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Old 6th February 2009, 03:11 AM   #1
jeapel is offline jeapel  Canada
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Default low zout vs output transfo

hi

For a ordinary output transfo (not top quality) 2.5k/8
and forget output power and damping factor is it a good idea
to drive with a low zout ~300ohm tube like 6as7 to
get the best (frequency range) for my "ordinary" transfo or same result with a tube with zout more normal 1000ohm and more.

thanks
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Old 6th February 2009, 07:24 AM   #2
Tweeker is offline Tweeker  United States
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Distortion, bandwidth and damping could be good, but you might be rather disappointed with power output using that tube. You cant really forget power out as your amp would have to work full blast where another would be coasting...

What is it driving?

Im assuming this is single ended.
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Old 6th February 2009, 11:43 AM   #3
jeapel is offline jeapel  Canada
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ok there is a relation with bandwidth and low zout
tube and maybe 2 x 1/2 triode for pa=26watt
to try more power solution
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Old 6th February 2009, 11:45 AM   #4
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maybe you could be more clear with your question... kinda confusing.
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Old 6th February 2009, 11:57 AM   #5
jeapel is offline jeapel  Canada
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hi mctavish

maybe ? the best way to drive a cheap output
transfo is to use a low zout tube
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Old 6th February 2009, 05:39 PM   #6
Jeb-D. is offline Jeb-D.  United States
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If your talking about SE:

2.5k is a pretty good load for 1/2 of a 6as7. It's possible to extract the maximum power out of it and give an output impedance below 2ohms with no feedback.

For both sections paralleled, 2.5k is too high. You may hit the tubes max voltage rating before extracting the full potential power output. 1.25k is the highest I'd go for both sections parallel.

In class A, expect 3-4Wrms output per section from this tube.

If your talking about a push pull transformer, 2.5k plate-to-plate would do well.
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Old 6th February 2009, 06:10 PM   #7
Tweeker is offline Tweeker  United States
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Low Z wont necessarily gain that much power bandwidth if your being limited by saturation rather than inductance.
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