EIA Codes, Dating, & Interpretation:

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Praise Him above ye Heavenly host, Praise Father, Son, and Holy Ghost. Amen."


If you want to date a guitar, amp, or other piece of equipment, a great way to do it is by correctly interpreting
the numbers stamped on a pot, cap, transformer, or other such part on the unit in question.
Code formats were never completely standardized, but a little deciphering will generally yield the information of interest.
  Note that many makers also stamped OEM numbers above or below the EIA code,
and in some cases parts makers elected not to include the EIA codes at all, so not all items or parts have them.
But, as an example, most US made speakers and pots have their EIA manufacurers's code printed or stamped on them.

They generally follow the following format:
(this particular example was off a pot on an Electro Harmonix effect pedal)

  137-7704

where 137 is the manufacturer code (in this case CTS), 77 is the year (1977), and 04 is the week.

  An alternate scheme is:
(this one off an old Jensen speaker)

220 940

whereby 220 is the EIA code (Jensen), 9 is the last digit of the year (in this case 1949), and the 40th week
Usually single digit date codes are from the 1940's, but have shown up in later decades even up through the 1970's.
If you have a general idea of the age of the item in question, usually the decade can be divined from that.

Another alternate is in the following format:

  188-5 69 32

188 is General Electric, 5 is the plant code, and 69 32 is 1969, 32nd week.

And one more is like this:

322 6104-1

322 is Tungsol, 6104 is 1961, 4th week, and 1 is the shift code.

Following is a list of manufacturers codes I've gleaned from a number of sources of the years.
If I've got any wrong or you know of any others, please  e-mail me and let me know!

Becker 24
Cornell-Dubilier 34
Eminence 67
Admiral 101
Aerovox Corp 102
Allen-Bradley 106
American Condensor 109
Amperex 111
Credence 117
Automatic Man. 119
Bendix 125
Panasonic / Matsushita 130
Talk-a-Phone 132
Centralab 134
Chicago Condensor 135
CTS (Chicago Telephone Supply) 137
Stancor (Chicago-Standard) 138
Cinch 139
Clarostat 140
Coil Engineering 141
Consolidated / Cinaudagraph 145
Crescent 150
Crosley 152
DuMont 158
Eby 160
Eimac (Eitel-McCullough, Inc) 162
Aerovox Hi-Q Division 163
Electronic Tube Corp. / Hitachi 169
Ensign Coil 172
Erie 173
Essex 175
John E Fast 178
Freed 183
Motorola 185
Gates 187
General Electric 188
General Radio 194
Hallicrafters 199
Hammarlund 201
Hytron (CBS-Hytron) 210
Dearborn Wire 213
IRC (International Resistance Co) 214
Jackson 216
Jefferson Electric 218
Jensen 220
E F Johnson 222
Kester 224
Lenz 228
Littlefuse 230
Machlett 231
Magnavox 232
Mallory 235
Thordarsen-Meissner 238
Merit Coil & Transformer 239
Micamold 240
James Millen 242
Muter 244
National Co. 245
Arvin 248
Ohmite 251
DuKane (Operadio) 252
Packard Bell 254
Philco 260
Philmore 262
Pilot 264
Quam-Nichols 270
Radio Condensor Company 273
RCA (Radio Corp of America) 274
Radio Craftsmen 275
Emerson / Radio Speaker 277
Raytheon 280
Rola 285
Ross 286
J P Seeburg 289
Mark Simpson (MASCO) 295
Solar 296
Speer 300
Sprague 303
Stackpole 304
Standard Coil 305
Stromberg 308
Superior Tube Co 310
Sylvania (Hygrade Sylvania Corp) 312
Triplett 321
Tung-Sol 322
United Electronics 323
Utah 328
Wells-Gardner 334
Western Electric 336
Westinghouse 337
Weston 338
Zenith 343
Astatic 345
Essex (Transformer Division) 352
New York Transformer 366
Best 371
Bourns Networks 381
Altec Lansing - Peerless 391
Foster Transformer 394
General Cement 396
BIC 409
General Transformer 412
Heath 416
United Transformer Corp (UTC) 418
North Amer. Philips Corp (Norelco) 423
Cleveland 433
Newcomb 437
Gudeman 438
Collins 439
Cannon 440
Good-All 446
Wilder 449
Empire Coil 452
Barker & Wiiliamson 461
Oxford 465
Delco 466
Pyramid 472
Radio-Television Products Corp 489
Caledonia 503
Hickok 508
United Condensor 516
Triwec Transformer 524
Ward Leonard 532
Anaconda 547
Midwest Coil & Transformer 549
Standard Winding Co 550
ATR 551
Amphenol 554
Waldam Elect. 555
Electrical Utilities Corp 569
F & V Coil Winding 572
Heppner 575
Belden 579
Bogen 589
Shure Brothers 590
Woodward-Schumacher 606
Consolidated 607
Simpson Electric 614
Illinois Capacitor (Condensor) 616
Pickering (Stanton) 631
Central Coil 637
American Radionic 648
Electro-Voice 649
Sangamo 658
Standard Electric Products 668
Electrical Windings 682
Keystone 699
Ajax 705
Pioneer 706
Bell 708
Standard Condensor 710
Taylor (aka Cetron-Taylor) 713
Carbonneau 719
Methode 720
Milwaukee Resistor 722
RMC (Radio Materials Corp) 732
Alpha 733
Lewis & Kaufman 738
Esquire 742
Russell 748
National Electronics (also Cetron) 749
Universal 756
Grand Transformers 757
Quincy 767
Penta Laboratories 771
Muntz 772
Forest Electric 773
Ogden Coil & Transformer 776
Vacuum Tube Products 781
Sonotone 787
McGregor 789
McIntosh 793
Harman Kardon 794
Atlas 795
Varian Associates 809
Dale 816
Midland 828
Triad 830
Better Coil & Transformer 831
Ampex 840
Tetrad 842
Klipsch 843
Internat. Rectifier Semiconductors 845
University 847
Drake 851
Precision (Grommes) 871
Acro Products (Acrosound) 878
Litton Industries 879
Mohawk 883
Condensor Manufacturers 885
Connector Corp 888
American Transformer 892
Tresco 897
Coilcraft 906
Aerocoil 908
Oaktron 918
Todd Electric Co. 926
Acme Coil & Transformer 928
Atlas 932
Magnetic Coil Mfring 933
Electrons, Inc 935
Northlake 1005
Pacific 1052
Fisher 1056
Channel 1059
Pyle 1098
Acoustic Fiber Sound 1113
Accutronics 1120
Hammond
1122
Curtis Mathes 1149
Micro Magnet 1191
Weber VST 1279






























Celestion Speaker Dating:

Since 1956, all Celestion chassis drivers have been stamped with a date code (2 numbers and 2 letters),
denoting the exact date of manufacture. The codes are added on the production line and are placed on the speaker's housing
 leg or the magnet edge. The following lists provide an accurate record of the date codes used.

1956 - 1962

YEAR
CODE
 
MONTH
CODE
1956 A   January A
1957 B   February B
1958 C   March C
1959 D   April  D
1960 E   May E
1961 F   June F
1962 G   July G
      August  H
      September I
      October J
      November  K
      December L

The date codes from 1956 to 1962 are written in the form: Day, Month, Year. For example: 15DE = 15th April 1960

1963 - 1967

YEAR
CODE
 
MONTH
CODE
1963 H   January A
1964 J   February B
1965 K   March C
1966 L   April  D
1967 M   May E
      June F
      July G
      August  H
      September J
      October K
      November  L
      December M

Note the loss of the 'I' from the month codes. The date codes from 1963 to 1967 are written in the form: Day, Month, Year.
For example: 19MK = 19th December 1965

1968 - 1991

YEAR
CODE
 
MONTH
CODE
1968 A   January A
1969 B   February B
1970 C   March C
1971 D   April  D
1972 R   May E
1973 F   June F
1974 G   July G
1975 H   August  H
1976 J   September J
1977 K   October K
1978 L   November  L
1979 M   December M
1980 N      
1981 P      
1982 Q      
1983 R      
1984 S      
1985 T      
1986 U      
1987 V      
1988 W      
1989 X      
1990 Y      
1991 Z/A      

The date codes from 1968 to 1991 are written in the form: Month, Year, Day. For example: KH7 = 7th October 1975

1992 -

YEAR
CODE
 
MONTH
CODE
1992 B   January A
1992 V   February B
1993 D   March C
1995 E   April  D
1996 F   May E
1997 G   June F
1998 H   July G
1999 J   August  H
2000 K   September J
2001 L   October K
2002 M   November  L
2003 N   December M
2004 P      
2005 Q      

The date codes from 1992 are written in the form: Day, Month, Year. For example: 29EJ = 29th May 1999

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