Originally Posted by koike
Originally Posted by tomb
No tweaks* - the E90CC/5920 is a drop-in replacement for the 6J6, but it is quite a bit superior - less noise floor, less distortion. An additional benefit is that they are tall enough that you can swap them out without taking the case lid off.
* Just to be sure, you need to implement both the zener diode tweak and the heater rectifier snubber caps. Those are the primary differences from the early Torpedo prototypes and kits versus now. Both make a huge difference.
I can't quite remember when I built my torpedo. I believe it has the Zener diode tweak. But regarding the heater rectifier snubber caps. I don't believe I've done that.
I think I built mine when you first released black cases.
You should do the snubber cap tweak. It finally removes all noise. The noise we thought was power supply ripple was actually around ~160 Hz. It was caused by the power transformer picking up the switching noise from the rectifiers and injecting it through the rest of the amplifier circuit. It's also very simple to fix - you just solder some small ceramic axial caps across the leads of each heater rectifier (D5, D6, D7, D8) on the bottom of the PCB. It helps to replace the rectifiers, too, to ones that were not so super-fast in their switching cycle (BY228GP). I thought that I had this detailed on the website, but I'll fix that today.
PM me your address and I'll send you the caps and the rectifiers for free.
Edited by tomb - 11/20/15 at 7:52pm