Kenwood KA59 - KA89

[GEirin]

Hi all.

I have decided to repair and to improve an old Kenwood KA 59.

My questions:
- What is your think about attached achematic power amp circuit of the KA 89 ( KA 59 and KA 89 are similar).

- What is your opinion of the C1: 2,2 mF 50V. C11 and C13: 1mF 50V, every are electrolytics capacitors.

Thanks for any opinions can give me.

Guillermo.

 

[GEirin]

Please.

Help.

What is the function of C11//R13 and C13//R15? or What is the reason for to use electrolitcs caps in the signal?
I can to use electrolitcs no polar caps, in C1, C11 and C13?

Other question
I can to substitute R53 and R55 for only resistor and to add a speedup capacitor?

Thanks

Guillermo

 

[Tube_Dude]

Please.

Help.

What is the function of C11//R13 and C13//R15? or What is the reason for to use electrolitcs caps in the signal?

Hi Guillermo

R13 and R15 are for , to limit the dissipation in Q5 and Q7.
The resistors are bypassed at signal frequencies by C11 and C13 respectively

I can to use electrolitcs no polar caps, in C1, C11 and C13?

Yes...if you want.

I can to substitute R53 and R55 for only resistor and to add a speedup capacitor?

You can substitute R53 and R55 for only a resistor of the value of 660 Ohms.
About the speed up capacitor you must check for stability (if the cap don't provoke oscilation )

Saludos 🙂

 

[GEirin]

Thank you.
Regards,


Muchísimas gracias, Jorge.
Saludos.

Guillermo.