[Adinoto]

Hi Jim,
The LS10 is really interesting - only one stage, simple and elegant.
What is the output impedance ? I guess would be around 1-2k?
How much is the gain ?
Could we connect low out of HAGDAC/JIMDAC and get away with only one stage?
Or maybe stack 1 or 2 stages before it and put RIAA in between?

Regards

[hagtech]

I think the output impedance will be just under 1k.  Gain is presently set for 16dB (calculated).  Although I burn off 6dB in front of the volume control.  So changing R14 to zero will boost you to 22dB overall.  That's more than I think is needed.  Bandwidth may not go too low, perhaps only to 10Hz.  Upper side will probably be something like 200kHz.

With just 22dB max, there is not enough gain for a HAGDAC.  That wouldn't even get you to 0.5V.  Anyway, the HAGDAC is being fitted into the DA-10.  No suprise, that schematic is also very similar.  The main difference is that I use a CCS for plate load instead of inductor.  The tube is a 7788 and will have enough gain for 2V output.  Oh yeah, and the heater supply is very big.



jh

[Adinoto]

Jim,
Isn't 7788 pentode? How you use this tube, as pentode or wired as triode?
What do you think about 6C45 / 437A family? This have gain of 50 and low plate impendance.

Thanks and regards
adinoto

[hagtech]

Isn't 7788 pentode?

Yup.  Pentodes might be cream of the crop.  Why make a discrete cascode with 6922 when you can do the exact same thing with a pentode?  I use the 7788 wired in triode.  Very linear.

What do you think about 6C45 / 437A family?

Very nice.  I'm using the 6E5P instead. 

jh