Hi Forum, My first juke restore was an M100C that had been modified with a G amp and a stereo redhead cart wired in parallel to feed the mono amp input. The amp had not been totally rebuilt but did have a few caps replaced (quite some time before). It also had the cartridge impedance resistor changed to 39K from the original 10K. I’ve since learned that the 10K was the appropriate resistor for the original blackhead carts, so when the conversion was made to the stereo redhead this resistor was changed. My question. Is - why 39K?
I know that the redhead expects a 47K resistor. I’ve seen multiple posts suggesting that when using a stereo cart wired in parallel that this resistance should be doubled - or perhaps even a bit more. I would have thought that the resistor should be changed to the equivalent of two 47K resistors in parallel (47K/2). Agree?
Anyone have any insights why 39K? I changed it back to 10K because at the time I just thought it was a mistake and the output level dropped, which makes sense. I am thinking I should change it back but would really like to understand what value I should use. The mods were clearly made by someone who knew what they were doing, so I doubt the 39K was just a mistake.
We all have different ears. Maybe that person decided 39K sounds better. On Thursday, February 12, 2026 at 10:51:58 PM EST, Steve Swaine via Jukebox-list jukebox-list@lists.netlojix.com wrote:
Hi Forum, My first juke restore was an M100C that had been modified with a G amp and a stereo redhead cart wired in parallel to feed the mono amp input. The amp had not been totally rebuilt but did have a few caps replaced (quite some time before). It also had the cartridge impedance resistor changed to 39K from the original 10K. I’ve since learned that the 10K was the appropriate resistor for the original blackhead carts, so when the conversion was made to the stereo redhead this resistor was changed. My question. Is - why 39K?
I know that the redhead expects a 47K resistor. I’ve seen multiple posts suggesting that when using a stereo cart wired in parallel that this resistance should be doubled - or perhaps even a bit more. I would have thought that the resistor should be changed to the equivalent of two 47K resistors in parallel (47K/2). Agree?
Anyone have any insights why 39K? I changed it back to 10K because at the time I just thought it was a mistake and the output level dropped, which makes sense. I am thinking I should change it back but would really like to understand what value I should use. The mods were clearly made by someone who knew what they were doing, so I doubt the 39K was just a mistake. _______________________________________________ Jukebox-list mailing list -- jukebox-list@lists.netlojix.com To unsubscribe send an email to jukebox-list-leave@lists.netlojix.com %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s Searchable Archives: http://jukebox.markmail.org/
jukebox-list@lists.netlojix.com
-
JIM & LAURIE DIRKSEN -
Steve Swaine