Hello fellow tube lovers,
I concocted two el34 driven by a transformer biased coupled ecc99 could sound reasonably ok if the power supply is regulated. Will I delusion myself or this is worth the build compared to push-pull
EL34 bias at 70mA each, 290V (140mA /ch) into a 40% ultralinear 2500/8 output transformer grid biased.
ECC99 maybe at -6V 180V 12mA , 5K / 5K hammond interstage
Power: a real 8 watts.
I concocted two el34 driven by a transformer biased coupled ecc99 could sound reasonably ok if the power supply is regulated. Will I delusion myself or this is worth the build compared to push-pull
EL34 bias at 70mA each, 290V (140mA /ch) into a 40% ultralinear 2500/8 output transformer grid biased.
ECC99 maybe at -6V 180V 12mA , 5K / 5K hammond interstage
Power: a real 8 watts.
So why do so many people waste their money building expensive single ended amplifiers?
Entertainment.
Well, the pp transformer is less good then a se transformer.
SE has no crossover distortion.
SE has no crossover distortion.
Class A PP has no crossover distortion.
PP OPT needs no gap, so can be cheaper for a given LF response.
Why some people prefer SE is something you would need to ask them. I have two theories:
1. some people prefer some low order distortion with their music - it adds 'warmth' and 'musicality'
2. some people falsely believe that simple circuits are better than more complex circuits, and they also have a naive approach as to what 'simple' means (for example, an SE circuit includes part of the PSU in the output stage - which it could be argued makes an SE output less simple than a PP even though superficially it looks more simple)
PP OPT needs no gap, so can be cheaper for a given LF response.
Why some people prefer SE is something you would need to ask them. I have two theories:
1. some people prefer some low order distortion with their music - it adds 'warmth' and 'musicality'
2. some people falsely believe that simple circuits are better than more complex circuits, and they also have a naive approach as to what 'simple' means (for example, an SE circuit includes part of the PSU in the output stage - which it could be argued makes an SE output less simple than a PP even though superficially it looks more simple)
The permeabilty in a se transformers is more constant then a pp transformer.
The performance at low frequencies in a pp is good at medium to high exitating levels but much less at low levels. And performance at low level in general is less good then se transformers, some signals simply disapear. SE transformers always work premagnetisated so there is always a magnetic field.
But on paper pp is better ofcourse.
The performance at low frequencies in a pp is good at medium to high exitating levels but much less at low levels. And performance at low level in general is less good then se transformers, some signals simply disapear. SE transformers always work premagnetisated so there is always a magnetic field.
But on paper pp is better ofcourse.
Are you suggesting that iron ceases to be ferromagnetic at low flux levels? If so, this would be news to people using AC coupled transformers in low signal level applications.esltransformer said:
I don't dispute that permeability may be nonlinear, but it doesn't disappear at zero flux - which is what you seem to imply.
So if there is no magnetic field, where is the permeability and what is permeabity in your opinion? And what about hysteresis?
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Interesting isn't it..
How much power does it take to magnetise a core and to what depth.
It's a different application, however I came across this the other day with someone using magnetic dye defect testing.
In theory a large core used with low power should be less efficient and in theory low level signals should be a different situation than higher levels..
So it will be interesting to hear the outcome..ie a high power Op Tx used at lower levels should give less distortion, however what about the magnetisation current?
Regards
M. Gregg
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My opinion is irrelevant. Permeability is permeability whether I (or you) understand it or not. Permability tells you how the flux varies with the field. Even when one is zero there is still permeability as it is a slope, not a ratio. Just as resistance does not disappear when a conductor has zero voltage across it.esltransformer said:
Hysteresis complicates things, but not to the extent that permeability disappears. Transformer iron has fairly low hysteresis.
Are you asking silly questions to try to trick me, or are you genuinely confused by this?
For low level applications there are special materials. In the past they used mumetall and permalloy(80%) for these applications, nowedays we use cobald amorphous alloys and nanocrystaline materials.
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If it is a slope as you say then at a certain point the slope is horizontal.
Btw, The induction drops rapidly at low levels.
Btw, The induction drops rapidly at low levels.
Is this supposed to be the reason for the amorphous cores in the "high end" OP Tx's?
Low level detail transfer?
Regards
M. Gregg
Some times yes but i am affraid that a lot of these so call "high end" transformers are not so special. Material is not the only thing that counts.
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