The new ST-120 Amplifier is now available. It has an output of 60 watts per channel with both channels driven from 17 Hz to 30,000 Hz at less than 1 % harmonic distortion. Contact Bob Latino at 508-347-9120 or Email at > Bob01605@aol.com for more information about the amp or to purchase an amp.
ST-120 amplifier internal wiring. The amp uses TWO C24-X or C-354 chokes which together can handle over 400 milliamps of current flow. The quad cap is an 80, 40, 30, 20 Mfd cap. Voltage on the first section of the quad cap is slightly over 500 volts DC. Also included in the power supply is a Supplementary Cap Module or SCM on a terminal strip bolted to one of the right side choke screws. The SCM adds an extra 165 μf of power storage. The fuse is a 5 amp slo-blo fuse instead of a 3 amp slo-blo as on the ST-70 The amp with tubes is shipped with a matched quad of KT88 tubes. 6550 or KT90's may also be used in this amp. Recommended bias voltage is .550 volts DC for each output tube which provides a bias current of 55 milliamps per tube. Where the ST-70 is a 35 watt per channel amp, the ST-120 will put out 60 watts per channel with both channels driven from 17 Hz to 30,000 Hz at less than 1 % harmonic distortion.
Comparison photo of a stock ST-70 and the ST-120 showing the differences in the transformer sizes. The ST-120 amp KIT is available for $980 with all tubes and $819 with NO TUBES. The ST-120 is also available wired and tested - $1,295 with all tubes or $1,145 with NO TUBES Shipping weight = 45 pounds Contact Bob Latino at 508-347-9120 or Email at > Bob01605@aol.com for more information about the amp or to purchase an amp.
This composite photo shows a square wave comparison between the old Dynaco 60 WPC Mark III with the original 6AN8 driver board and my 60 WPC ST-120 amplifier with the updated (and modified VTA driver board) at 10 KHz. There are a few changes that have been made to the components on the ST-120 VTA driver board as opposed to the driver board on the VTA ST-70 amp. These changes in a few components better deal with the higher voltages and larger current needs of the ST-120 amp. The comparison photo shows a quicker rise time, wider bandwidth and lower phase shift of the new amp.