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Old 5th November 2012, 08:47 PM   #8461
Salas is offline Salas  Greece
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I have tried those, so, so, they round the resolution. Avoid PIO there if you can. If you can bypass them with something fast 10nF-22nF they speed up.
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Old 5th November 2012, 08:53 PM   #8462
Doug R is offline Doug R  United States
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Thanks Salas. Will try a cheap ceramic (just kidding!)
Doug
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Old 5th November 2012, 08:55 PM   #8463
Salas is offline Salas  Greece
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FT-1 does a good combo with K40.
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Old 6th November 2012, 10:26 AM   #8464
Doug R is offline Doug R  United States
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Salas,
I am still curious if a 0.22 or 0.47 uF is OK there, or will it mess up the RIAA?
Thanks.
Doug
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Old 6th November 2012, 11:35 AM   #8465
Doug R is offline Doug R  United States
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One more thing, does the output cap need to be so large for a tube preamp?
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Doug
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Old 6th November 2012, 11:53 AM   #8466
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Depends of the input amps, output cap calculator link:

Coupling Capacitor Calculator by V-Cap

Cheers
Felipe
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Old 6th November 2012, 12:30 PM   #8467
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Doug R View Post
Salas,
I am still curious if a 0.22 or 0.47 uF is OK there, or will it mess up the RIAA?
Thanks.
Doug
Hi Doug

Do not go below 0.47uF because you will loose bass response.

This one forms a frequency dependent voltage divider with th 1M gate resistor in second stage.

It also interacts with the riaa curve response.... Follow Salas advice for a well equilibrated response.
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Old 6th November 2012, 01:13 PM   #8468
Doug R is offline Doug R  United States
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Thanks guys. That's what I thought.
Doug
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Old 6th November 2012, 06:19 PM   #8469
andyr is offline andyr  Australia
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Quote:
Originally Posted by RCruz View Post

Hi Doug

Do not go below 0.47uF because you will loose bass response.

This one forms a frequency dependent voltage divider with th 1M gate resistor in second stage.
But plugging 1Meg and 0.47uF into the output cap calculator link which merlin posted, gives you 0.34Hz. Which is surely, unnecessarily low?

So why can't you reduce it to 0.1uF ... which produces a result of 1.6Hz - which meets the "x10" rule?

Regards,

Andy
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Old 6th November 2012, 06:20 PM   #8470
Salas is offline Salas  Greece
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0.047uF he surely meant, probably a typo.
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