6SN7GTA Sylvania NOS Testing Matched Pair Tubes Phono Pre-Pre Amp Sound Tested

This matched pair new old stock-testing Sylvania 6SN7GTA with black winged plates and silver tops vacuum tubes was tested on our TV/U-7.  Tubes measured:

Tube One:  75 / 75 (99% / 99% Unbranded base - while cleaning base the 312 Sylvania and date code rubbed off; 6SN7GTA atop glass)

Tube Two:  72 / 70 (95% / 92%  Sylvania & logo stenciled on base with code AD; 6SN7GTA atop glass)

Minimum is 50 (65%); 76 is 100%; NOS-Testing is anything over 90%.

These NOS-Testing Sylvania 6SN7GTA tubes were sound tested while listening to Mobile Fidelity's Half-Speed Mastered, Original Master Recording™ of Pink Floyd's Dark Side of the Moon.  Tubes were in a Cern Tube Phono Pre-Pre amplifier and the album was playing on a REGA PLANNAR 3 with a ORTOFON X-5-MC Cartridge (hi-output moving coil).  See pics.  

Tubes played at full power on our 120W MOSFET Hafler amplifier.  There were no microphonics issues.  Also passed for use in a phono pre-pre amp as there is no feedback.  The phono pre-pre amp was 3 feet from the speakers woofer, and 2.5 feet from the tweeters.

Please see the oscilloscope & multimeter picture where the first pic is at level 11 (full gain) with no music input.  The other picture with music input was at level 6.

Pair have excellent frequency response, sound-staging, presence and dynamics (see pics).  Pair have black winged plates, short bottles and tall bases and are tight on bases with no debris or rattling sounds.

Check out my other Reverb listings for more tubes for your equipment needs.

Tubes ship via United States Postal Service (USPS) Ground Advantage with tracking for domestic U.S. sale.  International orders ship via USPS First Class Mail International.  Package weighs eight (8) ounces.

Combined shipping always welcomed.

TUBES ARE GUARANTEED GOOD AND IN WORKING ORDER AT SHIPMENT. TRANSIT VIA POST CAN DAMAGE TUBES.  THIS IS NO FAULT OF OURS BUT THE THIRD PARTY ENTITY THAT IS DELIVERING ITEM(S) TO YOU, I.E, USPS, UPS, FEDEX, YOUR NATIONAL CARRIER IF INTERNATIONAL, ETC. PLEASE INSURE THEM! WE CANNOT GUARANTEE FAILURES ON YOUR EQUIPMENT AFTER POWER UP AS THERE IS NO WAY TO ASCERTAIN HOW TUBES WILL INTERACT WITH YOUR ELECTRONICS; NOR IS THERE A WAY TO DETERMINE WHETHER THEY MAY HAVE FATAL FLAWS IN TUBES THEMSELVES!  THESE ARE USED VACUUM TUBES AND TIME MAY HAVE TAKEN A TOLL ON THEM OVER THE MANY YEARS SINCE THEY WERE MANUFACTURED. WE CAN ONLY TEST FOR THE PARAMETERS MENTIONED ABOVE IN ONE OR MORE OF THE FOLLOWING EQUIPMENT WE USE FOR MEASURING:  TV-7/U, JACKSON 648, AMPLITRIX & MAXI MATCHER 2.