Sound Skulptor forums

Build help and troubleshooting => MP573 Microphone preamplifier => Topic started by: biasvoltage on August 03, 2024, 05:54:28 AM

Title: Input impedance of older, non-switchable MP573?
Post by: biasvoltage on August 03, 2024, 05:54:28 AM

Hi JPK - I have an MP573 that I built in 2015, that does not have the input impedance switch. I'd like to build another to pair it with, and was wondering what the nominal impedance of the input is on the original one so I can set the switch on the new one to match.  

Title: Re: Input impedance of older, non-switchable MP573?
Post by: JPK on August 04, 2024, 06:32:00 PM

The input impedance can be set with the jumper JMP1 (in front of the input transformer):
o   o - o   o     1200 ohms
o - o   o - o     300 ohms

Title: Re: Input impedance of older, non-switchable MP573?
Post by: biasvoltage on August 04, 2024, 08:10:18 PM

Ah yes - it's been so long since I built it that I forgot about the jumper!  Thanks for the quick response.