P1.7 / APOX completed

[Klaus]

Originally posted by joho
Hallo Klaus,

I read about your tweakings with great interest and i have a few questions.

The 10nF MKP ERO1837 63V ??? is that old stock ?
I can only find Vishay MKP 1837 series 160V.
I hope it's almost the same.

What do you mean with "drilled cables for supply"? twisted?

By the way, Mundorf Supreme are really excellent. Did you alreaddy try the gold versions ?

Best regards,
Johan.

Hi Johan,

Of cause I meant "twisted"…

You are right. Vishay boght ERO. An old production series was the legend 1830 with 63V. You find it everywhere in OEM high end stuff. This small blue cubes. It seems that the 1837 extented to 160V is somewhat the successor. To be found here, sorry, in German language http://de.farnell.com/jsp/catalog/vi...rodId=3038543. A Fellow told me that he checked the performance of old 1830 and new 1837 and found no difference. It is a problem to get that small capacity caps for low voltages.

I had forgotten to mention that I checked any addition to my tweaky cascade, like Silver Mica, Styroflex (what is the English word for?) with values from 22pF up to 680pF – no improvement, just inhomogeneous effects to my ears. Styroflex always overlayed the sound with a plastic mat, mica made it to analytic and aggressive. Funny, how huge the sound changes caused by this small caps are! Just EMC behaviour at -70dB seems to drive the sound character. I have accepted, in spite of my problems not to know well explanations for this, forced as the EE I am who has to have a model for everything… Forget theory and use your ears!

I tested no silver or gold version – at that price level my tweaking stops. I am absolutely satisfied with this Supreme+Vishay 1837 trick. If it is consequently used from PSU to frequency crossover in the speakers the result is that outstanding that really no interest to spend more money is stimulated.

Regards

Klaus

[roddyama]

Originally posted by Klaus

...like Silver Mica, Styroflex (what is the English word for?)...

I believe you're talking about "Polystyrene".

[joho]

Hi Klaus,

It's all clear.

I already ordered some Vishay 1837 cap's by Farnell so i can try them soon in my experimental Aleph1.7

Best regards,
Johan.

[Klaus]

Originally posted by joho
Hi Klaus,

It's all clear.

I already ordered some Vishay 1837 cap's by Farnell so i can try them soon in my experimental Aleph1.7

Best regards,
Johan.

Hi again,

I hope you have just half of the benefit I got, than you will dance on the table...

I sent by the time to many fellows this small KP1830 drugs (rests here at the lab at my job) and they all couldn´t believe what they got. Coupling electrolytics and the best bypass impulse caps loose really 95% of their aggression and sharpness. As if these failures are catalyzed to pure sound and sound colors. It sounds so mad, but hope for positive results.

Let us know about your results!

Regards

Klaus

[tomchaoda]

Dear Arad:

Do you plan to share your Volume and Input/Output board design with all? (Gerber file, maybe?)

Thanks

Thomas

[ARAD]

Thomas,

we did the design for the boards but handed our files off to Kristijan (PCB Design) for manufacturing. Kristijan re-implemented the plans into his tool (PROTEL) and produced our boards. As said in an earlier thread - we do not mind Kristijan offering 'our' boards. Similar story for the APOX API board - we specified it and the APOX folks implemented it for us.
We do not have any Gerber files for these boards - if you want a copy of our original design which was the basis for Kristijan's implementation let me know. We used a German tool called 'Target', the homepage is http://www.ibfriedrich.com/english/index.htm.

Best regards,
Andreas

[zygibajt]

Hi Klaus,
you really got me interested by your post about tuning Alephs.
Great thing,and you are open minded guy.I like this aproach.

Could you please tell me how exactly does look the changes that you apply to the original Aleph 4?

Also (as I'm using Aleph P 1,7,too) those electrolitics that you meant to try in signal path (10 and 30uF).Do you mine bipolar or you used regular ,polar onesWhat brand of soft recovery types diodes did you use? IR or IXYS? Maybe some other?

Bartek

[Klaus]

Originally posted by zygibajt
Hi Klaus,
you really got me interested by your post about tuning Alephs.
Great thing,and you are open minded guy.I like this aproach.

Could you please tell me how exactly does look the changes that you apply to the original Aleph 4?

Also (as I'm using Aleph P 1,7,too) those electrolitics that you meant to try in signal path (10 and 30uF).Do you mine bipolar or you used regular ,polar onesWhat brand of soft recovery types diodes did you use? IR or IXYS? Maybe some other?

Bartek

HI BARTEK,

Excuse my late answer, I wasn't following up the tread. But here we go…

I showed my Aleph4 under Small Aleph 4 power block... Sorry, the picture quality is terrible. The problem of hum from the transformer was solved by changing to another producer. The first used transfos were a misconstruction and were accepted as reclamation w/o any problem by the supplier. I guess the iron core was not raisin baked and so it hummed terrible. The main tweaks: DC filter, 25A type soft recovery diodes, bypass impulse caps like mentioned at the main buffer, everywhere polarized 220uF Panasonic FC electrolytic caps bypassed with small 10nF cap like ERO1830/1837 or similar. No use of the vertical 680pF filter cap between input and feedback branch. Inductance free MPC71 metal band power resistors. Consequent P2P wiring – paralleled FETs and R´s are connected by a 2,5qmm copper rod. Small optimizations on Marcs downunder PCB. PCB made off hard paper type, no epoxy.

In my Aleph P like now in the D1 output stage under construction I use everywhere this polarized Panasonic FC electrolytic caps bypassed with small 10nF cap like ERO1830/1837. The values can vary, the voltages also. Farnell and others make them accessible. The sound is maybe maximum open and fresh, I have no harshness. W/O the small bypass they really hit the nerves, that is the reason for many prejudices against them, I think.

I used the diodes I easily got in Germany, http://www.schuro.de/Daten/IR/hfa25pb60.pdf. But I am quite sure that many other types with soft recovery and low resistance = types for high current applications will work pretty fine.

Regards

Klaus

[zygibajt]

Thanks Klaus,

How do you connect those Panasonic caps in signal path?
I mean which way "+" and which way "-"?
Or it doesn't matter?

Bartek

[Holger Barske]

Klaus,
have you ever tried non-polarized electrolytic caps (Frolyt EKSU for example) for the 220 µF?