Newbie question: Why did the designer leave off the cathode bypass capacitor?
On this (Jack Eliano) ultrapath amp there is no cathode bypass capacitor, I know Ck is optional if you want the degenerative feedback. But I dont understand why you'd decide to keep Rk bypased or not from one amp to the next. Some unconditionally always use a bypass.
Why do you think Jack Eliano left off the cathode bypass?
1) Does the ultrapath capacitor serve any functions similar to what Ck does? So he left it off
2) He needed lower gain to match better with the ultrapath noise injecting ratio? So he left it off.
3) He tried it both ways and this sounded better? So he left it off.
4) He prioritized distortion over power? So he left it off.
Was there anything unique about using ultrapath influencing his decision, as I've seen ultrapath amps with and without a Ck.
On this (Jack Eliano) ultrapath amp there is no cathode bypass capacitor, I know Ck is optional if you want the degenerative feedback. But I dont understand why you'd decide to keep Rk bypased or not from one amp to the next. Some unconditionally always use a bypass.
Why do you think Jack Eliano left off the cathode bypass?
1) Does the ultrapath capacitor serve any functions similar to what Ck does? So he left it off
2) He needed lower gain to match better with the ultrapath noise injecting ratio? So he left it off.
3) He tried it both ways and this sounded better? So he left it off.
4) He prioritized distortion over power? So he left it off.
Was there anything unique about using ultrapath influencing his decision, as I've seen ultrapath amps with and without a Ck.
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There is 470uF/2 of Ck via the power supply.
His distortion figure of 1% seems optimistic.
His distortion figure of 1% seems optimistic.
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The B+ has a 470uF cap to Ground.
The Cathodes have a 470uF cap to B+.
Therefore, the Cathodes to Ground Capacitance is 470uF/2 = 235uF.
The Cathodes ARE bypassed to Ground with 235uF.
And, Ground is the reference voltage for the output tubes Grids.
I hope that explains the analysis of this part of the circuit.
The Cathodes have a 470uF cap to B+.
Therefore, the Cathodes to Ground Capacitance is 470uF/2 = 235uF.
The Cathodes ARE bypassed to Ground with 235uF.
And, Ground is the reference voltage for the output tubes Grids.
I hope that explains the analysis of this part of the circuit.
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Windcrest77,
Glad to have you asking questions.
It keeps my old mind active, even if I do make mistakes.
Glad to have you asking questions.
It keeps my old mind active, even if I do make mistakes.
Member
Joined 2009
Paid Member
There are indeed some subtleties with ultra path. for one it tends to keep the signal current out of the power supply. Also, a combination of ultra path and CK, if set up in the correct ratio, can help reduce hummmm in the output.