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Gear / Technical Help => Microphones & Setup => Topic started by: scb on April 05, 2007, 01:10:06 PM
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http://www.schoeps.de/PDFs/Schoeps-CMD2U.pdf
has this been discussed here yet? i wonder if everyone will eventually go this route....
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Specifications
Microphone amplifier CMD 2U, measured with MK 2S capsule (omnidirectional):
Dynamic range: 115 dB (A-weighted, RMS)*; 103 dB (CCIR, quasi-peak)**
Sample word length: 24 bits
Sampling rates (set internally): 44,1 kHz or 48 kHz, 88,2 kHz, 96 kHz, 172,4 kHz, 192 kHz
Synchronization: none (operating mode = AES 42-2001, Mode 1); multi-channel applications
require inputs with sampling rate conversion
Powering: AES 42-DPP, 10 Volts, 100 mA
Input type required: AES 42 (i.e. AES 3 with AES 42-DPP digital phantom powering) ???
Maximum cable length: for ordinary microphone cable: 100 meters
with 110 Ohm AES-3 cable: > 400 meters
Sensitivity at the standard level of 94 dB SPL: -34.5 dBFS
Maximum SPL: 128 dB :-\
Equivalent noise level: 15 dB (A-weighted, RMS)*
27 dB (CCIR, quasi-peak)**
Output configuration: XLR-3M, AES 3, 110 Ohm characteristic impedance
Dimensions: Length: 116 mm (incl. 3 mm threading for the capsule)
Diameter: 20 mm
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some discussion here:
http://taperssection.com/index.php/topic,75883.0.html (http://taperssection.com/index.php/topic,75883.0.html)
and here:
http://taperssection.com/index.php/topic,40789.0.html (http://taperssection.com/index.php/topic,40789.0.html)
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the Solution D from neumann(also digital) has been getting some praise online too.
I doubt everyone will give up their beloved pres to go that route exclusively though..
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Bump
Any new information or field testing?
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Bump
Any new information or field testing?
Sam - You planning on picking up the CMD xt's :)
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And you know that notion just crossed my mind 8)
Not sure how this all works just yet and how it would interface with the 744.
Bump
Any new information or field testing?
Sam - You planning on picking up the CMD xt's :)
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The Schoeps CMD amplifiers use the same capsules and active accessories as the CMC ("Colette") series, and follow the same AES-42 connection standard as do the Neumann "Solution D" microphones. Thus they can be driven by Neumann's two-channel digital power supply--and since Schoeps doesn't offer a power supply/controller of their own, that's how I'd probably operate for simple stereo recording.
It's unfortunately a little complicated. Each microphone has its own clock, so to synchronize their signals, you have to convert both microphones' sampling rates at the input of the controller. As I understand it this approach was chosen so that ordinary XLR microphone cables could be used for short to moderate distances, but please pardon me if I grumble over that particular tradeoff.
Some years from now I suppose I will inevitably change over, along with lots of other people. But for now I'm not so perfect as an engineer, nor do I often get to record in such perfect circumstances, that I would urgently require the slight improvements in sound quality that such microphones have to offer.
--best regards
Edited over two years later to add: Arrgh. When I posted this message, I apparently misunderstood some things. Schoeps' CMD 2 amplifiers support AES42 Mode 1 operation only. While a Neumann interface can be used to send them digital phantom power, it can't synchronize the signals from a pair of these microphones because it has no sampling rate converters built in. If those are present in the next device down the line (e.g. a recorder such as one from Sound Devices), then the Neumann interface can be used with Schoeps digital microphones, but otherwise not. Sorry for my earlier misstatements.
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+T DSatz
If this involves more devices and batteries in my bag, I will have to pass. I think I have reached the back-breaking point.
The Schoeps CMD amplifiers use the same capsules and active accessories as the CMC ("Colette") series, and follow the same AES-42 connection standard as do the Neumann "Solution D" microphones. Thus they can be driven by Neumann's two-channel digital power supply--and since Schoeps doesn't offer a power supply/controller of their own, that's how I'd probably operate for simple stereo recording.
It's unfortunately a little complicated. Each microphone has its own clock, so to synchronize their signals, you have to convert both microphones' sampling rates at the input of the controller. As I understand it this approach was chosen so that ordinary XLR microphone cables could be used for short to moderate distances, but please pardon me if I grumble over that particular tradeoff.
Some years from now I suppose I will inevitably change over, along with lots of other people. But for now I'm not so perfect as an engineer, nor do I often get to record in such perfect circumstances, that I would urgently require the slight improvements in sound quality that such microphones have to offer.
--best regards
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There is a thread at Gearslutz about the XT's. No one is thrilled with them. Most if not all prefer the normal range caps. 8)
Here is the link to Gearslutz: http://www.gearslutz.com/board/remote-possibilities-acoustic-music-location-recording/140599-schoeps-buying-advice.html
added later: I was just wondering what I would gain by switching to digital other than more debt? What is the advantage???
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boojum, just to be clear--the "xt" is a special variety of CMC 6 amplifier (or CMD); it's not a special variety of capsule. All Colette-series capsules and accessories can be used with the CMC 6xt amplifier, just as with an ordinary CMC 6 or CMD amplifier.
However, ... actually, there are several "howevers."
- Response to "beyond 40 kHz" is available only from capsules such as the MK 2, MK 4 and MK 41 whose main axis is on the short, circular front of the capsule--and even then, only to such capsules that were built in the past ten years or so. Capsules that are "side-addressed" such as the MK 4V, MK 41V, MK 6 and MK 8, and older capsules generally, won't have any significant response beyond their usual range.
- The "xt" amplifier's response has a slight rise in the region below 20 kHz, so if you compare a regular CMC amplifier with a CMC 6xt, it's somewhat apples vs. oranges; it's certainly no test of whether you can hear response above 20 kHz or not--or whether such response is useful and desirable or not, even if you can't hear it--since the response below 20 kHz is different.
To put it another way, the "xt" amplifier is not suitable for proving or disproving the premise on which it was designed.
- The "xt" model was created at the request of specific customers who had a desire for some signal "up there" that was in the same general range of sensitivity as the rest of the microphone's range. But no serious audio engineer (including these customers) believes that humans can actually hear signals that high in frequency in any qualitatively critical sense. Thus the frequency response "up there" doesn't meet the standards which would apply in the main part of the range; in fact the response graphs "up there" are a bit unattractive in my opinion.
- The directional response "up there" doesn't match the directional response of these capsules in the audible range, either. There can be no pressure gradient in a microphone of this size at such short wavelengths; the response is a pressure response conditioned by the dimensions and shape of the capsule. Thus in all the capsules which have this type of response on an "xt" amplifier the polar pattern will be identically narrow.
By the way, that's not a problem unique to Schoeps or any other one manufacturer; it affects all but the teensy-weensiest of microphones.
This probably belongs more in a thread about the "xt" amplifiers, but here it is nonetheless.
--best regards
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the major benefit of the digital mics is they have a much lower noise floor.
this is diminishing returns for the type of audience recording most of us do. standard schoeps with 79 dB of dynamic range are still well below the audience noise floor.
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DS - Gotcha; thanks.
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Very true...however for those onstage moments or quiet venues the extra nectar could be *satisfying :headphones:
*Playback system dependant
the major benefit of the digital mics is they have a much lower noise floor.
this is diminishing returns for the type of audience recording most of us do. standard schoeps with 79 dB of dynamic range are still well below the audience noise floor.
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I am interested in this design which eliminates the external mic preamp and if anyone here can expain it. This direct to digital technology should yield higher fidelity, at least to the limits of PCM. However, I still think DSD will sound better with regular Schoeps analog bodies.
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> the major benefit of the digital mics is they have a much lower noise floor.
?? I don't see that in Schoeps' specifications; rather, I seem to see the opposite.
- CMD 2U with MK 2S: 27 dB equivalent noise (CCIR weighting, quasi-peak)
- CMC 6 with same capsule: 24 dB equivalent noise, same measurement conditions.
The A-weighted numbers are 10 - 12 dB lower as usual (and fairly meaningless as usual).
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> the major benefit of the digital mics is they have a much lower noise floor.
?? I don't see that in Schoeps' specifications; rather, I seem to see the opposite.
The lower noise floor comes from the fact that you do not have to allow headroom in the mic. pre. or in the A/D converter.
Neumann suggest a 25dB improvement in the presentations I have seen.
But AES42 digoital mics are moving forward.
Neumann were the first, Schoeps the second and Sennheiser the third (AES42 module for the MKH 8000 series should be available early next year) - and RME have an 8-channel AES42 interface due at the end of this year.
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John, just as a sanity check do you really believe that the noise floor of (say) a KM 184 can be reduced 25 dB in the digital version of the mike? That would result in a negative value for its equivalent noise specification. It would also imply that the circuitry of the analog KM 184 is contributing a very large amount of unnecessary self-noise, and I simply don't believe that that is true.
--best regards
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That would result in a negative value for its equivalent noise specification.
Actually, negative self noise is not impossible, there are a few very special mics with that. Makes sense when 0dB is defined as a specific sound level, below that and you get negative levels.
http://www.bksv.com/3103.asp?Types=:4179:
I cannot believe that the KM184 can be diminished 25 dB.
G.