Please, somebody, help identify the tube!

[Xolotl]

Please, somebody, help identify the tube!
Hi guys! Please help me to identify the tube! It serves as a driver tube on two-stage single ended mono-block power amplifier, where it is coupled with PX-25 direct heated triode output tube through Tamura interstage transformer . Production date: August 1963. Code stamped on the tube: 36P4. Five pins direct heated triode.
Thank you in advance!

 

[glen65]

Please, somebody, help identify the tube!
Hi guys! Please help me to identify the tube! It serves as a driver tube on two-stage single ended mono-block power amplifier, where it is coupled with PX-25 direct heated triode output tube through Tamura interstage transformer . Production date: August 1963. Code stamped on the tube: 36P4. Five pins direct heated triode.
Thank you in advance!

Do you have the make and model of the amp it was used in?

 

[markus]

the manufacturer's stamp looks Mullard-y . . . . .

 

[Xolotl]

Unfortunately, I suspect it is some 20 years old no name self-made Japanese power-amp, perfectly sounding though.

 

[Xolotl]

Could it be indirectly heated triode MH4 (VR 37) by Osram, Mazda, Marconi?
Or maybe ML4?
Or MHL4?
Thanks!

 

[Tom Bavis]

Measure heater voltage, heater current That may narrow it down...

 

[Xolotl]

It is very likely CV 1732= ML4= AC/P= NR57 tube:
I've masured the following parameters:
Heater voltage 4V
Anode voltage 200-216V
Current (anode, cathode) 16mA
Cathode grid -11V

May there be other options?
Thanks everybody!

 

[Tom Bavis]

Here's a list of triodes with that base from Duncan Amps database:

 

[Xolotl]

Thank You so much, indeed! I've already ordered CV1732 (ML4) - see if not suitable, will try the rest from the list.