Looking for recommendation for Phono Stage

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RhythMick
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#61 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

This is from a D3A datasheet. I appreciate this is for operation as a pentode, but I'm struggling to understand why BOTH a cathode resistor and a positive grid bias are recommended ? With 22mA through the cathode a 400R will set the cathode to 8.8v, leaving G1 at +1.2V ? What am I missing ?
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izzy wizzy
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#62 Re: Looking for recommendation for Phono Stage

Post by izzy wizzy »

RhythMick wrote: Mon Jan 28, 2019 2:46 pm This is from a D3A datasheet. I appreciate this is for operation as a pentode, but I'm struggling to understand why BOTH a cathode resistor and a positive grid bias are recommended ? With 22mA through the cathode a 400R will set the cathode to 8.8v, leaving G1 at +1.2V ? What am I missing ?

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It's being operated as a triode but you're missing the G2 current of 6mA which totals 28mA through 400R making 11.2V G1 so G1-K as -1.2V.

I've not seen this 10V bias thing before.

Cheers,
Stephen
Last edited by izzy wizzy on Thu Feb 21, 2019 3:52 pm, edited 1 time in total.
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izzy wizzy
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#63 Re: Looking for recommendation for Phono Stage

Post by izzy wizzy »

RhythMick
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#64 Re: Looking for recommendation for Phono Stage

Post by RhythMick »

izzy wizzy wrote: Thu Feb 21, 2019 3:48 pm I think these are better datasheets https://frank.pocnet.net/sheets/128/d/D3a.pdf
and https://frank.pocnet.net/sheets/009/d/D3a.pdf

Cheers,
Stephen
Thanks
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