OFF - FOR SALE: McAlister MA44 Amp
Item #649212848Info: McAlister MA44 Amp
||9 - Excellent (?)
Jul 04, 17 11:42am (PST)
Edited: Nov 14, 17 9:45am
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Just completely tech serviced and has new tubes with less than 25 hours, brand new output transformer, this amp is in a rotation of 6 amps and sees very little playing time, has excellent sound, and is in excellent condition.
The MA-44 stereo power amplifier utilizes four horizontal output tubes paralleled in triode mode to produce 22watts per channel in class A. The input stage for each channel utilizes my proprietary constant current/infinite plate load resistance design that combines both triode sections of a 6N1P as the voltage amplifier and a 6CL6 as the current source . This is a true constant current source with more than enough gain to properly respond to the small signal / voltage changes without a plate load resistor dropping large amounts of voltage typically in cascade designs. The driver stage uses a 6SN7of which one triode provides regulation with the other triode directly driving the output tubes in a cathode follower configuration without the need for capacitors. The only capacitors in the signal path are between the input and driver stage. The output stage for each channel consists of four 12DQ6 horizontal sweep tubes paralleled in triode mode with class A operation. No coupling capacitors are used to drive the output tube grids so in effect all tubes are connected together as one. This output configuration can pass a large amount of current with harmonic distortion in dB relative fundamental of 2nd -26, 3rd -44, and 4th - 60. A separate and well regulated bias supply with external top mounted chassis adjustment. The negative voltage is adjustable and fed to the control grid of the drive tube which determines the current flow in the output tubes. All of my power amplifier designs use a fixed bias voltage that eliminates the cathode resistor and electrolytic by-pass cap producing an amplifier with fast rise time, superior dynamics and transparency. The output transformers are custom designed and hand wound with four primary and three secondary interleaved sections with each layer varnished prior to insulation. The power supply has over 2,000uf of capacitance by-passed with film capacitors- electrolytic capacitors are only used in the power supply and never in the signal path. Plate voltage is delayed 30 seconds to prevent cathode stripping. This automatic system uses a damper diode providing D.C. relay voltage through a controlled warm up. Wiring is point to point with no circuit traces. A Separate power supply chassis that contains only transformers and relays with all rectification and regulation in the amplifier chassis. Only AC travels through the umbilical isolating D.C. signal voltages ensuring no possibility of interference .
Only film capacitors in the signal path
Hardwired point to point
Proprietary input and driver stage design directly connected to the output tubes
Special output transformer design
Thermal delay to prevent cathode stripping
Dimensions: 19”W x 14”D
Power Supply Dimensions: 12”W x 8”D
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