Schade Common Gate (SCG) Preamp

ra7,

The new version of the circuit looks like it would be much easier to make without a PCB than the original.

Is the schematic posted close to what the final will be or should I wait? You have mentioned changes to the power supply.

If I attempted point to point for the first stage it might be nice to use the buffer boards.

Are those still available?

Now that I have figured out how to use the line stage in my system with gain AND the fact that I managed to make a mess of my original PCBs I am anxious to give it a try.

Took me much too long to realize all I needed to do was attenuate the output from the DACs.

Thanks and take care,
 

ra7

Member
Joined 2009
Paid Member
ra7,

The new version of the circuit looks like it would be much easier to make without a PCB than the original.

Is the schematic posted close to what the final will be or should I wait? You have mentioned changes to the power supply.

If I attempted point to point for the first stage it might be nice to use the buffer boards.

Are those still available?

Now that I have figured out how to use the line stage in my system with gain AND the fact that I managed to make a mess of my original PCBs I am anxious to give it a try.

Took me much too long to realize all I needed to do was attenuate the output from the DACs.

Thanks and take care,
Hi Rick,

Now that BAF is done (and I've recovered from the high), I am switching my full attention to finishing the new boards. The buffer boards have been sent. Can you hold on for a couple more weeks for the new board? Buffer boards are available. I will send you a PM.

Thanks!
 
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ra7

Member
Joined 2009
Paid Member
For lower bias currents, say, below 25 mA, J113 is better than the DN series for capacitance. More bandwidth, less distortion. But you need the upper FET to shield the J113 from high voltage. It is a cascoded CCS with depletion mode devices that can operate at lower currents. You could also use an LND150 in place of the JFET.
 
I was fortunate enough to be at Burning Amp this year and had the opportunity to hear ra7 demo the SCG in combination with a few amps, including the Total Domination VFET amp. I was already intrigued by the design and following this thread - but now I am even more interested in building one than I was before. I really enjoyed the sound.

Looking forward to the next iteration of this project.

PXL_20231001_162059744.jpg
 
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