Subminiature tubes/valves for Hi-FI

[MagicBus]

So, if I have a complete power amp where do I measure the FFT? At the end of the preamp, output of the transformer(speaker)?

Normally, you will measure the device under test as a whole sending signal at the input and measuring the output. If it is a power amp you measure at the speakers' terminals with appropriate loading be it speakers or dummy load.

 

[Koifarm]

Just adding this from aliexpress and you have your volume control/input select. Just a view euro’s

Also with 6n16b tubes as mu follower.

https://www.diyaudio.com/community/...-preamp-and-power-supply.393318/#post-7203356

 

[PhilippS]

I used DL73 (or CV2299) in this minature PP amp.
The DL73 is a directly heated power pentode for use in mobile transceivers.

The output transformers are from a Stax electrostatic headphone amp, original secondary is now the primary.
The amp uses solid state input and phase splitter, due to a battery pack in a seperate box it´s fully mobile.
Initially intended for headphone use it can power small speakers as well.

 

[as_audio]

This looks like MD core, not seen in Japan before

 

[egellings]

Are replacements available for those tube?

 

[pcardoso73]

These are similar to the russian rod pentode 1P24B. Not a replacement though.
Russian rod pentodes are really interesting ....
http://www.radicalvalves.com/russian/russian-rod-pentodes-1/