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Old September 10th, 2005, 02:12 AM   #31
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We can always do a simple experiment to test whether mic can cope with a lower voltage or not. Plug it into mixer with your normal XLR cable connection and set the voltage to 12V or its lower setting. Talk to the mic and see if audio is coming out from mixer? Yes - you are in luck. I run all my Sennheiser ME66s and MKH50s + MKP70 at 12V phantom and have not encountered any problems with audio.
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Old September 13th, 2005, 07:05 AM   #32
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Thanks for that Jack. While we're on the subject of Phantom Power, some cheap mixers that SAY they offer 48 V Phantom Power, may, in fact, deliver 48 V and be able to power one mic.

On the down side, some of these mixers don't have the guts to power a full complement (8 ch, 16 ch, whatever) of mics, especially if those mics happen to be the hungry sort requiring more mA (milliamps) than the circuitry can supply.

Regards,

Ty Ford
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Old September 13th, 2005, 07:27 AM   #33
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Quote:
Originally Posted by Jack Smith
An example would be the Rode NT4. It can be used in either 48v, 24v, 12v or 9v.The current draw for each of this ,in the same order is 4ma, 2ma, 2.8ma and 2.4ma. As you can see the current draw at 12v is about 75% of 48v.Depending on your battery powered mixer the loss thru voltage up conversion would increase the difference a bit.On 12v would give about double the battery life.All dependent on mixer and mic.
But in essence TS is right the 12v setting on a mic designed for this would allow extended battery life.
And what about the sensitivity, and capability to handle high
SPLs without distorting at 48V vs. 12V or 9V with
the NT4?
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Old September 13th, 2005, 09:25 AM   #34
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Yes, I vouch for that statement. I once had a cheap mixer that could power up 2 mics at 48V. When I plug in the 3rd mic, all 3 mics died :-(. That mixer is, needless to say, in the dumpyard.

****

I did another experiment for the benefit of our members here. Using a 4 channel Sound Devices mixer (model 442), if I use 12V phantom, one pair ME66 (+ K6 power unit) and one MKP70 all works (together). If I plug in my MKH50 (just one of them), all of the mics fails. Pushing the voltage from 12V to 48V, any combinations of mics works.

(Note that Sennheiser says phantom is 48V, not 12V. So, by lowering the voltage to 12V, I am essentially on my own).

But, if I want to be stingy on batteries, I could couple the 442 with my MixPre (a 2 channel mixer). Run the pair of MKH50s off the MixPre (48V "factory setting") and the remainder on the 442 at 12V phantom.

You can easily experiment with your mix of mics and mixers and find which combinations can operate at 12V (provided the mixer allows you to use 12V and 48V) and you can optimise your battery uptime - knowing that the mics will still receive adequate power.

TS
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Old September 13th, 2005, 11:46 PM   #35
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Dave , I don't know if the specs change on the NT4 but I wouldn't expect much change as it is designed for 12v.Using the 9v might take a edge off because although they say you can use a 9v it falls in the 12v design level.

TS, I think we're talking about 2 different things.I'm talking about mics designed for lower voltages ,not using lower voltage on mics designed for 48v.
I believe you'll find Ty is right. If you undervoltage a mic it is not going to do the job at it's best.And after all that is what we want,get the best we can.Well at least thats what I want.
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Old September 14th, 2005, 01:25 AM   #36
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Hi Jack,

You and Ty are right. If the specs says 48V phantom, I will run it at 48V.

Some manufacturers don't publish specs or is ambigious. In such cases, I will experiment to see if mics fare well at lower voltages first. A pretty good example will be the ME66 with K6 powering module. That mic works perfectly well at 12V as well as 48V. No difference can be found for audio quality between 12 and 48. I can't find any specs for K6 phantom voltage requirements.

On the other extreme, the MKH50 cannot work at 12V - no sound. Very clear here. The specs says it clearly - phantom is 48V.

The MKH70 - although specs calls for it to be 48V, I found it can work at 12V as well. I have not made any measurements for audio degradation so far.

I hope I cleared all doubts now? If I am using ME66 or ME67, I will use it at 12V - no point at 48V. If I am using MKH50 or 70, I will be using it at 48V.

Cheers,
TS
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Old September 14th, 2005, 02:45 AM   #37
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I believe I did see a spec for K6P of 12V to 48V on
the Sennheiser site.
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Old September 14th, 2005, 03:03 AM   #38
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Hi Dave,

Thanks. It will explain why K6 with ME66 or ME67 works perfectly at 12V or 48V.

TS
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