10-22-2014, 08:02 AM
Seems like you have a real nice sounding system there. I also want to keep the tone controls and will probably go the same route you did with the PAS2. Luckily my front panel is in mint condition and just needs some cleaning. I am missing a knob though I believe knob kits are available.
With regards to the ST70 I am not sure whether to go the VTA route or with another upgrade and design my own constant current sources for the cathodes of the 6CA7 tubes. This will require running class A which gives lower distortion but less output power. A capacitor storage bypass could be added to allow more peak power without clipping. I'm not sure the extra effort will produce measurable listening improvements especially with my 65 year old ears! But it would be a fun project.
Thanks for the tip on the DIY Tube forum, I have just registered there as SteveBigD.
Steve D
With regards to the ST70 I am not sure whether to go the VTA route or with another upgrade and design my own constant current sources for the cathodes of the 6CA7 tubes. This will require running class A which gives lower distortion but less output power. A capacitor storage bypass could be added to allow more peak power without clipping. I'm not sure the extra effort will produce measurable listening improvements especially with my 65 year old ears! But it would be a fun project.
Thanks for the tip on the DIY Tube forum, I have just registered there as SteveBigD.
Steve D
