W A R N I N G !

W A R N I N G !

This page is full of non-facts and bullsh!t, (just like the internet and especially forums and other blogs), please do not believe entirely without exercising your intellect. Any resemblance to real things in reality is purely coincidental. You are free to interpret/misinterpret the content however you like, most likely for entertainment, but in no case is the text written on this blog the absolute truth. The blog owner and Blogger are not responsible for any misunderstanding of ASCII characters as facts. *cough* As I was saying, you are free to interpret however you like. *cough*

Saturday, July 5, 2008

More small sound upgrades

One more interesting upgrade I've done for now: Adding an Elna 470µF cap in parallel with the 47µF Panasonic FM and the 0.1µF Wima to the decoupling stage on my NeoMini USB DAC

After "upgrading" the power by using the power adaptor and cutting the supply from the computer, I had a hunch that the power adaptor, with lousy max power capacity and voltage regulation, is going to provide insufficient power at times (power dips), which may explain the small bit of loss in bass power when I removed the com power supply.

So I decided to add a reservoir capacitor. Digging around, I found a 470µF Elna, courtesy of alvin1118. This kind of capacitors (brand + size + type + packaging) are supposed to be good for audio power, although using something that costs more than $0.25 on such a mini DAC (pun intended) is a definite overkill. But hey, I love overkills, at least I don't even have to think that I'm sacrificing something else for an improvement.

470µF seems like an overkill for a decoupling capacitor for such application anyway. Or so common sense would tell us. Will it yield little improvement as expected or does my current setup superceds common sense? Lets find out.

Lesson on electronics for the newcomers: Decoupling
Decoupling, bypassing, power reservoir, power filtering, they are all the same; it's just a capacitor connected in parallel to the load i.e. connected to the V+ and ground or V-. But other decoupling and bypassing which have slightly different use and approach, power reservoir (or reservoir caps) and power filtering seem to suggest some extreme situations - power reservoir suggests a huge capacitance to compensate for a very bad power supply which cannot handle the loads, while power filtering suggests a more sophisticated approach (or plain marketing badass). After you read on how it works, you'll realize they're all the same.

Basically, your DC power source will never be perfect; there will be EMI noise, ripple, and voltage dips, which are the same ol' fluctuations in voltage but in increasing magnitude and decreasing frequency. If we want a cleaner (more stable) power, we add capacitors in parallel. The capacitors act as a backup storage, or think of it as a alternate (or engineers like to call it, local, because of their proximity to the load) source of power. The good part is, capacitors provide very clean power and releases them very quickly, at least compared to a battery (which is by some definition a capacitor also, lolololol). And in audio it's already known that battery > adaptor, and capacitor > battery, so it's sure to be good. (BTW decoupling caps are also used in battery-powered amps.

Now the bad part, capacitors store very little power for their size, and the faster/cleaner power you want (which is dependant on capacitor type), the less capacity you get. You starting to see the trend among all the power sources?

And so, how decoupling capacitor works in layman terms - when the voltage is at e.g. 5V, the capacitor charges up to 5V and stays there. When there is a voltage dip at the power source to e.g. 4.5V, the capacitor, being at a higher voltage, will allow the current to flow out of itself, hence providing the 5V for a short while. Hopefully, after that the voltage dip is gone, and the capacitor charges back up again. It works the same way but opposite for voltage spikes; capacitor absorbs the extra voltage/current. And so what you get is a cleaner and more stable power.

Ok, a .5V dip isn't really what capacitors are supposed to handle - what they handle is in the 0.001 to 0.010V range. But from what I observed, poorly-regulated switching power supplies (meaning almost all your power adaptors and many computer PSUs) can allow for voltage drops in excess of 0.1V. While this isn't a problem for computing since they allow for a 5% variation from the rated voltage, in audio this translated into a very nasty 0.25V. And many cheaper power adaptors (AND MAINBOARD USB POWER!!! <---- read) don't even meet this standard (which is why your 2.5" USB HDD fails to spin). So isn't that worrying?

So while in normal audio cases for power filtering a 0.1µF and a 47µF capacitors are used (to deal with different frequencies of noise - remember that smaller capacitance = faster?), in my case I need a power reservoir to handle variations of ~0.1V. 470µF sounds just about right for this.

Now now, in many cases 470µF isn't used, coz:

1. It's usually physically too big
Yes, indeed I had to lay it down (put it horizontal instead of standing upright), and on the underside of the PCB in order to make it barely fit in my case.
2. It's usually too slow due to the capacity
Using an Elna should give me some room. Plus larger voltage dips due to poor voltage regulation/power capacity are usually of very low frequency.
3. You won't usually see situations that require that big of a capacitance
Now you do. In fact, for lower-end devices using poor power sources, many DIY people have used 220 to 470µF caps for decoupling.
I actualy wanted to put a 3300µF cap considering the voltage regulation of my power source (which is shiet) but it wouldn't fit in my case.

Enough of the stuff-most-people-won't-even-bother-to-care part above which I considerately reduced the font size. All we care is about the outcome, right?

So here it is - drastic improvement to the highs; they sound freaking clear, lots of high harsh is gone and the sound follows through well, not to be confused with reverb but after the notes hit the volume does not decrease too quickly. Very good for high-pitched percussion/hit type instruments. Same improvement to a smaller extent can be seen in bass too. Overall the sound is much more natural with a slight increase in soundstage.

However, there seem to be a slight loss in dynamics. At first I didn't understand why that happens since I was expecting that a more stable power will give better dynamics thinking that huge dynamics cause voltage dips which is countered using capacitors. Turns out the dynamics were still there when I played back at the same volume with the SRS WOW effect turned off; in fact there was more indeed. But the decreased noise and more detail and soundstage and music lingering in the air means even more things were amplified with the WOW (surround sound) effect, so the dynamics kinda got covered up. And also, since the harshness of the high instruments and boomy bass were gone these notes also made less of a presence.

But because of this, on the whole it sounds very natural. Very uncolored sound.

Interesting how cleaner power actually led to this neutrality and loss in dynamics. Is it that the better your system, the more natural it sounds?

And interesting how a $1 capacitor can improve the sound so drastically. Heck expensive interconnects which all they do is color the sound.

And interesting how sucky your computer power supply (and cheapo power adaptor) is in order to make this work.

Canare 4S6 (17AWG equivalent)(Star Quad - 2 smaller conducters for one wire) against Belden 1307A (16AWG)

At first I only needed some extra cables for some wiring and soldering job. Then I thought, why not get some Canare 4S6 to fight against the Belden 1307A that I'm using now?

And so a trip to LHS. Wierd, I asked for the smallest Star Quad they had, they say Star Quads are not for speakers; speaker cables are never meant to be twisted (HUH?). So I asked for the 16-17AWG Canare speaker cable, and they gave me the 4S6. Isn't this like the Star Quad I'm looking for? And after stripping it up at home, it is definitely twisted. So what was the uncle talking about?

Preparing the 4S6 was a nightmare - you have twice the number of conductors to strip, and the paper and cotton fly everywhere and onto the bare cables themselves. Not very nice. Getting two wires to clip onto the same hole is the worst, first twist the wires together at a good angle - too little and the wires comes off too easily, too much and it becomes too thick to fit. Plus have to make sure that the wires approach together instead of one front one back, else the 17AWG cable becomes 20AWG. Took much longer to hook up compared to the Beldens. (The Beldens are actually very easy due to the thickness and toughness of the strands)

These cables are definitely meant to be soldered onto connectors.

Initial impression - they are not burnt in, yet they already exhibit a more prominent high (although not as clear... yet). Bass is lacking definitely, slightly less than my Beldens before burning in and a lot less compared to them now.

This is to be expected - Belden has very thick strands, while the Canare has two conductors of very thin strands. Skin effect tells us the Canare will be brighter.

I'd say the two cables are equal with different uses - Canare for clearer trebles, Belden for more (natural) bass power. Also, the Canare feels more pro and might possibly sound that slightly better too, but the Belden won't wear and tear as much from usage. Anyway, there's no way I'm going to use the Canare for wiring projects. Plus, more people in audio seem to be advocating thick solid copper core nowadays, and Belden is closer to that than Canare, so one more win for the thick strands.

I originally wanted to keep using the Canares for speakers and cut some Beldens for a project, but something happened the day after I installed the cables which forced me to use back the Beldens. Read on to my next post...

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