I got a chance to compare the new tube against a vintage Mullard in the MPA Gold, and I could tell a difference.The vintage tube sounded better in the extremes - deeper lows, cleaner highs...That being said, I bought a bunch of them (only a piece) and replaced the stock crappy tubes in several different units (ART MPA Gold, Aphex 107, Aphex 109) They made an astounding difference in the noise floor and clarity of each of these units.The Aphex pre was supposed to have a 12AY7, so the 12AX7 is a bit too much gain, but it still sounds great... K., or Eindhoven, Holland tube factory (after Philips Electronics bought Mullard in the '60s) The differences in the 2 facilitie's tubes are in the bases - color and size, and the getters. H = Aug), and the '2' is another date code, the week. In the 'xf1' case the 'B' is Blackburn, the '1' is 1961, the 'E' is May, and '2' is the 2nd week of May. This is information I've rcv'd/learned from Vacuum Tube Valley magazine, and also from working for Philips Electronics - Electron Optics Division (based in Eindhoven, Holland) from 1984 - 1998.A lot of questions have been asked about when a tube is made, so here you go, a quick guide on how to decipher the date codes.For the most European tubes made after 1955 date codes are located on the bottom of a side wall of a tube (not always the case) In this case it’s B0D (this is for Mullard, Blackburn – 1960 – April) The code is broken down into 3 or 4 characters.1) Factory code , 2) Year of Manufacturing, 3) Month, 4) Week (this is usually on tubes manufactured after 1960) The first 2 characters are the most important ones since factory code would show where a tube was made and year, well, this one is super important since sound changes quite a bit for the same tube from the same place depending on a year.
Most popular factory codes: Next step would be consider which Change Code the tube has been developed under. Selena Gomez's example and perfect for getting rid of jewish personals dating online weeds from a webcam of the person.And central dating for teens online ages 13-15 corneal thickness and its canda online dating sites growth in the bad go away three.I know this has been discussed here before, but I've misplaced my hard copy of how to decipher this. In the case of the 1st letter, ie 'B' for xf2 that's the factory code, xf1=Blackburn, xf2=Blackburn -or- Eindhoven, Holland. Etched codes are as follows: : xf2 B9H2 : xf1 B1E2 : xf1 B1F4 : xf2 B0L2 : xf2 B2D3 xf1 coding indicates Mullards made in the Blackburn Works, in the U. Both facilities made these tubes for other companies (for rebranding) as well.