(sorry for the cross-post w/ tapeop)
Ok so kinda newbie to figuring this stuff out but I'm changing out the UTC transformers in my ADM 780s with the JLM input transformers. I know I'm right on where I'm putting the leads, but what I'm not sure of is the resistor value across the secondary.
Check out the ADM schematic posted here:
Going by info on other preamps from Eisen audio (http://www.eisenaudio.com/diy500/tables/ipxfmrs/) and JLM (http://www.jlmaudio.com/Baby_Animal_Mic_Pre.htm), the JLM doesn't need a zobel network and should have a 10k resistor across the secondary.
Applying that to what I see on my schematics, it looks like r55 (75k on schematic) should be the 10k, r53 and c25 in series are the zobel network that can be removed. Am I right? C 26 should be left as-is, right?
Also, the mu-metal can on the UTC had a screw terminal to ground. Should I do this with the JLM too or not needed?
Ok so kinda newbie to figuring this stuff out but I'm changing out the UTC transformers in my ADM 780s with the JLM input transformers. I know I'm right on where I'm putting the leads, but what I'm not sure of is the resistor value across the secondary.
Check out the ADM schematic posted here:
Going by info on other preamps from Eisen audio (http://www.eisenaudio.com/diy500/tables/ipxfmrs/) and JLM (http://www.jlmaudio.com/Baby_Animal_Mic_Pre.htm), the JLM doesn't need a zobel network and should have a 10k resistor across the secondary.
Applying that to what I see on my schematics, it looks like r55 (75k on schematic) should be the 10k, r53 and c25 in series are the zobel network that can be removed. Am I right? C 26 should be left as-is, right?
Also, the mu-metal can on the UTC had a screw terminal to ground. Should I do this with the JLM too or not needed?
