I rarely ever use the term the holy Grail when it comes to tubes, but for Guitar tone this is it.

I chose very good condition because they don’t have a very good Excellent and I would say that one of the tubes is Excellent. One of the tubes is between very good and excellent excellent and the other one is very good cosmetically speaking.

Up for grabs here is an excellent condition June 1957 matched trio (matched codes, strength, matched construction, matched revision) long plate - top goal post square getter Mullard mC1 BF7 Blackburn factory 12AX7/ECC83 tubes.

If you want matching vintage Mullard in V1, V2 and V3 in your Marshall here’s the holy Grail

These tubes are hard to find even as singles to find a trio match like this with identical codes, and great printing that test strong as these is unheard of

These tubes were tested for leaks, shorts, and quality/emissions issues on a calibrated mercury model 1000 where the phenomenal new old stock average is 1000 µ℧ and the new Old stock average range is 900 µ℧ to 1100 µ℧, these tubes are all testing between roughly 800µ℧ and 900 µ℧ with one line testing a little higher at 925 µ℧ these tubes in essence are about 88-92% strength remaining according to my testers nominal test data.

WOW!!! the tubes have been lightly used, but an incredible condition from 1957 and an exceptional match to trio unheard of in 2027. These tubes just turned 70 years old in June and they still have very nice bold shield logos and matching printing Matching codes and they are nicely matched in GM.