The only other reason is that in most double triodes, there are small differences between the interelectrode capacitances between the two sections (not important for audio but it can be important for HF applications). By using a and a' or a1 and a2 or aI and aII it's clear which interelectrode capacitance belongs to which pins. Still no reason to 'catch' this in some kind of rule.
PCL200 you doubt the existence of something that's written into the opening pages of most English language , British valve manufacturers data books ?
and Ketje read my post #16 its to conform to an industrial SYSTEM .
By posting that picture you actually back up my point --
"Pins 6+7+8 is the most favourable section of the tube with respect to the hum" --end quote .
If Philips says that its obvious Mullard its tube subsidiary when they designate the same pins to the "first " section its logical the most sensitive input which is the first stage ( first section ) is the one that would be used.
and Ketje read my post #16 its to conform to an industrial SYSTEM .
By posting that picture you actually back up my point --
"Pins 6+7+8 is the most favourable section of the tube with respect to the hum" --end quote .
If Philips says that its obvious Mullard its tube subsidiary when they designate the same pins to the "first " section its logical the most sensitive input which is the first stage ( first section ) is the one that would be used.
Yes, I doubt its existence because I don't see it described in valve manuals. If it's in so many valve manuals, than just mention one specific manual in which your rule is described.
Conforming to an indicated practice is conforming to a rule otherwise don't bother designating different symbols to what you say are minute differences which you don't think apply to audio.
All very well with a standard input of 0.775 V /1 volt for full output but JLH had some of his power amps at a sensitivity of 150mv for full output that takes a very low noise input and good design not to hear minute levels of noise and I build them and watched the noise levels which were under 1mv rms if constructed carefully .
All very well with a standard input of 0.775 V /1 volt for full output but JLH had some of his power amps at a sensitivity of 150mv for full output that takes a very low noise input and good design not to hear minute levels of noise and I build them and watched the noise levels which were under 1mv rms if constructed carefully .
Now you make it look like the discussion is about the (un)usefulness of distinguishing between the two triodes in a double triode. But it's not and never was. It's about your claim that there is a rule about which of the two triodes is called system one.
Still no proof/source.
Still no proof/source.
You made a big point that Pro_Electron was only registered by the UK in the 60,s so making out it doesn't apply to earlier tubes but I have the larger Mullard/Philips Data books and found the same online .
In it ( January 1971 ) --scroll down to -List of Symbols .
Read -
These symbols are based on British Standard Specifications-
No,1409 :1950 .
Letter Symbols for Electronic Valves .
Notice the date ----1950 that's when they were introduced in the UK
If you do not already know in those days bodies like that were part ( or associated with ) HMG so they were official .
Same book - scroll down to-
List of Symbols --Symbols for Electrodes --Note 3.
Two or more similar electrodes which cannot be distinguished by any of the above means may be denoted by adding one or more PRIMES to indicate to which electrode system the electrodes form a PART .
Thus , the anode of the FIRST diode in a double diode valve is denoted
a( with a single tick ) .
Thats plain English if you cant accept that then we must agree to differ .
https://www.rsp-italy.it/Electronic...ents/Mullard Book 2 Part 3 Valves 1971-01.pdf
In it ( January 1971 ) --scroll down to -List of Symbols .
Read -
These symbols are based on British Standard Specifications-
No,1409 :1950 .
Letter Symbols for Electronic Valves .
Notice the date ----1950 that's when they were introduced in the UK
If you do not already know in those days bodies like that were part ( or associated with ) HMG so they were official .
Same book - scroll down to-
List of Symbols --Symbols for Electrodes --Note 3.
Two or more similar electrodes which cannot be distinguished by any of the above means may be denoted by adding one or more PRIMES to indicate to which electrode system the electrodes form a PART .
Thus , the anode of the FIRST diode in a double diode valve is denoted
a( with a single tick ) .
Thats plain English if you cant accept that then we must agree to differ .
https://www.rsp-italy.it/Electronic...ents/Mullard Book 2 Part 3 Valves 1971-01.pdf
Note 3 in the Mullard manual does not contain the rule you described earlier in this thread. It's just part of the way the electrodes of systems are distinguished from eachother in this manual. But it does not formulate a rule that points out which of the systems in a double triode is called system one.
Based on looking at the ECC81, ECC82 and ECC83 you stated that the system formed by pins 6, 7 and 8 has to be called system one. But again, there are many double triodes that don't follow your rule. And you still didn't provide proof of the existence of your rule.
But fine, let's agree to differ.
Based on looking at the ECC81, ECC82 and ECC83 you stated that the system formed by pins 6, 7 and 8 has to be called system one. But again, there are many double triodes that don't follow your rule. And you still didn't provide proof of the existence of your rule.
But fine, let's agree to differ.
If there is a rule that says pins 6+7+8 is the first section Philips had wrote "First section is the most favourable with respect to hum" 😀
Mona