Fuses do affect sound, the question is how much

[SIY]

Realistically, the leakage inductance in the transformer and the limited transformer bandwidth due to its core material is going to be by far the limiting factor on peak repetitive switching energy, that and size of the capacitor bank, i.e. the difference between the peak voltage and the capacitor voltage, max at full amp load (post turn on).

The small low ESR cap may generate higher EMI frequencies, but it won't stress the transformer or diode bridge more. That 2h inductor will reduce those stresses considerably. You can snub the diodes if you are worried about high frequency EMI.

Morgan showed that there’s a better approach than snubbing diodes.

PSUD really shows the effects of these choices, and the modeling correlates beautifully with experimental results.

 

[audio2design]

Morgan showed that there’s a better approach than snubbing diodes.

PSUD really shows the effects of these choices, and the modeling correlates beautifully with experimental results.

Diode snubbing is for high frequency EMI if you are concerned. That 2h differential mode inductor is going to take out just about everything out depending on how much parasitic capacitance it has. If I do choke stabilized I put some in front of the transformer, a larger capacitor after the bridge than 10uF then another inductor before the large capacitor bank.

 

[DonH56]

I do not know if this relevant -- please take that literally, I don't know, too long since I built a tube power supply.

In my world, capacitor and inductor ESR is a critical variable in designing filters for SerDes and other wideband analog circuits (PLLs, etc.) The problem with low ESR is that it causes peaking where the LC tank formed by the supply filter resonates. That leads to a lot of low-frequency (to us, say in the 10 kHz to 10 MHz range) noise spikes that translate to output jitter and such. I have chosen caps with higher ESR in order to eliminate series (snubber) resistors since component count is another critical parameter for boards sold in the millions. These things always get more complicated than I'd like, and then I have to explain to customers designing their own boards why changing a cap to a "better" one is not always the correct choice for the circuit at hand.

 

[SIY]

Diode snubbing is for high frequency EMI if you are concerned. That 2h differential mode inductor is going to take out just about everything out depending on how much parasitic capacitance it has. If I do choke stabilized I put some in front of the transformer, a larger capacitor after the bridge than 10uF then another inductor before the large capacitor bank.

That was the point of Morgan’s article- snubbing the secondary is superior to snubbing the diodes for EMI reduction. His measurements verified it.

 

[audio2design]

That was the point of Morgan’s article- snubbing the secondary is superior to snubbing the diodes for EMI reduction. His measurements verified it.

Morgan's article is just that. Capacitors across the diodes are to prevent rapid current change and the EMI that results from discharge of the junction capacitance which is different from transformer ringing which generates typically much lower frequencies. His articles really addresses the latter, not the former. Even in the case of the latter, a larger capacitance on its own, by virtue of natural transformer resistance can sufficiently damp this ringing in most cases if not resistance can be added.

 

[mhardy6647]

Hello, Guess I have to ask why the fuse would care what direction it is in the circuit? AC input, waveform is same in both directions. But what the heck, separating suckers from their money is a time honored tradition.

Ahh.. but music... music waveforms are asymmetric. There not just sine waves*.
That explains everything.



__________________
* Dude. What did that Fourier guy know about music?!?

 

[sq225917]

For transformer snubbing the Quasimodo thread on diyaudio.com is Interesting. I've yet to find a psu setup that couldn't be flattened easily with a simple c-rc filter of correct value.

 

[audio2design]

Hello, Guess I have to ask why the fuse would care what direction it is in the circuit? AC input, waveform is same in both directions. But what the heck, separating suckers from their money is a time honored tradition.

Fuses obviously have no sonic impact on the AC input side, but that the power is AC has nothing to do with this. If there was a difference it would be because of AC.

 

[SIY]

Morgan's article is just that. Capacitors across the diodes are to prevent rapid current change and the EMI that results from discharge of the junction capacitance which is different from transformer ringing which generates typically much lower frequencies. His articles really addresses the latter, not the former. Even in the case of the latter, a larger capacitance on its own, by virtue of natural transformer resistance can sufficiently damp this ringing in most cases if not resistance can be added.

After reviewing the junction capacitance and the transformer leakage inductance, he specifically put all that together to show how the interaction suggests a better and easier way to stop RF ringing.

 

[Holmz]

Cheap electrolytics are indeed pretty poor. I've had excellent success and long life from good quality 105 degree rated ones, though; haven't lost one yet. An interesting alternative is motor run caps, which are made for extreme conditions and high reliability. They're also relative inexpensive.
…

A more accurate statement might be, “poorly rated caps are often cheap”.

 

[egellings]

Snub the diodes? That sounds just rude!

 

[mhardy6647]

Snub the diodes? That sounds just rude!

wait 'til we start talking about perveance and snivets...

Perveance - Wikipedia

en.wikipedia.org

http://www.one-electron.com/Archives/RCA/RCA-AppNotes/RCA%201963%20AN-199%20Snivets.pdf