tntman Posted July 21, 2020 Share Posted July 21, 2020 (edited) Item Condition: 9/10 Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost. Suburb or Town: Sydney State: New South Wales Payment Method: Cash. PayID Reason for selling: NLR Further information: My current preamp can't use ECC83 anymore hence I am selling these extremely rare Mullards. They have about 500hours put on them at most, they are rated for 10000 hours. These are the golden gems of the ECC83 pre tubes. I will pack them carefully and arrange for transport of them via AusPost Express bag. Photos: Edited July 25, 2020 by tntman Price adjustment Link to comment Share on other sites More sharing options...
Murray Hodges Posted July 21, 2020 Share Posted July 21, 2020 I thought 10M’s had yellow print? What denotes that these are 10M’s if you don’t mind me asking. 2 Link to comment Share on other sites More sharing options...
Lochawe Posted July 21, 2020 Share Posted July 21, 2020 1 hour ago, Muzza71 said: I thought 10M’s had yellow print? Like this you mean? 5 Link to comment Share on other sites More sharing options...
Murray Hodges Posted July 21, 2020 Share Posted July 21, 2020 Exactly but 12AX7’s not 12AU7’s 1 Link to comment Share on other sites More sharing options...
tntman Posted July 21, 2020 Author Share Posted July 21, 2020 Sorry I made a mistake, these are not master series, they are just below them. I've updated price to reflect. Link to comment Share on other sites More sharing options...
doogie44 Posted July 22, 2020 Share Posted July 22, 2020 One is still drooling nevertheless...how good are NOS Mullards. GLWTS Link to comment Share on other sites More sharing options...
xlr8or Posted July 22, 2020 Share Posted July 22, 2020 They look to me to be I63 January 1969 Blackburn made with silver grid posts and welded perpendicular O getters. Link to comment Share on other sites More sharing options...
Lochawe Posted July 22, 2020 Share Posted July 22, 2020 41 minutes ago, xlr8or said: They look to me to be I63 January 1969 Blackburn made with silver grid posts and welded perpendicular O getters. Not sure what 163 January means, but I am intrigued how can you determine year of manufacture – I cannot see any date codes on these tubes? 1 Link to comment Share on other sites More sharing options...
xlr8or Posted July 22, 2020 Share Posted July 22, 2020 (edited) 6 hours ago, Aperalim said: Not sure what 163 January means, but I am intrigued how can you determine year of manufacture – I cannot see any date codes on these tubes? The left valve in the 4th photo above shows the horizontal etched date code of B9A* just to the left of the Made in Great Britain white print. The asterisk should be a number representing the week of manufacture but it's long gone from the glass envelope most likely smeared off with time. B represents Blackburn, 9 is the year of manufacture, in this specific case 1969, and A is the month of manufacture, January. The distinct features of 14 mm short grey anode plates, silver grid posts and the perpendicular O ring getter with a welded connection 3/4 along the height of the support rod identifies the revision code of I63. I am not going to comment on the gold plated pins. How the revisions codes progressed are I600, mC1, f91, f92, I61 and I63. Within each revision code there were several versions having distinct features - for example, in the I600 series, the prized possessions, there were 3 variants: black welded 17 mm toasted plate copper grid post wrinkle/mottled glass square goal post getters; grey welded 17 mm plate copper grid wrinkle/mottled glass square goal post getters; and, grey crimped 17 mm plate copper grid post clear glass square goal post getters. I can write books and books on this stuff. To the trained eye these things are very easy to spot. Edited July 22, 2020 by xlr8or 3 1 Link to comment Share on other sites More sharing options...
LogicprObe Posted July 22, 2020 Share Posted July 22, 2020 Goes off to check out stash of Mullards................. 2 Link to comment Share on other sites More sharing options...
Luc Posted July 22, 2020 Share Posted July 22, 2020 (edited) 5 hours ago, xlr8or said: To the trained eye these things are very easy to spot. Wow!. I was fascinated reading that explanation. @ OP , sorry for topic drift in your FS ad. But I've got to ask. How much would the master series tubes sell for? Edit: And what makes the yellow ones better? Edited July 22, 2020 by Luc Link to comment Share on other sites More sharing options...
sakabatou Posted July 22, 2020 Share Posted July 22, 2020 6 hours ago, xlr8or said: I can write books and books on this stuff. Maybe you should? I found this fascinating, but clearly I’m off topic for a FS post Link to comment Share on other sites More sharing options...
LogicprObe Posted July 23, 2020 Share Posted July 23, 2020 Don't worry............a good discussion keeps bumping his ad! 1 Link to comment Share on other sites More sharing options...
xlr8or Posted July 23, 2020 Share Posted July 23, 2020 12 hours ago, Luc said: Wow!. I was fascinated reading that explanation. @ OP , sorry for topic drift in your FS ad. But I've got to ask. How much would the master series tubes sell for? Edit: And what makes the yellow ones better? The 10M series are distinctly recognisable by the 2 inherent features of yellow print identifying the 10M label and gold plated pins. These valves were specifically hand selected for GPO and highly specialised applications requiring very tight tolerances in the matching of the dual triodes. They also exhibited very low microphonics and noise, and are most commonly selected for use in phono stage input or gain V1 or V2 positions in modern audiophile applications where low microphonics are highly desirable. They appeared in the 1960's and are the equivalent of comparing a CCa valve with an E88CC valve from the exact same factory made at the exact same time with the exact same manufacturing code. These valves were measured, tested and labelled for highly specified telephony applications. Think cold war, nuclear fallout and the criticality of comms in pilot warfare chasing those invisible migs and you get the message. Happy to answer any other queries off-line and refocus the post back to the OP's FS listing. 1 Link to comment Share on other sites More sharing options...
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