Felipe,
I do not want pictures, just look for the level of the sine wave as you move the frequency from 1kHz to 100KHz
They don' t look much different in mine.
I used an RC at the output to damp the ringing a bit.
I do not know though how they look with another transformer than the LL1660.
Listen first and maybe later you can add a zobel at the output to see what you like better.
There are no definitive rules for this.
It is used mainly to damp transformer resonance.
Maybe you like it or not. See also what happens with the scope. It' s an interesting lesson.
OK, thanks George. How to know the input impedance of the power amps: measuring with a ohm-meter?
Don' t you have their specs? Usually you can tell by looking at the schematic. Be careful with an ohm meter or lcr, it may overload the input. These things sometime have up to 9V out.
I asked Thomas Mayer aka Vinylsavor about Lundhals wiring, attached the correct wiring for next diyers.
So all measurements were taken with swapped the polarity at the output😱
Attachments
It doesnt matter. The thing is that your 26 preamp is an anode follower, and anode followers inverts the signal. That means that what is going out from your anode is an inverted signal from that of your source. As long as you do the same on both channels, there is no difference for the measures or the following amplifier.
If your scope has two channels you can put a sine on the input and measure input and output signals simultaneus. If the two sines has their tops on the same vertical line, your output is the same polarity as your signal. But, as I said, it really doesnt matter.
If your scope has two channels you can put a sine on the input and measure input and output signals simultaneus. If the two sines has their tops on the same vertical line, your output is the same polarity as your signal. But, as I said, it really doesnt matter.
Last edited:
I dont know. Depends on how Per Lundahl chosed to draw his spec. But you dont have to care fortunately😉
Hi Felipe,
as I wrote you can connect the secondary either way depending if you want the stage to be inverting or non inverting. Some transformers have different high frequency performance depending on the polarity. Not the Lundahls. So you can choose.
Best regards
Thomas
as I wrote you can connect the secondary either way depending if you want the stage to be inverting or non inverting. Some transformers have different high frequency performance depending on the polarity. Not the Lundahls. So you can choose.
Best regards
Thomas