The Gefell M221 has 120V on the capsule - taken from the 48V phantom via a DC/DC converter.

The 4041 series from DPA has 190V ... who offers more?

Has anyone tried to make these bars out of thorlabs parts?

The MK221 capsule (specifically on the Josephson) uses 200 volts. It is lower on the M221?

John, name me your source please. The polarization voltage of the m221 is not 120V, it would not work well. All specs are exactly the same as the Mk221 capsule which runs standard on 200V. It is not that difficult to make a dc-dc converter transforming 48V to 200V.

The maximum SPL is limited to 136dBA because the electronics still run on 48V, not on 120V. For those who want max SPL and clean signal should buy the digital version or stick to the old fashioned pre-amps with lemo's.

I just wonder: In which real world situation 136 dBA would be a limitation?

The AT-4050 does 149dB SPL off 48V, so it's NOT the phantom that is limiting the max output...Depending on the circuit..

The DPA/B&K 4007 variants have 153dB max SPL (before clipping) with P48. I really like them on hard hit metal percussion and alike.

A microphone's sensitivity usually determines the max spl level, but in most cases it is the circuit that clips, not the diaphragm. So more power can help to increase the spl handling, all other things being equal. The C617's sensitivity is through the roof. The maximum amount of gain needed to achieve clipping is about 17-20 dB in typical orchestral situations. You should not be sticking it into NASCAR engines or in front of guitar cabinets turned to 11.

The AT 4050 is rated at 1% THD, Microtech at 0.5%. This is comparing apples with oranges.

AT-4050

Open Circuit Sensitivity at 1kHz 15.8 mV re 1V at 1 Pa
Maximum Input Sound Level: 149 dB SPL, 1 kHz at 1% T.H.D.

Gefell M221

Open Circuit Sensitivity at 1 kHz 50 mV re 1V Pa
Maximum Input Sound Level: 136dB SPL, 1kHz at 0,5 % T.H.D.

BTW this is the distortion of the electronics, it becomes even more fun when you measure distortion including the capsule itself. That's what they do in the measuring technique. DPA as example specifies all its microphones including the capsule, what results in higher distortion levels.

The Gefell MK221 capsule + amplifier: 3% THD at 146dB SPL.( with 120V power supply)
The Gefell MK202 capsule + amplifier: 3% THD at 156dB SPL.( with 120V power supply)

Sound-Sampling for example …

"130 - dBA Loud hand clapping at 1 m distance (maximum level)"
"150 dBA Hammer stroke in a smithy at 5 m distance (maximum level)"

Table chart sound pressure levels SPL level normal voice sound levels pressure what measures sound intensity ratio sound units calculation comparison loudness decibel dB scale ratio factor unit examples - sengpielaudio Sengpiel Berlin

Sorry - just realised I never answered this.

My source was Gefell Technical, but there was a misunderstanding (it was at a show when I asked them).

The 120V is when the MK221 is used as a measureing microphone.

On the M221 it is, indeed, 200V.

Sorry about that.

MK221 capsule bias 200V amplifier 120V direct from special power unit.
M221 bias 200V with oscillator and amplifier runs on phantom power.

120V DC is what Gefell's measurement preamplifier needs. The MK221 capsule that their preamp can support (among others) is always polarized with 200V DC.

MK 221
http://www.josephson.com/gefinst.html

Still wondering if someone can do a comparison of Josephson C617SET with the Microtech Gefell M221...

Thanks for the good discussion of these mics. As you can imagine we are friendly with Gefell; we developed the C617 using their MK221 capsule (it also works with other standard capsules from other instrument mic makers) long before they did the M221. While we discussed things, circuit designers have different ideas and their circuit is different from ours (also their housing is prettier) although the capsules are the same.

There are several options to increase headroom in condenser mics. Building a new unbalanced circuit that runs on 130 volts (as DPA does) is one option. Sonodore's 60 volt system is another. You have the option with the C617 of using "super phantom" which is now part of the IEC 61938 international standard for microphone powering. This involves using precision matched 2200 ohm resistors instead of the usual 6800 ohm resistors in the phantom feed circuit, and allowing lots more current to flow. Our view is that you don't need more voltage, you need more current so that the effect of cable loading can be minimized. This works with some classic solid-state circuits like ours, some older Schoeps and other makers' but may not work with some modern designs.

The difference in sound between the Schoeps and C617SET mentioned in this thread is probably due mostly to the difference in capsule size. Making the capsule even slightly larger in diameter (even if the active area of the diaphragm is the same) creates a baffle effect that boosts high frequencies on-axis and rolls them off in other directions. Our choice was to minimize that as much as possible. But, there are options here too. You can use a 1" instrumentation capsule on the C617SET, with an adapter. You can build up your own baffle to go around the mic, acting the same way as a scattering surface (but you can't make a larger mic smaller!) Neumann of course did this years ago with the M50, and several companies offer a spherical baffle of the same 40 mm size that NWDR found optimal in specifying the M50 design. It's unfortunately not as simple as drilling a hole in a ball of wood or plastic. The surface of the baffle must meet the acoustic surface of the diaphragm at precisely the right point, or you get a major anomaly in the frequency response that can sound harsh. There's a good AES paper by Wieslaw Wosczyk some years ago explaining the function of these baffles.

Do you know the title of this paper by Wieslaw Woszczyk?

There is a test on harpsichord here.

"Diffraction Effects in High Quality Studio Microphones" AES E-Library

That was interesting. I listened blind and ended up liking the DPA 4006, the Microtech Gefell M221, and the Josephson C617. Of those three, the Josephson was my favorite and the DPA my second favorite; it's hard to describe, but they had a certain depth I found lacking in the others. The Josephson sounded to me like the ideal compromise between the richness of the DPA and the sparkle of the Gefell.

The Schoeps I didn't like as much as the other three, but in truth, all four are pretty darned good.