Output Transformer Bandwidth

[huggygood]

it's starting to be too complicated for me

 

[gabdx]

gabdx, were those results at the rated power (you mentioned 100W for first example, and 20W for second), and with matching primary and secondary resistances.

For the bandwidth yes, but for the phase it is done with a low signal. I guess it is proportional.

For the bandwidth yes, but for the phase it is done with a low signal. I guess it is proportional.

Phase wont change if I am right with the signal, because it is a matter of proportion with inductance and capacitance, if it is right at low power it is right at high power.

Those OT are symmetrically computer optimized windings , 2 or 4 C-cores.

Of course the Hammond and Edcor as very basic transformer compared to this. But it doesn't mean you cannot get great sound out of them.

 

[6A3sUMMER]

Perhaps in a few instances, the high frequency response will change at max power. Of course, music does not normally tax the amplifier to put out max power at high frequencies, so the following would be a non issue. It is just a noted effect for extreme testing:

At high frequencies and maximum power output, if there is not enough plate current to slew the capacitive reactance, then the distortion will rise, and the phase will also change.

 

[JJMontague]

Thank you all for the responses and discussion. I asked the question with a specific project in mind, but I really wanted to know for future use what design objectives would be most impacted specifically by the very high OT bandwidth, and I'm very happy with the depth of discussion and level of expertise that has weighed in. I believe I am now better informed!

My specific project is a SE 45 amp with zero negative feedback. It's one of Ale Moglia's designs seen HERE. From what I gather in this thread I'd expect a lower bandwidth OT to be sufficient. The schematics specify an OT from NP Acoustics with a 10Hz - 100kHz bandwidth (manufacturer's specs, not measured). Perhaps this is a case of over-engineering it simply because it avoids risks and is not too costly to do so.