OK. I adapted the power supply rails voltage and the idle current for the headphone use and the measurements improved, as expected. These are the graphs for a 2Vpp amplitude at low 33R load - second harmonic predominant, no raise in distortion with frequency : Tonight I`ll do the listening.
Attachments
Sorry, I mixed the marks.. 😁 I'm using KSC2690, KSC3503 is 100mA max. device and shouldn't be used for a headphone amplifier.
Btw, KSC2690 has interesting current gain characteristics, with new japanese devices is mostly flat line. On the graph you could see for KSC2690 the gain rises with current so it's kind of self compensating as I see it, higher the current, higher the gain.
Attachments
I've listened to it and can't find a thing to complain about, it sounds very good I couldn't find the difference compared to TPA6120a2. Anyway for me, main purpose will be the line amplifier and I hope I'll have a chance to compare it with commercial products in the future,,,
Cheers, Borko.
Cheers, Borko.
Hi Bogdan,
You made me curious about your project and I would like to try it, being passionate about listening to headphones.
Given that PCB files and other details are available, I would be grateful if you could provide them to me.
Thank you in advance.
You made me curious about your project and I would like to try it, being passionate about listening to headphones.
Given that PCB files and other details are available, I would be grateful if you could provide them to me.
Thank you in advance.
Hi Bogdan,
You made me curious about your project and I would like to try it, being passionate about listening to headphones.
Given that PCB files and other details are available, I would be grateful if you could provide them to me.
Thank you in advance.
Ok, no problem, but in a few days when I have some time to edit few small errors I had on the pcb.
Haha, I came up with small modification, that gives 10 times less distortion 😀 .
For now, approved in spice, tomorrow I'll do the real life measurements.
For now, approved in spice, tomorrow I'll do the real life measurements.
This is the new set of measurements for 33R load of the Version 2. These measurements are done with power supply configured to +/-15V and the bias is 83mA. With higher rails and higher idle current the results could be even better if needed. Tomorrow the PCB file will be ready. 😉
Cheers, Borko.
Cheers, Borko.
Attachments
Is there a way to set operating points and/or output devices for 5w into 32ohms with less than 0.05% THD and dominant 2nd order?
PCB File
This is the render of the finall PCB file. Anyone who wants to try it, send me an email in pm. PCB is two layer, 166 x 137mm.
Heatsinks are Ficher SK-104-25, for higher bias version, SK-104-38 or SK-104-50, should be used.
This is the render of the finall PCB file. Anyone who wants to try it, send me an email in pm. PCB is two layer, 166 x 137mm.
Heatsinks are Ficher SK-104-25, for higher bias version, SK-104-38 or SK-104-50, should be used.
Attachments
Last edited:
It could be done, but iit's a extreme case..that would dissipate lot more heat, this is a sepp output stage with maximum 2 x idle current.