ECM8000 - how sensitive to phantom voltage variations?

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calin

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Hi all

I have an ECM8000 that will be used for measurements. I'd like to know how sensitive it is to phantom voltage, ie. whether it needs to be regulated or not. I intend to use batteries for phantom power, because I have't found any other decent way of getting 48V from a 12V PS.


Thanks in advance
 
It's not sensitive to phantom voltage at all - I think 10 Volts is the lower limit.
 
This begs a bigger question I've never gotten around to posting. How sensitive are condensors in general to less that 48V phantom power (say, 24V)?

I seem to recall reading somewhere on the forum that they would work ok, but the signal to noise ratio might be compromised, or something like that. Haven't been able to dig up that thread though.

The reason I ask is that my brother found an old Electro Voice 6 channel phantom power unit at a garage sale for $3. He didn't even know what it was, but figured all those XLR jacks might be useful. The unit provides 24V. I quickly tried my condensors (AT3035 and Octava 012 pair) with it once and they seemed to work fine, but I wasn't listening closely - just a quick check to see if the unit would power the mics.

Thanks
 
Actually, this is what made me post the question. The ECM8000 datasheet specifies clearly that supported phantom power is between 15 and 48V. All this says is that it works with any voltage in this interval, but not if the output of the is the same, be phantom 16 or 47 volts. And if one uses batteries for phantom power and the mic is used for measurements not music recording it counts! Because one needs to have repeatable results.
I found a schematic for the internal amplifier in ECM8000 on this forum and I thought about simulating it. The result was that for phantom voltages below 20V or so the output was very distorted. I didn't dwell too much on it because I used generic models for the transistors and blamed the results on this but maybe that wasn't the cause after all.

Now you see why I'm asking.
 
I stand corrected; Behringer says +15 to +48VDC. A couple of 9 Volt batteries in series, with a pair of 6.8K limiting resistors (and some 10mfd blocking caps), should do the trick.
 
mshilarious said:
It depends on the condenser. Electrets tend to be less sensitive to low voltages. Check the specs of the mics you are considering, they will normally say.
Click to expand...

Thanks MSH. My AT3035 specs say it can take 11-52V, while the Octava specs only list 48V (+/-2).

Like I said, they both worked with the 24V phantom supply. I was just wondering whether there is some compromise that using the lower power presents.
 
Hello again

I just wanted to let you know that I simulated again the internal preamplifier of the ECM8000 and the result was that it's not sensitive at all to phantom voltage variations. The output was the same with 15 and 48V phantom voltage.
Seems that initially I used ny mistake a 1V voltage source instead of 1mV, and the output of the amp ran into power rails when powerr was low, there's where distortion came from.

So, my conclusion is: ECM8000 is not sensitive to phantom voltage as long as you keep it in the recommended range.
 
calin said:
So, my conclusion is: ECM8000 is not sensitive to phantom voltage as long as you keep it in the recommended range.
Click to expand...

That's typical for electrets--the max SPL before distortion drops at low supply voltages.
 
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