[DIY] Noise Filter Mod

[creatip123]

For those of you who don't already know, my everyday music gears are PC + Aune T1 DAC/AMP + HE-400 (reviews of the last two are on my sig). The Aune T1 was capacitors modded, more info here: http://linustechtips.com/main/topic/238148-diy-replacingupgrading-capacitors-on-the-aune-t1-image-heavy/

 

So my impression of the (cap modded) Aune was 'good DAC, kinda "meh" amp'. I always found the amp part to be a bit 'noisy', not really 'clear' or 'black' as with Fiio products. 

 

Okay, so a few days ago I was reading audio articles on the net, and came across articles about 'power conditioner', and 'EMI/RFI filter'. Googled 'power conditioner', and I got hits on devices that's about the size of an AVR, and some cost multi-thousand bucks. Googled 'EMI/RFI filter', oh hey, they're small, compact, and cheap, so I thought I'll give it a try, for better or worse. If done properly, the worst possibility would be no changes at all, which I don't really mind if that happens.

 

So I found an EMI/RFI filter that's the shape of a power socket, originally intended to be used with PC's PSUs. Something like this: http://www.ebay.com/itm/Delta-06GEEW3E-6-Amp-6A-120v-250V-AC-Power-IEC-Universal-Inlet-EMI-Noise-Filter-/171320435051

 

I got mine for a little less than $3, the same 6A, 3 pronged. Blue and brown wires are the signal and neutral poles, while the green wire is the grounding wire.

 

Now I'm not an electrician, so I didn't really know how to wire 3 poles to 2 poles power input of the Aune's PSU. So I asked around diyaudio forum (which is an awesome forum for diy-ers, btw), and got some awesome replies/explanations. 

 

Turns out that devices that are already designed with 2 pronged power plug don't really need a proper grounding in the power socket. But remember, because I'm going to use the RFI filter, that filter needs a proper grounding in the power outlet socket. According to most country's power companies regulations, all buildings should be installed with a proper grounding, but some old buildings don't have proper grounding implemented, so do a check. Google around on how to check your power line installation for proper grounding. 

 

 

Keep in mind, you're dealing with an extremely dangerous stuff, AC mains electric lines. Accidents could lead to electrocution, fire, or even death, so be extremely careful. I'm not responsible for any accidents you might do.... 

 

So I checked my power line for proper grounding, and indeed it already got a proper grounding. So that's step one done.

 

Step two is to wire the RFI filter accordingly.

 

 

I use a $2 power socket (the white box) as the interface. So 'A' is plugged into a properly grounded main power line, 'B' is used to plug my Aune's PSU. 

 

 

This is how it looks like from behind (of the RFI filter). Wire/connect all 3 wires into the power socket box, utilizing all 3 poles. That socket box is 'schuko' type socket that are commonly found in Europe. 90% of the sockets used in my country are that schuko type. Of course wire it accordingly to your own socket type.

 

 

This is the most important and possibly life saving step!! 

 

DO NOT PLUG IT IN THE MAIN POWER LINE YET. Take a DMM (digital multimeter), analogs can also be used but digital is easier to use, set it to 'close loop detector'. It will beep if 2 poles are shorted. Now test all the poles in the socket, the signal, neutral, and ground. None of them should give a beep. If you got any beep(s), open it up, and redo the wiring. Repeat until you got no beep(s) at all. IF THE SIGNAL AND NEUTRAL/GROUND POLES GIVE ANY BEEPS, AND YOU PLUG IT TO THE POWER LINE, YOU COULD GET ELECTROCUTED OR IT WILL CATCH FIRE!! Sorry for the caps lock, but this is very very important!!

 

After it's done, and you're sure no poles are shorted, go ahead and plug it to the main power line. Don't worry about the metal casing. I tested it with a test pen and DMM. If it's wired correctly, it got no electricity that could shock you, so it's safe to touch. Of course do the testing yourselves, with a test pen. Best thing to do is to put it in an enclosure, to protect it from water, humidity, and stuffs. Just get a DIY enclosure box, they're cheap. 

 

Next step is to plug the Aune's PSU into the socket, the 'B' part on the picture. If your amp/dac's PSU got 3 prongs, the filter will function better, because your PSU is utilizing all 3 poles of the filter. Mine only got 2 prongs, so the filter might not function optimally, but it's better than nothing

 

 

 

All done, powered up the Aune T1, played some songs for testing. How about the result?

1 single word: awesome!! I said above, and in my Aune's review that the amp part is kinda 'meh'. Turned out it's my office's power line setup that's detrimental to the sound output. Plugged in the socket, utilizing the RFI filter, the sound really got upgraded. It got lower noise floor, that's for sure. The amp part is now very clean and clear sounding.

 

I'm not sure the proper term, but for example, a part of a song where it goes: sound-silent-sound, that kind of part got more discernible. When it's supposed to sound, it sounds. When it's supposed to stop sounding, it goes to a complete stop and silent. Perhaps: it makes my HE-400 more responsive (still feels kinda off :unsure: )

 

What really surprised me was when I tried playing a few rounds of FPS game, L4D2 to be exact. The sounds/sfx got wider and it's much easier to hear enemies' positions. 

 

Honestly, I myself thought that this kind of differences from a simple device mod is kinda hard to believe, and I was actually half preparing if it turned out to be a total BS. Right now, while typing this post, I'm listening to my usual songs, and they all sound better, honestly.

 

Okay, I can accept that what I'm experiencing might be the true fact, but might also be just a delusional placebo. But honestly, with a $5 mod ($3 filter + $2 socket), I could care less of which one is which. 

 

Just remember again, if you want to try this mod, that you're working with AC main power line, so take extra extra EXTRA care....

[ShearMe]

I have no doubt that properly powering your T1 resulted in better performance. Ie, DUH!

[creatip123]

I have no doubt that properly powering your T1 resulted in better performance. Ie, DUH!

 

True....

 

Perhaps my real point was, 'even when you're sure the power lines setup is in perfect condition and working properly, it may not be the case, of which this noise filter mod might help'. This was what happened to me. I was really sure everything were in place and working optimally. Turned out it wasn't. 

 

Edit: come to think of it, the PSU's power plug is only 2 pronged, so it's designed to NOT benefit from the third/ground pole. In other words, it benefits from the noise filter, not from connecting it to the ground pole/grounding. 

[Lutkeveld]

So I asked around diyaudio forum (which is an awesome forum for diy-ers, btw), and got some awesome replies/explanations. 

 

I've seen you around mister c4ppucino 

 

I believe more in a good power supply than filtering. But as a cheap mod this is pretty cool.

[creatip123]

I've seen you around mister c4ppucino 

 

I believe more in a good power supply than filtering. But as a cheap mod this is pretty cool.

 

Yeah, for some reasons I couldn't register there with creatip. Dunno if I already registered that nick before (but forgot the pass), or it was just so happened the system was down. Forgot which one. 

 

The crazy thing is the whole mod costs under $10, solid core thick copper wire included + some elbow grease, and the benefit I got far outweighed the costs. 

 

This also got me thinking, how many times have I, or we (ppl in this forum) thought 'okay, this is the most I could squeeze out of this setup, so I gotta learn to live with *maybe* a bit below my standard', when actually there's some problem that got easy solutions, like in this case. 

[ShearMe]

Edit: come to think of it, the PSU's power plug is only 2 pronged, so it's designed to NOT benefit from the third/ground pole. In other words, it benefits from the noise filter, not from connecting it to the ground pole/grounding. 

 

I consider simple noise removal as proper. Kinda dumb that the wall wort doesn't have that built into it already.

[creatip123]

So, following the installing of RFI filter above, I thought might as well try ferrite beads. 

 

For those of you who don't already know, a ferrite bead is a passive device (don't require electricity/power for it to function) that acts as a filter for high frequencies electric noises. It's those cylinder thingy usually found on USB or HDMI cables. For more info:

 

 

Well, the most important thing is, they're dirt cheap. Of course avoid those 'made especially for audio equipment, to increase hi-fidelity orgasm' stuffs. Just get the regular stuffs used in automotives and electrical wiring. They're basically the same. I think I read that there are some calculation about 'A size is effective for B frequency range' or something like that, but yeah, I just order those based on the diameter size. These are the ones I ordered:

 

 

 

Like I said, they're dirt cheap. 2 of the big ones (13mm hole) + 4 of the small ones (8mm hole) = under $10 total, shipping accounted for. Now I made a bit of mistake when ordering the size. I always thought I gotta get the one that got the hole size about the same as the cable. When it arrived, I just realized that it's better to use a bigger holed beads, so the cable can be coiled 2-3x, like this:
 

 

This is the best way of installing it, coiling the cable 2-3 times around it, near the end that goes to the device. The cable above is the Aune T1's PSU cable. 

 

So I fired up the T1, played a song, and tried wrapping the beads around various cables while listening to the sound (real time). Tried on the USB data cable, the one from PC to the dac, no audible effect. Tried on my headphone's cable, a bit strange, sometimes I felt like I could hear a difference, sometimes I couldn't. Let's just chalk it to: no effect. The biggest effect was when it's wrapped around the power cable, the one from PSU to the dac, the one pictured above. Even with just light wrapping (not snapping the clamps, just holding it with my hand), I can hear the difference in the sound. So I ended up coiling the cable 3 times, to get better result. 

 

The result, believe it or not, the sound I get from my HE-400 is wider, more airy feeling, and tighter kicks. When I did the testing, I could really hear the kicks got tighter when the cable was wrapped, and I could hear the kicks 'bleed' when I took away the bead. As with the airy feeling, I really felt it when playing FPS games. I honestly was a bit surprised by the (better) sound I got, and loving it!!

 

Now of course, you don't need a fix for something that doesn't need fixing. If your power line chain is already good, unlike mine, then the beads will do little to nothing at all. Perhaps the important point here is, I'm already using my Aune T1 for almost a year now, and never once I suspected that my power line is 'dirty', which turned out it is. So it maybe a dormant problem that you're not aware of. And frankly, for a (possible) fix this cheap, you got nothing to lose. It's perfectly safe (unlike the installation of the RFI filter above), reversible (easily taken off), and the worst possibility that could happen is that it won't give any difference (it's not like it will wreck your device or something like that). It's the kind of 'fire and forget', or 'install and forget' stuffs. Install it, and just forget it's even there. Just enjoy the (possible) better sound

[SSL]

A word of warning to those reading, don't get carried away and install chokes on analog audio cables. This will do nothing at best and attenuate/distort the audio signal itself at worst.

 

Edit: Also, chokes selection IS kind of important. At the very least, it needs to actually block noise in the spectrum you are actually experiencing, otherwise it will, at best, do nothing.

[ShearMe]

it needs to actually block noise in the spectrum you are actually experiencing

 

Just block all the spectrums