This matched pair of GE Red Label 6SN7GTB dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas.
Transconductance measured 70/72 for Tube One and 70/73 for Tube Two. (Minimum (65%) is 50/50.)
They have O getters; copper support rods; a round and square hole in each mica spacer; great flashing and 63-26 188-5 date/factory codes for both.
I am playing them in my Cern Audio phono preamplifier as I write. It is fed by a Rega Planar Three with an Ortofon X5-MC cartridge on an RB-300 tone arm. Source material is the Mobile Fidelity half speed master of "Dark Side Of the Moon" and they sound outstanding and are dead quiet when the stylus is lifted. Their frequency response and sound-staging is excellent with airy mids and highs with great bass articulation as well.
BECAUSE OF THE BIZARRE, INTRUSIVE, PETTY AND DRACONIAN GERMAN PACKAGING REGULATIONS -- AND THE SEVERE FINES AND PRIVACY INTRUSIONS ASSOCIATED WITH THEM -- WE NO LONGER SHIP TO GERMAN ADDRESSES. WE WILL HAPPILY SEND YOUR PACKAGE TO A NEIGHBORING COUNTRY OR MAKE SUITABLE ARRANGEMENTS.
IN 2021 WE PURCHASED 150,000 VACUUM TUBES. IF IT'S NOT LISTED, WE PROBABLY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO" AND/OR CALL OR TEXT US AT 202-372-6931 IF YOU DO NOT SEE WHAT YOU NEED OR HAVE ANY QUESTIONS.
1. MOST OF THE TUBES WE SELL ARE OVER 50 YEARS OLD. WE CANNOT GUARANTEE FOR FAILURES AFTER POWER UP AS THERE IS NO WAY TO DETERMINE HOW TUBES WILL INTERACT WITH YOUR ELECTRONICS OR IF THEY WERE MISTREATED IN TRANSIT; NOR IS THERE A WAY TO DETERMINE WHETHER THEY MAY HAVE FATAL FLAWS! WE CAN ONLY TEST FOR THE PARAMETERS MENTIONED ABOVE. WE CANNOT TEST FOR CATASTROPHIC FAILURE. IF A TUBE FAILS AFTER YOU GET IT, IT IS YOUR TUBE THAT HAS FAILED. THERE IS A .1 % CHANCE THIS MIGHT HAPPEN. BE WARNED. NO REFUNDS IN SUCH CASES.
2. IN WELL OVER 7000 SALES, WE HAVE HAD FEWER THAN A DOZEN LESS-THAN-FOUR-STAR REVIEWS OR HAVE LOST A CUSTOMER BECAUSE I REFUSED TO EITHER ISSUE A REFUND FOR A TUBE THAT WENT BAD AFTER IT HAD BEEN USED OR A BUYER KNEW NOTHING ABOUT TUBE REBRANDING AND CLAIMED THAT SOMETHING MADE BY TUNG-SOL AND BRANDED BY EMERSON WAS MADE BY EMERSON, AN ELECTRONICS COMPANY THAT NEVER MADE TUBES!
3. ITEMS ARE GUARANTEED AS-DESCRIBED ON SHIPMENT. IF YOU FEAR DAMAGE OR LOSS OF PARCEL IN TRANSIT, PLEASE INSURE THEM! OUR SHIPPING RESPONSIBILITY ENDS WHEN THE PARCEL IS ACCEPTED AND SCANNED BY THE US POSTAL SERVICE. ETSY IS CLEAR ON THIS. SOMETIMES THERE ARE INITIAL SCANNING DELAYS. WE HAVE ACCESS TO THE SAME INFORMATION YOU DO AND IT IS YOUR RESPONSIBILITY TO DEAL WITH THE USPS SHOULD THERE BE DELAYS OR LOSS OF A SCANNED PACKAGE. PLEASE BE PATIENT FOR THE FIRST DAY OR TWO IF THE PACKAGE IS STILL MARKED AS "PRE-TRANSIT." WE SHIP THE DAY AFTER THE SALE IF THE SALE WAS AFTER 9:30 AM EASTERN TIME.
4. THIS IS NOT AMAZON. THERE WILL BE NO REPLACEMENTS FOR LOST PACKAGES OR TUBES THAT FAIL. IN PRACTICE THIS MEANS YOU TAKE ON THE RESPONSIBILITY FOR THE LOSS IF THE PACKAGE IS MARKED AS "IN TRANSIT" OR AS "DELIVERED." MAIL GETS MISPLACED, STOLEN AND LOST. SOME COUNTRIES DO NOT HAVE INTERNAL TRACKING. CHINA IS AN EXCELLENT EXAMPLE. IF YOUR COUNTRY IS SIMILAR, IT IS YOUR RESPONSIBILITY TO INTERACT WITH YOUR CUSTOMS AND POSTAL AUTHORITIES TO FIND THE PACKAGE. CUSTOMS DELAYS CAN ADD WEEKS TO DELIVERIES.
5. I BUY TUBES IN BULK. 10-15% OF THEM ARE NOT SUITABLE FOR HIGH END AUDIO APPLICATIONS. THAT LOSS RATE IS REFLECTED IN OUR PRICES. I LISTEN TO THESE TUBES IN TUBE EQUIPMENT. SOMETIMES TUBES THAT TEST WELL HAVE PROBLEMS AND SOUND AWFUL. THAT IS ALL I CAN DO. IF THERE WERE A TEST FOR FUTURE FAILURE, I WOULD USE IT. THERE ISN'T. THERE IS RISK IN LIFE. THESE PRODUCTS ARE NO LONGER MADE. THERE ARE NO MANUFACTURERS TO TAKE PRODUCT BACK BECAUSE OF DESIGN FAILURES OR QUALITY-CONTROL ISSUES. THE PRODUCT DEVELOPMENT AND IMPROVEMENT CYCLE IS OVER.