Powering cheap field mixer - 48v dc needed?

T

thabo

Well-known member
Looking at a cheap field mixer on ebay - Marenius MM-3100 Portable Mono Field Mixer, the specs say that the phantom power is equal to battery voltage!!!!! :( (that's why it's so bloody cheap right)

Internally the mixer takes two 9v batteries so that will be 18v for phantom power which will not work with my 48v mics - some newer mics can run on lower voltages but I'd like 48v.


Can I use a phantom power adaptor and just feed the 48v to the power supply of the mixer - (NOT TO THE MICS AS these units are normally used)?


Say this guy --- http://www.sweetwater.com/store/det...ampaign=none&gclid=CMvhy9KGrrICFQVgMgodyS8Abw or something similar? Looking for a cheap solution as I don't want to throw down the $$$ for the SD 302 just yet.
 
You might want to test that PPA to see if it puts out a hard 48v also. Most battery operated Phantom power sources aren't going to be a hard 48. What mic are you trying to power? Most "48v" field mics have a voltage range they can operate on.

And no, you would power the mic with the phantom power and feed the mixer the audio pass through signal from the power supply. Not power the mixer from the phantom power supply. Phantom power has an extremely weak amperage, designed to just power the electronics of the mic.
 
You should take a look again at the specs of the 4073a: Power Requirements Phantom 11 - 52v DC (quote from B&H site)

So 18v phantom power from the MM3100 is more than adequate. You are going to find that sourcing a battery operated power source that puts out 48v hard is going to be next to impossible and very expensive. You usually only find true 48v in recording studios where they are hooked into house power (120v ac)
 
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1) No you absolutely must NOT attempt to run the mixer from 48V (even if you could find 48V). That is guaranteed to completely toast it beyond any hope of life.
2) Doc Bernard is absolutely correct that your microphone is specified to run as low as 11V so it would likely be quite happy with 18V of phantom power.
3) If you REALLY want 48V phantom power, you could kludge a series connection of five 9V batteries and wire it into the phantom bus of the mixer.

You will hear far more difference from moving your microphone 4 inches than you will hear from 48V vs. 18V phantom power. Don't sweat the second-order effects.
 
thabo said:
Internally the mixer takes two 9v batteries so that will be 18v for phantom power which will not work with my 48v mics - some newer mics can run on lower voltages but I'd like 48v.
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Battery voltage has no bearing on phantom power operation, totally separate.

thabo said:
Say this guy --- http://www.sweetwater.com/store/det...ampaign=none&gclid=CMvhy9KGrrICFQVgMgodyS8Abw or something similar? Looking for a cheap solution as I don't want to throw down the $$$ for the SD 302 just yet.
Click to expand...

That will requite a power source, so not good for field audio unless you have some kind of BDS system. Look into an SD mix pre if want quality on a budget.
 
Pedantic Sound said:
Battery voltage has no bearing on phantom power operation, totally separate.

...
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According to the specs at the link thee OP posted, that particular mixer comes in two models. One model provides phantom power voltage equal to the voltage of the battery used - I presume 18 volts with the internal battery and 24 volts when powered by the specified external DC power supply. The other model provides full 48 volt phantom. Kinda weird design but that's they way the mfgr apparently chose to go on that one,
 
That recorder has a frequency response of 30Hz-16kHz at -3dB... with optional 48v phantom power (IDK what they mean by "optional"), not a great machine judging just by specs.
 
Pedantic Sound said:
That recorder has a frequency response of 30Hz-16kHz at -3dB... with optional 48v phantom power (IDK what they mean by "optional"), not a great machine judging just by specs.
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Optional means just what it says - the unit comes standard with a phantom supply that follows the voltage of the DC source applied to the mixer - 18 volt with the internal 9v batteries or 24 volts if you power it with an external 24 VDC supply. There is an optional, user-installed, power supply board available from the vendor that takes the phantom supply up to 48 volts. See page 3 of the specs PDF in that link. Doesn't sound like a very promising device for serious uses IMHO.
 
Pedantic Sound said:
Battery voltage has no bearing on phantom power operation, totally separate.
Click to expand...

In cheap implementations battery voltage does set the maximum. If the 18v is derived across the 2 batteries hooked up in series, that would be 18v, for 9 volt batteries. if a charge pump is used, one can easily get 18v as well.

If an alternate phantom power source were used, I believe a blocking circuit, such as a transformer or a couple of capacitors would be required to block the 'dc phantom power' from the recorder's power.
 
j1clark@ucsd.edu said:
In cheap implementations battery voltage does set the maximum. If the 18v is derived across the 2 batteries hooked up in series, that would be 18v, for 9 volt batteries. if a charge pump is used, one can easily get 18v as well.

If an alternate phantom power source were used, I believe a blocking circuit, such as a transformer or a couple of capacitors would be required to block the 'dc phantom power' from the recorder's power.
Click to expand...
Yep.
 
Pedantic Sound said:
That recorder has a frequency response of 30Hz-16kHz at -3dB... with optional 48v phantom power (IDK what they mean by "optional"), not a great machine judging just by specs.
Click to expand...

??? The spec is 20-20,000 +/- 1.5 dB. And it's a mixer not a recorder.

It actually looks like a pretty good box, and that was a great price (it goes for 475 Euros).
 
Steve House said:
Optional means just what it says - the unit comes standard with a phantom supply that follows the voltage of the DC source applied to the mixer - 18 volt with the internal 9v batteries or 24 volts if you power it with an external 24 VDC supply. There is an optional, user-installed, power supply board available from the vendor that takes the phantom supply up to 48 volts. See page 3 of the specs PDF in that link. Doesn't sound like a very promising device for serious uses IMHO.
Click to expand...

According to the manual the Phantom voltage is either 18 or 48 depending on the model. It doesn't list any other voltages but does say that phantom in the 18V model is based on the battery voltage (doesn't say power supply).

Almost all mics will run fine of of 18V. Many devices put out less than 48V and the phantom spec doesn't specify a voltage.
 
Noiz2 said:
According to the manual the Phantom voltage is either 18 or 48 depending on the model. It doesn't list any other voltages but does say that phantom in the 18V model is based on the battery voltage (doesn't say power supply).

Almost all mics will run fine of of 18V. Many devices put out less than 48V and the phantom spec doesn't specify a voltage.
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True ... I am assuming that "MM-3100/18 (/S) has phantom voltage equal to the
battery voltage" means that the phantom is 18 volt with the 2x9v internal batteries but if you give it a different power supply voltage, such as the 24 volt external power adapter, the phantom voltage will follow suit. In any case, since some of the better mics out there require a full 48 volts phantom source for optimal performance and since audio gear is a long-term investment, I personally wouldn't ever consider purchasing a piece of gear that didn't offer it even if my current mic collection might work okay with a lower voltage.
 
Pedantic Sound said:
http://www.marenius.se/products/mm3100.html

"Frequency response - 30hz - 16kHz -3dB"
Click to expand...

Interesting since if you download the manual from that link you get 20-20K

Screen shot 2012-09-14 at 11.12.35 AM.pdf
 
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