Fullwave Rectifier Substitution Box, Variable from 5Y3GT to SS Recto (no sag).
CCAP_SUB-FW Rectifier Substitution Box
Use: Fullwave (SS or Tube) rectifier substitution.
OK, I admit it. You can calculate circuit values until the cows come home but sometimes it’s so much easier and faster to just dial it in. I’ve been a ham and involved in engineering for over 35 years, and I gotta tell ya, these are undoubtedly some of the most indispensable tools I have ever had.
The C-Cap Sub Boxes are full wave or full wave bridge rectifiers with adjustable sag so you can emulate a tube rectifier of a certain type in the development of your high voltage circuit. The C-Cap Sub Box is adjustable from a 5Y3GT to a straight SS (no sag) rectifier and everything in between. For instance, if you determine by the setting on the C-Cap Sub Box that your amp sounds best between the setting of a 5V4 and a 5AR4/GZ34, you can use a 5AR4/GZ34 with a power resistor in series to split the difference between the two. The label on the C-Cap Sub Box indicates the approximate resistance between straight SS through and including a 5Y3GT, so you can do the math easily to determine that series resistor value.
This box is about 1/4″ taller than our copper cap module since it contains a rheostat. It also has two mounting feet on both ends, the same as the copper cap module. It may be installed in an amp permanently and used as an adjustable-sag rectifier.
The only issue is that the rheostat has a wiper and might move some due to the vibration in a combo amp or in a head sitting on a speaker cabinet. You could experience some slight noise or scratching sound if that occurs.