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In the Forum: Melquiades Amplifier
In the Thread: Single-stage Melquiades vs. DHT amps
Post Subject: Here is more data to reconcile.Posted by Romy the Cat on: 4/17/2009
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The voltages on the schematics are the actual live voltages driving a full power 5000kHz. The next 10mV at input clip the amp. I do not know yet what clip first’ driver stage, output stage of any of transformers. Anyhow, the full power set as a full 10 squares on the scope

Melquiades_YO-186_Draft4.jpg

Here I drive the same voltage all the way up until it hit -3dB. It is 23kHz. 

Melquiades_YO-186_Draft4_23k.jpg

Then I drive the same voltage all the way down. The -3dB is at 2.4K

Melquiades_YO-186_Draft4_2.4k.jpg

What is interesting is to drive the channel with something where transformers have no inductance. I took 500Hz. It is many dBs down and I added a lot of v/div. Still if spread it over the full screen then the distortions are visible but the tops are not clips – that is indication that the filter roles fast then minimum inductance – a good sign

Melquiades_YO-186_Draft4_.5k.jpg

What I do not like is below. This is a square wave into 5K that is perfectly in band-path. I did measured the same after the driver stage and blocking cap with 15K resistor on plate driven from 400V and the squares were MUCH better. So, it is not the filter and not driver state.

Melquiades_YO-186_Draft4_Square.jpg

I was loading the inner stage secondary and it has no impact…

The Cat

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