Original Historic TubeMuseum, Tuxedo Park, New York Established in 1928 as a premier research facility in Tuxedo Park, New York, that attracted such brilliant and most visionary minds of the twentieth century – Albert Einstein, Werner Heisenberg, James Franck, Niels Bohr and Enrico Fermi to name a few. The Tuxedo Park lab attracted these top-flight scientists who experimented with audio, sound, time measurement, and radar waves. He turned this Tuxedo Park laboratory into a meeting place for the most visionary minds of the twentieth century; Albert Einstein, and the aforementioned scientists. Today Sarasota location is the home of The Tube Museum New York.Welcome to …TUBEMUSEUM NEW YORKBEWARE OF THESE TUBES BEING SOLD WITHOUT TEST RESULTS! PRICE IS EACH MATCHED PAIR…”BEWARE OF THESE TUBES BEING SOLD WITHOUT TEST RESULTS! “…Triode-Heptode Frequency converter Controlling (mu)NOS MULLARD UNITED KINGDOMBLACKBURN FACTORY1961 NOS MATCHED PAIRfor the Mullard, U.K. tube enthusiast these were never opened for sixty-three (63-years) NEW IS NEW IS NEW! NEVER OPENED and ONLY OPENED TO TEST!ECH83 = “6DS8″(NOT ECC83/ 12AX7) ATTENTION:* NOT * FOR DAYTON-AUDIO HTA AMPSThese are 9-pin tubes and not 7-pin tubes! ATTENTION DAYTON HTA OWNERS with CHINESE (P.R.C.) 6P14A and (PRC) 6F1, or (PRC) 6F2: Can you use these tubes? No, you’re screwed, sell that amp. Those 2 tubes are Chinese fake-number tubes that are not compatible with any legitimate substitute. Don’t confuse these with Russian numbers with the P at the end (not A), because they don’t conform with the International Philips-Standard Numbering system universally shared with USA and European tube numbers. Sorry to let you know this – but get rid of it and buy a preamp that uses universally accepted tubes. IF YOU PURCHASE FOR A DAYTON HTA THERE ARE NO RETURNS. From information on the web (ECH83 versus ECH81 AT RADIOMUSEUM) we are told that these are may formable substitute for the ECH81 in certain applications TESTED IN THE TRUE FIXED-BIAS SETTINGS FOR ECH81 AND SEE THE RESULTS!According to our profound investigations and tests, the tubes ECH81 and ECH83 are equal – not even tested differently, but only stamped differently. They naturally show different values for a different usage (volts anode).100% money back guarantee less shipping if not satisfiedFEEDBACK YOU GET A MATCHED PAIR PER BID – FROM 100 MASTER CASE – NO BOXES INCLUDEDARRIVES IN BULK ROLLS AS DISPLAYEDMULLARD tubes were the oldest and Best!- LAU CAU CL3000, direct heating single-ended combined power amplifier- NOBSOUND ECH81 AMPLIFIER- Seefunkempfänger Skipsmottaker SM600- CAR RADIOS & TV’s- 1954/55 Telefunken Rondo THESE ECH83 ARE HAND SELECTED MATCHED PAIRS of TUBES NOS MUSEUM QUALITYThese were made decades ago!MATCHING ACID CODES!BL12 & BL12 = 1961″B” in the glass codes is the Factory Symbol for Mullard Blackburn Factory You will feel great knowing that you chose a real NOS Tube Museum Tubes! TubeMuseum tested tubes takes the guesswork out of the process of selection delivering you the best Audio tubes that there possibly can be.Terms of Auction International Buyers – Please Note: Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer’s responsibility.Please check with your country’s customs office to determine what these additional costs will be prior to bidding or buying.Per eBay’s terms of service which every eBay account holder must agree to as part of being an eBay member, a bid is a legally binding contract. Please read the Terms & Conditions carefully before bidding. By bidding on this auction, you understand and agree to eBay’s terms of service as well as all terms and conditions mentioned here.Buyer pays all shipping, Item must be in original condition including cosmetic lettering on tubes so handle with white-glove care, un-used with all original boxes, packing material, environmentally safe cornstarch pellets, and shipping box. All sales are final with NO RETURNS on self installed mic tubes. All exchanges must be pre-paid and returned in original packing, complete with no sign of wear or abuse, exactly the same condition as it was when you received it. In the event that the product is not in the same condition, and does not test the same as you received it, you will be subject to a refusal and return, a determined restocking fee, repair charge, or disqualification. RETURN AUTHORIZATION (RA) number and instructions is required before sending any items. Shipping and handling charges are non-refundable. We do not guarantee that your tester, or your tester’s measurements will be the same as the Amplitrex AT-1000. Older testers, different testers, or the same tester may report different test measurements, and may not measure the same tube meaningfully (due to current dependency), accurately (due to calibration difficulties) or consistently (due to internal circuit drift) There is no warranty or returns based on what any other tube tester reports. THE COST OF ALL USA SHIPPING INCLUDES INSURANCE, TRACKING NUMBER AND DELIVERY CONFIRMATIONDEPENDING ON YOUR COUNTRY’S MAXIMUM INSURANCE RULES “PRIORITY or EXPRESS SHIPPING” may be required for certain countries, U.K.,Italy, Russia, Indonesia, Australia, Pacific Rim, and others.(Please kindly ASK before you bid or we reserve the right to cancel your bid)International Buyers – Please note: Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer’s responsibility. Please check with your country’s customs office to determine what these additional costs will be prior to bidding or buying. Visit this seller’s eBay Store! TUBEMUSEUM NEW YORK PayPal Welcome! NOTICE: All text & images © 2002-2024 Copyright © of The Tube Museum New York ©All Rights Reserved By entering this site you are agreeing to be bound by the terms of this agreement. All photographs and text appearing in the Tube Museum New York (TubeMuseumUSA) site(s) are the exclusive property of The Tube Museum New York © (except where stated otherwise) and are protected under international copyright laws and treaties. They are made available for your personal viewing enjoyment only. No images or unique text are within the Public Domain. The photographs and text may not be copied, reproduced, redistributed, manipulated, projected, used, or altered in any way without the prior express written permission of The Tube Museum New York ©. 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