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Output transformer spec help

Apologize for the rough sketch, it’s been a long day
 

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6A3sUMMER

Member
2016-06-07 6:50 am
True Ultra Linear mode has a certain characteristic of a reduction in the level of the 2nd harmonic and/or the 3rd harmonic distortion(s). The curve has a dip in the distortion levels, and goes back somewhat on either side of the dip.
But these nulls are not only dependent on the UL Tap percentage %, they require a certain plate to plate impedance to make the null appear at a particular point.

Since many loudspeakers do not have constant impedance across the whole audio frequency band, I would not worry too much about the exact numbers.

Since some want to experiment with output tubes in pentode/beam power mode, Ultra Linear mode, and Triode wired mode, here is a generalization of the circuit modes:
Pentode/beam power mode: UL tap is at 0%.
Triode wired mode: UL tap is at 100%.
Taps that are >> 0% and << 100% are sort of Ultra Linear.

Have fun designing and building your push pull ultra linear EL34 pentode amplifier.
Then enjoy listening.

Tube rolling?
Plug in a pair of KT77 beam power tubes, re-adjust the bias for the same current as the EL34s were at, and then listen some more.

I have only used 40% UL taps on my UL push pull amplifiers (the only UL tap % on the UL transformers I have)
I have used 20%, 50%, and 80% UL taps on my UL single ended amplifiers.
 
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tjerneld

Member
2020-11-06 12:24 pm
True Ultra Linear mode has a certain characteristic of a reduction in the level of the 2nd harmonic and/or the 3rd harmonic distortion(s). The curve has a dip in the distortion levels, and goes back somewhat on either side of the dip.
But these nulls are not only dependent on the UL Tap percentage %, they require a certain plate to plate impedance to make the null appear at a particular point.

Since many loudspeakers do not have constant impedance across the whole audio frequency band, I would not worry too much about the exact numbers.

Since some want to experiment with output tubes in pentode/beam power mode, Ultra Linear mode, and Triode wired mode, here is a generalization of the circuit modes:
Pentode/beam power mode: UL tap is at 0%.
Triode wired mode: UL tap is at 100%.
Taps that are >> 0% and << 100% are sort of Ultra Linear.

Have fun designing and building your push pull ultra linear EL34 pentode amplifier.
Then enjoy listening.

Tube rolling?
Plug in a pair of KT77 beam power tubes, re-adjust the bias for the same current as the EL34s were at, and then listen some more.

I have only used 40% UL taps on my UL push pull amplifiers (the only UL tap % on the UL transformers I have)
I have used 20%, 50%, and 80% UL taps on my UL single ended amplifiers.
In a Single-end amplifier second harmonic has a dip.
In a Push-Pull amplifier second harmonic is 0 % (with matched power tubes), 3rd harmonic has no dip.
 
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