by arledgsc Wed Oct 09, 2013 8:22 am
You have to be careful using the SS rectifiers. This SS rectifier looks OK but is it compatible for the application you are using? 1). Without series resistance the voltage output is higher than with tube rectifier or Weber WZ34 or WZ68. In an ST-120 the voltage at the first three capacitors downstream would be very close the capacitors' maximum working voltage of 550V dc. 2). A relay board or standby switch to hold off the high voltage until other tubes heat up sufficiently would be needed or otherwise you risk blowing your expensive tubes at the moment of power on. 3). Bias voltage range adjustment may be needed to compensate for the voltage increase. 4). Inrush current would be large until the capacitors charge up. With no series resistance the uncharged caps look like a dead short circuit for a split second.
But in the right circuit the SS rectifier would be not only less expensive but more efficient as well. Some people don't like them and think they sound sterile. In my case I am perfectly happy with the WZ68 in the ST-120 which is a nice compromise in this amp. The Tube Depot's SS uses 1N5408 diodes which are beefy and can handle 3A of continuous current. So nothing marginal in their implementation.