The inductance is specified at 120 Hz; most likely measured with a digital inductance meter.
These meters put out 0.5 - 5 V which does not tell that much as inductance varies with frequency and signal level.
However 20 H is a bit too low for a 5k primary impedance; that is a mere 2k4 load at 20 Hz.
A good 5k transformer needs at least 40 H.
These meters put out 0.5 - 5 V which does not tell that much as inductance varies with frequency and signal level.
However 20 H is a bit too low for a 5k primary impedance; that is a mere 2k4 load at 20 Hz.
A good 5k transformer needs at least 40 H.
I know but these are not traditional audio tubes once used with transformer coupling. None of them was made for HiFi except the ECC99 which is recent.
The 6H6 is double diode. Did you mean something else?
I mean this one:
http://www.mif.pg.gda.pl/homepages/frank/sheets/112/6/6N6PI.pdf
Not "traditional", but there are many "modern" transformer coupled designs to be found with these tubes, also commercial ones.
http://www.mif.pg.gda.pl/homepages/frank/sheets/112/6/6N6PI.pdf
Not "traditional", but there are many "modern" transformer coupled designs to be found with these tubes, also commercial ones.
Nothing personal. I just refuse to explain you anything because it always ends with your personal attacks.
Then best to ignore each other
May be I am wrong, and misunderstand your tone because English is not your native language...
Max 5V input means minimum inductance. At lower frequency inductance will also improve because of less losses, especially in this case of EI core.
The standard for measuring inductance is 3-5V @50Hz. Between 50Hz and 20Hz there is very little difference.
I would say that the inductance of that transformer is at least 50-60% higher a low frequency and good signal.
At small signal tubes like the 45 and 4P1L are happy with lower impedance as well because they are linear. Even with 20H and enough current, say 30-35 mA, they could swing quite some undistorted voltage. Easily 30-40V @20Hz (cut-off at about 55-60V). Already perfectly fine from 25-30Hz.
I have never seen or found a "standard" for measuring primary inductance of audio transformers.
If you have please tell me where.
Most of the time this specification is incomplete as frequency, amplitude and applying DC current or not are not indicated.
My digital LCR meter puts out a mere 0.3 V, but comparing the inductance measurement with real measurement of the tube stage with signal generator and oscilloscope I have learned how to interprete.
Japanese transformers. They are THE reference because they re-started the business and perfected everything before anyone else.
Giving minimum inductance instead of maximum inductance is more informative. The reason is obvious especially in this case as it cannot be worse.
For this any good transformer book or well written core datasheet will tell the difference between small and large signal, 50Hz and 120Hz etc...
If you know how trasformers work, once inductance is measured you know the limit for a given application.
They have established a protocol that is more useful for the client. You don't have to do comparisons or measurements to understand the limits because giving minum inductance is enough. They are the best also for this reason. You know what you are buying. No unpleasant surprises.
Other brands are free to do what they want but it doesn't change the fact that such a protocol is more informative and true in relation to the application.
Especially in this case the transformer will work most of the time with small signals (i.e. few volts).
That is your subjective opinion; no problem with that.
However there are more parameters than LF bandwidth which make the sound quality of audio transformers (you will agree...).
Discussing the inductance issue has been done on this forum several times before, and in the meantime we are way off topic here, actually hijacking this thread.
So I leave now as more important tasks are waiting.
Not just mine.
Yes I agree and they are a reference also for the rest. They have been mastering winding techniques since a long time ago and always been the first to introduce new core materials and many other transformer materials like insulators, wires etc. Many of those materials have been developed by them.
One thing that some improvised transformer winders (you should know one that fortunately is not here anymore...
) don't get is how to draw comparisons. This possibly leads to wrong answers.Oh I know but if it comes back so often I would think it is not well understood or is brought up again by an inexperienced user. I don't see any problem. Repetita iuvant!
Ok. Bye.
Then at least we have that in common
It's what I thought. Back in 1999 some people complained that I was rude. But I did not know how to express myself nice.
hi,
do you have a design in mind? i would like to build one also. I won't be needing any gain as my amplifier is quite sensitive.
thanks
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