Ampli à tubes classic16: LA CLAQUE!!!!!!

[le_toine]

Ok but you removed R4... I don't need/want to do that... Is there another solution?

[Lowrider]

It doesnt matter if you remove R4 or not, you can still connect to the same ground, there are ground points marked GND, use any of them, I rewired all componentes on input and driver to connect to the same ground, hum disapeared, and sounds better...

[le_toine]

Replacing C2 with russian PIOs done!

I already had C4 & C5 replaced with K42Y. With the stock WIMA C2s it was only a small improvement (highs and mids better defined maybe?)

With the K40Y-9 just installed, amp and cd player not even warm, caps not broken-in, I can already hear a huge improvement: attacks and bass have much more impact. I'm happy because that was just what the Classic was lacking, in my opinion. High and mids are improved again, too, and soundstage seems deeper.

Lowrider, thanks for your help. From your experience how long does it take for the caps to fully break-in?

I wonder what the next step will be for me: diodes or power supply caps?

[Lowrider]

I did both toguether, K42 and K40, so I dont know which does what, but all toguether well worth the trouble and the cost...

They didnt take long to break-in, they sounded good from day 1...

The diodes did improve a little, but bypasses made a larger improvement, replace C11 and put some more around at least C12, C16, C18, and around the transformer windings for the accessories and for the heaters...

The supply caps didnt do much, except the Chinese polypropylene on C9, that did a very good bass improvement...

[le_toine]

There's no C11 in my amp, I guess I have an old PCB.
There's also an empty space for C27, what's the deal with that capacitor?

I'm still happy with my last mod except that sibilance has increased...

[Lowrider]

C11 is very important, it bypasses C10, you can connect the bypass capacitor between the top end of R27 and ground, to bypass C12 connect between the other end of R27 and ground...

To bypass C16 connect to TP3 and ground, to bypass C18, the left end or R29 and ground...

The sibilance might improve with a bit more use, the best cure is to remove R16 and R17, but with negative feedback you may get oscillations...

C27 is not necessary, it bypassed L1, but probably caused oscillations, so they removed it...

[Lowrider]

By the way, you dont just remove R16 and R17, you bypass them with bits of wire, easy to undo...

[le_toine]

I'll report in a few days if sibilance has diminished. If not I might try the R16/R17 mod... I have not tried triode mode yet. I don't know if it will be better or worst.

At first I dind't understand why you used 2*47 µF instead of 220µF in C9. I've found the answer here .
Francis says it's good to have C10 at least three times bigger than C9, with C9 at 100µF or below.
So basically what baleine did here with the 500µF JJ cap is wrong...

If I replace C9 I'll also need to replace C10. I've read you use 330µF Aerovox for C10 and C18 because you had them for free. Do you think there's a better option here?

One more thing, is FT-3 the best replacement for C11? Are you happy with the results?

[Lowrider]

Yes, I learned this in Cine Son...

Bigger caps have problems of their own, like more resistance, the Aerovox are great because they are reasonable size, from modern production I would probably use JJ 250uF...

They say FT-3 are one of the best, I bought a few on ebay, to tell you the truth, I didnt notice much difference for the Philips, but they sure look better...

[le_toine]

With a 250µF JJ in C10 that means that C9 has to be smaller than yours (<83 µF)... But you said one single 47µF was not enough... So is there a minimum value...?

[Lowrider]

My experience was:

1 - replace the 2 220 original Samsung by 2 330 Aerovox, the sound became worst, could be because the 330 had long leads, or not...

2 - replace C9 with 1 Chinese polypropylene 47 and move C10 close to center, short leads, great improvement of bass...

3 - then I thought with good caps I dont need bypasses, so I remove them, bad sound...

4 - put the FT-3, sound good again...

5 - put second 47 parallel to make 94 uF, no significant difference...

If I where you, I would start with the bypasses, Philips or, if you want to go big style, K40 or FT-3. Thenyou could get the Cree Scotkys, and one 47 to try...

I have extra 4 FT-3 that are dying to replace the K42, but they are so big, I dont think I could fit them...

[le_toine]

Ok, I had misunderstood. I thought bass came back only when you added the second 47µF in C9...

[Lowrider]

JJ 250 will not make a significant difference from my Aerovox 330, from what I read, it might even be better, not worst...

Thats what I was going to buy, recommended by my "gurus", only use the Aerovox because they where given to me free, but the smaller size makes them easier to place than the JJ...

[Lowrider]

Panasonic are supposed to be very good, low ESR, they have 330uF and 390uF 500V, similar size to my Aerovox...

http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name=P7460-ND

Still, I wouldnt expect any significant improvement over the standard Samsung 220uF, but you will only know if you try, and my speakers are quite different from yours...

[le_toine]

mmm ok... thanks... I'ill try the bypasses first