I recently acquired an Audio Research SP-10 preamp, specifically the well regarded Mk2 version. I immediately noticed a large bare area in the middle of the main circuit board, that clearly was populated in the prior revision. Attached are pictures of the Mk1 and Mk2 boards, as well as the schematics. I'm trying to work out the purpose of the removed circuit. I'm used to ripping out large seconds of code when optimizing software projects, but I've never seen it in a circuit design before!
Attachments
I performed a similar exercise, drawing an unfamiliar schematic, and in the end I got to know LTSpice so I could emulaithe circuit and get confidence in it.
When later in I decided to change the design it was easy to emulate the changes, and verify the sine wave at the other end looked reasonable, and gain was unaffected.
It is a bit of a learning curve, but fun and quite useful.
When later in I decided to change the design it was easy to emulate the changes, and verify the sine wave at the other end looked reasonable, and gain was unaffected.
It is a bit of a learning curve, but fun and quite useful.
