The circuit in post #1 is the circuit inside a mic condenser.
The circuit in post#1 is powered via 48V phantom power, coming from a mic preamp.
An externally hosted image should be here but it was not working when we last tested it.
The circuit in post#1 is powered via 48V phantom power, coming from a mic preamp.
So hey though, looking at the original circuit in the original post...
If I were to omit the lower bipolar circuit to make a single-ended output, and decrease or capacitor-bypass R2 to make the FET an amplifier, I'd have a single-ended high-impedance input, low-impedance output phantom-powered preamp...
Right? Or am I dreaming?
If I were to omit the lower bipolar circuit to make a single-ended output, and decrease or capacitor-bypass R2 to make the FET an amplifier, I'd have a single-ended high-impedance input, low-impedance output phantom-powered preamp...
Right? Or am I dreaming?
The circuit in post#1 is meant to interface the microphone diaphgrahm (photo here)
Maybe the above circuit is not for your application.
What is really your application? What do you really want to do? Do you really need it to be 48V powered?
Note that 48V phantom powering (by official specs) is limited to 10mA Max. Don't expect to draw more than that through the preamp.
An externally hosted image should be here but it was not working when we last tested it.
, to go to a mic preamp circuit. 
Maybe the above circuit is not for your application.
What is really your application? What do you really want to do? Do you really need it to be 48V powered?
Note that 48V phantom powering (by official specs) is limited to 10mA Max. Don't expect to draw more than that through the preamp.
Good information. Thank you!
If I answer your question about what I really want to do, I'll ignite a flurry of ill-tempered responses saying that that's stupid. And if I don't answer your question about what I really want to do, I'll ignite a flurry of ill-tempered responses saying that I'm an inferior human and should be banned from the site.
I want to head into the general direction of a Cloudlifter.
Cloudlifter CL-1 | Cloud Microphones | "Elevate Your Sound"
I could use a simple FET circuit like the hi-fi crowd uses for moving coil phono preamps and if it has enough gain it can be single-ended and I can bypass the input transformer in the preamp, which might be a benefit. I wouldn't want to drive a 500-Ohm load with a simple FET preamp.
If it has moderate gain but can run from a phantom power supply, I'd have to route through the input transformer in the mic preamp and that would be okay but it would be interesting to be able to bypass that and see how it sounds.
The circuit shown is all inside the mic and serves as impedance converter and balanced drive, the gain is a little less than two simply the difference between almost +1 and -1. There are ways of taking gain here as well, you might want to join the micbuilders site. Also I have several circuits in Linear Audio magazine that were all built and work.
Seems a little silly, "Like all Cloud® Microphones products, the Cloudlifter® Mic Activator® series is handcrafted using environmentally friendly methods, entirely in the USA."
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My background is more pro-audio, so I see what you're trying to do.
My personal opinion is in most cases, this in-line preamp isn't really needed if you have a very good, low-noise mic preamp at the other end, or if you're signal line isn't travelling several hundreds of feet (example: from stage to front-of-house FOH).
Now, on the other hand, if the mic from the stage has low output, and then also going into a so-so mixing desk (Behringer, Mackie, Samson, and the like), then *maybe* this additional inline preamp may help.
In a mic preamp, you definitely don't want to do that.
Why?
The input transformer in the mic preamp serves as an impedance matcher between the mic and the input circuitry, also offers galvanic isolation, and also as a DC blocker (for the 48V phantom power). It's usually a step up transformer too... 1:3, or 1:6 or 1:8 ratio to further give you "free gain." Also, any common mode noise on your mic input lines are cancelled by the transformer, and only the clean original signal is coupled to the secondary winding, to the mic gain stage. There are lots of great mic input transformers... Jensen, Cinemag, Altran, Carnhill, Lundahl. Pro-audio people usually prefer a mic input transformer design than a direct coupled design... yeah, opposite from the Hi-fi people.
Instead of doing that, why not use a THAT 1510/1512 mic preamp chip. They have an app note on how to wire that for single-ended supply. You'd have to regulate the 48V to 36V, then split it for a +/-18V to power the THAT chip. The 1510/1512 will accept balanced mic input signals directly.
The output of the THAT 1510/1512 is unbalanced, then route that to a THAT1646 balanced line driver. The 1646 is very beefy and you can run several hundred feet of even very high capacitance load on it. Both 1510/1646 are very lower power and also available in SOIC packages. You can set the gain on the 1510/1512 via a single resistor. It's an instrumentation amplifier, very low noise, high gain capable device. The 1646 then gives you an additional +6dB of gain (on top of the gain you set on the 1510/1512 chip... anywhere from +6dB to +66dB).
If you go this route, then your outputs can then go to the LINE INPUT on your mixer (not the MIC INPUT)... because after the 1646 stage, you're basically running at line level, balanced output.
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