FOR YOUR CONSIDERATION IS A *RARE* 1957MULLARDECC83/12AX7AUDIO VACUUM TUBE MADE IN GT. BRITAIN DATE/MFG CODE:f91B7I(I.10.7) LONG RIBBED PLATESGOALPOST SQUARE GETTER TESTED ON SENCORE MIGHTY MITE TESTERMINIMUM GOOD = 65NEW = 100 RESULTS:108/108(TESTED AS NEW) TESTED FOR GRID LEAKAGE AND SHORTS - NO ISSUES(FUN FACT - THE SENCORE MIGHTY MITE IS SAID TO BE ONE OF THE BEST TESTERS EVER MADE FOR GRID LEAKAGE) ALSO TESTED BRIEFLY IN PREAMP WITH NO ISSUES - SOUNDED AMAZING! EBayVintage ElectronicsDisclaimer: Please carefully read thefollowing disclaimer beforeproceeding with anytransaction involving vintageelectronics on this eBaylisting. By purchasing theitem, you acknowledge thatyou have read, understood,and agreed to the terms andconditions outlined herein. Age and Condition: Vintage electronics are defined asitems that are typically 20years or older. These itemsmay show signs of wear, use,and age-related deterioration.While we strive to provideaccurate descriptions andcondition assessments, it isimportant to note that vintageelectronics may have inherentflaws, functional limitations, orrequire specializedknowledge to operate orrepair. Please consider thesefactors before making apurchase. Compatibility andFunctionality: Vintage electronics may not becompatible with moderntechnologies, software, oraccessories. It is yourresponsibility to researchand verify the compatibility ofthe item with your intendeduse or setup. We cannotguarantee the functionality,performance, or longevity ofvintage electronics due totheir age and potential wear-and-tear. Any statementsregarding functionality arebased on our best knowledgeat the time of listing. Safety Precautions: Vintage electronics may not meetcurrent safety standards orregulations. It is crucial toexercise caution and takeappropriate safety measureswhen using or operatingthese items. We stronglyadvise against modifying,altering, or attempting repairswithout proper expertise. Weshall not be held liable for anyinjuries, damages, oraccidents resulting from theuse or misuse of vintageelectronics. Limited Warranty: Unless explicitly stated otherwise inthe listing, vintage electronicsare sold as is without anywarranties or guarantees,whether expressed or implied.We make no claims regardingthe longevity, durability, orfuture functionality of theseitems. You assume all risksassociated with purchasingand using vintage electronics. Authenticity and Originality:We strive to accuratelyrepresent the authenticity andoriginality of vintageelectronics. However, due tothe age and history of theseitems, it may be challenging to verifytheir complete authenticity ororiginal components. Anystatements regardingauthenticity or originality arebased on our research andbelief, but we cannotguarantee absolute accuracy. Returns and Refunds: Our return policy, if applicable, isoutlined in the listing.Please review it carefullybefore making a purchase. Ifyou encounter any issueswith your vintage electronics,please contact us within thespecified time frame to initiatethe return process. Wereserve the right to assessthe condition of returneditems before issuing refundsor exchanges. Liability Limitation: In no event shall we be liable forany indirect, incidental,consequential, or punitivedamages arising from theuse, misuse, or inability touse vintage electronics. Ourliability, if any, shall notexceed the total amount paidby the buyer. By engaging in a transactioninvolving vintage electronicson this eBay listing, youagree to release us from anyliability arising from yourpurchase, including but notlimited to disputes with otherbuyers, manufacturers, oreBay itself. We reserve the right to modifyor update this disclaimer asneeded, without prior notice.It is your responsibility toreview the disclaimer beforeeach transaction. Shipping Statement: We offer shipping servicesthrough FedEx Ground with ahandling time of 1-3 businessdays. Please note thefollowing importantinformation regarding ourshipping and handlingprocess: Processing Time: We strive to ship items promptlywithin 1-3 business days afterreceiving cleared payment.However, please understandthat unforeseencircumstances mayoccasionally cause slightdelays. We appreciate yourpatience and understandingin such situations. Shipping Method: We utilize FedEx Ground as ourprimary shipping carrier.FedEx Ground offers reliableand traceable shippingservices within the continentalUnited States. Please notethat we may opt foralternative shipping methodsor carriers for certain items orregions, at our discretion. 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Pleaseallow some time for thetracking details to be updatedby the shipping carrier. Combined Shipping: If you purchase multiple items fromus within a short timeframe,we may offer combinedshipping discounts. Thecombined shipping cost will becalculated based on the totalweight and dimensions of theitems. Please contact usbefore making payment toinquire about combinedshipping options. Shipping Restrictions: Certain items may have shippingrestrictions due to theirnature, value, or destination.It is your responsibility to ensurecompliance with anyapplicable laws, regulations,or restrictions regarding theimportation of specific itemsinto your country. Address Accuracy: To ensure successful delivery, pleaseprovide a valid and completeshipping address. We will notbe held responsiblefor undeliverable shipmentsdue to incorrect or incompleteaddresses provided by thebuyer. We strive to provide a smoothand efficient shippingexperience. However, pleaseunderstand that we cannot beheld responsible for anydelays, loss, or damages thatmay occur during transit. Ifyou encounter any issues withyour shipment, please contactus, and we will do our best toassist you in resolving thematter. Thank you for choosing us asyour eBay seller. Weappreciate your business andlook forward to serving you.

1 ECC83 12AX7 MULLARD Long Plate HiFi Guitar Amplifier Vintage Vacuum Tube Code f91 B8A Tube Tested on a TV-7D/U Tester 32 is Minimum Tube Tests New 54-54 PRICED TO SELL!!! Singerhouse Sound has been buying and selling vintage vacuum tubes and electronics for over 25 years. We will usually ship within 1 business day of receiving cleared payment. Please make payment within 2 days from end of auction.

1 ECC83 12AX7 MULLARD Long Plate HiFi Guitar Amplifier Vintage Vacuum Tube Code f91 B8A Tube Tested on a TV-7D/U Tester 32 is Minimum Tube Tests New 54-54 PRICED TO SELL!!! Singerhouse Sound has been buying and selling vintage vacuum tubes and electronics for over 25 years. We will usually ship within 1 business day of receiving cleared payment. Please make payment within 2 days from end of auction.

WELCOME TO YET ANOTHER GREAT DR-TRON AUCTION.                THIS SALE IS FOR A VINTAGE VALVE TUBE.....   Mullard ECC83 / 12AX7WHITE  PRINT. Goalpost/ Dual support, Halo GETTER. Long plates. MADE IN GREAT BRITAIN, Blackburn. Code = f 91 - B8D. 1958. VINTAGE. Perfect Balanced tube.TESTS 100%. A1 = 1.40mA. A2 = 1.35mA..... 100% = 1.2mA.FROM WORKING EQUIPMENT. Please note...... ALL MY TUBES ARE TESTED ON MY CALIBRATED ......  AVO  VCM-163 TUBE TESTER .... BEAR IN MIND ALL TUBE TESTERS GIVE SLIGHTLY DIFFERENT READINGS..... MY READINGS ARE ACCURATE AND HONEST. I  WILL SHIP THIS ITEM WORLDWIDE. PLEASE LOOK AT MY OTHER VINTAGE PARTS AUCTIONS. THANK YOU FOR TAKING TIME TO VIEW MY ITEM, AND GOOD LUCK !!!

1 ECC83 12AX7 MULLARD Long Plate HiFi Guitar Amplifier Vintage Vacuum Tube Code f91 B8A Tube Tested on a TV-7D/U Tester 32 is Minimum Tube Tests New 54-54 PRICED TO SELL!!! Singerhouse Sound has been buying and selling vintage vacuum tubes and electronics for over 25 years. We will usually ship within 1 business day of receiving cleared payment. Please make payment within 2 days from end of auction.

MULLARD ECC83 12AX7 CV492 type F91 Valve Pair 1958 Long Plate Blackburn production matched “goal post” (getter support) Special military select quality CV492. Excellent condition — report below. Gave a full-bodied bathing of music in my RIAA Phono stage (notably bigger sound, richer and more musical than late 1970’s / 80’s production Mullards) which I no longer use, so these valves are surplus to requirements. A rare pair of classic valves in production for less than 18 months in the late 1950s. Manufactured from late 1957 until early 1959 only. The F91 design was the Mullard long plate ecc83 that immediately followed their square getter MC1. Similar to, and all the quality of the predecessor legendary MC1 valve. Some prefer the F91 for its slightly smoother upper-mid frequency range. The F91 is the only Mullard design using a halo getter which incorporates the double goalpost getter support as used in the MC1. 17mm long plates” much rarer than the later 13mm short plates. Copper plate posts. CV492 print on reverse means these were selected for high specification; the best of the Blackburn F91 production. Design and date codes: F91 B8E, &: F91 B8G manufactured at Mullard Blackburn factory in May, and July, 1958. Tested good for shorts; continuity; microphony; and emissions. No hiss, no hum, no noise, no microphonics. Condition report September 2021 and stored since (from Deco Audio specialist (aylesbury), can provide details): A:triode 1, gain 35.0db, output 45vtriode 2, gain 35.2db, output 45vB:triode 1, gain 35.0db, output 45vtriode 2, gain 36.0db, output 45v Advice: “book values for our machine are 35db and 50v, however given the consistency across all four triodes I suspect it is my judgement of clipping (output voltage) that is off (this is done audibly and visually and there is a tolerance within which I think this falls), so in other words they are very close if not meeting tolerance and about as close to matched halves as can reasonably be expected, with A being the best”. Only the item listed is included in this sale. I will pack carefully for safe, insured, transit. Will be sent UK Post Office First Class Signed For . (Packed Item Weight not more than 250 grams) Please contact me first if bidding from overseas to find courier service and cost. All import / other duties will be the responsibility of the purchaser. Thank you for your interest.

Rare Mullard ECC83 / 12AX7 f91 Square Getter, Long plate, 1957 Valve/Vacuum Tube AVO Tested very strong and balanced. Date code B7I = Blackburn, September 1957. Tested on a recently calibrated AVO VCM 160 with the following results; IA GMValve 1: A1 1.3 1.8 A2 1.5 1.8 AVO NOS Specs: IA = 1.2 GM = 1.6 No leaks or shorts, shiny pins. eBay seller for over 20 years, buy with confidence - see feedback. Valve will be shipped next day, carefully packaged, tracked and insured. Please drop a note with any questions. Shipping happily combined on multiple items. For overseas purchases, please message for a shipping quote before purchasing. Dont use your amp as a circuit breaker, buy tested valves!

Mullard ECC83 F91 B8D Long Plate Halo GetterTested good on B&K tester

  TUBE HUNTER VACUUM TUBE GEMSTHESE ARE THE SPECIFICS OF THE TUBE/TUBES FOR SALE THESE ARE THE TUBE/TUBES FOR SALE:    MANUFACTURER:                              MULLARD PRODUCTION CITY:                                    ENGLAND TUBE TYPE:   12AX7 COPPER POSTS DESIGNATION:                                              BEST TONE PREAMP YEAR:     1958 MONTH:     SEPTEMBER Date code match    SINGLE SILK SCREEN CONDITION %:                    100% MICA:   2 PLATES:   GREY CURVE TRACER ma: NORMAL = 4.4ma   4.3ma AND 4.2ma AT 200PV AND 0G TRANSCONDUCTANCE: NORMAL=  1600  1560µmhos AND 1530µmhos PERCENTAGE OF BOGEY:                       98% AND 95% SINGLE/PAIR/QUAD/MULTI:   SINGLE GETTER:                                                         O   GETTER DATE CODE                                                    f 9 1    B 8 I THIS TUBE HAS BEEN CURVE TRACER MATCHED. THE CURVES SHOWN IN THE PICTURES ARE OF EACH TRIODE. EXAMINE THE CURVES FOR LINEARITY. THE gm PERCENTAGES IN THE TABLE ARE FROM THE B&K 747B I USED FOR NORMAL TESTING. CURVE TRACER MATCHED!!! TESTING ACCORDING TO DATA SHEETS FOR 12AX7’S ARE AS FOLLOWS: 200 PLATE VOLTS, MARGINAL GOOD 65%: 2.86ma, LOW NOS 85% = 3.74ma, NOS 100% = 4.4ma. THIS TUBE MEASURES: 4.3ma, 4.2ma. Very rare single example of f91 Mullard 12ax7. This tube measures very strong and perfectly matched. This tube will deliver the warmest sound known to man. So sweet and rich, every song in your collection will sound as never before, as you sit right up front. The music surrounds you and you breath it in like a sweet drug. This tube will deliver the goods............I guarantee it ! Normal 0 false false false EN-US X-NONE X-NONE Normal 0 false false false EN-US X-NONE X-NONE I want to see you happy with your purchase. I will never sell a tube that is below standard…… I have sold many tubes here on Ebay, and all my customers have been completely satisfied. I will work with you in good faith if there are any problems, or if you are unsatisfied in any way. I want your business now and in the future, so I assume you are the boss, and I am the employee. All tubes are tested for shorts, continuity, and emissions. I prefer PayPal. ALL CUSTOMERS PLEASE READ ALL NOTES BEFORE BUYING FROM ME !!1.  RETURNS: It is my highest desire that you are completely satisfied with your purchase from me. I will bend over backwards to make sure that you are a happy customer.If anything you buy from me is less than satisfactory, message me BEFORE you either open a case or hit the “item not as described” button.Sound quality is tremendously SUBJECTIVE. For tubes returned for noise or sound quality of any kind you pay for the shipping we refund the purchase. We refund the price of the item NOT THE SHIPPING COST. If we sent the wrong tube we will of course pay for return shipping. For any tubes that are DOA we require that you send a us a picture of the shipping box to show us the damage. We test EVERY tube sent out and none should be DOA unless broken in shipping.2.    PLEASE NOTE:  Tube silkscreen (lettering on the tubes) is VERY fragile. It can be wiped off and destroyed VERY easily. If you wipe off the silkscreen while handling the tube you diminish their value by up to 70%. DO NOT handle the tubes or hold them from the cylinder. ALWAYS hold them from the ENDS. If you are returning tubes and they are not in the same condition cosmetically I cannot give you a full refund. THIS IS VERY IMPORTANT.3.  UNLESS YOU MAKE ARRANGEMENTS WITH US BEFORE YOU PURCHASE, YOU MUST PAY FOR ITEMS PURCHASED WITHIN 2 DAYS OR A CASE WILL BE OPENED FOR AN UNPAID ITEM!!!4. TESTING: I test all tubes that I sell in one way or another, or I will state untested. I have a B&K 747 tube tester. This is a mutual conductance tester. It give a percentage value of gm for the tube under test and checks for shorts and grid emissions. I also use a Tektronix curve tracer for testing triodes. I give a number of evaluations for tubes. One evaluation is a screen shot of the tube with a high voltage applied to the plate. This helps the buyer see the linearity of the tube in question at the highest voltage the tube will see in a real circuit. The Curve tracer steps the triode through 10 gate/grid voltages starting with -10 volts and going to 0 volts. The lines show how the tube conducts throughout that range. At 0 volt the tube is at max conduction and is the top line on the display. It is easy at that point to take where that top line intersects the plate voltage, find the milliamp level and compare it to the datasheet. I give those numbers for you in the Item condition box. To further help the buyer I also include the Design values, for gm and ma readings in the table. This can then be compared to other tube sellers using inferior test methods such as Hickok,  Amplitrex, and other testers. The Tektronix curve tracer gives values within 3% of the actual value. The very best portable testers only can approach 10% accuracy.5.    Please note: The numbers given for gm are what I see on my tester. I DO NOT guarantee that you will see those numbers on your tester. I only guarantee that these tubes will test good, with no shorts, or gas, on a decent calibrated tester. I dont guarantee or imply anything else.6. VERY IMPORTANT!!! Vintage tube testers almost always, due to age, have VERY LOW HEATER VOLTAGES!!!  Every tester I have ever bought is below 6 volts when selecting 6.3 volts. They average 5.8 volts. The voltage NEEDS to be 6.3 and 12.6. You can calibrate a vintage tube tester all you want. If the heater voltage is not right, you will NEVER get the right gm value. I have customers complain that their tubes are not the same as what I see on my tester. They say they have a calibrated tube tester. I have 40 tube testers. On all of them I have an outside regulated DC power supply that feeds the tube tester the correct heater voltage.7. I dont check each and every tube for noise or tone. This is SUBJECTIVE and it is too time consuming. If you dont like the noise level or the tone we offer a hassle free refund policy.  International customers note:1. Please wait for us to invoice you for the correct amount. If you have purchased more than one item, we must calculate how much the shipping will be. Shipping will be HIGHER due to insurance and shipping methods needed for expensive item totals. If you are buying only one item this will not be an issue. 2. Under no circumstances will we state on a US customs a declared value of less than the sale price. This is an honesty issue. We are honest with everyone to the best of our ability to do so. We want you to trust that what we say is true. There cannot be that trust, if we make false statements knowingly to anyone. If your country has tariffs/taxes so high that they cause large numbers of normally honest folks to make false statements, we urge you to work for change of those laws.3 International buyers if you bought more than one item and want combined shipping it will ship in 2 days.4. And all the Angels sang because the heavenly music was playing and it was turned all the way up.    Listing and template services provided by inkFrog

Single Mullard ECC83 tube with f91 code and square getter. This is a bit unusual, as most f91 types were O getter. Early 1958 code suggests that this one was caught between the two varieties. Excellent balance between sections. Buyers from mainland China (not including Hong Kong): due to excessive losses and delays within your postal system, I will ship to you only via UPS. You must select UPS (not USPS) from the shipping options when you purchase. NumberECC83 / 12AX7 Brand on tubeMullardActual manufacturerMullard Country of manufactureGreat Britain Date codesf91 B8A Box typeWhite box Plate styleGray long Getter styleTop-square Glass styleClear Base style9-pin miniature Test results (measured , typical NOS)1050/1050 typical NOS is 1250/1250 Be sure to read my policies below, and contact me before you purchase if you have any questions. I have over 30 years of experience as an electronics engineer, certified electronics technician, and hobbyist, and have been collecting, buying, and selling tubes since the 1980s. Ive been an eBay seller since February of 2000. This is the only seller account I have on eBay and the pictures you see are of the actual tube(s) you’ll receive. Tubes are described, tested, and presented to the best of my ability, subject to the limitations of the equipment that I have available (Hickok 539C and 6000A). Test results are likely to differ between your equipment and mine due to many factors, and tubes are not tested for noise or microphonics. Discrepancies between your test results and mine, or the presence of noise or microphonics, do not qualify tubes as “defective” or “not as described,” as such variations are common and to be expected. Do you have tubes to sell? Contact me with your inventory!Return Policy Unless otherwise stated in this listing, tubes may be returned within 30 days for a refund. Please keep in mind that while I do allow returns, my purpose here is to sell tubes, not to loan tubes for rolling. Any tube to be returned must: a) still bear my identification stamp. b) be in EXACTLY the same condition in which it arrived to you. Things which may invalidate a return: defaced or smudged print on the glass, bases scratched from retainer springs, cracked or damaged glass, damaged or missing boxes (where original boxes were sent with the tubes), and electrical or physical degradation from improper operation or handling. Returns which do not meet the above criteria may be refused or may be subject to partial refund. Ebays return guidelines prohibit “using or damaging an item and then returning it.” I pay for return shipping on all returns within the USA, regardless of reason. You pay for return shipping if you are located outside of the USA. If the tube arrives to you DOA or significantly not as described (SNAD) I pay for return shipping. I do not pay for return shipping for any other reason. If a tube is returned as DOA or SNAD, but does not test as such upon return, I reserve the right to be reimbursed for any return shipping cost that I paid. International buyers, please note: Import fees and taxes which you pay to your border and/or customs agency are not refundable by me under ANY conditions or for ANY reason, regardless of the reason for your return. Shipping Your tubes will be professionally prepared for shipping using all-new packing materials and will arrive to you in perfect condition. Ive been shipping tubes for many years and know how to get them to you quickly and securely. International orders ship with proper customs documentation and tariff codes to ensure that theyre processed with minimal delay upon arrival in the destination country. DOMESTIC: Unless otherwise noted, free shipping is offered on all tubes purchased with Buy-It-Now. Orders that weigh 16 oz. or less and which total $400 or less are generally shipped via the USPS First Class Package service, while orders exceeding either of those values are shipped via USPS Priority Mail. Other services are available at additional cost. If you prefer a shipping method that is not listed, please contact me prior to purchasing. I can usually ship via any USPS, FedEx, or UPS method that is applicable to your ZIP code. If you need expedited shipping (Express, Next Day, etc.) please contact me first to confirm earliest available date of shipment, as cutoff times are generally early in the afternoon. INTERNATIONAL: USPS First Class Mail: This is the least expensive option but the availability of tracking is limited in many cases. Its available worldwide for packages with a value of USD$400 or less. Be aware that First Class Mail has been known to take up to three months to reach some destinations. Customs delays are also more common with First Class. If you select the First Class option I expect that you will be patient and wait three months before requesting a refund for “item not received.” If you require faster delivery please select an option below. USPS Priority Mail: This option is available for shipments with a value less than USD$1000. It typically takes a couple of weeks to reach most destinations. UPS Worldwide Expedited: This option is available worldwide for all shipments, and is required for shipments valued at USD$1000 or more. It is fast and reliable, with end-to-end tracking. I can also usually arrange shipping with other carriers at additional cost. Please inquire before purchasing if you have specific requests. I no longer ship to Italy. I ship to China only via UPS Worldwide Expedited, regardless of value. No exceptions. Orders valued in excess of USD$2000 may be shipped in multiple packages. Dont put too much faith in eBay delivery estimates for international shipments. They are often wrong by a considerable amount. I dont use eBays Global Shipping Program (GSP) because they treat tubes as hazardous material and will confiscate them.USPS is now requiring that all addresses be in “Latin” (abcdefg) characters (this means, for example, no Cyrillic (???????) or Chinese (???), etc.). USPS will return to the me any packages which violate this guideline, and the buyer will then be required to correct the address and pay postage again. Ebay places the burden of safe delivery on sellers, so I fully insure all shipments sent outside of the USA, regardless of value. Because I can insure only up to the declared value, ALL SHIPMENTS ARE DECLARED AT ACTUAL VALUE. You might owe significant import fees on higher value shipments once they cross your countrys border – check with your border or customs agency for details. I can ship to a domestic freight forwarder or other third party within the USA, provided their address is on the order at the time you place it. GENERAL: SIGNATURE REQUIREMENT: All orders valued at USD$750 or greater, and ANY order shipped via UPS or FedEx, automatically require a signature release upon delivery. Someone at your delivery address will need to be available at the time of delivery to sign for the package. COMBINED SHIPPING: Im happy to combine shipping on multiple purchases. Those shipping within the US will combine automatically. International orders must be manually combined after the purchase, and any excess shipping will be refunded to your payment source (due to the way eBay buy-it-now items are set up, this is the only way I can combine shipping on more than one item). HANDLING TIME: My handling time is one business day and eBay requires me to ship within that timeframe. I cannot withhold shipment for a later date. If you require shipment on a specific date I can often set up a special listing just for you on that date; please inquire. I usually ship every day of the week, except for Sunday and USPS-observed holidays, and orders often ship same day. Orders placed later in the day usually ship next business day. Orders placed on Friday or Saturday will sometimes not ship until Monday. All orders placed on Sunday or USPS-observed holidays ship the next business day. Expedited and express shipments (FedEx and UPS 2-day & Next Day, etc) must be placed by 12PM Pacific Time in order to ship same day. If you have an urgent delivery need its a good idea to contact me first so I can confirm exact day of shipment. SHIP-TO ADDRESS: Ebay requires that I ship to the address on the order. This protects both you and me. I cannot ship to a different address. If you require shipment to a different address please update your shipping information before making a purchase. R27

RARE MATCHED PAIR OF MULLARD ECC83 f91 LONG PLATE GOALPOST GETTERS BOTH HAVE THE SAME f91 B8E CODE FROM MAY 1958 IN BEAUTIFUL CONDITION AND FULL WORKING ORDER NOT NOS VALUES BUT WELL MATCHED AND BALANCED ??AVO VCM163 TESTED READINGS TUBE 1 - Ia 0.95/0.85 gm 1.3/1.3 TUBE 2 - Ia 0.85/0.95 gm 1.3/1.3 100% = Ia 1.2 gm 1.6 ? PLEASE SEE MY OTHER AUCTIONS ?

MULLARD ECC83 12AX7 CV492 type F91 Valve Pair 1958 Long Plate Blackburn production matched “goal post” (getter support) Special military select quality CV492. Excellent condition — report below. Gave a full-bodied bathing of music in my RIAA Phono stage (notably bigger sound, richer and more musical than late 1970’s / 80’s production Mullards) which I no longer use, so these valves are surplus to requirements. A rare pair of classic valves in production for less than 18 months in the late 1950s. Manufactured from late 1957 until early 1959 only. The F91 design was the Mullard long plate ecc83 that immediately followed their square getter MC1. Similar to, and all the quality of the predecessor legendary MC1 valve. Some prefer the F91 for its slightly smoother upper-mid frequency range. The F91 is the only Mullard design using a halo getter which incorporates the double goalpost getter support as used in the MC1. 17mm long plates” much rarer than the later 13mm short plates. Copper plate posts. CV492 print on reverse means these were selected for high specification; the best of the Blackburn F91 production. Design and date codes: F91 B8E, &: F91 B8G manufactured at Mullard Blackburn factory in May, and July, 1958. Tested good for shorts; continuity; microphony; and emissions. No hiss, no hum, no noise, no microphonics. Condition report September 2021 and stored since (from Deco Audio specialist (aylesbury), can provide details): A: triode 1, gain 35.0db, output 45v triode 2, gain 35.2db, output 45v B: triode 1, gain 35.0db, output 45v triode 2, gain 36.0db, output 45v Advice: “book values for our machine are 35db and 50v, however given the consistency across all four triodes I suspect it is my judgement of clipping (output voltage) that is off (this is done audibly and visually and there is a tolerance within which I think this falls), so in other words they are very close if not meeting tolerance and about as close to matched halves as can reasonably be expected, with A being the best”. Only the item listed is included in this sale. I will pack carefully for safe, insured, transit. Will be sent UK Post Office First Class Signed For . (Packed Item Weight not more than 250 grams) Please contact me first if bidding from overseas to find courier service and cost. All import / other duties will be the responsibility of the purchaser. Thank you for your interest.

Mullard ECC83 f91 B8D Long Plate Halo GetterTested good on B&K tester

Mullard ECC83 F91 (2) F91 B8A F91 B81 1.25 / 1.2 amd 1.7 / 1.7 1.2 / 1.25 and 2.1 / 2.1 104%/100% and 106%/106% 100%/104% and 131%/131% (nos/100% = 1.2 and 1.6) Blackburn 1958 Long plate / Halo getter uk onlyuk inlyuk only37

F91 B8F IA 1.2 / 1.2 and GM 1.4 / 1.4 100%/100% and 88%/88% IA 1400 / 1400 and gain 97 / 97 (new is 1.2 and 1.6) Within new range / lightly used.uk onlyuk onlyuk only36

  TUBE HUNTER VACUUM TUBE GEMSTHESE ARE THE SPECIFICS OF THE TUBE/TUBES FOR SALE THESE ARE THE TUBE/TUBES FOR SALE:    MANUFACTURER:                              MULLARD PRODUCTION CITY:                                    ENGLAND TUBE TYPE:   12AX7 COPPER POSTS DESIGNATION:                                              BEST TONE PREAMP YEAR:     1958 MONTH:     SEPTEMBER Date code match    SINGLE SILK SCREEN CONDITION %:                    100% MICA:   2 PLATES:   GREY CURVE TRACER ma: NORMAL = 4.4ma   4.3ma AND 4.2ma AT 200PV AND 0G TRANSCONDUCTANCE: NORMAL=  1600  1560µmhos AND 1530µmhos PERCENTAGE OF BOGEY:                       98% AND 95% SINGLE/PAIR/QUAD/MULTI:   SINGLE GETTER:                                                         O   GETTER DATE CODE                                                    f 9 1    B 8 I THIS TUBE HAS BEEN CURVE TRACER MATCHED. THE CURVES SHOWN IN THE PICTURES ARE OF EACH TRIODE. EXAMINE THE CURVES FOR LINEARITY. THE gm PERCENTAGES IN THE TABLE ARE FROM THE B&K 747B I USED FOR NORMAL TESTING. CURVE TRACER MATCHED!!! TESTING ACCORDING TO DATA SHEETS FOR 12AX7’S ARE AS FOLLOWS: 200 PLATE VOLTS, MARGINAL GOOD 65%: 2.86ma, LOW NOS 85% = 3.74ma, NOS 100% = 4.4ma. THIS TUBE MEASURES: 4.3ma, 4.2ma. Very rare single example of f91 Mullard 12ax7. This tube measures very strong and perfectly matched. This tube will deliver the warmest sound known to man. So sweet and rich, every song in your collection will sound as never before, as you sit right up front. The music surrounds you and you breath it in like a sweet drug. This tube will deliver the goods............I guarantee it ! Normal 0 false false false EN-US X-NONE X-NONE Normal 0 false false false EN-US X-NONE X-NONE I want to see you happy with your purchase. I will never sell a tube that is below standard…… I have sold many tubes here on Ebay, and all my customers have been completely satisfied. I will work with you in good faith if there are any problems, or if you are unsatisfied in any way. I want your business now and in the future, so I assume you are the boss, and I am the employee. All tubes are tested for shorts, continuity, and emissions. I prefer PayPal. ALL CUSTOMERS PLEASE READ ALL NOTES BEFORE BUYING FROM ME !!1.  RETURNS: It is my highest desire that you are completely satisfied with your purchase from me. I will bend over backwards to make sure that you are a happy customer.If anything you buy from me is less than satisfactory, message me BEFORE you either open a case or hit the “item not as described” button.Sound quality is tremendously SUBJECTIVE. For tubes returned for noise or sound quality of any kind you pay for the shipping we refund the purchase. We refund the price of the item NOT THE SHIPPING COST. If we sent the wrong tube we will of course pay for return shipping. For any tubes that are DOA we require that you send a us a picture of the shipping box to show us the damage. We test EVERY tube sent out and none should be DOA unless broken in shipping.2.    PLEASE NOTE:  Tube silkscreen (lettering on the tubes) is VERY fragile. It can be wiped off and destroyed VERY easily. If you wipe off the silkscreen while handling the tube you diminish their value by up to 70%. DO NOT handle the tubes or hold them from the cylinder. ALWAYS hold them from the ENDS. If you are returning tubes and they are not in the same condition cosmetically I cannot give you a full refund. THIS IS VERY IMPORTANT.3.  UNLESS YOU MAKE ARRANGEMENTS WITH US BEFORE YOU PURCHASE, YOU MUST PAY FOR ITEMS PURCHASED WITHIN 2 DAYS OR A CASE WILL BE OPENED FOR AN UNPAID ITEM!!!4. TESTING: I test all tubes that I sell in one way or another, or I will state untested. I have a B&K 747 tube tester. This is a mutual conductance tester. It give a percentage value of gm for the tube under test and checks for shorts and grid emissions. I also use a Tektronix curve tracer for testing triodes. I give a number of evaluations for tubes. One evaluation is a screen shot of the tube with a high voltage applied to the plate. This helps the buyer see the linearity of the tube in question at the highest voltage the tube will see in a real circuit. The Curve tracer steps the triode through 10 gate/grid voltages starting with -10 volts and going to 0 volts. The lines show how the tube conducts throughout that range. At 0 volt the tube is at max conduction and is the top line on the display. It is easy at that point to take where that top line intersects the plate voltage, find the milliamp level and compare it to the datasheet. I give those numbers for you in the Item condition box. To further help the buyer I also include the Design values, for gm and ma readings in the table. This can then be compared to other tube sellers using inferior test methods such as Hickok,  Amplitrex, and other testers. The Tektronix curve tracer gives values within 3% of the actual value. The very best portable testers only can approach 10% accuracy.5.    Please note: The numbers given for gm are what I see on my tester. I DO NOT guarantee that you will see those numbers on your tester. I only guarantee that these tubes will test good, with no shorts, or gas, on a decent calibrated tester. I dont guarantee or imply anything else.6. VERY IMPORTANT!!! Vintage tube testers almost always, due to age, have VERY LOW HEATER VOLTAGES!!!  Every tester I have ever bought is below 6 volts when selecting 6.3 volts. They average 5.8 volts. The voltage NEEDS to be 6.3 and 12.6. You can calibrate a vintage tube tester all you want. If the heater voltage is not right, you will NEVER get the right gm value. I have customers complain that their tubes are not the same as what I see on my tester. They say they have a calibrated tube tester. I have 40 tube testers. On all of them I have an outside regulated DC power supply that feeds the tube tester the correct heater voltage.7. I dont check each and every tube for noise or tone. This is SUBJECTIVE and it is too time consuming. If you dont like the noise level or the tone we offer a hassle free refund policy.  International customers note:1. Please wait for us to invoice you for the correct amount. If you have purchased more than one item, we must calculate how much the shipping will be. Shipping will be HIGHER due to insurance and shipping methods needed for expensive item totals. If you are buying only one item this will not be an issue. 2. Under no circumstances will we state on a US customs a declared value of less than the sale price. This is an honesty issue. We are honest with everyone to the best of our ability to do so. We want you to trust that what we say is true. There cannot be that trust, if we make false statements knowingly to anyone. If your country has tariffs/taxes so high that they cause large numbers of normally honest folks to make false statements, we urge you to work for change of those laws.3 International buyers if you bought more than one item and want combined shipping it will ship in 2 days.4. And all the Angels sang because the heavenly music was playing and it was turned all the way up.    Listing and template services provided by inkFrog

Mullard12AX7/ECC83Long PlateSquare GetterMade in England. Date Code: f91 B7FMade in June 1957 in Blackburn England. Fully tested by calibrated Hickok 539C tube testerwith no shorts, leakage or gas. Measurement: 1300/1680where minimum good value is 875 Tested in my preamplifier to make sure working as intended with no issues at all. I will gladly combine shipping upon request. __________ The tube(s) in this sale include a 30-day satisfaction guarantee.I strive to ensure you have a completely satisfactory purchase experience.If you are unhappy with your purchase for any reason,you can return the item for a full refund. Please contact me directly prior to opening a return or leaving feedback.I will almost always reply at least within 24 hours to remedy the situation for you with direct communication.