[Xcalibur255]

Probably the 5U8C...Glenn shipped me one with my GEL3N amp. It is huge. 5 amp heater draw I believe.

I believe that's the one, yes! The filament is so thick, on another level from any other tube I've held in my hands.

 

[triod750]

Regarding Melz 6H12C/6N12S, I received this from an tubeophile with a Russian wife: http://audio-db.info/AudioDB/BazaPraktiki/Usilenie/Lampy/Alfavit/6N/6N12S
A translation would be welcome.
Can only say that I agree with Eugen Komissarov

 

[mordy]

Regarding Melz 6H12C/6N12S, I received this from an tubeophile with a Russian wife: http://audio-db.info/AudioDB/BazaPraktiki/Usilenie/Lampy/Alfavit/6N/6N12S
A translation would be welcome.
Can only say that I agree with Eugen Komissarov

 

[mordy]

You too, dance from the stove?

 

[Zachik]

You too, dance from the stove?

haha - I wonder what that means... either google translate got it wrong, or maybe an expression we do not have in English?

 

[gibosi]

In the right column of text, I am very curious to learn what 300 and 500 indicate.

 

[gibosi]

In the right column of text, I am very curious to learn what 300 and 500 indicate.

After doing a little digging, it turns out that the maximum plate voltage for the 6N12S is 300V (typically, plus or minus 10%).

You might find this document interesting. The 6N12S is listed on page 37.

https://www.govinfo.gov/content/pkg...VPUB-C13-6925b02fb6dcaa88935be001eb551b4c.pdf

And I have no idea what the number 500 represents in the data sheet @triod750 posted.

Recently I measured B+ in my Glenn OTL with six 6N12S and found the value to be 320V. What this tells me is six of these tubes is fine, but running two or four is not a good idea. As the number of tubes in the output goes down, B+ goes up. And since the value is at max for six, I would not recommend less than that.

 

[gibosi]

Changing the subject, I've been rolling through different drivers and rectifiers to discover which combinations work well with the Telefunken 6080. Below is a GEC U18/20 rectifier and a pair of Ken Rad #76. And to my old ears, this is a very enjoyable roll.

 

[triod750]

After doing a little digging, it turns out that the maximum plate voltage for the 6N12S is 300V (typically, plus or minus 10%).

You might find this document interesting. The 6N12S is listed on page 37.

https://www.govinfo.gov/content/pkg...VPUB-C13-6925b02fb6dcaa88935be001eb551b4c.pdf

And I have no idea what the number 500 represents in the data sheet @triod750 posted.

Recently I measured B+ in my Glenn OTL with six 6N12S and found the value to be 320V. What this tells me is six of these tubes is fine, but running two or four is not a good idea. As the number of tubes in the output goes down, B+ goes up. And since the value is at max for six, I would not recommend less than that.

Do you have a guess on what the number 100 above 500 means? The text is almost the same for both numbers but for 500 it says something about 'automaticxxxxx'.
I guess 500 is the number of tubes you need to be on the safe side if you run four or two in GOTL.

 

[gibosi]

Do you have a guess on what the number 100 above 500 means? The text is almost the same for both numbers but for 500 it says something about 'automaticxxxxx'.
I guess 500 is the number of tubes you need to be on the safe side if you run four or two in GOTL.

Unfortunately, I have no idea, as the National Bureau of Standards document I posted above does not show a corresponding value of 100.

 

[Zachik]

a pair of Ken Rad #76

2nd time this past day or two that I see #76 used... Gotta find some (and adapters)...

 

[triod750]

Unfortunately, I have no idea, as the National Bureau of Standards document I posted above does not show a corresponding value of 100.

How about this for the number 100: https://www.qsl.net/dl7avf/roehren/trimax2.html#6N12S

I cannot read and understand this information. I am severly lacking. I'm sorry but not ashamed.

Se also: https://www.qsl.net/dl7avf/roehren/xref6n.html

 

[gibosi]

How about this for the number 100: https://www.qsl.net/dl7avf/roehren/trimax2.html#6N12S

I cannot read and understand this information. I am severly lacking. I'm sorry but not ashamed.

Se also: https://www.qsl.net/dl7avf/roehren/xref6n.html

Well, it appears to be "Heater-to-Cathode Voltage", and it would appear that this value is only relevant for circuit designers, so I intend to ignore it.

 

[triod750]

I'm in good company then - thank you very much!

In the right column of text, I am very curious to learn what 300 and 500 indicate.

The text before '500' says "Största motstånd i nätkretsen med automatbias (floating bias). kOhm" 'Largest/biggest (?) resistance in circuit with auto/floating bias in kOhm'. Translated by a Swedish fellow with a Russian wife. Wooha!

Found curves!
https://tehnodoka.ru/spravkalamp/6n12s.php

 

[L0rdGwyn]

I'm in good company then - thank you very much!

The text before '500' says "Största motstånd i nätkretsen med automatbias (floating bias). kOhm" 'Largest/biggest (?) resistance in circuit with auto/floating bias in kOhm'. Translated by a Swedish fellow with a Russian wife. Wooha!

Found curves!
https://tehnodoka.ru/spravkalamp/6n12s.php

That is the maximum value of grid leak resistor. The grid leak makes up part of the load for the previous stage and the DC path to ground for any grid current. You typically want to use the highest value possible per the datasheet. Usually it is around 500Kohm to 1Meg.

But there are some oddball tubes that can only take a small grid leak, like type 50, only 10Kohm! Which makes a bit of a problem. In this case, you can use a choke instead since a choke represent a high AC impedance (fulfills the role as the load for the previous stage), but a low DC resistance (fulfills the requirement for a DC path to ground for grid current).

Here is a picture as an example in cathode bias (autobias). They have sort of made a mistake though, the grid stopper should be connected directly at the grid to ward off parasitic oscillations. Note that because most tubes do not draw much grid current when operating in class A1 (grid always negative relative to the cathode), there is little-to-no voltage drop across this large value resistor, so the grid is at ground potential. The cathode is then made positive relative to the grid as current passes through the cathode bias resistor. This can be restated as the grid being negative relative to the cathode, even if the grid is at 0V and the cathode is positive. That's how cathode bias works, in a nutshell.