• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Re-build of my first OTL from 2000

Hi all you good fanatics out there in DIY utopia.
I am new to this site but quite long in the tooth when it comes to building OTL amps.

My first was a copy of the Rozenblit Transcendent 25W version which has been simplified in the meantime, but is now dead due to a failed mains transformer.
The transformer was a custom all windings on one core, but I have decided to now fit 3 off the shelf transformers instead.

P1020878.jpg


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The circuit is going to be re-built along the lines of the Rozenblit Son of Beast but with my own differences built in.

Since 2000 I have built another 3 OTL amp, all using different valve line-ups.
The 2nd amp was a test bed for different topologies and was sold a long time ago.
Number 3 is my own design low power miniature OTL using 6J6 and 6080 valves.

The last build is a copy of the Tim mellows but using alternative valves and a few modifications.
This shows amps 1, 3 and 4 together:

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As I shall be doing an extensive re-build I thought I would document it on here for your amusement.

Space created for new transformers:

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Components removed so far, including the dead mains transformer and the DC heater rectifier/heatsinks and capacitors:

P1030603.jpg


I'll keep the thread updated as I go along, new transformers now on order.
 
Some progress on this with the receipt of the new transformers.

A few more parts removed, the input stage was hidden inside the chassis but will now go on the top.

P1050538.jpg


The transformers are now in situ and the majority of the power supply has been tested:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Firebottle/Firebottle%20XXV%20re-
build/P1050539.jpg

Next is the fiddly job of re-wiring all the heaters, as they are now going to be AC rather than multiple series DC.