Referring to my earlier posting titled X-2 Capacitor Filter Tweak, dated 15th November 2008. Now that a few of my friends have tried it and have updated me with some feedback that might be use full should you wish to try.

When I did my tweak, I used 0.1uf rated 275V capacitor to short the "live" and "neutral" at the IEC plug end of my power cord. Some of my friends followed the tweak with the same value cap but reported no differences or perceived improvements in term of power line noise reduction. I have since asked them to try other values available.

You may purchase any of these X-2 capacitor values available at the electronics spares supply shop:

0.1uf @ 275V

0.22uf @ 275V

0.33uf @ 275V

0.47uf @ 275V

1.0uf @ 275V

2.2uf @ 275V

The suitable X-2 cap value to use as a filter tweak really depends on the power supply quality in your area. My area, near USJ Subang isn't too bad and I got very positive results using 0.1uf caps. Another friend who lives in Bandar Utama, near hifikaki and ML's place, reported no improvement when he first tried using 0.1uf caps. He later found that 0.47uf cap value gave him very good results.

Another fella in Kuantan reported he only found improvements after going all the way up to using 2.2uf cap value. I have being to his place a couple of times over the years and can testify that the power supply quality in Kuantan is pretty bad indeed, plus it comes with frequent black outs and brown outs(according to my long suffering friend whom almost gave up hifi because of power supply issues). I feel for him, as I feel for ML.

As usual, I will apply the caveat of non-liability should you suffer from damaged equipment, injuries or electrical shock, or worst death, as a result of this DIY activity, which invariably involves high voltages which is dangerous.

Also note that "your mileage may varies" in terms of results from this tweak.

Good luck.


tee said...


could you use better cap like Bybee,auricaps and the likes?

audioexplorer said...

Is there an negative in using the bigger sizes or using a couple of caps at once?

Panzer said...


I know, PLC products like Audience RA6 and RA12, uses Auricaps. However, as I've not seen the insides of such product, I could only speculate that they would have a diferent filter circuit, rather than just a X-2 cap plus an MOV for protection, like so many others in the market. For SAFETY reasons at this point, I would not recomend anything other than those comercially available X-2 caps. There's a reason they're called X-2, theres a built in fuse, located in between the 2 polariy of the cap and should a "short" does happen, the X-2 cap's built in fuse will self destruct, saving your equipment connected to it.


Technically, there are no negative on using higher value caps in the range that I have specified. As demonstrated by various products, Shunyata Hydra uses 0.1uf, Audio Prism uses 0.33uf and my own Isotek Sigmas uses 2.2uf.

However, if the power quality in your area is good enough, like in my case 0.1uf would sound the best, as the low pass slope would be less steep, i.e. more linear. If the power supply in your area is poor, you'd probably have to use higher values, like 0.33uf onwards to hear a quiter noise floor. However, to my ears, the higher value caps also means a steeper low pass slope, and they do sound just a little bit less than natural(note the high frequencies, they almost always affect the highs). So do try to use the lowest possible cap value and note for a fine line of compromise between noise floor and your high frequency reproduction. Lesson is do not be greedy with the cap values. Also try to keep things simple, remember the more multiple connections, the higher chances of negligence and result of poorer contact is also highly possible. Also think about the space you have to mount the cpas in to. An IEC plug is not very roomy inside, one smaller value cap is comfortable, a 2.2uf is already rather rather tight fitting.

Good luck guys.

Anonymous said...

I'm using a cascade of 1uf, 0.1uf and 0.01uf --> CMC --> 0.01uf, 0.1uf and 1uf with good results.. these really work!, for not much $. The Audience is also a bunch of Auricaps + CMC; you can try out with Auricaps as well since its proven in a commercial product. But as Panzer stated, for safety reasons, better stick with X2 caps, I'm using Vishays which are reportedly excellent for this purpose.

Panzer said...

Anonymous 1.25pm,

Thanks for sharing your thoughts on your DIY PLC. The design that you've mentioned is better to be built on bread boards then attached to the outlets.

I've previously built similar designs before with great results.