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Old 12th December 2011, 10:32 AM   #141
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Quote:
Originally Posted by AndrewT View Post
capacitor (C5) - only to damp ringing.

This does not sound right.
Hi Andrew,

I'm referrring to Mauro's 'Project My_Ref' document:

I condensatori C5 e C22 servono a smorzare i picchi di tensione generati dai diodi, in combinazione con l' induttanza parassita del trasformatore.
Il filtro che si viene a creare (a frequenze di circa 15-30 Khz a seconda del tipo di trasformatore) riduce notevolmente il rumore di rettificazione ad alta frequenza.


English translation:

C5 and C22 capacitors are used to smooth out voltage spikes generated by bridge rectifiers, combined with the parasitic inductance of the transformer.
The resulting filter (at frequencies of about 15-30 kHz, depending on the type of transformer) greatly reduces the high frequency noise.


Can you elaborate?

Maybe it's the term 'ringing' that isn't correct/precise?
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Last edited by ClaveFremen; 12th December 2011 at 10:37 AM.
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Old 12th December 2011, 10:39 AM   #142
AndrewT is offline AndrewT  Scotland
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Mauro's description would apply to R+C snubbers correctly applied to the impulsive signals around the rectifiers.

A capacitor alone is not usually suitable for damping ringing/resonances.
It appears from Forum posts and a bit of my own experience that a low loss capacitor is more likely to induce ringing and resonant behaviour. This is the opposite to what you claim (damping).

However, while it appears to me that you are revealing that removing C5 did not make the sound worse, I find your language very confusing. I find your reference to AC input caps and optional AC caps to be completely uninformative & misleading.

No wonder Soongsc had to seek clarification.
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Last edited by AndrewT; 12th December 2011 at 10:46 AM.
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Old 12th December 2011, 10:57 AM   #143
soongsc is offline soongsc  Taiwan
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I do recall there being a paper on snubberizing the diodes. The paper also tried cap across the rectifying diodes, and the performance was not as good. It was not used across the rectifiers like here.

This is a similar paper.
http://www.hagtech.com/pdf/snubber.pdf

I have not put in snubbers for MyRef yet.

I would expect the cap C5 for some power factor adjustments.
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Last edited by soongsc; 12th December 2011 at 11:06 AM.
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Old 12th December 2011, 12:13 PM   #144
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by soongsc View Post
I would expect the cap C5 for some power factor adjustments.
I hear quite a few members referring to Power Factor.

Can you explain the mechanism that C5 would play in our comment?
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Old 12th December 2011, 12:27 PM   #145
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Quote:
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However, while it appears to me that you are revealing that removing C5 did not make the sound worse
Actually I think that C5 removal is beneficial (in the My_Ref_FE context)

Quote:
Originally Posted by AndrewT View Post
I find your language very confusing. I find your reference to AC input caps and optional AC caps to be completely uninformative & misleading.
It's true that I could be more clear and I've understood that such terminology was not appropriate, in fact I clarified without problems.

But the wrong terminology doesn't change the facts, or the informative contest of such posts...

I can't understand why you had to point it out...Why in most of your posts I feel a sort of 'negative' energy?
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Old 12th December 2011, 12:53 PM   #146
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by AndrewT View Post
I hear quite a few members referring to Power Factor.

Can you explain the mechanism that C5 would play in our comment?
I have not pursued this before, but if the transformer secondary has inductive characteristics, using C5 to tune a resonant circuit to the frequency of the mains power should give a better transfer of power where the current and voltage are in phase with each other.

Does this make sense? I'm really trying to apply what we learned in school over 30 years ago. But since I have moved to existing switching power modules, I may not get a chance to play around with these. Having the value that came with the kit probably is just causing resonance at a wrong frequency effecting proper power transfer.
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Old 12th December 2011, 12:58 PM   #147
AndrewT is offline AndrewT  Scotland
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Originally Posted by ClaveFremen View Post
Actually I think that C5 removal is beneficial (in the My_Ref_FE context)...Why in most of your posts I feel a sort of 'negative' energy?
because I read your posts and find my reaction is a shaking of the head. Does that equal -ve? That is not what you said. What you said was
Quote:
In this moment I'm doing the last tests (LM3886 ground to GND and optional caps for AC input)

Wow
Bass is tighter, soundstage wider and deeper and dynamic gains too, even the output DC offset fall near 0V (from 2mV to 0.5V in one channel).

The AC input caps have also a clear effect
I have trouble understanding some of your conclusions. I have trouble understanding some of the logic leading to those conclusions. I have trouble just trying to understand what you are typing.
Sometimes I have trouble simply believing what you type.

All of this is probably down to me misunderstanding what you type, combined with me not understanding the science behind your experiments.

Yes, it leaves me feeling quite -ve. But, I keep reading hoping that some day I will reach the "I see" moment.
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Last edited by AndrewT; 12th December 2011 at 01:02 PM.
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Old 12th December 2011, 01:01 PM   #148
AndrewT is offline AndrewT  Scotland
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Originally Posted by soongsc View Post
....if the transformer secondary has inductive characteristics, using C5 to tune a resonant circuit to the frequency of the mains power should give a better transfer of power where the current and voltage are in phase with each other.

Does this make sense?
Not to me. So my answer is "no".
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Old 12th December 2011, 01:13 PM   #149
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by ClaveFremen View Post
...

The original MyRef has the LM3886 GND (Pin 7) referred to 0V (signal ground) while the Fremen Edition to GND (power ground).

The wow is obviously referred to Fremen Edition way.

....
Well, I just changed the MyRef C channel so that the LM3886 pin 7 connects to power GND. This seems more like what I am used to. But the details are somewhat less, not as much emotion in the music. I may get some time to do some measurements.
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Last edited by soongsc; 12th December 2011 at 01:29 PM.
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Old 12th December 2011, 02:15 PM   #150
soongsc is offline soongsc  Taiwan
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Not to me. So my answer is "no".
Maximum power transfer theorem - Wikipedia, the free encyclopedia
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