2A3 SET headphone amp?

[itsikhefez]

Sowter has a line of output transformers for headphones: HEADPHONE TRANSFORMERS

In the US, electraprint is known to wind custom ones:Electra-Print.com Line Output Transformers

Lundahl offer the LL2765. There seem to be multiple secondaries that in different combinations can produce 32/150/600 ohm

The Sowter seem to be similar in that aspect? Different combinations of the secondaries can provide 600/300/150/40

I had jack at electraprint wind a transformer for headphones with 2 taps. It was for 45 DHTs Something like 48 and 150 ohm outputs. Basically for low and high impedance cans.
I added a switch to select which tap to use.

It ends up being about turns ratio, so don't worry that if its not exact. I'm sure 300 ohm cans will be fine on he high impedance tap
You can also add a resistor to a lower impedance output.

It was easy to ask Jack questions over email, he responds pretty quickly.
Randy

Thanks. I've been following your thread over at tubelab and actually asked a question in one of the threads. This will also be for a 45 DHT.
I am curious why 48/150 were chosen...

 

[lordvader]

Bit of a bump - but just came across this thread.
I have agk701s, and since their impedance is 62ohms, feels like a normal, speaker 2a3/45 amp might work.

Is this a reasonable assumption?

 

[itsikhefez]

I am about to complete my 45 amp and based on my experience there I believe it should work OK but it depends on how much power the K701 need.

Assuming by "speaker" amp you mean one with 8ohm taps, then I believe you will get about 200-300mW to the K701 from a 45. 2A3's are double that I believe.

Some speaker amps also have 16 ohm secondaries.. that would give you more power if needed

 

[hpeter]

https://peteslab.blogspot.com/2015/11/stax-2a3-se-amplifier.html
still using this after years.
if i wanted dynamic headphones/speakers, i just need swap transformers+bias adjust. cant go simple that that; its just 2 basic stages. no rocket science
i wanted thyratrons at all costs, therefore the power trans(powersupply) is so big and expensive.

many producers make headphone trans.

 

[Giordano]

Do you guys have progress on it? I would also be very much interested in a 2A3 SE headphone amp.
Thanks,
JG

 

[itsikhefez]

I ended up building the Tubelab SE with a 45.
It can just as easily be built for 2A3 or 300B....
Some details (and pics) of the build can be found here:
https://www.diyaudio.com/forums/tubelab/331038-14-run-tse-die-48.html#post5910810