why phantom over battery?
 

after reading the abundance of information, both objective and subjective, on this forum regarding mic choices and usage, i found myself in the unfamiliar world of phantom powered mics when recently faced with buying decisions, specifically about the best mics for my budget and what i want to get out of them. after heading over to B&H and looking at some of the mid-priced ATs (and giving all the samples on this board a listen -- thank you beas, matt, ty, dse, etc), i sold my two battery powered ENG mics, and purchased the at4073a, at4053a, and a marantz pmd660 recorder (which has two xlr inputs that provide 48v phantom power).

my question is probably more technical than anything else... why are there so few quality battery-powered mics out there? in other words, why are all the real quality mics phantom powered? does the battery introduce interference or some level of noise to the audio acquisition process? or is it just an assumption that the real quality mics will be powered off of a mixer or other professional device?

thanks for indulging me...

If I am wrong, I hope someone corrects me....

Phantom power usually means you are running a balanced circuit, whereas battery power means an unbalanced curcuit. Balanced is obviously much better for quality. For my needs, I like mics that do both, like the AT825 and at897.

It's not really an issue of balanced versus unbalanced. There are balanced mics that can be battery powered and balanced mics that require external phantom powering.

After having spoken to some really great mic designers from Neumann, Sennheiser, AKG and Audio Technica about this question, I'm told that from a design perspective electret (or internally polarized) condensers can be made every bit as good as externally polarized condenser mics.

With a little time I could probably dig up a few electrets that sound better than some externally polarized mics, but I don't have the time. Suffice it to say that during the last five years there have been some truly crappy condenser mics that have come out of China.

The Neumann RSM-191 stereo mic (link below), on the other hand, is the most amazing stereo mic I have ever heard. And that's saying a lot. It can be run on batteries.

http://www.neumann.com/infopool/mics...&Language=Engl

That's not really the answer you wanted, but it's the best I can offfer. It remains a puzzle.

Regards,

Ty Ford

It's not really an issue of balanced versus unbalanced. There are balanced mics that can be battery powered and balanced mics that require external phantom powering.

After having spoken to some really great mic designers from Neumann, Sennheiser, AKG and Audio Technica about this question, I'm told that from a design perspective electret (or internally polarized) condensers can be made every bit as good as externally polarized condenser mics.

With a little time I could probably dig up a few electrets that sound better than some externally polarized mics, but I don't have the time. Suffice it to say that during the last five years there have been some truly crappy condenser mics that have come out of China.

The Neumann RSM-191 stereo mic (link below), on the other hand, is the most amazing stereo mic I have ever heard. And that's saying a lot. It can be run on batteries.

http://www.neumann.com/infopool/mics/produkte.php?
ProdID=rsm191&Language=Engl

That's not really the answer you wanted, but it's the best I can offfer. It remains a puzzle.

The bottom line is to get the best sounding mic you can.

Regards,

Ty Ford

Based on discussions with designers at AT and Audix, both say that inclusion or non-inclusion of a battery is dependent on weight, design appearance, cost target, and where/how the mic is intended to be used.
Keep in mind from the video side that until recently, few mics were designed with the film/television/video production world in mind. Those that were designed for these areas of use are pretty well accepted as standards, and virtually everything else is a 'newcomer' to the market when compared to some of the older ones. I think that Ty would agree that even 5-6 years ago, there were very few mic choices in terms of what was "accepted" whereas today, there are quite a few more models of reasonably comparative value to the well established standards.
As more mics are designed for the field production, film, and television industries, you may or may not see battery power creep in. At least cams now have phantom, whereas a few years ago only a handful of higher costing cams did.

thanks bob and ty...

bob, i read your post and you mentioned mics that do both, like the at897 and it got me thinking.

i did some fiddling around last night. i have an me66 that can also run by phantom or battery power vis the k6. i connected it to the pmd660 with and without the battery. when connected to a 48v phantom power source, the mic runs noticably hotter than when connected via battery.

i'm thinking the answer lies in the voltage being provided by the power source. perhaps the voltage from a battery wouldn't be enough to power many of the high-end condensers as designed. needless to say, this is completely speculative.

thanks dse... i didn't see your post as i was writing mine...

Henry I think you have it right about voltage. When I was shopping mics last year the Dynamic Range was always written in two versions, phantom powered and battery powered; phantom was always better. Here is an example with the at897.

Transducer Condenser

Polar Pattern Line + Gradient

Frequency Response 20Hz to 20kHz

Dynamic Range (Typical) Phantom: 112 dB, 1kHz at Max. SPL
Battery: 98 dB, 1 kHz at Max. SPL

Signal-to-Noise Ratio 77 dB, 1kHz at 1 Pa

Maximum Input Sound Level Phantom: 129 dB SPL, 1 kHz at 1% T.H.D.
Battery: 115 dB SPL, 1 kHz at 1% T.H.D.

Power Requirements Phantom Power: 11 - 52V, 2 mA typical
Battery Type: 1.5V AA/UM3

Output Impedance Phantom: 200 ohms
Battery: 300 ohms

Output Connectors 3-pin XLR

Pad No

Low Frequency Roll-Off 80 Hz, 12 dB per octave

Dimensions 0.83 x 10.98" (21.0 x 279mm) (Length x Diameter)

Weight 5.1 oz (145 g)

thanks jerry...

the reason why i asked this question in the first place, besides straight-up curiosity, is based on the simple fact that sometimes i have no other option than to run a camera mounted mic and my xl1 does not have native phantom power. i understand that camera mounting is a far-from-ideal use of any quality mic, but a lack of a live-in boom operator (unfortunately my wife doesn't qualify) often makes off-camera sound an impossibility. battery power offers me flexibility in this regard, but, again, the lack of high-end mics that are powered by battery makes things a bit more complicated. i'd love to put a "battery powered" sanken cs3e on a k-tek shock mount, with the optional camera mount adapter. when i need to run on-camera, i can put it in battery mode, and put the shock mount on the camera. when i want to run audio off-camera, i can unscrew the mic holder, put the shock mount on a boom and run phantom though a mixer. the point of minor frustration about all this is the fact that with all the money i've spent on mics i've accumulated to cover various scenarios, for a few hundred dollars more, i could have bought a schoeps AND an mkh60 (which are both in my ultimate plans). don't get me wrong... i'm really digging all my mics so far, but i would have loved to buy a high-end condenser which offered me the type of flexibility i mentioned and called it a day. i doubt sennheiser even thought someone would want to mount an mkh60 on a gl1 or xl1, but i think a mid-priced mic like the cs1 would benefit from offering this kind of flexibility considering the success of the me66 and at897.

several companies make small, battery powered phantom power boxes.

Ty Ford

My only non-technical observation on this is the fact that having to run on phantom power means that you can pretty well be assured of a constant voltage supply to the mic element. With battery power, you will have that point where the battery will die and possibly degrade the mic's performance just before doing so.

Again, no technical facts to prove this but just my thoughts on why a design engineer might choose to go this route.

=gb=

greg, that makes sense to me... thank you...

ty, i'm definitely going to give one of those power supplies you mentioned a shot.

Part Two -- Phantom Supplies

Please be aware that Phanton Power requires the enough voltage and current.
The formula fforr power is P=IxE. P is Power, I is current and E is voltage.

The point is some Phantom supplies only crank out 12 or 24 volts and dont have the current to power some phantom powered mics.

SOme mixers say they have 48 VDC Phantom and do, but the current is to low to power any more than one or two mics that really use a lot of current.

When a phantom powered mic is under powered, the result is higher noise and distortion because you are starving the mic. Most condenser mic spec show a rating of voltage and mA (millamps) required to power it properly.

Please make sure the phantom supply you choose can handle the mic you choose.

Other tips and tricks are in my Audio Bootcamp Field Guide book whicch is available on my site.

Regards,

Ty Ford

i just got back from b&h (no i don't camp outside the store... i just work a few blocks away), and talked to a rep about portable phantom power devices. he initially showed me the beachtek DXA-6.

http://www.bhphotovideo.com/bnh/cont...ist&sku=224231

it advertises sustained 48v phantom power to two channels off of a single 9v battery (i don't see how that math works itself out). it's not cheap at $250, and i wasn't thrilled about the stereo minijack audio out. i passed on it.

everything else they had in stock by way of portables advertised 48v mic compatibility, but, as ty stated, output only between 9-24v of true power to the mic. the sales rep said that there was nothing short of a $350 mixer that could kick out sustained 48v power to a mic that didn't have to be plugged into a wall. he did say that my ATs would probably run fine on something that could kick out around 18v, but i've read posts about hiss and noise being introduced when a portable mixer is underpowering the mic.

i guess this cuts right into the original question about why most high-end mics run off phantom power.

if i'm missing out on a product i should give a look, please let me know. thanks...

http://www.sweetwater.com/store/category/c494

Regards,

Ty