In late 1964 or early 1965, Richard purchased this Magnatone M13 Imperial amplifier, brand new, from a music shop in Pharr, Texas for $530.00. It came with two foot switches, a black vinyl cover and a four to five foot detatchable power cord. Listed at $650.00, Richard got a really good deal.

Made by Estey musical Instrument Corp. in Torrance, California the M13 Imperial has one of the most intricate, fascinating schematics that I have ever encountered, so follow this closely. It has 3 channels, each with high and low gain inputs, and a stereo input - for a total of 7 input jacks. Each of the 3 channels is preamp'd by half of a 7025 dual triode tube.

Channel 1 has bass and treble controls, as well as a treble plus/tone boost/bright/mellow contour switch. The tone section is driven with half of a 7025 dual triode tube and half of a 7247 split-mu dual triode tube. Channel 1 also has a vibrato circuit. Half of a 7025 creates the LFO (low frequency oscillator) to drive the 12AU7 dual triode pitch shifters.

Channel 2 has a volume control, a mellow/normal/bright contour switch, and a tone control. Meanwhile, Channel 3 has a volume control and a tone control. All three channels are sent to the reverb circuit and have individual level controls. Both sides of a 12AU7 dual triode drive the reverb input. The reverb return is amplified by a 7025 dual triode. A 7247 split-mu dual triode is used in the last gain section and for phase inversion. Two 6CA7 power pentode tube drive the output transformer, which is then internally switched between 4/8-ohm via the external speaker jacks and internal 8-ohm, 15-inch Jensen speaker and four 5-inch midrange tweeters. Power supply transformer numbers read: 20-0121 and 606521. The M13 is one of the "Cadillacs" of the guitar amp world.

Approx. 30-watts
Serial Number: Not available
Owner: Richard W. Brown, Not For Sale
Photo: ©1999 Richard W. Brown. Used by permission.