I've gotten to a place with this stuff that I just dive in at the get go and see what shakes out; I'll run some CD-4 test LPs in a bit to see if I can fine tune anything. Again, this demodulator came in looking very clean and the Separation & Carrier Level pot adjustments are still covered by the factory label. It came from the seller with no extras, so I don't have the original test record for this unit (I'm wondering if a Marantz disc would work?
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But the good news is that this Demodulator seems to be working fine as far I know. Yes, I still have a bit of background hum from it, but not as much as my Marantz. So some low level Noise Reduction took care of it.
I just hooked it up and ripped it to AA3 at 96x24 with a +6db boost since it's a Japanese CD-4 (12dbs was too much on this LP.)
here's the discogs for the LP I ripped:
https://www.discogs.com/release/2691902-Takeshi-Onodera-Los-Onoderas-Dynamic-Latin-Drums
The cart. I used here was the AT-15S
You can see by this pic of Side 1 of the wav Spectrograms, the 30K carrier signal appears to be locked in pretty well.
View attachment 90265
I've also attached a small lower res. Quad file of a section of song #2 below; that has a lot of Organ movement around the speakers at one point.