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01-27-2025, 03:25 PM
Hi Guys
The transformers in the LA-02A circuit are nothing special inasmuch as you can use standard available modern devices to build the circuit. The input TX is 600:600 if you go vintage with values, but can just as easily be 10k:10k.
Since the use of 600-ohm lines came about from telecom design, it was already unnecessary for broadcast and PA applications, as there is no need in the latter situations to transmit power; we only need to transmit voltage, hence the suitability for line level 10k transformers.
The Whyte cascode follower at the output allows the use of a 1:1 output transformer. The vintage unit might have been rated for 600-ohms, but we can use 10k here, as well.
Some of the power amps that were current when the LA-2A came out needed quite high line levels compared to modern PAs. So, it was not uncommon for a line amplifier to have significant gain as here, 36dB instead of maybe 8-20dB.
Regarding the transformerless compressor from TUT2, I used a dual triode as a dual rectifier simply to be able to build the circuit quickly with available parts. Every electronic tube evolved from a diode
The transformers in the LA-02A circuit are nothing special inasmuch as you can use standard available modern devices to build the circuit. The input TX is 600:600 if you go vintage with values, but can just as easily be 10k:10k.
Since the use of 600-ohm lines came about from telecom design, it was already unnecessary for broadcast and PA applications, as there is no need in the latter situations to transmit power; we only need to transmit voltage, hence the suitability for line level 10k transformers.
The Whyte cascode follower at the output allows the use of a 1:1 output transformer. The vintage unit might have been rated for 600-ohms, but we can use 10k here, as well.
Some of the power amps that were current when the LA-2A came out needed quite high line levels compared to modern PAs. So, it was not uncommon for a line amplifier to have significant gain as here, 36dB instead of maybe 8-20dB.
Regarding the transformerless compressor from TUT2, I used a dual triode as a dual rectifier simply to be able to build the circuit quickly with available parts. Every electronic tube evolved from a diode
