"Standard" EIC power input vs. Filtered EIC

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Hi Everyone: I'm ordering parts for my Pass a40 amp and have gotten to the part where I need to find AC power cords and connectors. I stumbled across some EIC receptacles that contain RFI filtering and was wondering about using this instead of just a "regular" power input. Any comments or pro's and con's I should be aware of with these?

Thanks for your help!
You need it!

Get a real one with filtering.

They are actually intended for protecting the net from garbage generated inside your device (such as switching diodes etc.). They come in various flavours. I put one in my CD player -- one of the bigger upgrades I have done. I also got a totally awesome one and put in my poweramp -- same thing happened.

Consider getting one with a ground inductor if you connect to ground -- in Norway we don't usually have ground in our living rooms, so I have not tried those.

I have previously posted more under "X100 backengineered" under solid state forum, about page 3 or so.

Thanks for the links

Hi Petter: Thanks for the links! I looked up the Corcom website, plenty of good material there. It looks like the Q series is the only one that will handle over 10 amps, but they're pretty pricey - near $100. They're also pretty large. I like the size (and power switch) of the C series, maybe I'll have to look into those as well...

[Edited by Eric on 05-15-2001 at 08:26 AM]
Heatsinking & Current Draw

Petter: The amp will probably only draw 2-3A under normal conditions (dissipate ~100wpc), but what I'm concerned about is the ability of the filter to handle the inrush current to charge 96,000uF of capacitance. The inrush capability of the C series is listed at 51A, so this should be OK.

As for heatsinks, I've got 8 Wakefield 423A units, rated at 0.67c/w each. This gives a total heatsinking of 0.0837c/w, where the original design calls for 0.125c/w so I've got a little margin of safety... I just like to over-engineer a little - makes me feel better that things won't blow up as quickly.
Try putting a thermistor in series with the transformer primary. On turn on, the resistance will be high, limiting inrush current, but will fall as its temperature rises.

Another method I've seen is to put a power resister in series with the transformer and shunt it with a normally open relay. After 20-30 seconds, a timer closes the relay.

51A of inrush current is going to put a strain on every part of your power supply, not to mention probably pop your circuit breaker.


Jon: I don't know what kind of inrush current will occur as a result of the filter caps, which is why I was looking for higher rated filters... I wasn't implying that the inrush current will actually BE 51A, just that the RFI filter could safely handle up to that amount.

In this case, I'd suspect the filter would be pretty comfortable handling whatever inruch happens with powerup. However, the thermistor isn't a bad idea at all. Thanks for the tip!

Inrush current will typically always be in the 100 amps or more for a good amp. This is not the way to rate your filters ...

Thermistors work great unless you turn off, then almost immediately on, when the thermistors are still hot (but then you would still have some charge on your caps.

Thermistors are the el-cheapo way out. BAT VK60 has 5 ohm version for 110V and 10 ohm version for 220V -- they come in various sizes and get very hot. Why el-cheapo? Because you always have an extra pass element with finite resistance and you also have heat generation, might not work right if power fails, you don't know if it is broken or not (high temp usually means shorter life).

Check out the size on http://www.balanced.com ... compare with Plitron units at http://www.plitron.com.

However, it will vary with type of rectification/filtering and output voltage.

You can buy a resistive kit from http://www.lcaudio.com/tilb.htm -- 330 ohms for 3 seconds, probably OK with half the resistance for US. Nice, I might just get a couple but they are not free.

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