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Input stage tube
Input stage tube
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Old 6th October 2005, 02:05 PM   #1
Steen Bentzen is offline Steen Bentzen  Denmark
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Default Input stage tube

Witch double triode to prefere for the input stage in a power amp. I need a amplification factor of approx. 55 and have good sound?
The input stage are balanced with a CCS in the catode.
Is 12AT7 a possible choice?
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Old 6th October 2005, 02:27 PM   #2
SY is offline SY  United States
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Input stage tube
A 12AT7 will work well in that application. My measurements show that as a differential amp, it can have quite low distortion at moderate voltage swings. In a CCDA, expect a gain of something like 30. A single stage gain of 55 can only be gotten with a VERY high mu triode, a cascode, or pentodes.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
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Old 6th October 2005, 04:39 PM   #3
ErikdeBest is offline ErikdeBest  Switzerland
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Input stage tube
Im Valve Amplifiers Morgan Jones refer to a (big and heavy) regulated PS using cascaded 12AT7's in a differential amplifier. Probably the same concept can be used here, gain would be more than enough - but you need two tubes (instead of one in a simple CCDA).


PS. I am a newbie - but the other people know that and can correct what I say!
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