#164763  by waldo041
 Thu Feb 14, 2019 4:51 pm
R/C Filter Calculator

Duncan Tonestack Calculator

Cathode Capacitor Calculator
https://www.ampbooks.com/mobile/amplifi ... capacitor/

Resistor and Capacitor decade boxes help as well as a 4 and 8 ohm dummy load resistors with the correct wattage. A signal generator, current limiting device and Oscope also help to get even more detailed in your search.


milobender liked this
 #164800  by waldo041
 Mon Feb 18, 2019 9:06 am
Jblue76 wrote:
Mon Feb 18, 2019 7:31 am
Anyone know where to buy a polystyrene 250pF 400v cap for the treble?
get a 250 mica.

 #164895  by Jblue76
 Sat Feb 23, 2019 11:41 am
Hey all,
Just dropped off my amp to get all fixed up with the new parts and connected to the Mac! Thanks again to everyone for all your help and patience.

How important is taking out the 68k resistors at the input and using switching jacks? The tech suggested having no resistor there can lead to a squealing noise and he advised against taking them out. Thoughts?

Thanks again!
 #164898  by waldo041
 Sat Feb 23, 2019 1:08 pm
It is possible he does not know how to wire the switching jack so he is advising against doing that mod. Squeal? RF interference possibly, if the unit is not shielded correctly, but I have never had it "Squeling" because i removed the 68k input grid resistance.

 #164899  by Jblue76
 Sat Feb 23, 2019 1:17 pm
Thanks. He may not have said squeal— can’t recall the adjective, but it sounded undesirable... Is there a better instruction I can give him, explaining how the switching jacks need to be wired? All I said to him was remove the 68k resisters and put in switching jacks.