seen anything pertaning to the one I have. Specifically, I've seen this: www.geocities.com/quadaud...b9001.html about the x001s and am wondering if this applys to my unit as well.

I'm also a little curious about the different modes we have here. QS Synthesis, Surround, Hall, matrix, discrete, what does it all mean? I'm guessing discrete is for a 4 channel tape, not a CD-4 disc, right? The others, I'm wondering if anyone can shed some light on those modes.

And I'm hoping that the bit of hum I'm getting is from living in a house with circa 1948 electrical and not a problem in the gear. It's not a HUGE hum, but a little one you can hear in the quiet passages via headphones. Just a minor annoyance and for $15 what do I want, right?

Finally, if anyone knows where I can get some knobs for this sucker, I'd appreciate that. I'm missing the volume and the input and sound output ones. Not vital, but it looks ugly without them.

Thanks!

Rob

 

[The Quadfather]

I'm not sure about that unit. It may have a Variomatrix decoder for QS records. That is good if it does. Most of the QRX models did. As for the hum, do you have the ground wire on the turntable connected? QS synthesis is for QS records and is the QS mode. Hall is a mode for stereo records. I'm not sure about the others. Maybe Surround is for SQ records? Discrete is for a four channel source such as a tape deck (8 track) Usually a reel to reel was connected to the tape monitor loop. Some of the QRX series have built in CD-4 demodulators. If it has one, you will see 2 separation controls, and a carrier level pot on the back or bottom. You will need a compatible phono cartridge for CD-4. The Audio Technica AT331LP will work. I use it's predecessor, the Trackmaster 8. These cartridges are not advertised as CD-4 compatible but they work well. They have linear contact stylli, which are an advancement on the Shibata type of the quad era. The hum could be a bad filter cap in the preamp section or a bad regulator. It is doubtful that the house wiring would have any effect, as long as it delivered the proper voltage (120 volts A.C.). You can expect to spend some money eventually for repairs, these units are made well, but they are old. It's worse if they have been sitting on a shelf unused for a long time. But once you get the bugs worked out, you will have a nice unit. Radio shack sells generic knobs. Make sure that if the shaft is a split shaft design, that you position the screw so that it spreads the shaft rather than crushing it. Good luck.

The Quadfather

 

[captainwrong]

AFAIK, all the QRX units were Variomatrix. I'm pretty sure I read that somewhere, but it doesn't say anything to that effect on the unit. Somone might correct me on that.

The thing about the hall and surround modes is they both fall under QS decoding. I've been playing around with some QS discs, and I can't tell too much difference. Maybe the hall mode has a bit of delay on the rears?

As for the hum, I was getting it before I had anything hooked to the receiver (except headphones.) It doesn't seem to be passing the hum to the speakers, so maybe something's wonky in the headphone area. No biggie there, I don't have quad phones anyway.

And I don't appear to have a CD-4 demod on this one. If there is, they sure hid it well. I flipped the mode to discrete for my borrowed quad 8 deck and that's certaintly what that one is.

Now if I can figure out what the other matrix setting is. I'm guessing it's some kind of SQ-type thing. I'll run some SQ disc through it tomorrow and see what I come up with, but since it's been so long since I've heard them decoded, I wouldn't know if I'm actually getting proper decoding or not.

I'd forgotten how much I enjoyed listening to my Guess Who Q8! American Woman just sounds so meaty! Now I gotta find a Q8 deck of my own (and some better rear speakers) and I'll be set.

Thanks for the help.

 

[The Quadfather]

You might want to consider adding a CD-4 demodulator if it doesn't have one. Unlike in the quad era, CD-4 works quite well now, due to the improvement of the linear contact stylus. As the stylus gets played, it actually starts sounding better! This was not true of the early shibata types.

The Quadfather

 

[captainwrong]

I flipped my receiver and the only thing I see on the bottom is a big yellow DEMO stamp, with a couple of kanji characters next to it. Hmm...I also have a sticker on the side that says 117v. *shrugs*

So, Any suggestions for a CD-4? I'd be game for picking one up. Since I live in the land of RCA (Indianapolis) I see QuadraDiscs quite a bit around town.

I've got my eye on a JVC. I know this is their first model, but I'm assuming it'll still be a decent purchase.

 

[captainwrong]

Hehe...just read the next post about the Marantz CD-4. Seems like there's my suggestion list. Sorry about that.

 

[quadanasaziland]

Hi Welcome to the group!
Here is the stats on the QRX3000- made from 1974-1976, 8 wpc x 4 from 20 - 30,000 hx @.5. Listed for $429.95.

The unit is a bit of an enigma because of the model # and the time it was made here's why. I don't know any one who has looked inside one so what follow is educated conjecture and folly. You need to remember that Sansui had some ryhme and reason for model #'s and prefixes like the early quad units were QR and were only basic matrix units with 3 db's of separation. Then in 1973 came the QRX(3,5,6,7)500 units with the improvement being 12-15 db's of diagonal separation (hence the QRX prefix) still using descrete circuts (caps & transistors). then in late 74 early 75 came the QRX6001 & 7001 that had (3) ic's on the quad baords that gave 35db's of diagonal separation, hence the 01#. (by the way the 01 units should be looked at as the true Variomatrix because of the 3 ic's). Now my High Fidelity consumers guide for 1975 sez "similar features to the QRX3500" only difference being half the watts of the 3500. So if that is true then it has 12-15 db's diag. sep. and 3 db's for adjacent channels. So why not call it the QRX2500? 1974 -1976, hum, digressing a bit but that was the same time Sansui made the QRX5500(A) and the 7500(A) that had (2) ic's on the quad boards that gave 15 db's of separation all the way around, if it incorperated the same improvements (ic's) why not the QRX2500(A)? Enuff of this sillyness! Do you think I could talk you into taking pics of the unit with the cover off top and bottom. This would fill in a missing piece of Sansui quad history and would interest a lot of Variomatrix freaks like me! This post is getting long so I will follow up on functions if some body doesn't beat me to it

Dave

 

[captainwrong]

Fantastic! Thanks for the info!

I'd be more than happy to take some pics of the internals for you. I'd love to find out more about this unit myself, and since I haven't the foggiest what I'm looking for, I'd be more than happy to let someone who knows do the sleuthing for me.

In fact, I was looking under the hood earlier this evening, trying to clean it up a bit. In addition to the hum, I'm also getting the right front going wonky on me from time to time. It does this in 2 channel and QS modes. Sounds like it's losing all the bass and breaking up what's left. It'll do this for a while, and then correct itself. Know anything about that?

I can tell you from very subjective listening, it sounds like I'm getting some good front to back seperation and average side to side. Since this is my first time with QS, I don't have anything to compare to, nor do I have a test disc of any sort. You still know you're listening to a matrixed recording, but the quad effect is very much there.

I got some time on my hands the next few weeks, so let me know if there's anything specific you need a snap of and I'll get it off to you.

Thanks!

 

[captainwrong]

Hey, I got those pictures of the internals for you. Let me know if you still want them.

Also I think I figured out why my right front channel keeps breaking up. Thanks to the old Deja group and the wisdom of Hoodcrow, I'm pretty sure it's the rotary selector switch that's giving me the trouble. I keep cleaning it and cleaning it, but it looks like a rebuild may be in my future.

 

[quadanasaziland]

Great! here's my email [email protected]
hey tonight i will go over the functions.

Thanx!
Dave

 

[captainwrong]

Hey, I was trying to send these photos to you earlier, but my 56k was having problems attaching them. I zipped them into a file and it still was pretty big.

Also, the pictures are pretty bad. I hadn't looked at them till this morning, but my camera is fixed focus and does not like close ups.

I may have to wait until I get back to work next monday and get to the good connection I have there. If I get real ambitious I'll try to get some better snaps, but I got about a million other things to do before I have to start the grind again!

Sorry.

 

[quadanasaziland]

Hi sorry that I haven't responded sooner about the functions.


Your question. "I'm also a little curious about the different modes we have here. QS Synthesis, Surround, Hall, matrix, discrete, what does it all mean? I'm guessing discrete is for a 4 channel tape, not a CD-4 disc, right? The others, I'm wondering if anyone can shed some light on those modes."

SQ- This unit decodes sq at 3db's or so of separation to adjacent channels and around 12db's diagonally. So again that's only 3db's of separation on the front channels but it sounded very quad at 12db's diag. compared to alot of other gear at the time.

QS- Is probably a little better then sq at adjacent channels since it's their scheme for their circuit (early variomatrix).

QS Synthesizer- Converts 2 channel to 4 at about the same results as qs with some thing stereo that decodes very well.
Two settings for this-
Hall- This is for ambiance rear channel stuff like classical music where you want the musicians to sound like they are in front of you.

Surround- This setting is for being surrounded by the musicians with the volume level more matching the front level.

The QRX-3000, 3500. 5500. 6500 have no cd-4 capability so a demodulator would be connected to the 4 channel aux. inputs leaving the 4 channel tape loop for RTR and Q8. The 3000 with 8 wpc and limited decoding capability would be best in a small area say an office or just as a collector piece. If you want to build a system around a vintage Sansui unit the 01 units are the only way to go due to the decoding ability and higher watts.

Hope this helped!

Dave

 

[captainwrong]

Yeah, that helped. Thanks!

I'm going to try for some better snaps today. I got the service manual yesterday, so I know what I'm looking for now. I think your earlier guess that this has the earlier VairoMatrix is correct, but I'll have to unscrew the boards to see if they match your description.

Despite being low powered, this reciever puts out enough sound for me. Of course I live in an apartement so I don't have so much space to fill! I think I'm sold on Sansui though. Some day I'd love to get an 001, but wouldn't most of us?