[Jukebox-list] AMI R145 Amp Modification

[Ron Rich]

James,
  Just off the top of my head--without looking at the schematic--there is no "mute relay" in that amp--"muting" and "squelch" is done by switches on the mech. You might be able to add a relay to cut off the heater to the AVC tubes, during MP3 operation, and switch  the signal input to the MP3, at the same time. Ron Rich

Steve Wahl <steve at pro-ns.net> wrote:
  On Thu, Jun 07, 2007 at 08:42:00AM -0500, WHITE, JAMES P wrote:
> Hi Karl,
> I too wonder what kind of sound this will result in. I'm hoping for
> just a good quality momo sound - with lots of volume of course!
> 
> Going from a stereo signal to a mono amp is not one of my concerns -
> only because I have had some success with this. The last machine I
> restored was a Seeburg 222 which had a stereo cartridge but a HFMA-2
> mono amp. I wired the tone arm cable as recommended by one of our list
> members and it sounded fine. I could be missing something here however.

Don't forget the RIAA EQ curve that must be in there somewhere.
Unless you inject your signal after it, it will greatly attenuate the
high frequencies.

http://stereos.about.com/od/gtgtturntables/a/riaa_eq.htm
http://en.wikipedia.org/wiki/RIAA_equalization

I have no idea where in the amp's signal path this occurs, as I don't
read schematics that well; so maybe you've already handled the problem by
injecting past it.


       
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