Brimar Factory Codes
Factory Codes
Some valve/tube manufacturers put a cryptic code on the glass, in addition to the normal valve type and logo etc. The factory code is often etched into the glass, so may remain when the normal printing has been rubbed off. The codes used by Philips/Mullard/Valvo etc. are well documented on the web (for example, see Philips Code List), but there is little information for the codes used by Brimar and other Thorn group brands (such as UK Mazda and later Ediswan).
I have gathered together some Brimar codes here. Some are gleaned from the web - I have tried to give correct attribution. Others are from my own collection - there seem to be lots of Mazda valves around on eBay in the UK at present.
Anyone owning Brimar/Mazda valves will know that their factory codes tend to be harder to read than the Philips ones, and more easily smudged. In many cases the code is less resilient than the normal printing, but there will be times when the code may be the only way of identifying the valve type so a list will hopefully be useful.
Structure of Brimar Codes
The suggestion given here is not my own, but gleaned from the Vintage Amps bulletin board - see the Wed Mar 07, 2007 9.08am post by saros141. A Brimar code consists of two parts. The first part is three characters, number-letter-number, which give the date of manufacture. The last number is the last digit of the year (so this suffers from the same ambiguity as the Philips code). The letter gives the month (A=January etc.), while the first number gives the week within the month. For example, 2C7 is the second week in March 1957 or 1967. However, I have a 6/30L2 (ECC804) which has a date code of 1N8 so are some letters omitted from the month code sequence, or is it more complicated than we think?
The second part is just a number, usually three or four digits long, which gives the valve type. Different versions of a particular valve type will have different numbers, although these may sometimes be grouped together. For example, 1573 and 1574 are types of ECC83 but so is 2162.
Between the two parts of the code there may be a slash /, or a space, or nothing at all. Sometimes it is difficult to distinguish a three-digit number preceded by a slash from a four-digit number with no separator, so there is some uncertainty in some of the four-digit codes starting with 1. For example, the code for ECC82 is said to be 1571 (see ref AA1), but I have some which are clearly marked 571. However, I have some 19AQ5 marked 660, and others marked 1660, so perhaps xyz and 1xyz are sometimes related? Digits 5 and 8 can look quite similar. The code may be horizontal or vertical, and could occur at almost any height on the glass envelope. Sometimes it will be obscured by the normal printing.
Brimar Codes
Ref Code Eu US Other Notes
DPK 195 EBC90 6AT6 DH77
DPK 229 EK90 6BE6 X727
DPK 244 6BR7 CV2135 see 8979
VA1 422 6V6GTY CV511
DPK 524 9BW6
DPK 557 12AH8
DPK 571 ECC82 12AU7 CV491 see also 1571
DPK 585 12BH7? valve is unmarked but looks internally like a 12BH7
DPK 660 HL90 19AQ5 150mA version of EL90/6AQ5, see also 1660
DPK 977 E83CC 12AX7WA CV4004, 6057 box anode, black, 1 flange, D getter - see 3977
DPK 1175 or 175? 6AK6
DPK 1224 EF93 6BA6 see 6224
DPK 1234 EF90 6BH6
DPK 1252 6BW6 see 3981
DPK 1274 EL821 6CH6 CV2127? see 3986
DPK 1291 PF818/EF812 7ED7/6EL7 30F5/6F23 30F5 and 6F23 are very similar, was one a mislabelling?
DPK 1294 EE80 6F28
DPK 1426 or 426? EZ90 6X4
VA1 1432 6X5GT
VA1 1565 ECC81 12AT7
AA1 1571 ECC82 12AU7 CV491, CV4003, 13D4, 13D5, 13D8 see also 571
DPK, VA1 1573 ECC83 12AX7 CV4004 half-boxed-plate
DPK, VA1 1574 ECC83 12AX7 14mm plate
DPK 1576 or 1876? ECC804 6GA8 6/30L2 I only have one of these; looks identical to 2195 version.
DPK 1660 HL90 19AQ5 150mA version of EL90/6AQ5, see also 660
DPK 1676 PCE800 9GB8 30FL2
DPK 1681 PCC805 7EK7 30L15
DPK 1682 PCC806 30L17
DPK 1686 PCL801 30PL1
DPK 1687 PCL800 16GK8 30PL13
DPK 1791 ECL82 6BM8 6PL12 pentode anode grey, staples facing out, no grid tabs, see 2242
DPK, VA1 1796 EL84 6BQ5
DPK 1822 PL84 15CW5 300mA version of EL86
DPK, VA1 2160 ECC81 12AT7 black wing anode with rounded end
DPK, VA1 2162 ECC83 12AX7 CV4004 14mm plate
DPK, JR1 2167 ECC88 6DJ8 see also 3910
DPK 2195 ECC804 6GA8 6/30L2 most of my ECC804 have this code
DPK 2242 ECL82 6BM8 6PL12 pentode anode black, staples facing in, grey heat tabs on control grid posts, see 1791
DPK 2510 PC97 4FY5
DPK 2520 PCC84 7AN7 30L1
DPK 2540 PCF80 9A8 30C1
DPK 2562 PCL84 15DQ8
DPK 2563 or 2568? 30PL15
DPK 2701 KY80 2J2 U26
TC1 3876 5965
JR1 3910 ECC88 6DJ8 see also 2167
VA1,DPK 3977 ECC83 12AX7 CV4004, 6057 box anode, grey, 1 flange, O getter - see 977
DPK 3980 ECC81 12AT7 CV4024 SQ version, black single-flange anode with square end
DPK 3981 6BW6 black anode, round getter, double support (see 1252)
DPK 3982? QV03/12 6062 CV4039, SQ 5763
DPK 3986 or 3988? EL821 6CH6 CV4055 see 1274
VA1 3987 ECC82 12AU7 CV4003 17mm plate
DPK 6224 EF93 6BA6 CV454 see 1224
DPK 8979 6BR7, 6059 CV4006, VX7081 SQ version? see 244
References
Ref Name Ref Location
AA1 Audio Asylum bulletin board
DPK My own collection
JR1 Jogis Roehrenbude website
TC1 Virtual Valve Museum
VA1 Vintage Amps bulletin board
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updated 26 Jan 2009: correct Philips link
