1972 AMPEG SVT
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For the first part of 1972, SVT serial numbers were stamped into the chassis, seen through a "cutout" in the middle of the removable back panel. The cutout was located between the standby switch and the external amp jack. During the year (sometime after # 11217x) the serial number was no longer stamped into the chassis, therefore the back panel cutout was omitted. The serial number was now a sticker on the back panel right side. There was occasionally an additional serial number sticker inside the wooden box or on the chassis. During the year, the face of the speaker cabinet began to be sprayed black and also included a serial number sticker.
Other 1972 SVT characteristics: "Blueline" silkscreened graphics with detail etched into the metal, two channels, small black "D shaft" knobs with silver tops, black plastic tone adjustment rocker switches, two metal power switches (with at least one black), small round red power light, silver grille cloth with no badge logo, preamp mounted underneath box top, exposed plastic fan, two prong power cord and outlet, fuse, 4 pin XLR speaker cable, Linden or Magnavox manufacturing stamp, four metal cord wraps, black painted chassis, (3) black transformers: power, filament and output, 6550 power tubes, circuit boards, capacitors, CTS potentiometers with metal "D shafts", vinyl handles, vinyl covering over black painted wooden box, tube chart sticker, manila envelope containing schematic, six rubber feet, eight chassis connector bolts, 8x10 inch speaker cabinet with three handles, metal bullseye logo, CTS speakers and matching dolly, literature.
Ampeg serial number dating is undocumented and very difficult. Some examples of 1972 SVT serial numbers are 10847x, 11030x, 11220x, 1274x and 1707x. For more precise dating cross reference the serial number with the amplifier's transformer, potentiometer, capacitor and speaker codes.
Component code dating vintage SVT's: As with all vintage gear, the manufacture date is determined by the newest component/date stamp on the unit. On vintage SVT's, the newest date code on the unit is usually the four digit white ink stamp on the large output transformer. The first two numbers indicate the year, the third and fourth numbers indicate the production week of that year. Example: 7211 means a transformer made in the 11th week of 1972.
Other codes to determine the manufacture date: The other large power transformer and the adjacent smaller filament transformer should both have six digit codes stamped into the metal. The first three digits indicate the company's personal manufacturing code. Those should be 682, which indicate the Electrical Windings Company. The fourth number indicates the year. The fifth and sixth numbers indicate which week of that year.
Potentiometers are also date encoded. There is a seven digit code stamped into the metal. The first three digits indicate the company's personal manufacturing code. Those should be 137, which indicate Chicago Telephone Supply or CTS. The fourth and fifth numbers indicate the year. The sixth and seventh numbers indicate which week of that year. Capacitors and speakers can also be dated in a similar manner.