Beppe,
I doubt that the problem with your KA-801 lies in lack of quality of the preamp section ... In my experience, separates are not always superior just because they are separate.
Dear friend, I do not say that the integrateds' pre sections are bad in general, but usually they are not "straight" as they should be.
There are tone controls, loudness, balance (I prefer without balance) etc.
Sometimes they use also electrolytic coupling caps.
> I think that replacing all capacitors will solve most of the problems.
How true are your words.
I would like to tell you my own experience on the topic.
I have a 30 year old italian amp (an Aloia project if you know the man).
I replaced some days ago the two original Sprague Powerlytic 7200uF/50V with two brand new RIFA PEH 200 series 10.000uF/63V.
I could not believe to my ears. Everything has improved. And in such a remarkable way that now I rate these white Rifas very highly.
As a side note, after using them I found that the high end brand Gamut use them in their exceptional power amps.
You maybe are thinking: " Well, then put some of those Rifas in the Kenwood".
They have screw terminals while the caps in the Kenny are soldered.
Looking at the specifications I can see that the best caps on the market (and expecially those of higher capacitance) are all screw terminated.
> You say that the amplifier was not used for two years (at least) - this is one of the worst things that could happen to the capacitors.
They deteriorate much faster when not used.
In my study/computer room, I have a 20+ years old Sansui amp.
A friend of mine has exactly the same model.
He left his amp unused for some time.
He tried to use it again, but without success - many of the capacitors leaked and developed some bulges.
My amp plays music at least six hours every day and it still works and looks as new.
Sound is OK too, maybe not as good as new - the change is gradual and I can't remember how it sounded 20 years ago
Some people even recommend that you should keep your gear on all the time...
This is very interesting. I did not know. Thank you so much for your very valuable advice. I have to say that just playing music on the Kenny for two days has improved sound remakably.
But the bass remains soft and not defined, like that of the other amp before recapping.
But after ... what a sound.
It is an integrated (about 70W/channel on 8 ohm) as well, but with the pre-main splitting option.
> I could not believe the change in sound when I replaced capacitors in my speaker's crossovers.
Before recapping, the sound was fatiguing and harsh.
Mine was soft and without power. Not particularly harsh.
Sprague is also a very good brand for caps (Krell used them).
> Recapping totally transformed them!!!
This mirrors my own experienece as well. Very fascinating phenomena.
Since that moment I have already purchase 8 big (unfortunately too big to be used without space problem) 15.000uF/100V Siemens Sikorel about which I have read great things.
But these Rifas have impressed me very much indeed. Very good caps.
The sound has gained an impressive transparency.
> Some people are avoiding replacing big power supply caps since they are expensive... I'm afraid that you will have to replace them too if you want that powerful sound.
Reach the pleasure through the sacrifice eh, eh, eh.
If the outcome is nice that sacrifice is very acceptable.
I think that the best caps can work for a very long time (as you perfectly confirm). At least ten years of very beatiful music.
Good luck!
Aleksandar
