This EI smooth plate 12AX7 / ECC83 tube was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas.
It measured 38/46 where minimum (65%) is 32 and 100% is 49.
This tube has minimal-but-excellent silkscreening; 17MM plates; copious flashing and an O getter.
Ei Tubes are very similar to Telefunken as Telefunken engineers set up their manufacturing plant with Telefunken equipment and supplies. This tube is a wonderful example of where politics intersected with the consolidation and the demise of vacuum tube manufacturing.
Please note that this tube does not have Telefunken diamond in its base, nor are their any codes normally associated with German tube companies.
I have played it in my Bottlehead Crack headphone amplifier as a 12AU7 substitute and it sounds very good. It is dead quiet when the CD player is paused with no artifacts such as hum and hiss. I do not recommend using 12AX7s in the place of 12AU7s in this device at least; but it is good to know that it has no defects and will acquit itself well where a 12AX7 is called for.
WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY 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 FORMS OF SHIPPING -- EXCEPT MEDIA MAIL -- ARE AUTOMATICALLY INSURED UP TO $100. ETSY PURCHASE PROTECTION COVERS ITEMS UP TO $250 IN VALUE. IF AN ITEM IS MARKED "DELIVERED," AND YOU HAVE NOT ACTUALLY RECEIVED IT, THE FIRST STEP IS FOR YOU TO CONSULT YOUR MAIL CARRIER TO GET THE EXACT COORDINATES OF THE DELIVERY AND ARRANGE FOR YOUR ITEM'S RETRIEVAL. IF IT APPEARS THE ITEM HAS ACTUALLY BEEN STOLEN, IT IS YOUR LOSS AND YOUR RESPONSIBILITY TO FILE A REPORT WITH THE POSTAL INSPECTOR. ETSY MAY REIMBURSE YOU EVEN IF IT WAS STOLEN, BUT THAT DEPENDS ON THE LUCK OF THE DRAW.
2. MOST OF THE TUBES WE SELL ARE OVER 70 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.
3. IN NEARLY 9000 SALES, WE HAVE HAD A DOZEN OR SO 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!
4. TUBES ARE GUARANTEED GOOD 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. WE 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.