Russian 6N16B-V instead of 12A...7 in a mic

Tried to search, but didn't find anything. What do you guys think about this tube. One of my mics Nady 1050 equivalent with soldered tube went bad, needs tube swap. It doesn't have place for socket, so i'm thinking about this one.

12A...What?..7
6N16B-V  is quite far from all 12A...7, In addition, she has 6.3 volts of heater instead of 12.6, it is closer to ECC89.
6N17B-V is closer to 12AX7, but also has 6.3 volts of heater.
If it possible, try 6S31B-R, but do not forget about 6.3 volts heater.

12ax7 is too hot for this mic. 6N16B-V should be closer to 12at7 so i was thinking it should be right in that respect.

Filament voltage in this mic is reported to be 6.3v.

Are there any mics that use 12A_7 tubes that have the heaters in series, anyway?

All the schematics i've seen either have them wired in parallel, or only using one triode.

kingkorg said:

12ax7 is too hot for this mic. 6N16B-V should be closer to 12at7 so i was thinking it should be right in that respect.

Filament voltage in this mic is reported to be 6.3v.

Click to expand...

I pondered about doing something similar with a 6s6b. You should just give it a try, 6s6b-V are pretty cheap and I got excellent results in a m49 clone. I'm pretty sure it would run in a Elam 251 with bias raised to 2.2k and it might  even "sound better" than a 6072a

The  6s6b is a great tube for microphones. Very low noise.
I prefer it over the 5840.

I have to report that Russian 6N16B works like a charm instead of 12ay7 i had in there. 

Now, i am not very familiar with all the parameters that should be considered when doing such swap, but 6N16B has less noise, less distortion (0.12%) compared to Electro Harmonix  12AY7 (0.23%). i have in another exactly same mic, same power supply used, stock bias resistor.  I will tune that one eventually. As i read on the nett these should be direct replacements for bigger 12..7 russian equivalents (6n3p or 6n2p) with different pinouts. I will let it work for several days and give feedback.

Wrapping my head around pinouts was tricky, but i managed to figure it out. 

By the way i paid 7 dollars for 4 pcs!

If the B+ voltage is 200V or higher i would drop it a little. For example to the 160V.
Do you know the 1050 output transformer ratio?
Since it's sub mini double triode - you can try to use it in parallel as a plate follower
If the output transformer is ca. 11:1 then i would go  for 200K plate resistor.
Just some idea

I did drop voltage. I believe transformer is about 10:1. Will try paralel configuratiin, thanks!

Power supply transformer is getting hotter with this tube. What should be upper temperature limit?

How did you drop the voltage?
If only by changing zener diodes, then measure output voltage inside PSU, is it exactly as it should be - if it's lower then use lower value resistors (at least two last) .
Another thing is heater supply -  6N16B suck 100mA more than 12ax7.
If the heater supply have dropping resistor before voltage regulator, then change it for lower value or even replace with jumper.
Also you can replace with the jumper rectifier diode from  voltage regulator to ground (if it's used in your PSU).  Without it and with proper value resistor (or even without), you should get underheating on a decent level and less stress for transformer

I am not sure if this is an issue, after several hours temp is around 43 celsius. Otherwise, the voltages are ok.


By the way i am amazed how quiet this tube is.