EL504 push pull power amplifier build

In this video I show you my latest power amplifier build!
It can deliver 45 watts for each channel and works in ultra linear mode without any feedback.
The sound in this video is recorded from the loudspeakers (Yamaha NS-1000M) using my phone.
The schematics are shown at the end of the video. I had the power transformer custom made for this.
To make this amplifier work correctly you should have driver tubes with matched halves and the output tubes should also be carefully biased correctly. Using a multimeter, oscilloscope and tone generator is a must to check and adjust this amplifier, this way you can also pick the driver tubes. It uses 12AV7s as drivers and one ECC83 as phase splitter.
When idle it's drawing 150 watts of power.
I’ve also used a 50 ohm thermistor which turns into 10 ohm in series with the primary of the power transformer, since this is a beefy toroid.
The output transformer used here is the Hammond 1650H (6,6K primary) but a transformer with a slightly higher primary impedance can also be used.

If you're trying to build this amplifier you're doing so at your own risk, knowledge of working with vacuum tubes is a must since the voltages in this amplifier are dangerously high... but that accounts for almost any vacuum tube device. This also applies to all of my videos ;)

Music: 'Alpha Waves' by Simon Mills
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