1st Stage of Stand Alone Power Amp

vvillium3

New member
Hello All,

I have always wanted to build a stand alone power amp and I'm finally going to get it done. It will be the power section of the Soldano SLO. Originally I thought I could simply chop off the pre-amp section before the master volume and go from there. However, I listened to an interview with Mr. Soldano where he said he had to design in a driver stage into his rack power amps. Building off a schematic is easy, but designing this first stage is a little over my head. I'm slowly getting a grasp by reading through design books, but hopefully you all can lead me in the right direction faster.

First off, what is the importance of the driving stage? Is it simply a input voltage control from unknown input sources? Or is it a current source issue for the phase inverter? Last, is it a bad idea to have the volume control first in-inline from the input?

Should I simply use the last 12ax7 tube buffered stage on the backside of the effects loop for the first stage (from the SLO preamp)? Or will something like the AX84 parallel input stage be better suited since there will be a "open" side of the 12au7 to use? That or any other suggestions are welcome.

See attached images for the items mentioned above.

Thanks,
Jason
 

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  • soldano.JPG
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Forgot to include this in my original post, but oddly have had this OPT sitting around since 03' to try out. Not sure how long they sold them for, or what the differences were from the SLO's OPT? But it should go nicely in this power amp build.
 

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  • DMI OPT.JPG
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