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Old 22nd March 2013, 09:45 PM   #1581
iko is offline iko  Canada
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Interesting! Maybe I'll give it a try.
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Old 22nd March 2013, 11:10 PM   #1582
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Old 23rd March 2013, 07:22 AM   #1583
stajo is offline stajo  Sweden
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Quote:
Originally Posted by vgeorge View Post
B+ 295V now, at 16,5 mA.
What is your bias for that?
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Old 23rd March 2013, 07:57 AM   #1584
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I have 12,3V across the 750R cathode resistor.
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Old 23rd March 2013, 08:31 AM   #1585
stajo is offline stajo  Sweden
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So your anode voltage is about 183 in idle?
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Old 23rd March 2013, 08:38 AM   #1586
vgeorge is offline vgeorge  Greece
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Correct.
I know not optimum, but the only way to up the voltage would be to get a new rectifier tube.
I tested it with a sovtek 5ar4 and got 15V on the cathode with 330V B+, 220V on the anode.
Unfortunately, I use this for my power amp.
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Old 23rd March 2013, 08:52 AM   #1587
stajo is offline stajo  Sweden
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It is very hard to see on schematics because the 6V6 in this application is working so low compared to its capacity and normal operating area that it is almost impossible to judge from the loadline on paper. But your measures on the scope shows good results.

I wonder how Salas came up with this idea, cause its a bit odd but showes good results.

At this currents a 1660 gaped for 18 mA (wich I happen to have somewhere) would be happy.
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Old 23rd March 2013, 08:55 AM   #1588
vgeorge is offline vgeorge  Greece
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I am going to listen soon at 20mA and report if there is a difference.
I would be very interested for your opinion if you try the LL1660 here.
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Old 23rd March 2013, 10:34 AM   #1589
Salas is offline Salas  Greece
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Quote:
Originally Posted by stajo View Post
It is very hard to see on schematics because the 6V6 in this application is working so low compared to its capacity and normal operating area that it is almost impossible to judge from the loadline on paper. But your measures on the scope shows good results.

I wonder how Salas came up with this idea, cause its a bit odd but showes good results.
The blue rectangle point is what George has now. The red point is what we use when B+ is plenty. When assuming that the reissue tubes are staying roughly on that old GE map of course. Each valve is consuming 3W when on the blue, 4W when on the red. We go a little >200V >4W usually for the red, but I centered it for clarity.
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Old 23rd March 2013, 10:45 AM   #1590
stajo is offline stajo  Sweden
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And heres Georges approximate loadline. I put some marks around where the tube operates with 2 V RMS in.

Click the image to open in full size.
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