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Old 12th March 2012, 04:41 PM   #1751
dhtrob is offline dhtrob  Netherlands
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No gap because the maker has generously put in a shield... (and it looks better)
..and since when do you consult your wife for amplifier design?
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Old 12th March 2012, 04:51 PM   #1752
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..and since when do you consult your wife for amplifier design?
I consult her for everything I do (or plan to... )
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Old 12th March 2012, 04:53 PM   #1753
dhtrob is offline dhtrob  Netherlands
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She *must* be reading this forum as well...
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Old 12th March 2012, 06:49 PM   #1754
vgeorge is online now vgeorge  Greece
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Hi there,
Worth mentioning: I experienced some serious noise (hiss) at the output of the preamp which came from the used 12Watt resistor which became too hot.. Replaced it for a 100Watt type and now the noise is almost gone. Guess paralleling is the way to go here? Anyone tried graphite resistors?

If interested I can post diagram and/or photo's.. :-)

Thanks, Rob
I see that you used a variable resistor. I don' t think that paralleling is necessary.
I use a 10ohm 95W resistor and with Rod' s regulators there is no noise.
Also grid stoppers may not be necessary. I did not have any issues with my #26. You could try and see.
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Last edited by vgeorge; 12th March 2012 at 07:18 PM.
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Old 12th March 2012, 06:54 PM   #1755
dhtrob is offline dhtrob  Netherlands
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OK, thanks.
With a little help from Bas I will be able to give Rod's regulators a try.. Curious though, since I used the VCCS total noise- and humfree on a '45 as output stage on my DAC.

Rob
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Old 12th March 2012, 06:57 PM   #1756
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I would not use 6J51P here for cathode follower, it wants more voltage. 6J52P would fit much better.

Or 6J9P
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Old 12th March 2012, 07:18 PM   #1757
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What´s wrong with a triode-strapped 6E5P?
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Old 12th March 2012, 07:22 PM   #1758
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What´s wrong with a triode-strapped 6E5P?
Price only, I assume.
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Old 12th March 2012, 07:31 PM   #1759
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Price only, I assume.
. Have not checked for a while. Have they gotten too popular?
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Old 12th March 2012, 07:48 PM   #1760
mogliaa is online now mogliaa  United Kingdom
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I would not use 6J51P here for cathode follower, it wants more voltage. 6J52P would fit much better.

Or 6J9P
Hi Anatoly,
You're probably right. See attached trace of the 6J51P. I should have extended the anode voltage swing beyond 100V, but it doesn't look that is the most linear region there.

I have a couple of 6J9P around and the filament current will fit the 01A as well, so will try them instead
Thanks
Ale
Attached Images
File Type: jpg 6Z51P.jpg (190.8 KB, 426 views)
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Last edited by mogliaa; 12th March 2012 at 07:51 PM. Reason: forgot attachment1
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