Hi
in attach the first proto of 300B OT with nano
It is 3k primary
5 ohm secondary (single)
Around 40H -100Hz but some adj with gap will be possible.
At the end it will be potted.
The first test are almost fine.
The Freq. answer; there is a little step at 50kHz, but it will be fixed
Zs are 700 ohm (blu) and 1 kohm (red)
At thr moment out of the power stage that will be ready soon
The phase
cancelled due an error
in attach the first proto of 300B OT with nano
It is 3k primary
5 ohm secondary (single)
Around 40H -100Hz but some adj with gap will be possible.
At the end it will be potted.
The first test are almost fine.
The Freq. answer; there is a little step at 50kHz, but it will be fixed
Zs are 700 ohm (blu) and 1 kohm (red)
At thr moment out of the power stage that will be ready soon
The phase
cancelled due an error
Last edited:
The "step" is a dip resonance. It gets fixed by playing with the distribution between Cp/Cs capacitance. Anyway, 50kHz is pretty okay.
This is the first coil wounded in a home made support
The intention is the use a greater primary wire to lower the Rdc
The intention is the use a greater primary wire to lower the Rdc
Usually, the treatment for dip resonances are to dump primary to secondary capacitance into primary to primary, reduce primary to secondary capacitance and avoid connecting secondaries in series that have a capacitance difference, or big difference related to their primary layers.
A dip resonance like this one, well above the audio band… any impact on sound ?
Will it add a signature to or disturb what We hear ?
Will it add a signature to or disturb what We hear ?
It is now a proto
Then it will be put in a circuit
At the end after test lab there is a listening session
Walter
I would expect a phase shift at 50KHz. I suspect is more likely some 50KHz signal getting into your measurement.
The fact that the phase looks fine but the response has a little dip probably means it is just a glich in the measurement.
It is visible in the phase response, just a slight kink, because the Q factor is really small. I wouldn't bother about it. Keep in mind I'm mentioning my observation just because of fun and passion, do not take it as criticism. Hats off for your work, I admire fellow winders and designers.
Many things might be the cause of a mini peak and mini divot at 50kHz.
It seems to be well dampened, so not to worry.
Try running the sweep at a slower rate, to be sure the jog does not get larger. Over-fast sweeps causes a higher Q resonance to look as if it is a lower Q resonance.
Ask me, a spectrum analyzer specialist, how I know that. Just my experience, we all trip.
I would guess that if you drive the transformer with a 300B, that you will not use global negative feedback, Right?
So, as they say in the Philippines, Walang Problema (No Problem).
Perhaps . . .
Secondary distributed capacitance in combination with primary to secondary leakage inductance?
Primary distributed capacitance in combination with primary to secondary leakage reactance?
I would be glad to use a pair of those output transformers for 300B, 2A3, Triode wired KT88, etc.
but they are probably too expensive for me . . . sales price, shipping, and import duties to the US.
Have fun when you get the amplifier built.
It seems to be well dampened, so not to worry.
Try running the sweep at a slower rate, to be sure the jog does not get larger. Over-fast sweeps causes a higher Q resonance to look as if it is a lower Q resonance.
Ask me, a spectrum analyzer specialist, how I know that. Just my experience, we all trip.
I would guess that if you drive the transformer with a 300B, that you will not use global negative feedback, Right?
So, as they say in the Philippines, Walang Problema (No Problem).
Perhaps . . .
Secondary distributed capacitance in combination with primary to secondary leakage inductance?
Primary distributed capacitance in combination with primary to secondary leakage reactance?
I would be glad to use a pair of those output transformers for 300B, 2A3, Triode wired KT88, etc.
but they are probably too expensive for me . . . sales price, shipping, and import duties to the US.
Have fun when you get the amplifier built.
This is the first step after we have found a good supplier of nano iron
The entire circuit is ready but I will test it offline also in the backward method ( if you remember)
I am waiting also a new coil with same architecture with bigger wire on primary.
About costs at the moment is not possible to fix something
We have ready a step up for MC coils and a interstage trafo 5k:600 ohm and 5k:5k with 30 mA max each primary, always nano
With the same iron for 300B is planned a p-p and a version with KT150
This is 2nd version
Different implementation.
Now the Rdc is 80 ohms, the previous was around 140 ohm
the frequency response
the dimensions are 120 x 120 x 100 mm , 3,5 kg nude
The L is around 80H similar to the previous one where I wrote a wrong number
One more version to be tested
Different implementation.
Now the Rdc is 80 ohms, the previous was around 140 ohm
the frequency response
the dimensions are 120 x 120 x 100 mm , 3,5 kg nude
The L is around 80H similar to the previous one where I wrote a wrong number
One more version to be tested