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Old 30th August 2010, 12:42 AM   #11
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The 4 blue tantalums you see there are the 4 caps that are directly
in the signal path and has been replace to Mundorf MKP (Metalized Polypropylene) and they sound great.

I will locate all tone control caps and mark them in the photo and repost
the photo to make sure with you guys that it will be fine to mod them.
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Old 30th August 2010, 12:48 AM   #12
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When you use caramic use NPO or COG, they are low distortion. If you want to replace the ceramics i made the best experience with siver mica. The layout matters too and when you replace the ceramics with big foils you can screw up the layout badly and end up with oscilation.
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Old 30th August 2010, 12:55 AM   #13
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Quote:
Originally Posted by Joachim Gerhard View Post
When you use caramic use NPO or COG, they are low distortion. If you want to replace the ceramics i made the best experience with siver mica. The layout matters too and when you replace the ceramics with big foils you can screw up the layout badly and end up with oscilation.
What is NPO and COG? brands? types?

What does oscillation cause?

And what will be gained by replacing ceramic with ceramic like you suggest?
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Old 30th August 2010, 01:07 AM   #14
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NPO or COG material is the best ceramic material in use for ceramic caps. It does also have the lowest dielectric constant so caps made that way are bigger then caps from less good material. NPO/COG have much less distortion then other ceramics and value is stable over temperature. I whould expect a sound that is cleaner and less tempramental using this caps. Oscilation is caused when the circuit ( i asume it is a wideband circuit ) is terminated at the PSU side by a varying impedance over frequency. For example an unfortunate combination of cap values and layout could result in an output impedance of the PSU that looks like a comb filter over say 100kHz and goes wildly up and down. A high speed circuit is only stable when PSU impedance is flat and low to high frequencies. You could call an amplifier a modulated power supply and the you may get closer to understandig high speed electronics.
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Old 30th August 2010, 01:12 AM   #15
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Quote:
Originally Posted by Joachim Gerhard View Post
NPO or COG material is the best ceramic material in use for ceramic caps. It does also have the lowest dielectric constant so caps made that way are bigger then caps from less good material. NPO/COG have much less distortion then other ceramics and value is stable over temperature. I whould expect a sound that is cleaner and less tempramental using this caps. Oscilation is caused when the circuit ( i asume it is a wideband circuit ) is terminated at the PSU side by a varying impedance over frequency. For example an unfortunate combination of cap values and layout could result in an output impedance of the PSU that looks like a comb filter over say 100kHz and goes wildly up and down. A high speed circuit is only stable when PSU impedance is flat and low to high frequencies. You could call an amplifier a modulated power supply and the you may get closer to understandig high speed electronics.
Well, thanks for the info, i understand the stuff about the ceramic's material types but i didn't understand anything bellow that.

Thanks alot anyway.
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Old 30th August 2010, 01:32 AM   #16
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It's only really useful speaking about parts specs in relation to their circuit functions. Like anything it's all about trade offs or balance.


Yes there are low K ceramic dielectrics that behave themselves. but they are only economical in low values, say below a few hundred pF. Yes they are great for critical audio filters and timing circuits, but they can get mighty pricey tho, again in larger sizes > 500 pF. Not too useful for DC supply bypass , snubbers, non critical low impedance RF filters. For HF filters small size is important to keep SRF high, and NP0 C0G are much bigger than their high dielectric counterparts. X7R ceramics will still be around for a long time.
FWIW
Forget replacing 0.1 and 0.01 uF surface mount or ceramic discs with NP0.
I would venture a guess that the Pioneers amps freq. compensation caps are already NP0 / C0G. They are easier to make to low value tight tolerance caps anyway
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Last edited by infinia; 30th August 2010 at 01:43 AM.
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Old 30th August 2010, 02:17 AM   #17
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I did not say he should replace the SMD caps with COG. I just wanted to inform about the performance differences. When the Pioneer is working fine i see no reason to replace anything. Could be that there are some primitive Elcaps in the signal path and that is where i would try to improve. There are some good Elcaps like Elna Silmic2 and Nichicon Muse that are very good in the signal path too. I whould bypass them with a 1 to 10nF of good qualtily though . At extreme high frequencies the losses in the Elcaps go up and although we are not talking about frequencies under 20kHz difference intermodulation product could get audible if the Elcaps are not bypassed but giving advice about tuning on this forum where a lot of scientifically oriented people express their opinions i found that talking about very small subjective differences usually ends up in fierce discussion with the result that the thread is closed so any ( tiny ) subjective improvement you can wring out of your component is your personal enyoyment. I hear diffences that i can not measure and i can life with that. I whould never insist though that others hear the same diffences or it could be that i am just a victim of my own illusion.
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Old 30th August 2010, 02:37 AM   #18
infinia is offline infinia  United States
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Hi
I don't think you are wrong , I'm just trying further some generalities which are "always" (pun intended) dangerous. I don;t think there are any SMD here anyways.

I just have a deep concern when inexperienced people go willy nilly part exchanging based only on a caps dielectric matériel due to rumors and innuendos. Its not so simple as a bad cap good cap thing. I had visions ( delusions?) of some newer folks running to replace all ceramic caps with NP0 because some Guru says he has them in his gear.
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Last edited by infinia; 30th August 2010 at 02:42 AM.
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Old 30th August 2010, 05:36 PM   #19
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OK here is a nice pic of the amp with the treble and bass caps
marked in red: http://www.milkbands.co.il/caps.jpg

The disc caps are for the treble and the green ones (NP1) are for
the bass.

Also, the right red circle shows the same cap pattern but for the balance
pot. If i mod the bass and treble, would i benefit from replacing the balance caps too?

Why don't they write the capacitance value on the disc caps and NP1 caps? i found them by the copper tracks and not by the values (because
they only have numbers that aren't related to capacitance value as far
as i can see).

What do you recommend doing to improve the sound? to replace them
to which type? Also, i always place the bass pot very low (3 out of 10
in the marks of the face panel) because the bass is very "closed"
very "smudgy", so what can i do to make it more accurate and punchy?

About the treble...i don't like those disc caps...

What do you guys think?
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Old 2nd September 2010, 02:20 PM   #20
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Quote:
Originally Posted by rg12 View Post
Why don't they write the capacitance value on the disc caps and NP1 caps? i found them by the copper tracks and not by the values (because they only have numbers that aren't related to capacitance value as far as i can see).

I think you need to read up some on Capacitor "BASICS" and at least learn to properly identify the different types before attempting to replace them.
Here is a good starting place --->http://www.amqrp.org/reference/na5n_cap_guide.pdf

Ceramics usually only have #'s printed on them like "102" "103" etc... and these correspond to a specific value - .001uF; .01uF etc..etc... I won't go into all the derivations... Just scroll down on the link I provided and you'll see a table with the most commonly used/seen values.




Quote:
Originally Posted by rg12 View Post
What do you recommend doing to improve the sound? to replace them to which type? .....what can i do to make it more accurate and punchy? About the treble...i don't like those disc caps...
What do you guys think?

I don't think you're listening to what "other" more experienced members are saying! Not EVERYTHING needs to be replaced/changed to achieve a "better/improved" sound! Ceramics STILL have their uses.

If you're just hell-bent on changing them, regardless of what "others" are advising, then buy a bunch of different "types" (same value of course) and swap them out, listen to the way "it" sounds and repeat! You will be VERY surprised at how little they differ, if at all!





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