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Calculating output transformer impedance

How to calculate the output transformer impedance of an OPT with unknown values

Working with tube amps you may need to calculate the output transformer impedance especially when we have an old transformer or a transformer with unknown values.
All we have to do is to calculate the turns ratio of the transformer. To do this we need an AC voltage source and an AC voltmeter.
So we apply an AC voltage to the primary of the transformer and we measure the output voltage to the secondary.

audio-output-transformer

DIY horn loudspeaker review

After living with my DIY Back Loaded Horn loudspeakers for more than 2 years, I think its time to share my listening impressions with you.

First of all I recommend you ( if you are planing to build this design), to take the time to experiment with setup and placement to get the best of this kind of speakers. The sound produced by these specific BLH's is affected both by the behavior of the speaker in the room and the size of the room.

DIY-loudspeakers

EL34 audio power amp

Giannis Spathopoulos made this one-off treasure audio power amp. This prototype model featuring four JJ EL34 power output pentodes per channel in an ultra linear push pull configuration. With an ECC83 as a pre stage, an ECC85 as a phase splitter, and a 6FQ7 as a buffer, this extremely dynamic and sweet sounding design is rated at 30 Watt in a class A configuration, and 70W in a class AB1 configuration.

el34-audio-power-amp

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