C3m linestage

[bequerel]

Thanks, got it!

I have stash of C3m and C3o tubes to experiment with during the summer.

 

[Dr.X]

Couple of C3m questions...

Hi,
I have a couple of questions re. triode-connected C3m if anyone could help...

1] Triode-coupled, what's the approx. amplifcation factor?

2] How do they sound? Specifically, compared to the Russian 6c45 or similar?

Many thanks!
Doc

 

[AndreasS]

Re: Couple of C3m questions...

...
1] Triode-coupled, what's the approx. amplifcation factor?...

Depends of the circuit..., µ g1/g2 = 19.

Andreas

 

[bequerel]

AndreasS, hope you will take a minute to answer a simple question since you obviously know this tube well:

Is the Ri in triode mode around 2k?

 

[AndreasS]

The Ri (triode mode) is shown on datasheet page 17

http://frank.pocnet.net/sheets/009/c/C3m.pdf

For the operation point @ 16 mA Ri is around 2,5 kOhms

Andreas

 

[Dr.X]

Re: Re: Couple of C3m questions...

Depends of the circuit..., µ g1/g2 = 19.

Andreas

Thanks Andreas

 

[bequerel]

The Ri (triode mode) is shown on datasheet page 17

http://frank.pocnet.net/sheets/009/c/C3m.pdf

For the operation point @ 16 mA Ri is around 2,5 kOhms

Andreas

Thanks a lot AndreasS!

 

[mach1]

bequerel,

to determine the plate resistance of any tube at any operating point, plot the operarating point on the plate curves, then draw a line tangential to the curve that runs through your operating point. The slope of that line (delta V over delta I) is the plate resistance.

Easy !

 

[bequerel]

bequerel,

to determine the plate resistance of any tube at any operating point, plot the operarating point on the plate curves, then draw a line tangential to the curve that runs through your operating point. The slope of that line (delta V over delta I) is the plate resistance.

Easy !

Thanks, I will print out your reply and save in my drawer.

 

[milen007]

i would like to build one myself. have the siemens tubes in my drawer.

got any schematic to share? TIA

erwin

 

[bequerel]

i would like to build one myself. have the siemens tubes in my drawer.

got any schematic to share? TIA

erwin

The only two schematics I have ever seen are the one from kstagger who replied further up in this thread, and one that was posted over at vt4c.com some time ago:


http://www.vt4c.com/bb/viewtopic.php?t=1567

 

[sganti]

C3m pentode linestage

Hi
I have built and using a C3o linestage, but operating C3o in a pentode mode. C3o is a 6.3V version of C3m.

Somebody else posted a very useful warning, do not remove the tubes after you have turned off, I usually wait for 30 minutes. I lost a few C3m's this way, before I went with C3o. When I had the C3m, I was rectifying it, with C3o, I have a/c filaments.

The power supply uses Hashimoto PT-100, with a Hashimoto Choke for choke input supply. Then I have 4 regulators - one for each plate and one for each screen. These are current sourced -- shunt reg's. I am sorry I cannot post the schematic here, 'cause it is a borrowed schematic and not my own. You can also use Allen Wright's SuperReg - two of them, one for both Plates and one for both Screens.

Please shoot me an email to sridhar.ganti@gmail.com if you have any questions. This is the best linestage I have heard/built.

I also use VH Audio 1mF teflons for the o/p caps and Goldpoint 50K volume control and Goldpoint selector switch.

Chung had posted a copy of this at vt4c.com forum also.

Thanks
ganti

 

[sganti]

I will try to attach the schematic in this post

ganti