| Quad Bob is chock full of information AND the technical skills to convert an already awesome receiver such as the Sansui QRX-9001 into a "super receiver." There's a link at the bottom of the page so you can contact Quad Bob. "Restored" Sansui QRX-9001/8001 Quadraphonic Receiver This receiver was Sansui's top of the line and last generation quadraphonic receiver. Rated as the best quadraphonic receiver ever built by MANY quadraphiles! What isn't as well known is that the QRX-9001 had a number of design flaws and as with ALL electronic equipment approaching 30yrs old performance and reliability suffer due to aging components. However, when functioning properly the QRX-9001 is unsurpassed in beautiful quadraphonic sound reproduction. QuadBob@prodigy.net can both remove and repair the design flaws, and enhance the performance through replacement of the electrolytic capacitors and modifying the design for increased performance and enhanced flexibility! The QRX-9001 had a suggested list price of $1,150.00 in 1977, and this receiver can be enhanced with additional parts and labor! The design flaws inherent in the QRX-9001 include: 1) Sansui's "Stereo X2" mode or bridged amplifier is prone to self-destruct and blow the power amp section when used. Additionally, the relays involved in the Stereo X2 mode often develop poor contacts and result in reduced output signals in 4 channel mode. 2) Sansui deleted pre-amp out and main-amp input RCA jacks for economy and rear-panel constraints. 3) Sansui's Vario-Matrix Type A decoder/synthesizer while the BEST that has ever been designed into a quadraphonic receiver, utilized "blend" resistors to help maintain a balanced quadraphonic soundfield. However, these resistors also detract and lessen the QS chips separation and discreteness allowing minimal "bleeding" between adjacent channels. While still MORE discrete than any other quadraphonic receiver....overall performance suffers in comparison to what IT COULD BE! 4) The pre-amp section of this receiver was so complicated for its day that Sansui couldn't fit all the board runs on a single sided circuit board as was common at the time. They therefore used "pass-through" joints in the circuit board to allow board runs on both sides of the circuit board. These soldered joints after repeated heating and cooling cycles and many years of aging fail causing "weak" or no channel output. Sansui even realized this while the QRX-9001 was in production and last production models included "rivets" as well as solder in the pass-through joints. However, after 20yrs....even these improved joints fail! Ok, now you know the "unusual" problems of ALL QRX-9001 receivers! Here's what I do to fix these problems: 1) The Stereo X2 mode is disabled. The associated relays are removed and hardwired to bypass the Stereo X2 mode and convert the receiver to pure 4 channel operation. There are many fine "stereo" receivers if that's what you want........this is the best "QUAD" receiver! 2) Pre-amp out/Main-amp in RCA jacks are added to the rear panel through modification of the AM antennae mount. 8 more RCA jacks are now "custom" mounted on the rear panel allowing the receiver to either operate normally, or with additional processors or separate amplifiers externally. 3) The QS decoder/synthesizer circuit boards are modified by REMOVAL of the blend resistors. Additionally these circuit boards have ALL the electrolytic capacitors replaced with new caps of the same ratings. The performance is thus enhanced tremendously over "stock" QRX-9001s. Discreteness is on par with a Fosgate TATE II decoder utilizing quadraphonic test recordings. 4) All the pass-through joints are resoldered and pinned utilizing high quality silver solder, ensuring reliable performance and fantastic sound from all 4 channels. 5) ALL, electrolytic capacitors ("caps") throughout the receiver are replaced with NEW same rating capacitors. This is the "restoration" process. Caps have a "normal" life expectency of 15-20yrs.....as these receivers are all well past this age, the performance of the receiver suffers from weak and leaking caps. Replacement of all the caps along with the above modifications offers sound and performance exceeding that of the receiver when new in the '70s! 6) For an additional affordable fee I offer to upgrade the caps on the decoder pcbs to "audiophile quality polypropelene capacitors" instead of the stock electrolytic caps. This modification results in a fantastic sound improvement over the original caps! Lows are lower, Highs are higher......and the music has a very "open" and effortless sound, greatly enhancing the quadraphonic soundfield and listening experience. The overall result is a QRX-9001 with the design flaws eliminated, reliability improved and quadraphonic performance better than even a QRX-9001 built just yesterday, instead of 20+ years ago! These receivers are now appreciating in value ($900 recently on a eBay auction. ed. AND... a QRX-9001 modified by QuadBob auctioned at the price of $1,400!!!!! The word is getting around about the quality of QuadBob's work) so the restoration is an investment in your listening enjoyment as well as the value of the receiver!. For additional information or questions please contact: QuadBob@prodigy.net The restoration takes me 1-2 months depending on my "normal" work. Please e-mail for prices. You need to pay for shipping both ways. I require a 50% deposit to start on the receiver, and the other 50% plus return shipping (or billing account number) and any additional parts cost required upon my notifying you of completion and the receiver ready to be shipped back to you. If you would like the "audiophile" upgrade to the decoder pcbs, then I will need extra for the upgrade added to the initial deposit. References are available upon request. Mr. Quad.... I'll have to take you up on that fix/upgrade some day!!!! I was lucky enough to find a QRX-9001 locally. I willingly paid the $230 in 1994 even though it seemed like a lot for a used receiver... even a quad one. Then, I heard how well it worked and the great synthesization of a stereo source into quad and I was convinced.... the Sansui QRX series are the primo units!!!! EXTRA!!!!! Recently (October 2003) a QuadBob modified QRX-9001 sold at the eBay auction site for $1,400!!!!! The word has gotten around about the quality of QuadBob upgrades. Contact him for prices, shipping information, etc. If you want to read what others have said about QuadBob's work try the QuadQuadraphonic message board. You need to register but, the site is run by a hobbyist as a non-profit gathering place for those involved with quad and modern multi-channel surround sound. You will NEVER be spammed because you registered!!!!! Site Map Next Page: Requisite Links Jump Ahead to More Quad Bob |