300B/n

Full Music has 2.5 printed on the base.
TJ 300B/n doesn’t say
Neither does Sophia Electric
Can’t find a definitive answer on pad
 
So, are the TJ 300B/n filaments able to handle the 2.5A @ 2.5v and also can work at 5v?
Of course with the correct bias.
 
RPMac said:
So, are the TJ 300B/n filaments able to handle the 2.5A @ 2.5v and also can work at 5v?
Of course with the correct bias.
Click to expand...
Bias has nothing to do with the heater voltage/current. 300B has 4 pins : heater, grid and anode. There is no place to accommodate multiple heater voltages, unlike something like 12AX7 with 3 connections heater.
 
Wntrmute2 said:
EML has a 2.5V meshplate. Im listening to them currently. 🤣
Click to expand...
EML labels their tube 300B25.
I guess what I’m asking is, does a tube labeled 300B/n mean it is to be used with 2.5v filaments? How do I use TJ 300B/n tubes?
 
I would assume that each manufacturer has their own way of designating the filament voltage. Not universal
 
If a 300B has been specially made with a 2.5V filament, the manufacturer will mark the tube appropriately so you don't plug it into a normal 300B amp.
 
paul_b said:
If a 300B has been specially made with a 2.5V filament, the manufacturer will mark the tube appropriately so you don't plug it into a normal 300B amp.
Click to expand...
This is how I have done it. The Full Music 300B/n has 2.5 printed on the base…the TJ 300B/n doesn’t.
Last question…what does the “/n” mean?
 
IIRC, /n identifies a “mesh” plate premium tube. Their graphite and carbon plate tubes have different identifiers.
 
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