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Receivers - Sansui QRX-9001

SANSUI QRX-9001
THE LEGENDARY MONSTER FROM SANSUI



I-.INTRODUCTION.


The receiver is a type of device that has disappeared from the current High Fidelity market : we know no manufacturer that still has a receiver in its catalog.
But during the golden age of the High Fidelity, the receiver was proposed by almost every brand. It consists in an integrated amplifier + a tuner in a single chassis. then the buyer founded 2 advantages : the reduced cost and the reduced required space.


In the Receivers world, a small number of them were designed seriously with a lot of care regarding both  the amplifier quality and the Tuner quality. Most the time, they were the most powerful models of the manufacturers, because merging 2 devices in a single chassis while keeping intact the quality is not a simple exercise.
Amongst this small number of receivers, it exists an even smaller number of models that were designed to demonstrate the know -how of the manufacturer, both to the potential buyer and to the competitors.


Of course, only the most famous brands, such as MARANTZ, SANSUI, TECHNICS, PIONEER, …, tried to seriously take this challenge.
Amongst them what are those that walked across the years and became a legend nowdays ? Of course, only the most prestigious of them... and the fingers of ours hands are enough to count them...


-the MARANTZ 4400 serie
-the biggest PIONEER receivers (look like theSX-1080, SX5570 for example)
-the biggest TECHNICS (SA-1000 for example).



Here is a photo of the MARANTZ 4240 :

Marantz 4230.jpg



After having spent a lot of time to read and look these prestigious machines, one of them touched my heart, because of its look, its «  out of the common standards » specs, in terms of size, power, reputation, etc... It is the SANSUI QRX-9001.

It is the biggest Receiver ever made by SANSUI of all times. It is a quadriphonic device, able to deliver 2x120W RMS or 4x60W, that was an enormous power at this time.
Its price on eBay turns around $1,500 even for a not fully functionnal device ! This a very high price for a more than 25 years old receiver, showing how much it is highly regarded by the fans... But the other « monsters » manufactured by the other brands are equally expensive...

Here is a photo of what we are talking about :

QRX-9001 upgraded_small.jpg



Yes we agree : waouh, it is superb !


Everything in this receiver is beyond what is usually founded in the receivers, even in the top models. The look is the first indicator that let us believe that it is not a common device : the number of buttons and command immediately tells us that this receiver has a lot of functions, far more than the common standards.
Secondly, we see 6 vu-meters, and of course this indicates that it has something particular. there are 2 vu-meters for the Tuner and 4 other ones for the power amplifier, one per loudspeaker.
Thirdly, its size : the QRX-9001 is a big device ; with 60cmx43cmx19cm and a weight close to 25kg, you should not expect to place it in a normal rack , its volume is too big and a convenient space is necessary.


Finally, we see a lot refinements that we found during the golden age, and they are a pleasure :


-bass and treble have their own button, and...
-they are even separated between Front loudspeakers and Rear loudspeakers.
-a microphone input, that has of course been removed nowdays by the cost killers and other vampires
-a very rare DOLBY for the Tuner : we know no actual tuner that offers this feature
-2 headphones outputs,
-etc...


The QRX-9001 that we have found for sale in Germany has 2 particularities that are almost impossible to find nowdays :


-the wood cabinet is in a so perfect condition that the QRX looks like a new one...
-it has the blue plastic DOLBY flyer (look on the rght of the photo) : this flyer is extremely rare to find !


But it also had 2 problems not mentionned by the vendor :


-the On/Off switch was sometimes faulty and required a visit to Power Electronics
-the power relays were also damaged and needed a maintenance.


For a so rare machine, it does not matter. At all.
 



II-A FASCINATING BUT DIFFICULT RESTORATION.

Our ThresholdLovers readers know that the restoration of vintage (or modern) devices is my preferred hobby, but the restoration of a Sansui QRX-9001 is far more complex and difficult than usual.


Except if you have serious skills and a few years of expertise, I recommend you to not try to restore it by yourself, and to ask qrxrestore in USA or another skilled technician such as Power Electronics in Europe to service it.


We repeat : the QRX-9001 is a complex device with approximately 200 capacitors to be changed in a full restoration process...in addition, there are various traps such as the relays or the F-2632 board that makes this restoration a difficult challenge.

My QRX-9001 had problems wit the power relays and the On/Off swich : these have been fixed by the Magician, I mean Dumitru from Power Electronics, because I had no time to spend on this.

The 1st step for such a complex restoration is to perform a complete and manual inventory of the capacitors installed on the various boards : as often, the Service Manual contains a lot of errors regarding the value of the capacitors, so you need to check directly on the boards.

The 2nd step is to decide what the new capacitors will be, and on the QRX-9001 you must care about the available space : because the QRX-9001 is as filled as an egg, you must check that the replacement capacitor has enough space to be soldered on the board.
The original capacitors are ELNA or NICHICON most of the time, proving that SANSUI did care about sound quality, even if the overall quality of this QRX-9001 seems a little bit lower than the 9090 one.
On most devices, I use the NICHICON KZ or EL NA Silmic II as replacement caps, but with the QRX-9001 both of them are often too big to be chosen. Therefore, the smaller Nichicon FG are very welcome...

The 3rd step is to understand that such a restoration is a marathon, not a sprint ! You must prepare your self to be patient and organized, because of a lot of difficulties and traps :

 

  • there is a lot of boards in this device,
  • a few of them are difficult to extract from the chassis, because they have multiple cables attached (soldered) to them
  • the fuse resistors become faulty with the years : you have both to replace them AND prepare yourself to a complete setup and tune of your amp when they are replaced
  • the relays are often a problem
  • some boards, such as the F-2632, can occasionnaly be faulty : not totally out of order but occasionnaly faulty. It is not always easy to fix the problem... although on the F-2632 you mainly have to rebuild all the « join sections » coming from a side to the other side of the board : de-solder the junction, and replace them by a new freshly soldered one.
  • and a lot of other difficulties due to the high density of boards


But if you succeed in this restoration, you will get one of the most beautiful and very best receiver on the planet !
 



III-THE RESTORATION IN DIRECT-LIVE....

The 1st question that you asked yourself when starting such a huge restoration is : what will I begin with ?
As often, starting with the Power Supply is a good choice....

III-1.The restoration of the Power Supply.
When we begin to change the capacitors in the P.S. section, we immediately see that the modern capacitors are smaller than the old ones (even at a high quality level).
The photo hereblow compares the Bipolars ELNA 4,7µF 100V that are hidden  below the P.S. board. On the left the stock model, and on the right the new one, the ELNA RBD Bipolar :

 

Elna_bipolaires_small.jpg


 

PS02_before_small.jpg


Here is the board after restoration :

PS02_after_small.jpg


 

And a close  up :
 

PS02B_after_small.jpg


The opposite side of this board is fully populated with a lot of capacitors ; of they have all been replaced with the beloved NICHICON Muse KZ or FG, or ELNA Silmic II : we have replaced the stock capacitors with the same brand everytime it was possible.

Here is a photo of this board during the restoration with a few new NICHICON Muse KZ (and few smaller Nichicon FG when the available space was not enough to implement a KZ), a few old Nichicons. A large part of the board is hidden by the power capacitors of the Power Supply.
At the top of the board, you can see 8 ELNA capacitors, and on the top of them there are 2 connectors that hold the 2 daughter boards F-2624.

PS01_after_small.jpg


Before going further, I have extracted from the Service Manual the list of the boards of the Sansui QRX-9001 :
 

Board reference Board function
F-2087 QS Matrix Board
F-2088 QS Phase discrimination section circuit board
F-2589 Equalizer & CD-4 circuit board
F-2590 Tuner circuit board (QRX-9001 only)
F-2614 Tuner circuit board
F-2615 Tuner SUB circuit board
F-2624 Driver circuit board
F-2632 Selector circuit board
F-2633 Dolby change circuit board (QRX-9001 only)
F-2634

4 channel function switch & REC CAL

Tone circuit board

F-2635

4 channel function switch & REC CAL

Tone circuit board

F-2636 Volume and Filter circuit board
F-2637 Tone control circuit board
F-2638 Power Supply circuit board
F-2639 Pre-Power Supply circuit board
F-2640 Illumination circuit board 1
F-2641 Illumination circuit board 2
F-2652 Dolby Sub control board (QRX-9001 only)
F-2686 4 Channel function switch and REC CAL Tone circuit  board
F-2688 Dolby circuit board (QRX-9001 only)
F-2689 Protector circuit board




Here is a photo before restoration of one of the two F-2624 boards (Driver circuit board) that are plugged in the Power Supply board showned above :
 

F-2624_before_small.jpg


And the same board after a full recaping with the big NICHICON KZ and a few FG. You should note that the (horrible sounding) mica orange capacitors have also been replaced by ELNAs or NICHICONs after the photo herebelow has been taken :

 

F-2624_after_small.jpg



Here is a photo showing the two boards installed on thier respective connector. The small circular potentiometer are used to setup the BIAS of the amplifier.
 

F-2624_after_mounted_small.jpg



Finally, we have of course replaced the big power capacitors in the Power Supply. The stock ones were 4 NIPPON CHEMICON SME 10,000µF 71V, the new ones are NIPPON CHEMICON SMH 22,000µF 80V, meaning that the storage is more than twice bigger than it was initially.
Despite their double capacity, the new caps have exactly the same size : this gives you an idea of the improvement that has been achieved in 25 years. Much more capacity for the same size.
Here is a view of the 4 new capacitors :

 

PS04_after_small.jpg



All this work on the Power Supply brings a lot of serenity : we can be sure that the P.S. will be robust and more powerful than before… and even better than when the QRX went out of the factory !
We will see later that this new P.S. also brings another surprise…


III-2.The restoration of the rest of the Sansui QRX-9001.
In terms of difficulty, the Power Restoration is the easiest part of the work : the rest of the QRX-9001 is much more difficult to restore.
This is because there are a lot of boards, difficult to remove from the chassis, or soldered with a lot of cables, there are a lot of traps, etc…

Here is the F2087 (QS Matrix board) after it has been upgraded, located just beside the F-2088. The density of parts is very high (particularly on the F-2088) and you must care about the available space for any new capacitor : if you choose a too big cap, it will just be impossible to solder it ! This is why we have been sometimes obliged to implement the NICHICON FG instead of the NICHICON Muse KZ or ELNA Silmic II, that are bigger caps than the FG.

 

F-2087_02_upgraded_small.jpg



Similarly, here is the F-2088 board (QS Phase discrimination section circuit board) before the restoration :
 

F-2088_before_small.jpg



And the same one after restoration (the orange caps have been replaced after the photo has been taken) and insterted in its location. At the back upper left, you can see the Tuner board with its 5 gangs before restoration:
 

F-2088_after_installed_small.jpg



We continue this restoration with a bigger board, referenced F-2589 (Equalizer & CD-3 circuit board). You have to unplug 7 connectors to extract it from its location. Here it is before it was extracted :
 

F-2589_before_small.jpg



There is enough space on this board to use the capacitors of your choice in replacement of the stock ones. As usual, we have use our favorites NICHICON KZ and FG, as well as the ELNA Silmic II, and the orange capacitors that you still see on the recaped board have been replaced after the photo has been taken.
 

F-2589_after_small.jpg



When recaped, you just have to place it back in its location and reconnect the 7 connectors. But before doing this, you have to take the opportunity to recap a board that is located just under the F-2589 : this card is not difficult to extract nor to recap, you just have to do the things carefully.

Next are the boards that manage the bass and trebble registers. When looking to the QRX-9001 from the front, you see 4 buttons to set the bass and treble for the front and rear speakers. Behind each pair of these buttons, there is a board (consequently there a 2 boards) named F-2637.
They merit to receive high end capacitors because they are on the signal path. Here is one these 2 boards after restoration, the other one being exactly identical.

 

F-2637_after_small.jpg



Our trip across this QRX-9001 restoration continues with the F-2639, the « PrePower Supply Board » (that we should have maybe present in the previous PS upgrade section) located just before the main power supply board. Here it is before the restoration :
 

F-2639_before_small.jpg



Before to show it after recaping, please have a look at the photo, as far as possible : you can see the enormous toroidal transformer : this one is toroidal whereas it has a square form factor on the Sansui 9090. The Sansui 9090 transformer looks bigger but it is normal as a square transformer is always a bit bigger than a toroidal one for the same VA rating.
Here is the F-2639 after recaping :

F-2639_after_small.jpg



Our trip continues with the F-2689 board located deep inside the QRX-9001 : it is difficult to access to it. The problem is not to change the capacitors or any other part, but to extract the board from the chassis.
Here is the F-2689 recaped, note the green capacitors that are the well known NICHICON ES Bipolar. We have used these NICHICON ES because they are available is a wider range of values than the excellent ELNA RBD bipolar, the later being available most of the time in 100V only.

 

F-2689_after_small.jpg



Now it is time to work on another beautiful board : the Tuner board. It holds a 5 gangs tuner, showing that SANSUI has put a lot of his knowledge in its top receiver.
Here is the board before upgrade :

 

Tuner unit_before_small.jpg



As you can see, there is a small daughter board that has been of course also recaped :
 

Tuner unit_after01_small.jpg


and here is a view from another angle:

Tuner unit_after02_small.jpg


To avoid a too long article and show all the boards, I will pass over the F-2633 and F-2634 boards ; Be aware that these 2 boards are extremely difficult to extract from the QRX-9001 ! it is a true nightmare to reach them, and consequently it is a challenge to recap them.
If I would like to show all the steps of this restoration, the article would be toooo long !

Another point that you must know relates to the F-2632 board. This 4 channels board is known to be a source of problems on a large number of QRX-9001. The source of the problems comes from the solder joins that make a link between the two sides of the board : these joins are not good enough, and after more than 20 years they are often faulty !
You should replace all these joins by a short length of solid core cable and solder this cable on the both sides of the board, in order to ensure a long life to this board. Be patient : there are more than 30 joins to fix !
My QRX-9001 is not affected by this problem, but most of the F-2632 boards are a source of problems. I cross the finger fo my unit !

QRX-9001 Hall of Fame.jpg




As a conclusion, the QRX-9001 restoration is a fascinating experience : I got the feeling to make it alive again. By working on it, you immediately feel that this device has been designed with passion by fanatics,  in an era where the brands compete to demonstrate their know-how. Before the era of the marketing and the cost killers... who have destroyed most of these companies.


Who cares today about SANSUI or MARANTZ ? they just manufacture the same crappy devices than the other chinese (or not chinese) companies...

The QRX-9001 is without any doubt one of the most fascinating vintage device that I have seen to date. Technologically , as well as in terms of design or manufacturing quality, it is clearly a flagship receiver from a high end brand.

Do you want another proof ? My wife and my daughter, who do not care at all about any electronic gear, have immediately said as soon as they saw it : «  waouh ! this one is absolutely wonderful ! ». And they want me to keep it : so do not ask me if it id for sale, but it will stay with my family for the next 20 years !

As I do not plan to sell it, I am happy of this WAF evidence !

OK guys, now that we have made a long travel across the restoration, we still have another question work on : how does it sound after the restoration ?

You are lucky : this is explained in the next section...


IV-.THE LISTENING SESSION AFTER UPGRADE.

The restoration work is finished ! it was a huge but fascinating workload...but the usual question comes back in our mind : how will it sound ?...
In this case we are even a bit more anxious because :

  • it took us a long time before we found a near mint QRX-9001 without a crazy price tag
  • we have worked a lot of hours to restore it,
  • we have chosen the best parts as we believe it merits them
QRX-9001 upgraded3_small.jpg



and also because this QRX-9001 is so beautiful, that we are a bit afraid to be disappointed...will it be just beautiful ?...
Time is arrived to start : connect the loudspeakers, connect a source, connect the AC plug, and... turn the power switch « on »...

We browse our NAS, go into the « Jazz » directory and chose Marcus MILLER « Silver rain ».

 

Marcus MILLER_Silver rain.jpg



FOOBAR is the software and we press « start ».
Waouh ! what a musicality ! are you sure that this device is a 30 years old papy ?? We are very surprised by its sense of detail, its subtile trebble. This device disappears and let the music play.

The advantages of the restoration appear in full light : the best possible capacitors as well as the upgraded Power Supply (4x22,000 µF instead of 4x10,000 µF) provide 2 major added values :

  • the sound is subtile, refined, pleasant and never tiring.
  • the bass is in-cre-di-bly powerful and varied.

The loudspeakers that we have connected have never sound like that. We have chosen a small pair of FOCAL loudspeaker,  just to check if this papy merits more sophisticated lourdspeakers for a complete review, or if it appears that the age is definitely an issue,  and we will not get any very good result from this device.


The result is clear : we had never heard these small loudspeaker sound so good. The bass is just incredible : the authority of the amplifier proves that there 2x120W (probably more) but also enough Amperes to drive anything, with deep, articulated, authority in the bass, while keeping details in the mid and high.
The bass domain is so good that is establishes the basement for the rest of the music, which appears very fluid, helping us a lot to follow the melody and sink into the music...

I did not expect at all this level of quality for a 30 years old device : it is a true surprise to me. Another thing that surprises me is the feeling that the different octaves are continuous one to each other : the bass, mids and highs seem to not be separated, they apply with a lot of harmony and intimity, I should say « complicity ».
This QRX-9001 says you : « hey guy, you thought I was an old man and an out of date Papy ? stop crying guy, I am just still alive like I was when I got out of the box ! »

Conclusion :
This QRX-9001 is the superlative device, made by SANSUI to demonstrate its know-how at this period (because like the other brands, SANSUI has switched to more common devices...).

It is enormous, powerful, extremely beautiful, offers a lot of functions. It is built like a tank, and once the problems of the F-2632 board are fixed (solder joins and fuse resistors), it is sure that it will still be alive in decades.
It is charming : one of the very few devices that have charmed all my family members who have seen it. You love it first for its look and you fall again in love when you lesson to it...

I believe that at least 90 % of the current devices (integrated amplifiers or preamp+power amp) costing less than 10,000€ cannot compete with this QRX-9001 after it has been properly upgraded. Some of them will be more powerful, more detailled, etc..., but the QRX-9001 is very homogeneous, never tiring, charming, with an incredible basement (bass) ; a sort of alchemy that let you listening during hours without any tiring. Its homogeneity is a challenge for the current manufacturers that have bet too much on the marketing and on the look, and not enough on the quality.

For sure, if it was still manufactured nowdays with the quality parts that we have implemented inside, its cost would be high. And selling it at this price would require a marketing able to explain why it costs a lot, instead of explaining nothing with pseudo technologies that the engineers themselves do not know …
Even worse, there is no manufacturer still building a receiver : the iPOD and the horrible MP3 files are the ultimate graal as everybody "knows" !...
The pleasure we get by turning a knob to finely tune a station is unknown for most of the new generations. But curiously, they are charmed as soon as they touch it : my 15 years old daugther has been charmed by this QRX !...

We agree that we begin to get high quality dematerialiazed sources, but to know more about it, our readers have to wait a bit more weeks (a scoop is on the way....) !

We stop here the 1st part of this review : we will lesson to the QRX with high end loudspeakers in a second part, but you already know that this SANSUI QRX-9001 has hypnotized us ! we love it and we keep it !
We sell very often the devices that we review, but this time we keep it for our personnal use... I say « we » because its W.A.F. (Wife Acceptance Factor) is so high, that my wife and my daughter want to keep it in house....

Pros :

  • Oustanding look, high WAF (Wife Acceptance Factor)
  • manufacturing quality is excellent
  • very rare on the market : a piece of collection
  • nothing new on the market can be compete with its charm
  • belongs to the cream of the receivers of the Golden Age
  • excellent five gangs tuner
  • quality, authority and articulation of the bass domain (after recaping) : truly excellent
  • other domains (mids and highs) are also very good and should improve after the burn-in period
  • Musicality : this amp disappears behind the music
  • very powerful : 2x120W RMS, it seems that it holds the double...
  • a lot of functions
  • no heat after restoration
  • reliable if correctly serviced


Cons :

  • it must be serviced and seriously recaped : firstly to get the best from it, secondly to make it reliable again for decades
  • the power transistors are no longer available : in case of problem, you should ask http://www.qrxrestore.com to get new pairs of equivalents
  • the power relays are less reliable than the rest of the machine : they should be changed by the equivalent available from "qrxrestore"
  • Heavy and big : but so beautiful...
  • complex and contains a lot of boards : you must have a true expertise to restore it, if not we strongly recommend you to ask to a professional
  • recaping is mandatory  (25 years old) as well as offset and bias calibration
  • The F-2632 board is a source of problems and should be seriously serviced
  • expensive and rare on the market, because it is highly regarded

 

TL_5stateart.jpg


This article has been written by Nounours - May 2016.

 


Creation date : 28/05/2016 @ 18:32
Last update : 28/08/2016 @ 18:46
Category : Receivers
Page read 108 times


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