Dynaco ST-120 60 WPC stereo TUBE amplifier KIT

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Up for Buy It Now is a new Dynaco "ST-120" stereo tube amplifier KIT. This is the 60 watt per channel version of the upgraded Dynaco ST-70 KIT that I also sell. It is built on the same Dynaco ST-70 stainless steel chassis and contains all new parts. T are no recycled parts from any original Dynaco tube amplifier. It differs from the ST-70 kit in the following ways .. 1. The VTA driver board, as used on the ST-70, has a number of modifications for use on the ST-120 to better drive 6550 or KT88 output tubes. 2. The ST-120 power transformer has the same footprint as the PA-060 transformer found on the original Dynaco ST-70 amplifier but has a 2.7 inch stack lamination and puts out 420-0-420 volts on the secondaries @ 425 milliamps. This transformer weighs about 5 pounds more than an original PA-060 power transformer. Over 490 volts DC are seen on pin 3 (plate) and pin 4 (the ultralinear screen tap) of the output tubes. 3. The two output transformers used on the ST-120 are USA made and feature interleaved/layer windings with M6 silicon steel grain oriented laminations. They have 4200 ohm primaries and 40% ultralinear screen taps. They are 3 7/8" tall, 3 1/4" wide and 3 1/8" deep (about 1/2" taller, 3/8" wider and 1/4" deeper than a stock A-470 output transformer). Each output transformer has 4, 8 and 16 ohm secondaries and weighs about 2 pounds more than a stock A-470 output transformer as found on the ST-70. (See comparison photos ..) 4. The amp uses TWO C24-X chokes which together can handle 480 milliamps of current flow. 5. This ST-120 features a Supplementary Cap Module or "SCM" which adds another 165 Mfd of power storage. The power supply also uses a set of wideband bypass capacitors for ESL reduction. 6. The fuse is a 5 amp slo-blo fuse instead of a 3 amp slo-blo as on the ST-70 NOTE - The tubes are OPTIONAL on this amp kit. 6550 or KT88 or KT90 output tubes may be used with this amp. Recommended bias voltage is .550 volts DC for each output tube which provides a bias current of 55 milliamps per tube. The other tubes are 3 X 12AT7 and one GZ34 or one solid state rectifier. The kit contains the following items listed below ... 1 - Assembly manual with pictorial and full color interior wiring photo 1 - Stainless Steel chassis frame with all original Dynaco markings 1 - VTA driver board with parts set 7 - Quality Celanex octal tube sockets 1 - PA-060-120 power transformer with bottom plate 4 - Neoprene isolation washers for the power transformer 2 - A-260-120 USA made custom interleave/layer wound output transformers 2 - C24-X chokes 1 - multi section (80, 40, 30, 20 Mfd) quadruple electrolytic capacitor 1 - three lug terminal strip 2 - main grounding lugs 1 - pair of gold plated RCA input jack jacks with mounting board 2 - pair of gold plated output binding posts with mounting board 1 - rubber grommet 1 - fuse post with 5 amp SLO-BLO fuse 2 - SPST 11 amp rated slide switches 1 - 13 amp rated AC power cord 2 - .022 Mfd 600 volt capacitors 4 - 1000 ohm 1 watt resistors 4 - 10 ohm 2 watt bias resistors 1 - 7500 ohm 2 watt resistor 1 - Supplementary Cap Module (SCM) 1 - set of wideband ESL reduction capacitors 1 - hardware kit for amp with all stainless steel screws 1 - 22 foot coil of 20 gauge tinned solid core copper wire 1 - 600 volt rated triode/pentode kit for both channels $819 + shipping for the complete kit LESS TUBES - One year warranty on all parts OPTIONAL tube set for this amp kit - 4 X (Sovtek) KT88 (matched quad), 3 X 12AT7 and one rectifier (customer choice of tube or solid state rectifier) + $159 OTHER OPTIONS available 1. Hand matched set of 4 Russian PIO K40-Y .22 Mfd @ 1000 volts coupling caps + $30 2. Driver board upgrade power supply caps... read more

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