Grid choke for R1 on the group buy PCB
Not sure if you have used the same nomenclature for all of the variations of the circuit (and too lazy to look back).
First, please forgive my attempts at mixing tube circuit ideas with your FET design.
BUT, could there be something good about using a 47K 2000 H grid choke instead of the 47K resistor?
My curiosity could not be quelled so I had to ask.
Thanks,
Not sure if you have used the same nomenclature for all of the variations of the circuit (and too lazy to look back).
First, please forgive my attempts at mixing tube circuit ideas with your FET design.
BUT, could there be something good about using a 47K 2000 H grid choke instead of the 47K resistor?
My curiosity could not be quelled so I had to ask.
Thanks,
Hi guys.
very strange thing happen to my PSU.
I finished it , and measure, everything is fine - 48VDC in each channel when connected directly to the 230V.
when I am trying to build the box with the fuse , I am keep blowing the fuse even with no load. I first thought there is a short somewhere , but there isn't. the led is first on - then the fuse blows , and it slowly got off as the capacitors unloaded.
the fuse is 315mA , 250V - which should be OK.
any ideas ? does anyone used a fuse with similar values.
very strange thing happen to my PSU.
I finished it , and measure, everything is fine - 48VDC in each channel when connected directly to the 230V.
when I am trying to build the box with the fuse , I am keep blowing the fuse even with no load. I first thought there is a short somewhere , but there isn't. the led is first on - then the fuse blows , and it slowly got off as the capacitors unloaded.
the fuse is 315mA , 250V - which should be OK.
any ideas ? does anyone used a fuse with similar values.
Now, I promise to build it as is!
Got my bag of parts and can't wait to hear what you have wrought.
THANKS for your patience with my questions.
Take care,
Got my bag of parts and can't wait to hear what you have wrought.
THANKS for your patience with my questions.
Take care,
Based on a position of complete ignorance (never been to Waterloo, never measured mains voltage there, and have never used one of these transformers) I would say that my impression is that most Canadian cities have excellent regulation on their mains voltage, and Hammond xformers have an excellent reputation and are spec'ed at 115V (not 120V) so I would wager a small sum that you would have no issues with that xformer, and it will also reduce heat dissipation in the regulator circuit slightly. But like I said, I really don't know.
OT. Not many would know that we have Octoberfest here. Second largest in the world. It's like a long party. You line up at noon to get in and somehow leave for home about 1am. Lots of drinking games and dancing to Oom Pah Pah style music. I remember a few of them.
The voltage is usually about 125V, so the transformer should be fine. I have ordered one.
Jim
The voltage is usually about 125V, so the transformer should be fine. I have ordered one.
Jim
I have a question about Miller capacitance for this phono stage.
AIUI, the Miller capacitance of the JFETs which make up the 2nd gain stage means you should subtract this amount from the theoretically calculated value for C2?
Surely, the JFETs which make up the 1st gain stage must also exhibit Miller capacitance - which could be quite high, given the large gain? (CMiller = specified Gate-Drain capacitance x (gain+1) ... which could easily be 30pF x 100 = 3,000pF).
So, surely this means that an MM cart is going to be faced with a massive amount of input capacitance?
Regards,
Andy
AIUI, the Miller capacitance of the JFETs which make up the 2nd gain stage means you should subtract this amount from the theoretically calculated value for C2?
Surely, the JFETs which make up the 1st gain stage must also exhibit Miller capacitance - which could be quite high, given the large gain? (CMiller = specified Gate-Drain capacitance x (gain+1) ... which could easily be 30pF x 100 = 3,000pF).
So, surely this means that an MM cart is going to be faced with a massive amount of input capacitance?
Regards,
Andy
The MM is getting to see the first stage as an MC does. So it is cascoded input in each case. That shield kills most of the Miller. The higher degeneration when set for MM kills almost all of what is left.
C2+C2Y is combined with the 2nd stage JFET capacitance in the analysis and measurements done.
C2+C2Y is combined with the 2nd stage JFET capacitance in the analysis and measurements done.