Are the THD measurements done with constant input level or with constant output power ?
If with constant input level, then the result of the Sowter for example is quite misleading.
The frequency response of Sowter at 20 Hz is attenuated some 4.5 dB.
This means that the output level at which the THD is measured is not 1W. It is only some 350 mW (-4.5 dB).
This makes a huge difference if the output level were real 1 W.
Also, is it worth to analyze transformers at 1 W, since all those should be capable for more than 10 W ?
If with constant input level, then the result of the Sowter for example is quite misleading.
The frequency response of Sowter at 20 Hz is attenuated some 4.5 dB.
This means that the output level at which the THD is measured is not 1W. It is only some 350 mW (-4.5 dB).
This makes a huge difference if the output level were real 1 W.
Also, is it worth to analyze transformers at 1 W, since all those should be capable for more than 10 W ?
It is costant input level, the reference is 1 w at 1 Khz. Always in this test, as intl specifications.
Ther is also a thd vs level but normally we use in the ss amps. In s.e. is not so important.
I have other digrams but are published on magazine.
Yes there are FFT at 1 watt and freq. answer at 8 watt for 300B and 10 watt for KT150
Walter
Ther is also a thd vs level but normally we use in the ss amps. In s.e. is not so important.
I have other digrams but are published on magazine.
Yes there are FFT at 1 watt and freq. answer at 8 watt for 300B and 10 watt for KT150
Walter
That is what I thought. If, in case of Sowter, the output power were 1W, the THD would be some two to three times higher.
The way you have done the measurement gives too good view of a transformer that in reality has bad low frequency performance.
But again; Do you think is it worth to analyze transformers at 1 W, since all those should be capable for more than 10 W ?
Hello,
The best version of E88C is 8255 TELEFUNKEN, i try this tube for drive 300B.
In the same time, i try EC8010 MULLARD, C3G et C3M SIEMENS / TELEFUNKEN.
I will try 328A ITT, to see what the 310A do.
The best is EC8010 with 12 Hz - 65 KHz, 0 - 1 DB and 3 % of THD to 10 watts, C3G is just after.
I have no try E55L, but this tube is a good issue as a triode.
On this forum, one people help me on another topic.
My humble contribution.
Eric
The best version of E88C is 8255 TELEFUNKEN, i try this tube for drive 300B.
In the same time, i try EC8010 MULLARD, C3G et C3M SIEMENS / TELEFUNKEN.
I will try 328A ITT, to see what the 310A do.
The best is EC8010 with 12 Hz - 65 KHz, 0 - 1 DB and 3 % of THD to 10 watts, C3G is just after.
I have no try E55L, but this tube is a good issue as a triode.
On this forum, one people help me on another topic.
My humble contribution.
Eric
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