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coco
PostPosted: Tue Apr 20, 2010 3:35 pm 
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Voltage on that pin will be due to the tube gain, cathode resistor value and raw plate voltage. the cathode resistor is 3% lower than design which will lower the voltage by a few %. This would actually give you less headroom.

What is the voltage on pin 6? Anything less than the 272 posted will mean less on pin 8 as well.

Big question is how does it sound as it stands now? I don't think you will hurt it to play it.

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Local Lad
PostPosted: Tue Apr 20, 2010 3:39 pm 
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It's not there with the gain turned down as well
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coco
PostPosted: Tue Apr 20, 2010 4:04 pm 
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I think you are going to get some crosstalk since they use a common tube. I dont think they are perfectly isolated.

Never heard anyone really complain about it.

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Stoo
PostPosted: Tue Apr 20, 2010 4:16 pm 
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Hi Stephen. glad you stopped by on this thread. Daves concern is that there is only 150 odd volts on the cathode of the follower and same for the anode of the preceeding triode.
stew
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zaphod
PostPosted: Tue Apr 20, 2010 5:37 pm 
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FYI this same question got asked on 18watt.com and here is what I said.
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Local_Lad wrote:
V2- pin1 149
pin3 0.94
pin6 265
pin8 150

If pin 6, which is directly connected to the preamp's positive rail, is at 265V, this means the preamp rail is at 265V. V2a has an 820 ohm cathode resistor, according to the schematic on Trinity's site. So 149V on V2a's anode (pin 1) looks around what I would expect with that value of cathode resistor. 180V actually sounds on the high side to me. You also get some variation between tubes, even apparently identical ones. Since V2b is a cathode follower, you get almost exactly the same voltage on its cathode as on its grid which is directly connected to V2a's anode. So that all looks good. What really matters is most is that the amp sounds good to you.

HTH

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Local Lad
PostPosted: Tue Apr 20, 2010 7:24 pm 
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Ok, thanks for the replies guys, I'm going to mount it in the cab and give it a good play. I'll let you know how it sounds.

Seriously now, what did I do before Internet forums, how did I get stuff done and find things out.

Cheers

Dave
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