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WIMA MP3-X2 Safety Capacitors: Alternative to the Auricap Tweak

Images: WIMA MP3-X2 0.47µF 250V AC rated RFI suppression safety capacitors (metalized paper in epoxy), Vishay Dale CMF RN55 50k 250V AC rated safety resistors.

Before I begin this experiment, I decided to post some information about the matter in the forum for the sake of potential discussion. It may or may not be a successful evaluation, and If I find it to be unsatisfactory, at least the cost of the bags of capacitors and resistors will not go to waste, since discussion of a topic such as this tends to be of interest in Tweakers' Asylum.

One of the more questionable tweaks over the years discussed in this forum was the Auricap Tweak, which involves a pair of rather high-value (nearly 1µF total capacitance for the application) Auricap 0.47µF 600V metallized polypropylene film capacitors connected in parallel across the Live and Neutral contacts of the IEC inlet for an audio component, most often as mild fitering for a digital audio application such as a CD transport or DSP to suppress RFI and avoid digital backwash from polluting the AC delivery system, but with considered better sounding performance than a conventional AC rated safety capacitor for the purpose, with no downsides other than the Auricap capacitor is not safety rated.

Listeners who decided to install the Auricap Tweak were expected to take a leap of faith, and do the unthinkable and break a cardinal AC safety rule to use a non AC rated capacitor for the purpose. Audience was said to implement the configuration using their Auricap capacitor product in the design of their AC power line conditioners at the time. As to why two capacitors are placed in parallel with nearly 1µF total capacitance was never clear to me. Perhaps it simply sounded better. Nevertheless, I've used the Auricap Tweak for many years installed in a Monarchy DIP (Digital Interface Processor) powered-on 24 hours a day for many years, without issue.

There are more than just a digital audio component that may benefit from a pair of good sounding capacitors as mild RFI noise suppression filters for the task, including the AC input of a power line distributor, and even a power line conditioner if there is no attention payed to RFI suppression at the AC input, which is different than only using a single small-value noise suppression capacitor placed across the Live and Neutral contacts of each AC outlet, which is commonplace. Based on Al Sekela's trustworthy recommendation of the WIMA MP3-X2 AC rated safety capacitor as a good-sounding option, I use a WIMA MP3-X2 0.1µF 250V safety cap for the application with good results. A caveat is the WIMA MP3-X2 is surface-mount design with short-length solid core leads, which requires short lengths of wire to be soldered onto the leads in order to install them onto an AC outlet or IEC inlet (I use very stiff 16 AWG MIL-Spec SPC PTFE stranded wire for the task).

So what is first planed is to swap-out the pair of Auricaps installed in the Monarchy DIP with a pair of WIMA MP3-X2 0.47µF 250V safety caps for a direct comparison. This will be the most telling evaluation.

Secondly, if the first test is satisfactory, is to install pair of WIMA MP3-X2 0.47µF 250V caps placed across the Live and Neutral contacts of the IEC inlet for a Vans Evers Reference Model 12 power line conditioner, and compare the larger value pair of WIMA MP3-X2 0.47µF 250V caps vs. a single smaller value WIMA MP3-X2 0.1µF 250V cap currently in use.

Thirdly, I'll install a pair of WIMA MP3-X2 0.47µF 250V safety caps at the IEC inlet of the power distributor for my main audio system, currently with only a single WIMA MP3-X2 0.1µF 250V cap placed across the Live and Neutral contacts of each AC outlet for RFI suppression.

Forth will be to install a pair of WIMA MP3-X2 0.47µF 250V safety caps placed in parallel across the Live and Neutral contacts of the IEC inlet for an MIT Z-Strip power line distributor with upgraded AC outlets, and only a potted presumably non safety rated stock MIT capacitor of unknown value for the purpose. Since the MIT Z-Strip power line distributor is used for a pro audio application that requires a long-length unshielded power cord to be plugged into a power line conditioner located across the room, I've wanted to install additional capacitive filtering at the input, to hear if there might be improvement due to the unusual situation. I might also disconnect the potted MIT cap to compare one configuration vs. another.

In addition to the pair of WIMA MP3-X2 safety caps installed in the power line distributor and power line conditioner (no need to use it with the Monarchy DIP), I decided to include a 50k Vishay Dale CMF RN55 250V AC rated safety shunt resistor to discharge the capacitors just for safe measure while I'm at it. I plan to post a report in the forum sometime down the road. AA Inmates who are not familiar with the Auricap Tweak might like to read previous posts in the AA archives.

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Topic - WIMA MP3-X2 Safety Capacitors: Alternative to the Auricap Tweak - Duster 03:43:18 08/10/20 (14)


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