Kondo KSL-M77 phono preamp clone project

[gerrittube]

Macces,

Lovely built! What type/brand are the orange connectors between the transformer and the board?

Reghards, Gerrit

 

[Macces]

Gerrit,

the connectors are from Wago.
Perfect industry standard for cable connections.
https://www.wago.com/de/c/installationsklemmen

 

[nerdorama]

I've used some of the WAGO parallel splices before but haven't seen the inline splices. Just ordered some. Thanks for showing your project.

 

[gerrittube]

Thanks for showing!

Regards, Gerrit

 

[Macces]

Those resistors should discharge any DC coming from a source, as I have noted a clicking sound when changing the input. 100k in my case, but they can be anything maybe up to 500k.

Finally found out the clicking noise is caused by something else (relay decoupling)...... This can be cured with a diode in parallel to the relay coil, with the cathode to "+"

Based on your suggestion,
I simply soldered in Zener diodes. 5.1V-1.3W (BZX 85C 5v1).
No more quiet cracking in the speakers.🙂
Thank you Hesener.

 

[Erman]

È possibile avere una foto per quanto riguarda i diodi da applicare sulla bobina del relè? Grazie.

 

[planet10]

Is it possible to have a photo regarding the diodes to be applied on the relay coil? Thanks.

English please.

dave
diyAudio moderation team

 

[Erman]

Is it possible to have a photo of the diodes to apply to the relay coil? I also have this problem when selecting the channels. Thanks.

 

[Macces]

Hello Erman, you're lucky. I took two pictures of it. Good luck.

 

[Erman]

Grazie mille, molto gentile.

Ti farò sapere il risultato.

Ciao.

 

[Boydk]

English please.

dave
diyAudio moderation team

@Erman wrote:
Grazie mille, molto gentile.
Ti farò sapere il risultato.
Ciao.



Obviously very easy to forget 🤣 🤣

 

[JoeAlders]

I have read this very long thread with great interest. Is one of the builders willing to publish a RIAA accuracy measurement of their build?
An inverse RIAA circuit (for instance the Hagerman iRIAA2) at the phono input and measuring the accuracy at the phono output
between 20Hz and 20kHz.

 

[hesener]

Here is the RIAA response of my build, including the modifications indicated earlier in this thread, with the Neumann modification. The channel imbalance is due to my slightly sloppy setup, I should have calibrated the two channels before measurement, but that does not affect the frequency response, fortunately 😀

the other picture is the RIAA response of the original network. I did not spend too much time analysing and interpreting (so I am not sure where that LF hump is coming from), since after simulating it was clear that some adjustments are needed.....

 

[JoeAlders]

That looks very good!
Apart from the (ultra) low frequency approaching 20Hz, everything within +/- 1dB.
Congratulations, good job! 🙂

 

[hesener]

thanks. it obviously pays off if you make the inverse RIAA yourself, to fit your designs 😀