Yes, for phantom mic power, it's usually either center-tapped transformers or electrolytic coupling caps. However, signal level are typically pretty low, so not a lot of AC voltage on the caps to make a lot of distortion.
Here's somebody's project to get around that: http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=598
It may also be that there are a few commercial mic preamps that also get around using coupling caps for phantom power, perhaps this one: https://www.massenburg.com/products/gml-8304
Also, here's another app note regarding some related issues: http://www.thatcorp.com/datashts/AES5335_48V_Phantom_Menace.pdf
Here's somebody's project to get around that: http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=598
It may also be that there are a few commercial mic preamps that also get around using coupling caps for phantom power, perhaps this one: https://www.massenburg.com/products/gml-8304
Also, here's another app note regarding some related issues: http://www.thatcorp.com/datashts/AES5335_48V_Phantom_Menace.pdf
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How old is this standard 48v? about a hundred years to be compatable with old microphones. Not the best way any more. But stuck with old standard mic usage. I am sure there is a better way.
Microphonics in caps is a mfr problem not inherent in film caps. If you want No microphones, then use better film cap mfr'er...... REL Cap are not microphonic. Just ask the owner (PHD in material science).
THx-RNMarsh
None of my cheap field recorders are microphonic. Picture is my Scarlett 2i2
gain up all the way during a 5 knuckle shuffle right on the lid. There are ways with ordinary off the shelf stuff.
Attachments
Like I said, it depends on the mfr. For a DIY'er it is hit and miss. Give the name brands/model for the DIYer which work best to be sure someone doesn't get a crap type construction. For films, you can always be sure of near perfection with REL caps. There may be others. Mostly, it is how tightly wound the layers are made and for film if they are also annealed.
Finding ordinary cheap parts that are also well made is not the norm. If you discover such, let us all know.
But for polar electro caps, the DA can be (in high Z circuits) a sound destroyer no matter how non-microphonic the part.
If one can design the circuit to be direct coupled or use lower C values ---- 10mfd/50vdc films from WESCO are a better choise (such as their poly carb type) and very compact in size (and not microphonic). . .
THx-RNMarsh
Finding ordinary cheap parts that are also well made is not the norm. If you discover such, let us all know.
But for polar electro caps, the DA can be (in high Z circuits) a sound destroyer no matter how non-microphonic the part.
If one can design the circuit to be direct coupled or use lower C values ---- 10mfd/50vdc films from WESCO are a better choise (such as their poly carb type) and very compact in size (and not microphonic). . .
THx-RNMarsh
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Flying rails stuff, can't see it being a particularly cost effective solution. Can't see how a 2012 patent could have been granted.
... and there is the life issue..... films last forever..... electro's all have limited life (1000-2000 hours for cheap ones before spec is exceeded) and life and parameters vary considerably under temp changes.
Number one failure in equipment comes from bad electro caps.
-RM
Number one failure in equipment comes from bad electro caps.
-RM
<rant>
I know you don't mean it this way, but the latter part drives me bananas -- I "essentially" have a Ph.D in Mat Sci too (EE with very heavy materials focus whoop dee doo) and, while you're trying convey confidence from his/her background, I'd rather you show me a simple test showing a lack of microphonics. I wouldn't trust me as far as I could throw me either, in case you're wondering. 😀
</rant> (Sorry, pet peeve of mine)
Phantom power is still 48v, although, yes, it could be argued using a battery powered arrangement is superior. BUT if it works, it works, and all the better if it works in an already established environment.
Apropos nothing of the rest of my reply: as far as your prior message about having excess equipment, etc, I apologize about not responding and I do want to thank you, and publicly, for your offer. I'll PM you when I have a clearer idea of our needs. In the meantime I picked up a nice-to-me Keysight oscilloscope (200 MHz 4 channel analog + 20 MHz integrated AWG) and Krohn Hite lab amp (among so many other things). Lab toys! 😀
Well, some interesting input, and even a few questions.
Yes, 48V phantom powering can be a problem. It is truly a compromise, but even in 1980, when we built a studio board for Elliott Mazer, we used dual 8uf polyprop REL caps for the 48V phantom powering. They worked great!
I've known the work of George Massenberg for many decades. I even went to LA (when he lived there) to talk with him and hear his sound system. I used his modules in critical areas in my master recorder designs for bias drivers, and even for a low noise front end to couple to my first ST1700B. I still have one of his EQ's as well. George is well aware of cap problems and virtually everything else. I would love to see his solution to removing any caps in the mike stage. Anybody got a schematic?
There is a partial answer to the electrolytic cap problem and that is Silmic caps. That is what we use IF it is almost impossible to avoid them.
Yes, 48V phantom powering can be a problem. It is truly a compromise, but even in 1980, when we built a studio board for Elliott Mazer, we used dual 8uf polyprop REL caps for the 48V phantom powering. They worked great!
I've known the work of George Massenberg for many decades. I even went to LA (when he lived there) to talk with him and hear his sound system. I used his modules in critical areas in my master recorder designs for bias drivers, and even for a low noise front end to couple to my first ST1700B. I still have one of his EQ's as well. George is well aware of cap problems and virtually everything else. I would love to see his solution to removing any caps in the mike stage. Anybody got a schematic?
There is a partial answer to the electrolytic cap problem and that is Silmic caps. That is what we use IF it is almost impossible to avoid them.
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OTOH, probably 99.999% of all those well-regarded recordings from the last 50 years or so we find so fantastic, have been made with mics on 48V phantom. So the 'problem' seems quite relative, so to say.
Jan
Jan
The path to audio corruption lies everywhere! The electrolytic caps in the phantom power supply are only the first of many.
Worry not everyone, at this moment I am listening through a pair of Silmic caps chosen by OPPO for the 105, and I'm not greatly complaining. Of course the REST of the audio thru-path is cap free. That is what I do!
Worry not everyone, at this moment I am listening through a pair of Silmic caps chosen by OPPO for the 105, and I'm not greatly complaining. Of course the REST of the audio thru-path is cap free. That is what I do!
I don't think they sound all that great --- compared to live.
Compared to what else? who knows...and with LP?
-RM
Nah. I'm not going to do that. It isn't what I want to do right now... going backwards for me..... But you and Bas Lim (REL) would be better talking directly to each other. I know all his processes (from him). One thing I did do and maybe you can do it yourself is to measure the C variation with vibration or knuckle rapping.
THx-RNMarsh
.
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And once more what you are all forgetting is that one distortion does not mask
another !
You may have 9 gross capacitors in series and a 10th will add the same subjective
amount of grunge as the 1rst did !
another !
You may have 9 gross capacitors in series and a 10th will add the same subjective
amount of grunge as the 1rst did !
if its at a higher level and the same frequency then it certainly does
also upward frequency masking is strong at higher SPL levels - so even a lower frequency distortion could in some cases mask a higer frequency, lower level distortion
but all of this known Psychoacousitcs involves gross distortion levels, not the stuff -80 below concurrent music signal
also upward frequency masking is strong at higher SPL levels - so even a lower frequency distortion could in some cases mask a higer frequency, lower level distortion
but all of this known Psychoacousitcs involves gross distortion levels, not the stuff -80 below concurrent music signal
Name dropping (and then deflecting) must be an high end audio modus operandi 😛.- Status
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