1976 AMPEG SVT
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1976 was a major transition year for the SVT's appearance. The silkscreened "blackline" graphics transitioned to black graphics with rounded corners. The plastic rocker switches transitioned from black to white. The metal power switches transitioned to a white plastic rectangular power switch and the small round red power light changed to a rectangular power light.
Other SVT characteristics: Two channels, small black D shaft knobs with silver tops, silver grille cloth with plastic badge logo, preamp mounted underneath box top, Magnavox manufacturing, non exposed fan, fuse, three prong power cord and outlet, four metal cord wraps, black painted chassis, (3) black transformers: power, filament and output, 6550 power tubes, circuit boards, capacitors, vinyl handles, vinyl covering over black painted wooden box, tube chart sticker, manila envelope containing schematic, chrome sheet metal plate mounted to inside bottom of box, six rubber feet, eight chassis connector bolts bolts, 8x10 inch speakers, "tilt back" speaker cabinet with "towel bar" handle,
1976 SVT serial numbers were located on a sticker inside the box, on the back panel left or right side and on the back plate of the speaker cabinet. Ampeg serial number dating is undocumented and very difficult. Some examples of 1976 SVT serial numbers are 7476x and 12737x. 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, we've consistently seen the newest date code on the unit as being the four digit white ink stamp on the large output transformer. The first two numbers indicate the year, the third and fourth numbers indicate which week of that year.
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. Again, 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.