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Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Posted: Sun Dec 29, 2019 8:32 pm
by mediatechnology
Very nice!

I tried the MC preamp with the TDK switcher and as long as the preamp board wasn't near the primary-side and heat sink bar it was as quiet as the linear bench supply.
With yours at right angles and on the far side of primary it ought to be quiet as well.

I like the RJ-45 bulk-head female-to-female termination. I would never have thought to use a RJ-45 turn-around. That's very clever.

You might want to reverse the jumper shunts - they're upside-down from they way I usually install them and will be easier to pull if inverted on the header with the large end on the top. They're easier to grab with needle-nose.

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Posted: Mon Jan 20, 2020 7:33 pm
by grufti
I can report on two improvements since I finished the MC preamp. I switched to tabbed jumper shunts. Those are so much easier to move around and I had simply run out.

The other item is more interesting. I found a very nice 5W +/-15V switcher at mouser for $20. It's a RECOM RAC05-15DC. The 10W version RAC10-15DK/277 costs only $10. Not sure why that is. I'm very happy with the tiny 5W switcher.

https://www.mouser.com/ProductDetail/RE ... KYOmsuw%3D
https://www.mouser.com/ProductDetail/RE ... vSbg%3D%3D

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Posted: Mon Jan 20, 2020 8:01 pm
by mediatechnology
I put one of those supplies in my cart to check out on the bench.
Thanks for sharing that.

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Posted: Sat Sep 26, 2020 7:13 am
by mediatechnology
When I first built the MC preamp I "temporarily" used the box I had made for the MM preamp.
That was about a year and a half ago.
The MM preamp was left without an enclosure.
I finally got around to making a box for the MC preamp and was able to remount the MM preamp in its original enclosure.

The box for the MM preamp wasn't really tall enough for the MC board.
I used a Hammond 1590JBK for the MC board.

Image
Flat Balanced Input Moving Coil Phono Preamp Using the ZTX851.

DB-9 connectors are used to allow me to switch between the MM and MC preamps.