I know. I can hear that too. But since we don't trust non-DBT hearing reports, I'm afraid you will have to show DBT. (not really, but let's just say I don't trust you so I call you out to produce "proof." Will you do it on my demand?)
Always a need for DBT if there are the slightest doubts, isn't it?
Not true. When I say there are listening tests I believe are credible, I seriously mean it. I have tried to explain before how I do it with my listening panel, but its wasted breath or wasted words; nobody gets how its blind enough. It is in line with certain methodology used in modern perceptual science, however.
Also, by saying that there are listening tests, I make no claim as to the operative mechanism. I don't claim to know in this case that noise involved singularly or in combination with other factors. Here I am only making a claim as to audibility.
The discussion of audible noise in Panasonic FM caps was only for illustrative purposes. They have a distinctive sound IME. Depends how they are used if the sound is noticeable though. That's another whole complex subject, so I will leave off here for now.
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Sure. SINAD is all there is that really matters. SINAD per dollar is all you need to know to make a wise purchase decision. Just go ask over at that other website. They will tell you how to read the
The best anyone can do is not to take a bait. Markw4 has developed into the exemplary troll, hijacking every thread possible with his FUD stories about possible, eventually, probably, in some unspecified cases, for some unspecified equipment ….. for chosen golden ears … bad effects on sound.
When asked for any evidence above his opinion, he resorts to snide comments and to attaching papers that are not related to the discussed matter. Latest example is this very thread and paper on 1/f capacitor noise.
Though, very telling is the fact that he didn’t open a single thread on views he is pushing on any occasion available into the countless other threads. Yup, 17.000 posts and not a single thread opened on topics he likes to discuss.
When asked for any evidence above his opinion, he resorts to snide comments and to attaching papers that are not related to the discussed matter. Latest example is this very thread and paper on 1/f capacitor noise.
Though, very telling is the fact that he didn’t open a single thread on views he is pushing on any occasion available into the countless other threads. Yup, 17.000 posts and not a single thread opened on topics he likes to discuss.
Here's a solid dc and emi filter. No audible or measured issues 🙂 DC circuit shouldn't be below 47000 uF, on the bright side it can be 16v.
As for audible, everything i've implemented so far to clean up mains (and smps dc supply) has improved system performance.
As for transformer, i've already explained to nixie (his transformer in latest build is very close to signal circuitry) what @Bonsai wrote about two tin cans. It is a wonderful and cheap solution.
As for audible, everything i've implemented so far to clean up mains (and smps dc supply) has improved system performance.
As for transformer, i've already explained to nixie (his transformer in latest build is very close to signal circuitry) what @Bonsai wrote about two tin cans. It is a wonderful and cheap solution.
False. The search function doesn't work very well for finding who started threads, but there have been some started by me. For one example: https://www.diyaudio.com/community/threads/paul-frindle-is-this-truth-or-myth.371790/ Your complaint post has other problems as well.
The problem with you guys is you want to believe that you know how to measure everything that matters. If someone tells you that you that there is no easy measurement for something, your response is to say, "prove it by showing a measurement of it." And then you get mad because someone points out you don't have a measurement for everything that matters. You want to ignore that little inconvenience.
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As usual, when confronted with hard facts you are bringing up subjectivist vs objectivist debate. Why don’t you open a new thread? (not that a new one is needed with dozens already locked) That would be honest thing to do.
And, as usual, your view of those who measure their equipment is distorted by your need to position yourself as the righteous audio prophet, spreading “the truth”. Unfortunately, we are not accepting something as a fact based on mere speculation or what someone believes he has heard. Contrary to your claims, we do listen to our equipment very, very, very carefully, opened to find anything that measurements don’t show. Yes, soundstage can’t be measured but there are some very good clues in measured amplifier properties.
If you would measure anything, you would know what a failure is your assertion that capacitor current noise is responsible for signal change or coloration. It has nothing to do with noise but nonlinearity of capacitor. I’ve measured distortion introduced by electrolytic capacitors (yes, those Panasonic FC included) and their contribution at 1 Arms current passing through, is below -110 dBc level. Harmonics distribution remains the same.
Don’t expect this discussion to continue. You are breaking forum rules and you are on my soft ignore list but some things had to be said.
If enough AC voltage is allowed across the cap only, IIRC, according to Doug Self.
Don't know about FC, I mentioned FM only.
Did you measure for noise? If so, how?
I believe that those polarized capacitors in the DC blocker suffer a lot, from reverse voltage to high currents. The current is not sinusoidal, but a bunch of strong pulses when there is a diode bridge on the secondary of the transformer and a lot of capacity behind the bridge. I don't have any serious measuring equipment (only one USB oscilloscope). I don't have an isolated probe for measuring at 230VAC mains voltage.
It is obvious that you need a lot of capacity in the DC blocker so that it does not affect the sound of the amplifier (or at least keep it minimal), to make the ESR as small as possible so that the voltage drop on caps is as small as possible. For small toroidal transformers and EI transformers it's not that necessary to have a DC blocker, only for these toroidal ones larger than 300VA. If the transformer has a primary DC resistance of 1-2ohm, and the mains voltage contains some 3-4VDC, the core of the transformer can saturate.
It is obvious that you need a lot of capacity in the DC blocker so that it does not affect the sound of the amplifier (or at least keep it minimal), to make the ESR as small as possible so that the voltage drop on caps is as small as possible. For small toroidal transformers and EI transformers it's not that necessary to have a DC blocker, only for these toroidal ones larger than 300VA. If the transformer has a primary DC resistance of 1-2ohm, and the mains voltage contains some 3-4VDC, the core of the transformer can saturate.
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For the DC blocker, it is best to consider the capacitor AC impedance at line frequency as being in series with the primary AC impedance and the AC line impedance. If you size the caps correctly, the DC blocker impedance will be a small fraction of the total impedance, and therefore of very little consequence. I use 4 off 10 000 uF 6.3 V caps, so the total diode bypass capacitance is 10 000 uF (10mfd//10 mfd in series with 10 mfd//10 mfd) . The other important thing to consider is to ensure the continuous maximum load current is not greater than that of the capacitors- that by the way is why I ended up using 4 caps. Each cap is rated at 2.3 A 3000hrs at 105C and in parallel that’s 4.6 A.
The DC blocker technique's works very well - it is an excellent solution to a common problem. Bryston have used it for decades.
The DC blocker technique's works very well - it is an excellent solution to a common problem. Bryston have used it for decades.
Due to the pulse shape of the current through the transformer, I think that 4-5A is too little for, say, my 650VA transformer. 🤔
When I made that DC blocker, I didn't really know what I was making. I got a diagram from the transformer manufacturer and put it together quickly. I didn't like the effect on the sound, so I gave up. The next iteration will be better for sure. Otherwise, I think that the schematic I used is good, each capacitor is protected by one diode. Only larger capacitors and a bypass of block capacitors with the highest capacity should be installed.
When I made that DC blocker, I didn't really know what I was making. I got a diagram from the transformer manufacturer and put it together quickly. I didn't like the effect on the sound, so I gave up. The next iteration will be better for sure. Otherwise, I think that the schematic I used is good, each capacitor is protected by one diode. Only larger capacitors and a bypass of block capacitors with the highest capacity should be installed.
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The current waveform on the mains side is very non-sinusoidal but caps are rated at the RMS current rating because it’s the heating effect that causes problems. You can get this data from the spec sheet along with temperature vs longevity. If your cap is running at much lower temps (lower RMS current and/or lower environmental temperature) you get longer life.
I know that, I always choose capacitors with the highest possible ripple current, i.e. lowest ESR. And primarily those for 105 deg. C.
And for that DC blocker, I would like all the current to go through the capacitors and the diodes never turn on, it creates extra noise, which may not pass through the transformer, but it's better not to have it. With higher capacitance, the voltage drop across the caps is lower and the inverse voltage is lower as well.
And for that DC blocker, I would like all the current to go through the capacitors and the diodes never turn on, it creates extra noise, which may not pass through the transformer, but it's better not to have it. With higher capacitance, the voltage drop across the caps is lower and the inverse voltage is lower as well.
Current through primary of transformer looks like this:
We can observe that duty is about 40%, so current peaks are about 2.5 x of average primary AC current. We can observe as well that adding resistance in series with primary, haven’t affected current shape. This was measured during another debate on mains network impedance effects and mains noise filtering.
On the secondary side are huge shunting capacitors and RC filter. Mains AC voltage waveform contains distortion and noise many orders of magnitude above anything capacitors in the DC blocker could introduce. How would any additional AC waveform distortion (allegedly introduced by DC blocker) reach DC output at any level above barely measurable with best equipment? We should not forget that amplifier circuits have some PSRR as well. Eventual stories about radiated noise from the DC blocker belong to the nonsense category.
Capacitors at 22 – 47 mF range are low ESR and their impedance at 50 Hz could be in the 100 – 50 mΩ range. Rated RMS currents are 4-5 A. AC current duty and peak values conversion to RMS equivalent applies. So, it doesn’t look like capacitors are anywhere close to their limits.
What baffles me the most is why anyone using DC blocker and noticing change in sound, would assign this to “evil capacitors”? Isn’t change there because DC blocker does its job and transformer works under nominal conditions providing different output than with primary DC voltage present?
I did not use Low ESR capacitors, but the first ones I found. They weren't exactly evil, but they weren't good either. Some cheap Chinese, Jamicon.
What happens when the capacitors are too small (that is, the series resistances are too large) and the diodes start to conduct?
What happens when the capacitors are too small (that is, the series resistances are too large) and the diodes start to conduct?
Definitely condition to avoid. It would introduce additional harmonics after rectification and would make DC blocker only partially effective. Under normal operation, diodes should never conduct. They can at switch on and initial transformer inrush current.
All large PS capacitors fall under pretty low impedance category. How much AC/DC voltage is across them can be measured with any cheap multimeter. They are all precise enough at 50 Hz.
That was exactly the fault of my former DC blocker. And I found those little capacitors at Rod Elliot's site as well, and I thought it was fine to be that way. Capacitors conduct a little, diodes a little. It's a mistake. 🙄
https://sound-au.com/articles/xfmr-dc.htm
And if there is more than 1.5V DC in the mains, it will pass through two diodes, maybe there should be three diodes in a row (6 for both directions) like @Brijac schematic #146?
https://sound-au.com/articles/xfmr-dc.htm
And if there is more than 1.5V DC in the mains, it will pass through two diodes, maybe there should be three diodes in a row (6 for both directions) like @Brijac schematic #146?
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