why phantom over battery?

Henry Cho · June 7th, 2005, 05:24 PM

thanks for the link ty. i'm going to take a look at the stewart bps1. the sennheiser is too expensive for me, and everything else seems underpowered or needs a wall to plug into.

Dave Largent · June 8th, 2005, 05:36 AM

Henry,
Awhile back I was in your situation and a real pro mixer
here recommended me a reputable portable
phantom powering unit that she actually uses in
her work. It is Denecke brand. Costed around
$125. Seems real solidly built. Runs on one 9V
and puts out 48V phantom. Has an option to
activate a 15dB attenuator. Has low battery
indicator. I remember being told that one nice
thing about it was the way the battery is connected,
that it's a real solid connection.
Don't recall the model number off the top of my head,
something like P-1a or something, I think.
Anyways, I've been happy with it. If you need me
to check the model number let me know.

Henry Cho · June 8th, 2005, 07:46 AM

dave,
i really appreciate the suggestion. funny enough, after doing some research last night, i bought the denecke ps-1a from trewaudio... i like that the denecke looks like it could take a beating and it's size is compact enough to possibly velcro mount to my ma-100... if it all works out, i'll post some pics of the rig. thanks again...

Dave Largent · June 8th, 2005, 08:05 AM

Yeah, Henry, that's the one that I've got. I even think
I purchased it from Trew Audio! You know if Trew
sells it, it's probably a good unit. The owner of the
company not only has that store but also works
as a pro mixer as well so I don't think he'd be selling
stuff that wasn't pretty decent quality.

Bill Binder · September 4th, 2005, 09:57 AM

Back to the subject line of this posting... Although I am no expert, I believe it is common knowledge among "audience tapers" that using phantom over battery (when you evenhave the choice) can provide a wider dynamic range, and more importantly, can help prevent brickwalling in high SPL enviroments. Not sure, but this might depend on the mic. As stated in an early post, some mics even list out this difference in the technical specs. Please note that this comment is most applicable if you are recording in LOUD environments like rock concerts.

TingSern Wong · September 9th, 2005, 02:39 AM

ME66 powered by phantom and powered by its K6 internal battery does have some audio differences. But, I speak only for ME66 - I don't know of any other mics (which I have no access to). The differences are so small I think you need to be a bat or a dog in order to hear the difference. I use a digital oscilloscope to test (A-B). Phantom power appeared to have a flatter frequency response in the low end. Mid and highs are essentially the same. I do not know why this is the case.

Also - note the following ... if your mic can accept 12V phantom, please use it, instead of upping the voltage to 48V. Sound wise, the mic and mixer will not see any difference. But the battery driving the mixer will say thanks to you for using 12V rather than 48V. Because the consumption of battery power is 4 times greater in 48V phantom as opposed to 12V. Hence, if your mixer and/or portable phantom power generator can switch between 12 and 48, try 12 first.

TS

Ty Ford · September 9th, 2005, 04:31 AM

On the other hand, starving your mic by not feeding it enough voltage results in distortion.

It's not just about voltage. The mic requires POWER. The formula for power is P = I x E, where I is current and E is voltge. Dropping the voltage from 48 to 12 causes the mic to try to pull more current to work properly.

Batteries are cheap. Keep your mic happy. It will draw what it needs.

Regards,

Ty Ford

Dave Largent · September 9th, 2005, 07:03 AM

Something I haven't been able to figure out is this.
I have a Rode NT4 that is specified to operate on
either 12V or 48V phantom. Using a Sound Devices
preamp set to 15V phantom, the NT4 won't fire
up from trurned "off". Now, if I fire it up with 48V
for the first few seconds I can then back it down
and it will run on 15V.

TingSern Wong · September 9th, 2005, 09:18 AM

Hi Ty,

Power drawn from a battery is independent of the voltage supplied. If the mic requires 100mA (let's say - then it will draw 100mA, whether the voltage is 12V or 48V). I am referring to the power needed from the battery to the mixer in order to supply 12V or 48V. Nearly all mixers use 1.5V x 4 or less = total of 6V or less at source. To generate 12V or 48V, a DC-DC stepup convertor is used. If you measure the power drained from the batteries to supply 12V versus 48V, the power required is 4X greater at 48V when compared to 12V.

Therefore, if your mic can cope with only 12V phantom, use it - instead of pushing the mixer's circuit to generate 48V.

TS

Ty Ford · September 9th, 2005, 05:16 PM

Quote:

Originally Posted by TingSern Wong

Hi Ty,

Power drawn from a battery is independent of the voltage supplied. If the mic requires 100mA (let's say - then it will draw 100mA, whether the voltage is 12V or 48V). I am referring to the power needed from the battery to the mixer in order to supply 12V or 48V. Nearly all mixers use 1.5V x 4 or less = total of 6V or less at source. To generate 12V or 48V, a DC-DC stepup convertor is used. If you measure the power drained from the batteries to supply 12V versus 48V, the power required is 4X greater at 48V when compared to 12V.

Therefore, if your mic can cope with only 12V phantom, use it - instead of pushing the mixer's circuit to generate 48V.

TS

You're suggesting to many people who can't tell the difference (or don't know what thespecs mean) that in some cases lower votage can be used. Many may have NO CLUE as to whether or not their mic "can cope" with less voltage.

Much less whether or not the phantom supply is antagonistic to the batteries inside some electret mics. (but that's another story.)

Ty Ford

Marco Leavitt · September 9th, 2005, 06:17 PM

Ty,
But if the mic manufacturer specifies that the model can be used with either 12V or 48V, you're better off using the 12V, right? Or is there more to it than that?

Dave Largent · September 9th, 2005, 08:57 PM

Quote:

Originally Posted by Marco Leavitt

Ty,
But if the mic manufacturer specifies that the model can be used with either 12V or 48V, you're better off using the 12V, right? Or is there more to it than that?

I can't recall where (a review of a Rode, maybe)
but I thought it was claimed "but of course the
best performance will be at the maximum 48V".

Jack Smith · September 9th, 2005, 09:30 PM

I would suggest using what ever the designer has specified.If 12v is specified fine.As Ty stated the designed CURRENT draw for 48v would differ from a designed 12v supply even when the POWER requirement stays the same.The battery longevity would NOT be proportional to the voltage change. If supplying a non designed voltage the current draw would typically change due to the load of the circuit.Bottom line using the design voltage should yield the best result.

Dave Largent · September 9th, 2005, 09:35 PM

So, Jack, you're saying that using 12V would
not give you 4X the battery life as using 48V?
My Rode is specified to use 12V, 24V, or 48V.

Jack Smith · September 9th, 2005, 10:58 PM

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.

September 9th, 2005, 04:31 AM	#22
Ty Ford Inner Circle Join Date: Nov 2004 Location: Baltimore, MD USA Posts: 2,337	On the other hand, starving your mic by not feeding it enough voltage results in distortion. It's not just about voltage. The mic requires POWER. The formula for power is P = I x E, where I is current and E is voltge. Dropping the voltage from 48 to 12 causes the mic to try to pull more current to work properly. Batteries are cheap. Keep your mic happy. It will draw what it needs. Regards, Ty Ford __________________ Ty Ford's Audio Bootcamp Field Guide Ty Ford's Audio Video Blog

June 7th, 2005, 05:24 PM	#16
Henry Cho Major Player Join Date: May 2005 Location: NYC Posts: 516	thanks for the link ty. i'm going to take a look at the stewart bps1. the sennheiser is too expensive for me, and everything else seems underpowered or needs a wall to plug into.

June 8th, 2005, 05:36 AM	#17
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Henry, Awhile back I was in your situation and a real pro mixer here recommended me a reputable portable phantom powering unit that she actually uses in her work. It is Denecke brand. Costed around $125. Seems real solidly built. Runs on one 9V and puts out 48V phantom. Has an option to activate a 15dB attenuator. Has low battery indicator. I remember being told that one nice thing about it was the way the battery is connected, that it's a real solid connection. Don't recall the model number off the top of my head, something like P-1a or something, I think. Anyways, I've been happy with it. If you need me to check the model number let me know.

June 8th, 2005, 07:46 AM	#18
Henry Cho Major Player Join Date: May 2005 Location: NYC Posts: 516	dave, i really appreciate the suggestion. funny enough, after doing some research last night, i bought the denecke ps-1a from trewaudio... i like that the denecke looks like it could take a beating and it's size is compact enough to possibly velcro mount to my ma-100... if it all works out, i'll post some pics of the rig. thanks again...

June 8th, 2005, 08:05 AM	#19
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Yeah, Henry, that's the one that I've got. I even think I purchased it from Trew Audio! You know if Trew sells it, it's probably a good unit. The owner of the company not only has that store but also works as a pro mixer as well so I don't think he'd be selling stuff that wasn't pretty decent quality.

September 4th, 2005, 09:57 AM	#20
Bill Binder Major Player Join Date: Jun 2005 Location: San Francisco Posts: 542	Back to the subject line of this posting... Although I am no expert, I believe it is common knowledge among "audience tapers" that using phantom over battery (when you evenhave the choice) can provide a wider dynamic range, and more importantly, can help prevent brickwalling in high SPL enviroments. Not sure, but this might depend on the mic. As stated in an early post, some mics even list out this difference in the technical specs. Please note that this comment is most applicable if you are recording in LOUD environments like rock concerts.

September 9th, 2005, 02:39 AM	#21
TingSern Wong Major Player Join Date: Jan 2004 Location: Singapore, Rep of SINGAPORE Posts: 749	ME66 powered by phantom and powered by its K6 internal battery does have some audio differences. But, I speak only for ME66 - I don't know of any other mics (which I have no access to). The differences are so small I think you need to be a bat or a dog in order to hear the difference. I use a digital oscilloscope to test (A-B). Phantom power appeared to have a flatter frequency response in the low end. Mid and highs are essentially the same. I do not know why this is the case. Also - note the following ... if your mic can accept 12V phantom, please use it, instead of upping the voltage to 48V. Sound wise, the mic and mixer will not see any difference. But the battery driving the mixer will say thanks to you for using 12V rather than 48V. Because the consumption of battery power is 4 times greater in 48V phantom as opposed to 12V. Hence, if your mixer and/or portable phantom power generator can switch between 12 and 48, try 12 first. TS

September 9th, 2005, 07:03 AM	#23
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Something I haven't been able to figure out is this. I have a Rode NT4 that is specified to operate on either 12V or 48V phantom. Using a Sound Devices preamp set to 15V phantom, the NT4 won't fire up from trurned "off". Now, if I fire it up with 48V for the first few seconds I can then back it down and it will run on 15V.

September 9th, 2005, 09:18 AM	#24
TingSern Wong Major Player Join Date: Jan 2004 Location: Singapore, Rep of SINGAPORE Posts: 749	Hi Ty, Power drawn from a battery is independent of the voltage supplied. If the mic requires 100mA (let's say - then it will draw 100mA, whether the voltage is 12V or 48V). I am referring to the power needed from the battery to the mixer in order to supply 12V or 48V. Nearly all mixers use 1.5V x 4 or less = total of 6V or less at source. To generate 12V or 48V, a DC-DC stepup convertor is used. If you measure the power drained from the batteries to supply 12V versus 48V, the power required is 4X greater at 48V when compared to 12V. Therefore, if your mic can cope with only 12V phantom, use it - instead of pushing the mixer's circuit to generate 48V. TS

September 9th, 2005, 06:17 PM	#26
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	Ty, But if the mic manufacturer specifies that the model can be used with either 12V or 48V, you're better off using the 12V, right? Or is there more to it than that?

September 9th, 2005, 09:30 PM	#28
Jack Smith Major Player Join Date: Nov 2003 Location: ontario Posts: 445	I would suggest using what ever the designer has specified.If 12v is specified fine.As Ty stated the designed CURRENT draw for 48v would differ from a designed 12v supply even when the POWER requirement stays the same.The battery longevity would NOT be proportional to the voltage change. If supplying a non designed voltage the current draw would typically change due to the load of the circuit.Bottom line using the design voltage should yield the best result.

September 9th, 2005, 09:35 PM	#29
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	So, Jack, you're saying that using 12V would not give you 4X the battery life as using 48V? My Rode is specified to use 12V, 24V, or 48V.

September 9th, 2005, 10:58 PM	#30
Jack Smith Major Player Join Date: Nov 2003 Location: ontario Posts: 445	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.