• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Cinemag S217D

Got a pair of the CineMag S217D and they look pretty nice and looking to build a line preamp with them.

So basically a 12.5K primary to 600 ohm output. The tertiary is throwing me for a bit of a loop. I see 22.2: 4.96: 1 ratio and I take it 1 = 600 puts the primary a bit higher than the specd 12.5K, (13.32K) so is the tertiary 4.96 or ~3K?

I would imagine the loading of the tertiary would effect the primary.

The Pultec seems to be the only schematic I can see using this and this is a balanced usage all the way through.

I was thinking of using a 220H loading some med mu tube and feeding back through the cathode with the tertiary with like 1-2dB of feedback. Parafeed 1.5uF blocking cap.

Thoughts? Help?


  • CM-S217D.pdf
    277 KB · Views: 23