Best 6550 listed at

6550 / 6550A PENTODE (US BRANDS ONLY)

(click on links below to check stock) 6550A GE welded plates 1970's 6550A GE stapled plates 1970's - 1992 JAN-6550A GE stapled plates 1970's - 1980's 6550 Sylvania 1970's - 1982 6550 Tungsol gray plate with holes 1963 - 1970's 6550 Tungsol gray smooth plate 1960 - 1963 6550 Tungsol black plate 1950's - 1960


6550A GE 1970's (welded plates)

1 pair $350) 6550A GE NOS 1970's "welded plates" original boxes 1 tube) 90ma GE branded International, black bottom, and etched circle on glass (on right) 1 tube) 89ma GE branded GE brown bottom (on left) SINGLE TUBES: ------------ 1 tube $150) 6550A GE branded INTERNATIONAL NOS 1970's "welded plates" original box (82ma) 1 tube $175) 6550A GE welded plates brown bottom NOS 1970's (105ma) 1 tube $50) 6550A GE welded plates brown bottom mid-1970's RF date code used/60% (55ma) 1 tube $85) 6550A GE welded plates brown bottom mid-1970's RH date code used/75% (74ma)


6550A GE 1970's - 1992 (stapled plates) (warm and punchy midrange, good bass, a very good 6550 second only to Tungsol 6550 in overall sound and drastically superior to Svetlana or Sovtek 6550) - ARC VT60, ARC VT100 MarkII and MarkIII, Ref. 300, Ref. 600 - Audio Research Reference 3 line-stage power supply - Luxman - Rogue - Cary - VTL MB300, MB450, ST-150 - CJ Premier 8 and 11A, 12 - Jadis - Ampeg SVT - Comins Alessandro Jazz Guitar Amp - Cary SLI-80 - THD - VAC PA100/100 - McIntosh 275 MK IV 2005 - Harmon Kardon - Audio Aero Capitole Integrated amp 6550A GE NOS PAIRS: ------------------ 1 pair $295) 6550A GE NOS early 1980's same build 1 tube) 84ma 1 tube) 85ma 1 pair $295) 6550A GE NOS 1992 same build 1 tube) 95ma 1 tube) 90ma 1 pair $265) 6550A GE NOS same build 1 tube) 81ma NOS JAN-6550A 1978 brown bottom 1 tube) 80ma NOS 1992 black bottom 1 pair $189) 6550A GE used/good around 1980 same build 1 tube) 86.5ma 1 tube) 86ma 6550A GE SINGLE TUBES: --------------------- 1 tube $125) 6550A GE 1970's like new, brown bottom (RM) date code (90ma) 1 tube $99) JAN-6550A GE NOS brown bottom 1978 top section of getter is faded (95ma) 1 tube $79) 6550A GE used/good 1970's in white box (SG) date code (88ma)
JAN-6550A GE 1980-1985 (stapled plates) (warm and punchy midrange, good bass, a very good 6550 second only to Tungsol 6550 in overall sound and drastically superior to Svetlana or Sovtek 6550) - JADIS - VTL: MB300, MB450 - Audio Research (ARC): D 79C MKII, D-250, VT60, VT100 MarkII and MarkIII, Ref. 300, Ref. 600, Ref. 610 - Conrad Johnson (CJ): Premier 8 and 11A, 12 - Ampeg SVT - Comins Alessandro Jazz Guitar Amp - Eden VT 300 Bass Guitar Amp - Rogue - Cary Integrated - CAT - LUXMAN MQ-360 - Marshall JTM combo 50 watts 1978 - Cayin VP-100i Integrated Vacuum tube amplifier
6550A GE JAN NOS 1985 listed below JAN-6550A GE NOS (GREEN printing 1985): --------------------------------------- 1 Platinum Pair within 1-2ma $325) JAN-6550A GE NOS 1985-1986 original boxes JAN-6550A GE NOS (WHITE printing 1980): --------------------------------------- sold


6550A GE SONIC COMMENTS: ---------------------------------- I recently purchased nine GE JAN NOS 6550A's (8 for the amps and one spare) for my conrad-johnson premier 12 monoblocks. As most of you know, the amps originally came with NOS GE's factory-installed, but when they became scarce, Svetlanas were substituted. My amps fell into the latter category. I decided long ago that if the opportunity ever arose, I would buy GE's to restore the amps to their "original state." Thanks for this to Brendan Biever of Tube World and his patient response to my questions and prompt, excellent service. The tubes are truly works of art. They're obviously sturdy and beautifully-constructed. Even the original cardboard boxes are made of heavy stock. Installation and biasing in the premier 12's was, as expected, a snap. First up: the JVC xrcd of the Capriccio Espagnol and Capriccio Italien conducted by Kondrashin, from the old RCA Living Stereo spectacular, recorded at Manhattan Center (one of my favorite recording venues). The opening brass fanfare of the C. Italien was stunningly projected, full and impactful, with plenty of ambience surrounding it. The orchestra was believably reproduced, with plenty of weight in the lower frequencies—something the Svetlanas seemed unable to supply. As I proceeded on to the xrcd of Stokowski's "Rhapsodies" (also a Manhattan Center job), Ella and Basie, Ella Sings the Gershwin Song Book, and the early Decca recital of the tenor Carlo Bergonzi, I was in all cases virtually transported to the recording site (to the extent the recordings made it possible). The image moved approximately one foot in front of the CLSes, and the depth increased roughly threefold vis-a-vis the premiers with the Svetlanas. The low end also improved markedly, imbuing orchestral sound in particular with a welcome weight and impact. Most impressive of all may have been the improvement in detail retrieval made possible by the GE's: orchestral sections—both in the classical and pop selections—now were rendered as a collection of individual voices rather than a congealed mass of sound. Ultimately, the GE's improved the sound of my system in very "audiophile" ways: imaging was markedly better, depth deeper, lows lower, and separation of instrumental choirs was more clear. On the other hand, the GE's were not tubey, as I expected them to be: they were fresh and revealing in an almost microscopic sense. This resulted in an improved audio bottom line: realism was enhanced and the listening experience rendered more believable as a replica of the real thing. I would not recommend the GE's to someone looking for a '60's "tubey" sound—this is a mercilessly revealing tube, more in the "modern" vein. If you're searching for "mellow," you won't find it here, at least as partnered with the c-j premier 12's. As originally conceived, they make for an excellent coupling with these amps; as for other combinations, I can only speculate. Still, they surprised me: a marked improvement in every area over the Svetlanas, but not a sound for golden age tube afficionados. I can see that paired with an extremely fast, revealing tube amp, the GE's might not be the best choice. With something like the c-j's, all is well—perfect symbiosis. 6550A GE SONIC COMMENTS: ---------------------------------- "Thanks very much for the GE 6550A's that I put into my ARC VT100 Mk3 amp. When I first put them in, I called you to say that the high end seemed muffled, and I was going to reload my cartridge to compensate. Well, it was simply a matter of time that was needed to get them to sing. The high end opened up all the way, and the low end is not as overdone as it was at first. But the lows and mids have a presence, a sense of reality, that was not there with the Svetlana 6550C's. Strings and piano and percussion are all more there now. I had thought my system was analytical enough and that everything was coming through, but the emotion of the music wasn't until these tubes. Please also note that I have gone through 3 iterations of the VT-100 over the past 6 years, using all ARC Svetlana power tubes, with one try at KT-88's, which I did not like in the amp. These GE tubes take the amp to a whole new level, adding life to the midange and giving up none of the analytical qualities that I like so much about the Mark 3."


6550C Winged C SED - St. Petersburg, Russia sold out
6550 SYLVANIA welded plates 1977 - 1983 (these are very rare great sounding 6550, next best sound to Tungsol) (very dynamic, alive, open, clean, not dull, very good highs, tight bass) - MacIntosh MC60 - Audio Research Classic 60 Best 6550 Sylvania matched pairs listed at single tubes: ------------ 1 tube $135) 6550 Sylvania branded RCA 1970's like new in RCA box, faded printing (91.5ma) 1 tube $89) 6550 Sylvania branded RCA 1977 used/good (89ma) 1 tube $85) 6550 Sylvania rebranded Philips late 1970's used/very good (95ma)
6550 TUNGSOL 1960's - 1970's (Holes in Gray Plate)

6550 DATA SHEET

6550 DATA SHEET

(The original 6550 Tungsol are the best built, best sounding, longest lasting 6550 ever made) (They have superb bass, lots of power and inner resolution) (The re-issued 6550 Tungsol made in Russia is sonically inferior to the original Tungsol made in the USA) - ARC VS 110 and other ARC amps - Audio Research Reference 3 line-stage power supply - Rogue 90 - VTL amps; MB300, 450, many others - Gibson guitar amp - McIntosh 275 - Beard P100 MKII 1984 - Cayin A-88T "SOFIA" curve tracer matched: (450Vplate, -12Vgrid) 1 pair $549) 6550 Tungsol NOS (7233=1972) same date codes - 3 large shiny getters on each tube - reboxed - best pair 1 tube) 92ma 1 tube) 95ma 1 pair $549) 6550 Tungsol NOS around 1970 - 3 large shiny getters on each tube 1 tube) 87ma branded Raytheon 1 tube) 84ma branded GE SINGLE TUBES: ------------ 1 tube $275) 6550 Tungsol NOS (7233=1972) - reboxed (83ma) 1 tube $249) 6550 Tungsol NOS (6532=1965) slightly smaller side getters (97ma) USED: ---- 1 tube $159) 6550 Tungsol branded RCA used/good (6509=1965) (105ma) 1 tube $159) 6550 Tungsol branded RCA used/good (6509=1965) (90ma) 1 tube $59) 6550 Tungsol used/50-60% 1974 (60ma, Gm=5000)


6550 TUNGSOL Smooth Gray Plate 1960-1963 (superb sounding 6550, next best to black plate, detailed, good bass) COMMENTS: -------- "I am using a Cary sli80 integrated tube unit. In case you get another customer with one I thought I would pass on the results of my bias tweaking with the smooth plate Tung Sol 6550's. Cary says anywhere from 75ma-100ma per pair. 75 is cool, detailed but little warmth. 85 is warm, clean and has nice high end extension. 90 is too warm and loses the high end. So 85ma it is. Yes I tried 80 but 85 is still better." - recommended for Audio Research Reference 3 line-stage power supply - recommended for Audio Research Reference 5 line-stage power supply 1 platinum pair $599) 6550 Tungsol NOS smooth gray plate original boxes early 1960's 1 tube) 93ma branded Sylvania taller bottle 1 tube) 94ma branded Tungsol SINGLE TUBES: ------------ 0)
6550 TUNGSOL Black Plate 1955-1960 (The original and best sounding 6550 ever made) 6550 Tungsol black plate with 1 getter (left) 2 getters (middle) 3 getters (right)

Tested in pentode mode: Vplate=450V, Vscreen=200V, Vgrid=-12V - Audio Research Reference 3 line-stage power supply - Audio Research Reference 5 - Cary amps - VTL amps - WAVAC driver tube 6550 Tungsol black plates used: ------------------------------ sold 6550 DISPLAY TUBE (not for use in amp): -------------------------------------- 1 display tube $25) 6550 Tungsol black plate used/gassy 1958