XOno problem

[enaB]

Hi!

I made XOno MM preamp using this(link) schematic few days ago, with only minor changes (2SK170 instead 2SK389, green LED and adapted R67/R53 values, 220R instead 221R resistors), but when I take some measurings with my sound card, it looks that there is a problem in high frequency equalization 😕
PCB is my design, but I can't find any problem on it. Here is the picture to describe better, I am not very good in English 🙂 (ignore the bumpy curve)


Thanks!

 

[nar]

It seems fairly good, to my eyes, your 1k reference and lfe curve is perfect.
It could also be your soundcard, you just have about +1 dB in the 2k - 20k range ... and this is very gradual, so no worry.

What you measure is deviation from a reference curve. There are some slightly different reference curves too 🙂 Not directly related to sound quality 🙂

As a doubt, you can tweak better your capacitors in the feedback network, in absolute precision, maybe you can be closer to the green curve then.

Best,

nAr

PS: R5 can be referenced to ground instead of +30V, if I recall. Oh well, not a big issue.

 

[enaB]

It probably could be tweaked, but why this is happening with original values is what bothers me 🙂
Couldn't be due to capacitor tolerance. Soundcard makes some error too, but not so much





Thanks for reply!