Any good lavalier that requires phantom 12v ?
- Thread starter deleuze3
- Start date
There are a lot of mics that have phantom power requirements of 12-52v not just 48v these mics if you run at a lower voltage they often have a higher current draw.
So in other words lower volts = more current draw.... Higher voltage = less current draw. (ohms law)
This means the battery won't often last as long on 12v. (you would need to do further 'REAL LIFE' testing)
So in other words lower volts = more current draw.... Higher voltage = less current draw. (ohms law)
This means the battery won't often last as long on 12v. (you would need to do further 'REAL LIFE' testing)
Noiz2
Sound Ninja
Couple of things. Phantom power is not just 48V, that happens to be the most common voltage used but it is not a requirement. Phantom power is more in reference to how the power gets to the mic as opposed to the earlier standard of T power.
The current = voltage doesn't really apply. The mic only draws so much power it doesn't go up significantly with the voltage because whatever is sent to the mic is knocked down to what the mic actually needs which is generally around five volts. But you waste power to convert battery voltages of a few volts to 48 volts and you waste more knocking 48V down to what the mic needs. I had a pre that used five nine volt batteries to provide the phantom voltage. They lasted essentially the shelf life of the batteries.
To the OP. you probably won't find any mic specing 12V phantom power since that would be silly. What you need to look at is the phantom power spec. It will usually say something like 12V - 48V. Most phantom powered mics will work on 12V since it's still higher than what they actually need, but they have to be designed to accept variable phantom power voltages.
Since a lot of the portable recorders out there don't provide 48V there are probably quite a few wired lavs that will work at 12V.
The current = voltage doesn't really apply. The mic only draws so much power it doesn't go up significantly with the voltage because whatever is sent to the mic is knocked down to what the mic actually needs which is generally around five volts. But you waste power to convert battery voltages of a few volts to 48 volts and you waste more knocking 48V down to what the mic needs. I had a pre that used five nine volt batteries to provide the phantom voltage. They lasted essentially the shelf life of the batteries.
To the OP. you probably won't find any mic specing 12V phantom power since that would be silly. What you need to look at is the phantom power spec. It will usually say something like 12V - 48V. Most phantom powered mics will work on 12V since it's still higher than what they actually need, but they have to be designed to accept variable phantom power voltages.
Since a lot of the portable recorders out there don't provide 48V there are probably quite a few wired lavs that will work at 12V.
GaryNattrass
Veteran
I have some low cost ultradisc lav's that need 1.5-10v (plug in power unbalanced) but find that I can use them direct with 12v T-Power.
As others have said phantom power spec is 12-48 volts but it is also a balanced system so requires a special adapter to use it on a lav mic that is for use with low voltage or plug in power type systems.
T-Power is a different system altogether and only certain mixers can provide it but it seems to work fine with my unbalanced electret mics that need low voltage.
As others have said phantom power spec is 12-48 volts but it is also a balanced system so requires a special adapter to use it on a lav mic that is for use with low voltage or plug in power type systems.
T-Power is a different system altogether and only certain mixers can provide it but it seems to work fine with my unbalanced electret mics that need low voltage.
Rick R
Veteran
"so the rode lav can be use with 12v power??"
> Not necessarily, 'Phantom Power' and 'bias current' are delivered differently. The RØDE XLR adapter/transformer may need the full 48 Volts of Phantom Pwr. to supply the mic with the needed lower voltage current. It's a question of the MiCon XLR adapter/transformer, we already know know the mic wants 2 to 5 volts bias current. RØDE states the adapter/transformer requires 48V, so I suspect it would not run on much less than 48P.
Contact RØDE for an authoritative answer.
> Not necessarily, 'Phantom Power' and 'bias current' are delivered differently. The RØDE XLR adapter/transformer may need the full 48 Volts of Phantom Pwr. to supply the mic with the needed lower voltage current. It's a question of the MiCon XLR adapter/transformer, we already know know the mic wants 2 to 5 volts bias current. RØDE states the adapter/transformer requires 48V, so I suspect it would not run on much less than 48P.
Contact RØDE for an authoritative answer.
Bruce Watson
Veteran
Power is power. P = IV. For a given amount of power, as voltage goes up, current goes down. Changing your voltage level won't likely have a material effect on the power needed by the mic. And therefore, it won't have a material effect on your battery life.
If, OTOH, the mic actually uses less power when the voltage is decreased, then reducing voltage will increase battery life. But probably at the expense of mic output and therefore sound quality.
Bottom line is, if you want more battery life, you need to find a more efficient mic. Not just one that will run on lower voltage. You need it to use less power to generate the equivalent output.
I'm just sayin' that power, current, and voltage are not interchangeable terms.
Noiz2
Sound Ninja
I think I talked about this in this thread but? While what you are saying is true it doesn't apply directly to this case. None of these mics need 48V, they need much less. What eats batteries is the conversion losses of boosting your 3 V or so power supply to 48V and then the loss of converting it back down to what the mic needs. Depending on how these conversions are done they can be VERY wasteful. So as a general rule you will get much longer battery life on portable gear if you can run your phantom power at 12V VS 48V.
So while on the micro you are correct what you are missing is that it uses up more power to get up to 48V and it wastes more power getting back down to the 5V or so the mic needs. On the macro level in this particular situation current draw does go up with voltage because more work is being done at 48V than at 12V.
Bruce Watson
Veteran
OK, I've done more research and I think you are indeed correct and I am wrong. Sigh... Not the first time.
Found this interesting document on the SD website. To cut to the chase, it says: "Since power draw is in direct proportion to voltage level, power draw is significantly increased when running at higher phantom voltages. ... Since there is no performance benefit to running some condenser microphones, like AKG Blue Line mics, at 48 volt phantom, running at 15 volts reduces power draw considerably."
I have trouble with this, however. I don't see why microphones draw power in direct proportion to voltage. That implies that they do more work at higher voltages. Do they? Do they return a higher signal strength if fed a higher voltage? Else, what do they do with the increased power that they draw at higher voltages? If it's all just wasted, what's the point of 48V phantom power -- why isn't the standard 12V? I'm missing something...
I think what confused me here might be the fact that my mics are never hot, or even warm. I figured that the small surface area of a lavalier would make an inefficient conversion obvious because it would make the mic hot. But... it occurs to me that if the mic is connected to a cable, it's got all that copper wire to use to dissipate waste heat. Sigh...
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Noiz2
Sound Ninja
Mics don't draw enough power (over phantom) to generate enough heat for you to feel. Some mics and the built in signal amplifier in the mic need more juice than others, but I believe the main issue is how the mic takes the phantom voltage down to what it needs. You can do it with circuits that are fairly input indifferent like voltage converters and zener diodes or you can do it with circuits that are very input sensitive like resistors. Since most mics are used with mains powered preamps that are running 48V phantom you can save space and cost with a resistor bridge and have no downside. Till you try and use that mic with a 15V phantom supply.
The reason higher phantom power eats batteries in the mixer has nothing to do with the mic (well a little) it has to do with the fact that you are powering the thing from some 1.5V batteries. So to get 48V out of 3V (in the case of the MixPre) you need to boost the heck out of that voltage. How? Well you can't easily do it with DC so you need to convert to AC, multiply the AC voltage (there are a number of ways) and then convert the 48V AC back to DC. That is a lot of work and you haven't even gotten the phantom out of your mixer yet.
On the mic end it can either take what it needs and basically reject the rest or it can send enough to ground so that the effective voltage is what it needs. The latter sucks a lot more power than the former.
In both cases it lakes less work to only boost to 15V than it does to go to 48V, and you toss away less at the mic end at 12V than 48V.
So it's not the "mic" that uses the power it's all the converting.
You also have some drop over the length of the mic cable. That however works in reverse. The higher the voltage the lower the loss. So that is another reason you might want to go for 48V if you have really long mic runs, but it will cost you in batt. life.
The reason higher phantom power eats batteries in the mixer has nothing to do with the mic (well a little) it has to do with the fact that you are powering the thing from some 1.5V batteries. So to get 48V out of 3V (in the case of the MixPre) you need to boost the heck out of that voltage. How? Well you can't easily do it with DC so you need to convert to AC, multiply the AC voltage (there are a number of ways) and then convert the 48V AC back to DC. That is a lot of work and you haven't even gotten the phantom out of your mixer yet.
On the mic end it can either take what it needs and basically reject the rest or it can send enough to ground so that the effective voltage is what it needs. The latter sucks a lot more power than the former.
In both cases it lakes less work to only boost to 15V than it does to go to 48V, and you toss away less at the mic end at 12V than 48V.
So it's not the "mic" that uses the power it's all the converting.
You also have some drop over the length of the mic cable. That however works in reverse. The higher the voltage the lower the loss. So that is another reason you might want to go for 48V if you have really long mic runs, but it will cost you in batt. life.
Bruce Watson
Veteran
Um.... not using switched mode conversion? Which has been around for... decades? And can be as much as 98% efficient? In this battery operated field, why the heck not?
OK, I'm getting a nice education here. I always thought that a cheap dime-a-dozen switched mode DC-DC converter was pretty efficient. But looking at the Linear LT1676 (picked at random, first 48VDC input converter I found) and looking at the efficiency curves, it's clear that efficiency varies wildly depending on current draw. I didn't know, but now I do. Cool.
So the problem on the mixer end is designing for the worse case (most power hungry) mic. The problem on the mic end is designing for a wide range of input voltages. Both of which hurt efficiencies.
Which is why the industry moved to 48V phantom power. Makes sense.
Noiz2
Sound Ninja
Switching power supplies use high frequencies to shrink the transformer and make it all more efficient. So in a package they are doing what I described. I suspect that many do use the DC to DC converters. But inside the converter they are changing to AC stepping up and rectifying back to DC. They are very tight packages and quite efficient compared to doing it all discretely. The thing you have to build around is that because of the high frequencies they use to do the conversion they can generate a fair amount of RF. So IF you use them you are going to have to shield that section really well. Lower frequencies have less RF problems but are less efficient so...