QRX-9001, how does it work?

[Veech]

Hi all,

I'm a newbie here, been browsing around a bit though. I just got my Sansui QRX-9001 out of the shop after being tuned and tweaked, took it home and it's awesome! Jeez, 4x60RMS is underrated, I think.

The main reason I got the thing, though, was to play regular stereo CDs through it and press some magic button and be awed by the supposedly great job it does decoding the stereo signal into an ersatz quadrophonic signal. I know it only works on some recordings and is based a lot on the original mix, so I wasn't expecting a lot but even then what I've tried so far is pretty underwhelming. Perhaps I'm doing it wrong?

I started with McCartney's album Ram as I understand it's supposed to quad out nicely. I haven't hooked up speakers yet, but I was monitoring the rear output via headphones. I heard a couple of interesting things, but again it didn't sound greatly different from what the front stereo signal was; there was some bass roll-off, it sounded compressed, and a bit "processed" but not what I would consider something that knocked my sox off.

Anyway, could someone help me out with the best settings to put this thing on? I'm using the QS Synthesizer Surround button, is that the best one to use for faux quad?

Don't get me wrong, I've put over $600 into this thing and I really want it to work, but am I expecting too much? Is there a way to goose the fake quad effect?

thanks all,

Veech

 

[JonUrban]

SOunds like you are doing everything correctly. Problem is that with quad syth from non-encoded sources, you really need the interplay between the front and rears to get the best effect. If you listen to only the rears, you miss any delay, echo, or timing variances that you would percieve if you had all fours on.

You really need to try a well-encoded QS LP. These are not too easy to find.

 

[sqdave1975]

I love my QRX-8001 to bits. Slightly less power and no on-board dolby, but who cares? I'ts Variomatrix

See the section "Stereo Sounding Great In Quad" for suggestions of stereo CD's and records to try in "Surround" mode. The first CD i tried was Metamatic by John Foxx (Virgin CDV2146). It was so awesome it could almost be a properly encoded quad recording. But it's not!

Variomatrix rulez! :rollin:

 

[quadanasaziland]

Jon hit the nail on the head, trade the phones for some speakers, quad phones won't even compare to 4 matched speakers. Ram on is very great in variomatrix. The most quad like stereo cd I have is Thomas Dolby "She Blinded Me w/ Sience. Just about every thing goes better with variomatrix!

Dave

 

[Veech]

thanks for the replies.. maybe I'm expecting more than i should from the technology. If I hear you folks correctly, the only way to really enjoy the experience is through a 4-speaker set-up, correct? It doesn't translate into headphones (I understand the problem with quad phones, it's a goofy concept to begin with!)

I discovered oopsing a while back, and the effects of that process were very dramatic, and very evident on headphones. I had hoped that the vario-matrix process took this effect to the next level, a kind of four-channel oopsing, where channels three and four were dramatically different from channels one and two. Is there any type of hardware technology available that you folks know of that does this kind of thing?

thanks again...

 

[quadanasaziland]

Don't know just what you are expecting but basically that's what variomatrix and other quad synth circuts do is take the oop signals and put them to the rear channels. Nothing does it better then Sansui! In my system it can give me chills with the right software. When a 9001 is recapped thats just part of the resto, the quad boards also need to be recalibrated and I can assure you that your home town tech does not know how! Even with out the cal, once you get some speakers hooked up that thing should be amazing you unless some thing is wrong inside. Set the synth to surround not hall. It works on every thing that contains oop signals, every artist I own sounds better with variomatix except my Leon Redbone stuff because he uses very little oop during recording. Report back after some speakers have been attached.

Dave

 

[Veech]

the quad boards also need to be recalibrated and I can assure you that your home town tech does not know how!


?? You can? How can you assure me of that?

 

[quadanasaziland]

There is only 4 or 5 people I know that can do it right. The best at it and the guy who perfected it posts here, Quadbob

I'll let Bob take it from here....

Dave

 

[QuadBob]

Ok........guess I better wade in here!

But, this is probably going to quickly turn into a number of posts to cover the subj. matter.

First off Veech, it sounds like you've already experimented/experienced a basic OOP experience. The 9001's VM decoder SHOULD be giving you a much more discrete experience. If it isn't, you may still have a problem with the 9001.

Now, what the others have posted is pretty much spot on (Jon and Dave and whoever I'm forgetting!). So, to confirm that your VM decoder is operating properly and calibrated you should set the decoder to the "QS" position and play a QS test record (or CDR) through the decoder. You should see each channel respond to its test tone, with only minor "bleeding" into the LR and RF channel when the LF tone is present. Minor bleeding will be present when a RF tone is played in the LF and RR channels. If you are monitoring the signals on the VU meters of the 9001 (I prefer a Quad Reel decks meters myself) When the LF tone is at 10watts, you should see bleeding on the order of 1-2 watts.....this constitutes the "separation" of the decoder.
Ok, you don't have a QS test lp or cdr? Then take the 9001 back to your local shop, and have them demonstrate it using theirs. Ok, they don't have a QS test lp or cdr? Then they COULDN'T have calibrated the decoder properly and confirmed its performance!! You could then ask them if they have the Sansui supplement instructions for calibrating the QS decoder.....IF, they do have it.........please make a copy for me as I will be happy to pay for a copy of that!!!!
As there are a number of us that would like to see the actual Sansui instructions! Then you might ask them exactly what they DID use to perform the calibration.
Then you can post us here, and we can better advise you on the next steps to take!

"Quad" Bob

 

[Veech]

Yeah, I've heard about him and read some of his posts, trouble is he's very expensive and seems to take quite a bit of time doing the refurb, of course it's probably warranted due to the difficulty of the task at hand. However, the tech that did my refurb is an ex Sansui tech that owns his own high end audio store in Los Angeles. They only service Marantz, McIntosh, Sansui and one other (i forget), and that's based on if he's in the mood - literally if he doesn't like your request he'll just refuse to do it. Anyway, he lit up with joy when he saw the 9001 and treated it like a baby. He knew everything that QuadBob recommended (I had brought along a printout to reference, but he mentioned it all ahead of time) and was pretty adamant about keeping the unit in original condition (i.e. no mods) using only genuine Sansui parts to repair with. For now i'm ok with that.

Anyway, let me continue to explore and find out what other fun i can have with it. I need to select four good and cheap speakers though to go with it, I'm going crazy researching it!! rrgghh!!

thanks all..

Veech

 

[Marcsten]

Ok, Veech. I hate to see a newbie founder! Where are you at? I have a qs test record and some qs discs. If you have a cd player, I could burn the test part of the qs test record (some of it is some crappy music!) and one of my qs discs. Shoot me an email if it sounds like it might work for you. No charge (unless you're in Europe or something!) Let me know.
[email protected]

 

[Obbop]

Borrowing from my Web site:

"The May 1988 Stereo Review magazine says (while retrospecting on the quad years) that
". . .one of the joys . . ." of using quad equipment was finding the hidden ambient aspects of music recorded in stereo (Another way of saying that synthesized quad from a stereo source sounds neato)."

"One audio magazine writer claimed that quad died due to the lack of ". . . 'Oh Wow' effect." Hmmm some folks I know are not impressed by quad. Others think it sounds great and went looking for their own quad stuff."

Maybe the lack of the "oh wow effect" is the problem. I have witnessed this. For some reason some people seem to be unable to experience quad as others do.

 

[QuadBob]

Ok, now I'm really curious!

I'm expensive? Can't argue the time required..as it is just a hobby for me......but your tech is a Mac dealer? They usually get top dollar for bench time! I've pretty much gotten the restoration time down to between 50-60 hours of bench time (not including burn-in time).

So, what exactly did he do for your 9001 and what did it cost? Did you have all 264 electrolytics replaced? How long did it take?

As to the modifications that I make on them.......

Preamp/Amp jacks simply add flexibility...if you need/want more power or want to run it into a modern 5.1 receiver......you can, if not...connect the jacks and it performs as designed.

Bypassing the stereo X2 mode is done for RELIABILITY. ....there a 3 relays involved switching the audio signals......so eliminating their contacts simply improves the signal path!

The only other mod is the decoder pcbs.......polypropelene caps in the signal path to improve sound quality, and removal of the blend resistors to improve decoder performance......
Stock it is rated at 20+ db of separation (which I've found is due to the blend resistors). Pull the blend resistors and you easily have 40+db of separation (Sansui's white papers say it is "infinite" in theory). Oh.......and this is where you started, if you want the max out of the decoder......mod the decoder pcbs!

QuadBob

 

[Veech]

Hello all, and thanks for the replies

Marcsten, I'll contact you privately and let you know my addy, I appreciate the offer! I'm in LA.

Thanks, QuadBob for your info.. hope I didn't come across harsh, I appreciate the info you've made available to newbs like me. There is no doubt that he didn't put as much time in as you do, he replaced 6 or 7 parts (caps I think) and cleaned up the unit. His goal wasn't to replace everything, I didn't really want him to at least at this point. I asked him to get it back to original specs, partly because I ddin't have a ton more $$ to spend on it. I do trust that his work was top notch.

Maybe what I need is what you recommend, mod the decoder pcbs to get the thing above and beyond original specs, to improve the channel separation. Let me snag a test disc from Marcsten and see how discreet the channels are, then go from there.

Thanks again, all...

 

[QuadBob]

Hey Veech,

I hope you realize I feel the same....not trying to be harsh, its just that when someone describes what I do as "very expensive".......my habit is to go back to my basic engineering mind and ask "What is your point of reference?" I can do a basic cleaning/repair for $100 too, but I also have the experience and knowledge to realize that doing just that will not resolve all the problems inherent in a 25yr old piece of electronics. Replacing 7 or 10 or 12 capacitors that have completely failed and result in the receiver not working......will not prevent the 250+ other capacitors from quickly failing also if you try to use the receiver on an ongoing basis.
And, because I've been through the process myself with my own equipment.....recapping and repairing failure after failure over the course of a couple of years, I've experienced both the frustration and the joy of finally getting it completely done. My own receiver runs 3-4hrs per day, every day.....and I don't have to wonder each time I turn it on.......will it work? Or.....is that the way it is supposed to be?
Here's where I'd like to leave this for you (or anyone else) being as you're only about 120 miles away. You'd be welcome to visit my "shop" anytime we can arrange it. Come on down.......listen to what a completely restored QRX-9001 can sound like, listen to how the modified Vario-matrix decoder performs on either you're own music or from my collection. I pretty much "always" have a QRX-*001 receiver in the process of restoration on my bench......so you can see what is actually involved in the process. Then you'd have a "point of reference" to develop a knowledgeable opinion. Last Saturday I had the opportunity to demostrate just this for one of the members of the Classic Sansui Yahoo group who had a "dead" QRX-7001.....so he had never heard VM decoding, or even been able to hear what the receiver could sound like. I'll end this note with his review he posted on the Sansui group.
Email me at [email protected] if you'd like to make an appointment to get together.....I'd welcome the chance to meet you!

QuadBob

ps; If you'd like to bring your 9001 down with you, I'd be happy to take a quick look at it for you too, I can probably show you a couple of "tricks" with it. No charge........

[classicsansui] QuadBob Restoration for QRX-7001

This weekend I had the pleasure to visit QuadBob in San Diego to listen what quad really sounds like. He had a European version of QRX-9001 and it was a beautiful thing. He had hooked up to four Klipsch speakers and played some quad and even plain FM radio. It was quite amazing! The sound imaging was very dynamic and
spacious. It almost felt like a live concert and it's only
60w/channel.

WSJoe

 

[JonUrban]

Whatever QuadBob charges and however long it takes, it is worth it. If you are going to do it, do it right.

:-jon

 

[Veech]

Hey all,

Been away for a few days, just got back. QB, thanks for the kind offer, I'll get with you off-list and maybe we can set something up. Funny, I bought my 9001 on E-Bay from a shop in San Diego.

I received the test disc from Marc (thanks amigo), will fire it up soon and see what's happening with the channel separation. I also spent about $40 at radio shack buying cables & adapters to enable me to hear front and/or rear channels on headphones without pulling the jack in and out of the front/rear outputs, will make A/B testing a lot easier.

After all that is done, I want to find a way to record the rear (processed) channels onto my computer. Do the 9001's have a fairly decent S/N ratio?

thanks all..

Veech

 

[QuadBob]

Ok Veech,

I look forward to hearing from you. Which shop did you get the 9001 at? And, you can easily record the V/M decoder outputs through the Tape 2 play jacks.

QuadBob

 

[vinyleater]

I am a relative newbie to quad. My first purchase was a mint condition Pioneer QX-8000. I have been impressed with this unit for synthesizing quad from stereo sources, which is my main interest. Hearing so much about Sansui quads, I next purchased a QRX-7500, which seems to be in pretty good condition. I have not been as impressed with it as I am with the Pioneer. In QS Synthesizer mode, the two rear channels produce sound that lacks depth and color, and has little or no stereo separation. The front channels are stereo. Also, while the bass is strong, the Sansui's sound seems less lifelike to my ears than the Pioneer's. Maybe this is the fault of my particular unit, or maybe the 7500 just isn't on a par with the 001 series receivers. I am not inclined to pursue another Sansui receiver, but I'm open to and looking for feedback on this.

 

[Qsd-Dan]

I'm sure your unit needs a little attention. My buddies 7500 sounds a HELL of a lot better than my pioneer 949, and almost on par with my 9001's, just lacks a little power.

With the age of these units, all of the electrolytic caps need replacing as they leak and cause all kinds of issues at the 20-year mark. Those caps affect the operation of the unit, operation of the decoder, and the sound. If any one of the caps fail, all of these functions deteriorate (depending on where they're in the circuit).

One more thing to note is that the 7500 (non *A* units) have the Type B decoder, which is a little less discrete than the Type A. However, I have read that the Type B decoder can be tweaked to give the same performance of the A's. Removing the blend resistors and using polypropylene caps on the decoder boards also helps dramatically.