Description
The Sony ST-J75 was a world-class, ground-breaking FM Stereo component tuner when released in 1981. For the first time, S/N ratio was over 92dB in Mono and 87 dB in Stereo! This was when turntables offered the best S/N of only 50-60 dB! Most tuners could only manage similar noise rejection as turntables or tape. Even CDs were only 90 dB and this tuner approached that in Stereo and exceeded it in Mono. As long as an FM station could broadcast what this FM Tuner was capable of receiving (usually LIVE NPR performances), it represented the single finest component source of Audio in an audiophile system! Not only was noise several tens of dB lower than any tuner before it, Distortion was in the low hundredths of percent. In addition, the tuner is quite sensitive with excellent rejection specs: 1.9 uV Mono, 3.8 uV Stereo, Selectivity is 90 dB, Image, I.F., and Spurious Rejection are 95 - 100 dB. This is the finest FM tuner I have owned, save for a highly-modified Sony ST-S730ES tuner that I sold on Ebay a few years ago. However, this tuner is actually more sensitive and will grab more stations at greater distances than the ST-S730ES. ** Note the photo showing all five strength meter bars lit for the NPR station in Atlanta (WABE - 90.1) - from only a small set of TV rabbit ears on top! ** The work that Ive performed on this tuner is substantial (I operate Beezar Audio):All power capacitors, not related to the digital tuning section, have been replaced with the finest Nichicon UHE and Panasonic FM electrolytic capacitors. The power supply capacitor was upsized to 3300uf (2200uf was standard from Sony).Solen 4.7uf, 400V audiophile film capacitors used on the audio opamp outputs.Genuine Sprague Vitamin Q paper-in-oil film capacitors are used as bypasses on electrolytic capacitors in the Audio and Detector circuit sections.Both opamps in the Audio section have been replaced with sockets and TI Burr-Brown OPA2134 opamps. The sockets will allow you to roll your own opamps, if you prefer.The power supply transistor was replaced with a substantially higher-rated transistor both for power and longevity.Here are the specifics on the cap and opamp replacements, taken directly from reviews at fmtunerinfo.com. Note that Panasonic FM (better than FC) caps were used where sizes were available instead of Panasonic FC. Audio section:C224 and 225 - 10 ?F, 16v to 33 ?F, 50v Panasonic FC w/0.1 ?F polypropylene bypass (upgraded to 0.22uf Vitamin Q instead).C230 and 231 - 4.7 ?F, 16v to 47 ?F, 6.3v Black Gate NX non-polar (upgraded to 4.7uf 400V Solen film capacitors instead).C226 and 229 - 100 ?F, 16v to 330 ?F, 16v Panasonic FM.I.C. 201 and 204 - NJM4560 to OPA2134 (also sockets installed) Detector circuit:C217 - 3.3 ?F, 25v to 33 ?F, 50v Panasonic FC w/0.1 ?F polypropylene bypass (upgraded to 0.22uf Vitamin Q instead).C206 - 22 ?F, 16v to 50v Panasonic FC w/0.1 ?F polypropylene bypass (upgraded to 0.22uf Vitamin Q instead).C201 and 202 - 100 ?F, 16v to 680 ?F, 16v Panasonic FM. Power supply:C601 - 2200 ?F, 35v to 3300 ?F, 35v Nichicon UHE.C605 - 470 ?F, 16v to 820 ?F, 25v Panasonic FM.C615 - 100 ?F, 25v to 820 ?F, 25v Panasonic FM. You cant buy an appreciably better tuner than this one; only one with more convenient features. For instance, in the ST-S730ES, the tuning encoder knob is almost everything, but is ultimately only a convenience, not an improvement in performance over the J75. Here is your chance to own one of the best FM tuners Sony ever made and one thats been professionally upgraded (I operate Beezar Audio). P.S. If the winning buyer will share an email address, I have numerous PDFs to share including the users manual, service manual, and a copy of the original Leonard Feldman review in Audio Magazine, April 1981: This tuner will become a new standard against which all other tuners will be judged.
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