In similar position. Haven't touched a personal audio item in months. Protection board is in line. Probably number 3. Progress is much slower now. Odd as the projects to be done are going to be permanent pieces. If you will be offering cars for F5x preamp, it may become back burner project until then
After finishing the DAO Headphone Amp, time to catch up with the F5X Preamp.
Today, both amp modules tested.
Work first time without any problems or oscillations.
DC drift is very low, output to ground single digit mV; differential DC < 1mV.
Even with the simple "heat sink", it is not even warm to hand.
So when put into the case there should be no thermal problems.
Frequency response is flat to 1MHz.
100kHz triangular wave has a slight rounded tip, but some slight overshoot for 100kHz square wave.
One can get rid of the overshoot by increasing gate stopper values.
But looking at the clean frequency response, I would leave it as is personally.
Output impedance per phase is measured to be 130ohm, meeting expectation.
Patrick
.
Today, both amp modules tested.
Work first time without any problems or oscillations.
DC drift is very low, output to ground single digit mV; differential DC < 1mV.
Even with the simple "heat sink", it is not even warm to hand.
So when put into the case there should be no thermal problems.
Frequency response is flat to 1MHz.
100kHz triangular wave has a slight rounded tip, but some slight overshoot for 100kHz square wave.
One can get rid of the overshoot by increasing gate stopper values.
But looking at the clean frequency response, I would leave it as is personally.
Output impedance per phase is measured to be 130ohm, meeting expectation.
Patrick
.
Attachments
I forgot to mention that green was functions generator input in the oscillographs.
This was then converted to balanced input to the F5X Pre by a battery powered DRV134.
Cyan was positive phase output to Gnd.
From memory (of the F5X Power Amp, to many years ago ....), the square wave overshoot came from the DRV134 and not the amp itself.
But as said, it is more cosmetic than a real SQ issue.
Patrick
This was then converted to balanced input to the F5X Pre by a battery powered DRV134.
Cyan was positive phase output to Gnd.
From memory (of the F5X Power Amp, to many years ago ....), the square wave overshoot came from the DRV134 and not the amp itself.
But as said, it is more cosmetic than a real SQ issue.
Patrick
That's what he said a well .......
DIY – so gerade noch | Holger Barske
(Use google translate.)
Patrick
DIY – so gerade noch | Holger Barske
(Use google translate.)
Patrick
