Hi everyone!

Direct-powered microphones (such as DPA4003, 4041S, and similar) are known for its top-notch sound performance, impossible for P48 models. But they have also important cons:

- Incompatible with P48 when you need it.
- Requires special multi-wire cables.
- You are always tied to the PSU (or special pre).

I'm developing these microphones. https://web.facebook.com/resolabs/

It seem we've found a solution of the problem. We've designed a mic powering architecture capable to achieve the speed and clarity of direct powered mics without special cables, but by using a high voltage phantom power 100V. But that's not all. The amplifier designed the way that literally the same microphone work at P48 too, providing the performance of the best P48 mics. (Magic?) This made possible by long research, meticulous design and modern high-speed semiconductors.

The system is called Reso Xpower, this is how it works:

-The microphone has a regular XLR-3 connector.
-Being connected to P48 pre it works at max performance possible for P48 mic in terms of sound and specs. (for instance Reso X41P has 124dB dynamic range).
-When you need the top transient accuracy and dynamic range, you can connect the external P100 phantom power source. The microphone will automatically change its mode to getting best performance possible depending on powering used.
-No special cables, only XLR-3 connectors. The P100 PSU can be connected as an insert in any spot of mic line ( e.g. close to preamps).
-100% safe for all P48 environment. This is a vital issue. PSU has a safety system. When mic is disconnected - high-voltage is blocked. If the wrong mic connected - the current protection blocks it from damaging.


Sound examples. Steel guitar, two pairs of X41P on the same bar, P48 vs P100.
https://cloud.mail.ru/public/5CFM/5BdJY7ryq


All the Reso mics are equipped with P48/P100 since the start, but for instance Schoeps CMC-4,5 (6?) could be modded for P48/P100 too.

The PSU is designed, prototyped and tested, but has not been serial produced yet.

I'm very curious what you think.

B&K capsule on the Reso mic?

Once we get back to recording, and if you have a demo pair floating around the USA, I would like to compare them to my Josephson C716 (P48), day-to-day DPA 4006-TLs (P48) and my Rens 60V schoeps. Cool idea in any case.

D.

I too would be interested in a demo! Looks pretty, has the grid of the dpa, and the diaphragm of the gefell? All Russian at this point anyway.

Cheers

Is this a question or a fact? "All Russian".

D.

Yes, the capsules are 200V nickel diaphragm, made in Russia versions of B&K design. X41 is close to 4145, but the top end is extended up to 20k. X21 (1/2") closer by design to the gefell MK221 with more opened B&K-style grid.

Here are more examples: https://cloud.mail.ru/public/243s/3H8We5Y2j

Does this mean the capsules are interchangeable with other measurement capsules?

For easy change of 1" and 1/2" capsules we made a base with unified thread. Technically all the measurement transducers with nickel membrane are more or less clones of B&K capsules. They differ by a thread pitch, polarization (external or pre-polarized) and some other details that can affect freq response and sound.

Any info on the mic body electronics? Transformers or not? Noise specs, bandwidth, slew rate, THD+noise? Are there thread adaptors to fit Schoeps and AKG 1/2" capsules?

The Josephson C617set takes P48 and provides 200v polarization to the capsule.
Why bother with special power supplies
when you could use the Josephson technique?

Patents?

D.

Secrets! I saw a video on which Dr. Josephson comments that they have a few tricks that they do to reduce noise, which are not able to be reverse engineered. (Hit youtube for reference, I've forgotten which one)

And their body does +48v to 200v too; you can just have a higher fidelity with the power supply. I like the concept, and at their sale price I would demo it, and probably just jump on a pair- looks to be about the price of a pair of gefell capsules by themselves.

But since I'll be recording in living rooms for the foreseeable future, I can't justify omnis number 9+10 to my CFO (wife). I'll be content with my Josephsons, Schoeps, Gefells and mbhos

I have a pair of the 617’s and they sound terrific. Very realistic-like being there.

My brand new C617s are SO lonesome! Sitting in the mic locker all dressed up and nowhere to go. Sad!

If, and if, we wanted to buy a pair, where could we shop? ETA for the PSU and ballpark cost? And. Would the Schoeps conversion get a whole new PCB, much like the Rens mods? So any old Schoeps amp with the proper dock for an Mk(?) head would work for a conversion?

I think I really do want to hear a pair.

D.

To tie it back in, Do the Resolab mics have a standard measurement threads? Or interchangeable capsules?
So if we had other measurement capsules could we use, for instance, 1" Gefell capsules on these?

I like that the Josephson fan club is here. I just pulled mine out to make sure they still existed...

Doug, the Resolab fb page is the font of information (no website yet?) $3200 for a pair, on sale for $2099. Screenshot attached

Thanks. I am not sure I would buy them sight unheard but if our Dan would be interested in sending a pair and a preamp to the USA for a demo, I would be responsible for sending it around and getting it back to the USSR after people have had a chance to listen.

D.

The USSR. Lol.

Ooops, no offense intended. The Russian Federation. My bad!

1991! And me, a history major :(

D.

P100 is not about polarization. It's about getting better resolution and transient dynamics from amplifier circuit. For polarization we have a discrete Dc/Dc converter on board that supplies a capsule with very clean 200VDC, at both P48 or P100. Else no chance to get a good S/N ratio and sensitivity. A lot of time spent to make it work really well since ~ 2013.

Noise optimization was one of main goals. Especially because 1/2" capsules have 14 dB SPL EIN and its capacitance so low, that the parasitic input capacitance of amplifier can produce up to 2 dB attenuation by sensitivity and S/N. To avoid this I used a technique, implemented in B&K measuring microphones - active faraday shield surrounding the whole Hi-Z chains and isolating them from the grounded body. This eliminates the parallel input capacitance virtually to nothing, so we getting the lowest attenuation while working with 1/2" capsule. Not sure if C617 uses this. Gefell M221 does. (below the view on input terminal of Reso Pre (left) where active shield is visible. And C617 input (right) for comparison.

Circuit design was deeply optimized. A lot of low-noise FETs and input stages tested to choose the best one by perceived noise - as the subjective hiss the most important. This is not a hi-tech or something that can't be reverse-engineered. This is rather a very meticulous, careful application of quite old, well-known technologies. )) I attached noise comparison of X41, X21 and Schoeps MK2S. (Euphonics ML530 pre -> Prism ADA8XR)

The amplifier is discrete transformerless, impedance-balanced. The THD is about -90 dB at 0 dBu / 1kHz (1n input source, 3k output load). It could be easily made way better for a picture, but numbers not equal to sound. I came to the achieving of the most natural timbral texture and musicality by using very minimalistic signal path of max quality. Like in tube amplifiers. You can hear it in the examples.

Our microphones designed to be used with 200V-polarization capsules, any adaptors for 60V capsules are hardly possible.

The P100 PSU is designed and tested, but not produced in series yet. If the interest to P48/P100 will grow, we'll be doing it very soon )

The modification of CMC amps can be done on the same board, I believe.

Gefell MK102 capsules not compatible with our threads. Compatible: B&K 1" and 1/2", Gefell 1/2"

USSR This is checkmate. You've got us figured out

I think this is quite possible, especially if there are enough people willing to try it . We are actually thinking on dealership in USA.

BTW Here is the comparison of X21 vs 4006tl. You can assess the noise level as well. Recorded by Peng Huang, Peabody Conservatory, Baltimore.

https://soundcloud.com/reso-labs/set...p-vs-dpa4006tl

24/96 Unprocessed WAV:
https://cloud.mail.ru/public/3B4n/vjuoW8tJd

Not sure about the Josephson design details but noise level is 14 dBA ( vs 15dBA for M221). Sensitivity is 66mV/Pa (vs 50mv/Pa for M221).
and freq. response is 10-20k +/- 1dB (vs 20-20k +/- 2dB for the M221).

What are equivalent specs. for your mic
at P48 and P100?

Thanks,
Bill

The data for Reso mics :

http://reso-labs.ru/reso-x21-41-specs.pdf

Small difference in specs between C617 and M221 is rather formal, as the main part determining noise level and freq curve is literally the same - MK221 capsule.

+-1 dB in noise requires side-by-side comparison. But declared noise for Gefell MK221 is 15 dB. B&K 4165 (this is a reference capsule for IEC standard for all 1/2" capsule) has 14.5 dB thermal noise. And this is the physical limit for this type of capsules.

Hey Dan. Unless this is top secret, would you be willing to show us a picture of the PCB? I only ask because seeing the board would be an indicator to me of "build quality". I have looked at some other mics and was impressed with the sound quality but was not happy with my perceptions of build quality (as a side note, these were pre-production demos and that could all be fixed by now.)

To you all in The Russian Federation, stay well!

D.

Thank you! ) Wish you very well in this unstable time for a whole world!

I can't show everything, but only a part.

Fair enough. Those look very nice.

Okay, how about a package price on two X21s and a 100 volt power supply?

Doug

I've send you a PM, to not misleading people in case of price changing. ))

Thanks for the info.
Any reason the sensitivity is reported at 250Hz rather than the standard 1K?
What is the sensitivity at 1K?

250 Hz is a freq of pressure actuator that used for calibrating and matching of capsules. 1k corresponds to a very close value since the freq graph is nearly ideal in this range.

Nice test!
The comparison sounds like expected from the gap between the spectra of the two tracks exhibiting a peak at 4 kHz in favour of the X21P.

Yes, also 20 Hz HPF was applied on X21 track. (Recording engineer Peng Huang was mentioning this)