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Old 13th May 2013, 08:18 PM   #2241
6L6 is offline 6L6  United States
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Because between the different manufacturers there are many differences in the physical construction and materials used to arrive at (theoretically) the same electrical performance. And tubes wear out with use.

Also, nobody could measure back then like you can today... When those tubes were designed, the best research lab in the world didn't have access to the information you can get off your basic digital scope.

Last edited by 6L6; 13th May 2013 at 08:20 PM.
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Old 13th May 2013, 08:21 PM   #2242
Zen Mod is offline Zen Mod  Serbia
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filament starving is for sissies

same as in case when using CCS heating for voltage oriented filaments , where you need to fine tune CCS observing voltage - for each tube separately - you also need to fine tune starving filament voltage not for every brand , but even for every batch of tubes in same brand

so - every old toobster will tell ya - leave it kiddoe - that hassle is nothing else than trouble - feed them as intended , and then you'll have expected behavior across entire
life span
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Old 13th May 2013, 08:32 PM   #2243
stajo is offline stajo  Sweden
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Quote:
Originally Posted by 6L6 View Post
Because between the different manufacturers there are many differences in the physical construction and materials used to arrive at (theoretically) the same electrical performance. And tubes wear out with use.

Also, nobody could measure back then like you can today... When those tubes were designed, the best research lab in the world didn't have access to the information you can get off your basic digital scope.
That doesnt really explain the differences in frequencys to me. My wild guess is that I'm looking at a combination of filament interference and microphony planting from the mains tranny. Maybe. Wild guess, but can be tested.

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filament starving is for sissies

same as in case when using CCS heating for voltage oriented filaments , where you need to fine tune CCS observing voltage - for each tube separately - you also need to fine tune starving filament voltage not for every brand , but even for every batch of tubes in same brand

so - every old toobster will tell ya - leave it kiddoe - that hassle is nothing else than trouble - feed them as intended , and then you'll have expected behavior across entire
life span
Old toob guy. Those fellows are intended for stuff that cant reproduce any 50 Hz and also as noice cancelling push pull output toobies configs. Then 6,3 AC is fine, even as it would have been a DHT. But we're in a different area now. Suggestions?
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Old 13th May 2013, 08:43 PM   #2244
stajo is offline stajo  Sweden
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Quote:
Originally Posted by 6L6 View Post
Nice 'scope, by the way...
Yes, Salas recommended just this one
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Old 13th May 2013, 08:45 PM   #2245
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by stajo View Post
.........


Old toob guy. Those fellows are intended for stuff that cant reproduce any 50 Hz and also as noice cancelling push pull output toobies configs. Then 6,3 AC is fine, even as it would have been a DHT. But we're in a different area now. Suggestions?
clarify "those fellows"

too many threads in same time , too many posts ........ and I couldn't cope with all mistakes you made in measurements ( taking in account that you were in good company ) .

so - what's the problem now ?
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Old 13th May 2013, 08:49 PM   #2246
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be kind, rewind
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Old 13th May 2013, 08:55 PM   #2247
stajo is offline stajo  Sweden
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Those fellows is the 6V6es. In a push pull output tube config its ok with several voltages of ripple and it cancels out in the OPT. In an SE preamp config millivolts apperantly makes differences to the result.

I am aware of that this is not their intended use, as I am of my faulty measures (I'm here to learn) but I really think this is a perfect example of learning to both tackle the problems and use the tools to analyze it.

If you dont agree please say so.

Look at the last 3 pics. They are taken with the same config, same environment just 3 different fellows. Explain the differences.
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Old 13th May 2013, 09:02 PM   #2248
Zen Mod is offline Zen Mod  Serbia
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differences as result of different physical/electrical virtues of each toob

you still need to learn that each tube is result of hundreds of small very precise steps in manufacturing procedure and that there are hardly two same tubes in existence

but - as I wrote already - heating of tube is fundamental , most important condition for exploitation ; heat them as they intended to be heated , but in most proper way you can make it .

that way differences and spread of electrical characteristics will be minimized

CCS based heating is my choice ;

edit : few mishaps :

- I'm not here to not agree with learning , steepness of someone's learning curve etc. ...... just said that I didn't had time/energy to follow or even help , in case that I can and know how to help

- SE came historically before PP , so that was their intended use - especially in time when each uF was golden
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Last edited by Zen Mod; 13th May 2013 at 09:05 PM.
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Old 13th May 2013, 09:18 PM   #2249
stajo is offline stajo  Sweden
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Apperantly heating is one thing that needs to be investigated using those kinds of tubes for this intention. My first try was AC, second elevated AC and now some other ways.

Note that I have yet not listened to the different configs. I got stuck on measurment results and interpretation of the same.

I agree with both 6L6 and ZM that the tube charm is much about their individual charachteristics. Im still puzzled about the differences in curves frequencys tho. I think I can gather around 50-100 different 6V6es without going to far. A stupid thing would be to measure them all.

Hey ho, captain Ahab!
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Old 13th May 2013, 09:25 PM   #2250
Zen Mod is offline Zen Mod  Serbia
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heater PSU must be rock solid stable , same as anode PSU

make first one in quality as you have second one , and result must be good ;

if you have trouble/disturbance from dirty (input) side of any PSU , only cure is to make it more remote , while keeping final reg elements near load ( tube itself)

choke in anode PSU is on dirty side - ringingzingingspitting creature , exactly intended to do these nasty things , instead of tube itself
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