220uF coupling cap for ono Film or BG? - diyAudio
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Old 4th December 2008, 10:07 PM   #1
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Default 220uF coupling cap for ono Film or BG?

Hi Folks,

as i was surfing on internet to search for parts i came across to this cap (see the attached picture)
There is a 220uF for 58euro and 100uF for 28euro.
I think i saw these caps on some of the hi end stuff on the market but i can't remember where.

Anyways my doubt lays between using this cap on the coupling signal path on the ONO phono or usinghe Blakgate FK 220uF, which by the way is the FK series eventually the most indicated for coupling purposes?

I believe that a film cap would be better than an electrolytic in any case.
I don't know if anybody knows these caps and used them actually.

Thank you for the attention
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Old 4th December 2008, 10:27 PM   #2
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from the logo and by researching on google i think they are Solen cap, i don't know if i am right though!
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Old 5th December 2008, 09:16 AM   #3
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any opinion? nobody
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Old 5th December 2008, 09:24 AM   #4
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Hi,
a polypropylene in lieu of an electrolytic for audio coupling must be better.
Do you really need 100uF/220uF?
or
what about a 220uF bipolar Panasonic paralleled with a 4.7uF 250V MKP? an affordable experiment that may turn out to give all you need/expect.
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Old 5th December 2008, 10:31 AM   #5
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well.. i don't really need 220uF on the coupling path.
Just keep in mind that the question needs to be asked to Mr Pass, since he switched from the 10uF on the old version to 220uF on the XONO.

It can be seen on the simulation that a better low frequencies response is achieved this way.

I guess that your suggestion is inexpensive and thus can be tried on, but still, in order to gain a clear idea on what is better, I would still have to try this out against the the blackgate and the film cap.

I am wondering if anybody had a similar experience with these film caps or similar film caps and compared them to a good electrolytic or something.

Anyways Andrew thank you for your idea.
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Old 5th December 2008, 11:16 AM   #6
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Hi Stefano

Built the MM part of it several years ago and found it ok but not spectacular. The MC part i really dislike. It has a lot of flexibility with the variable gain but once you choose a cart you wouldn't have much use for setting gain and no matter how you look at coupling caps it just has too many of those. If i had to use an active MC step-up device i would rather use a parallel common cathode fet fed by an entirely separate high quality (Jung?) regulator.

Of course 220uF is completely unnecesary in this circuit. 10uF is more than enough and if you decide to use MC carts only you can go even lower by increasing the value of R20. It is set to 47k for compatibility with MM carts but can easily be increased to 100-200k. Alternatively you may want to investigate a switching arrangement (relays?) which when switching from MM to MC will also connect another parallel input resistor.
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Old 5th December 2008, 12:36 PM   #7
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Hi analog,

thank you very much for your instructive answer.
I am planning on using a nice shunt all fet PSU design.
I am also planning on using auricap caps on the RIAA network and PRP resistors....and other good stuff for the stage.

I don't like the idea of having multiple coupling caps on the signal path ether.
I got rid of the output coupling cap by adjusting the offset at the differential stage...so one less....but for the others: no possibilities to be eliminated.

I am planning on building only the stage MC (so NO MM) for a specific cart (Denon DL103) so no relays no switches for loading adjustments.
I am making researches on how to properly load a cartridge to obtain maximum performance, which by the way, if you have some useful links at hand, please go ahead and post it if you wish.

Therefore, since no MM stage will be included, you told on the previous post i can lower the 220uF and increase the resistor R20 up to 100k or more and that would fix the bottom end response.
I am eventually going to replace it by a 10uF auricap film cap or less....i will explore the different options with the simulator.

But how about the other 220uF coupling cap on the MC stage? Can this be lowered as well accordingly to your experience?

And one last question: about the 220uF coupling cap for the feedback network on the MC stage: can this be lowered? does the quality of this cap affect the sound of the phono stage?


thank you very much for the attention.
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Old 5th December 2008, 02:00 PM   #8
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To tell the truth i don't know if there is much point in having the second stage (Q15) at all. The only real purpose behind it is to invert phase. At the time i had a fet MC step-up i found a single common source stage was more than enough (gain around x25). And it sounded better to me than a cascode. The value of C37 is high as it may need to work into 5k load if J2 is shorted. If you avoid J2 then C37 can be many times lower. Same is true for the feedback cap C27. It's the minimalist's nightmare And i don't think it was designed by Mr Pass.
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Old 5th December 2008, 02:16 PM   #9
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yes, you are right.
The Ono wan't designed by NP as far as I know but by Colburn.
I read lots of good impression on the sound of the ONO all over the forum but i do agree with you that it doesn't seem to be as minimilastis as it should ...in the good sense...of course.

I made couple of adjustments on the RIAA network and got a little more precise RIAA equalization.

Also, I lowered all 3 coupling caps down to 10uF and frequency response seems to resent just a little bit by this modification at least on the bottom end response but i guess i can live better with a 4Hz cut frequency but a good film cap rather than 3.5Hz and 3 electrolytic on the signal path .

Your point on the Inverting stage Q15 is interesting and i will reflect on this and see whether i can take it out or not.
Although I like to think that it is not elegant for me to have an inverted sine wave at the output, I do think that the less the better in certain cases as for example the inverter at the output stage.....off!!!

Thank you again for the good points you brought in this thread.
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Old 5th December 2008, 02:31 PM   #10
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Iirc the original Ono was criticised mostly for the bass. It may be the reason why all coupling caps are over the top in the X. I'll be very interested in your build and subjective assessment. Mine was certainly not as ambitious and i only used mundane parts: cheap metal film resistors, Wima MKP and Cerafine caps. The end result was highly listenable and musical but not having any outstanding qualities.
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