Mics straight to ADC - no preamp
Old 19th February 2013
  #1
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Mics straight to ADC - no preamp

Here's a lovely piece by Ennio Morricone from his The Mission movie soundtrack that I just recorded in live concert with a pair of Josephson C617Set mics with 40mm spherical baffles on a Schneider disc.

Mics went straight into a Benchmark ADC1; there was no mic preamp. Phantom power was supplied by a Denecke PS-2.

No reverb added - the sound is 100% natural. MP3 reduces the organ's low end, but the rest survives well enough.

Click here for a CD audio WAV version.
.
Attached Files
Gabriel's Oboe.mp3 (5.72 MB, 306 views)
Old 19th February 2013
  #2
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Very nice sound. Are the C617's that hot? How many mV/p do they output? I've only been able to do this with a DPA 4041, which doesn't even need a preamp with 100mV/p of output.
Old 19th February 2013
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Originally Posted by tenor39 View Post
Very nice sound. Are the C617's that hot? How many mV/p do they output? I've only been able to do this with a DPA 4041, which doesn't even need a preamp with 100mV/p of output.
66 mV/Pa (-24 dB ref 1V/Pa)

I have to admit cheating a little as the Benchmark ADC has some line-level gain. I boosted by about 20dB.

I thought this worth posting because it's an interesting setup that I've never tried before. It also helps that the music is beautiful.
Old 19th February 2013
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Isn't there an impedance mismatch between the low imp. Mic and the high imp. Line input?
Old 19th February 2013
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Originally Posted by king2070lplaya View Post
Isn't there an impedance mismatch between the low imp. Mic and the high imp. Line input?
It's quite common to terminate lower impedance sources into a high impedance input. A principle of modern balanced circuit design is to let source devices operate without loading, drawing little current from them.
Old 19th February 2013
  #6
The bass on those 617's always give me goosebumps. I love it.

I remember not having to use very much gain at all on these mics, about 20db sounds about right. The spheres seem to add a perfect amount of high frequency boost.
Old 19th February 2013
  #7
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Quote:
Originally Posted by MichaelPatrick View Post
Here's a lovely piece by Ennio Morricone from his The Mission movie soundtrack I just recorded in live concert with a pair of Josephson C617Set mics with 40mm spherical baffles on a Schneider disc.

Mics went straight into a Benchmark ADC1; there was no mic preamp. Phantom power was supplied by a Denecke PS-2.

No reverb was added - the sound is 100% natural. MP3 reduces the weight of the organ's low end, but the rest survives well enough.
I love it. Excuse my ignorance but what would be the difference between adding gain on the ADC and using a mic pre? Is the advantage a purer signal due to less electronics?
Old 19th February 2013
  #8
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Originally Posted by shosty View Post
I love it. Excuse my ignorance but what would be the difference between adding gain on the ADC and using a mic pre?
Good question. There may be little difference.

Having said that, I imagine fewer devices might help make the sound truer to the original. It's nice to hear good microphones like these with little coloration.
Old 19th February 2013
  #9
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Quote:
Originally Posted by MichaelPatrick View Post
Good question. There may be little difference.

Having said that, I imagine fewer devices might help make the sound truer to the original. It's nice to hear good microphones like these with little coloration.
Makes sense. Whatever the reason, the poof is in the pudding. It sounds great.
Old 20th February 2013
  #10
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Quote:
Originally Posted by MichaelPatrick View Post
Here's a lovely piece by Ennio Morricone from his The Mission movie soundtrack that I just recorded in live concert with a pair of Josephson C617Set mics with 40mm spherical baffles on a Schneider disc.

Mics went straight into a Benchmark ADC1; there was no mic preamp. Phantom power was supplied by a Denecke PS-2.

No reverb added - the sound is 100% natural. MP3 reduces the organ's low end, but the rest survives well enough.
Very clear and smooth sound. Love the evenness of this recording (listening on monitoring that goes to 15 Hz).

Just a question about the impressive output level of those mics: Do you find it a problem with louder source material? Some of my mics must be padded down pretty heavily at times to not distort the input stage of some preamps (KM140 on loud guitar amp come to mind).
Old 20th February 2013
  #11
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Mats,

The high output hasn't been a problem with loud material as long as the mic preamp has minimum gain of 3dB to 6dB or so. Preamps that start above that are a problem when SPLs are high.

There's a WAV CD audio version here for those who want to hear the organ lows more clearly.
Old 20th February 2013
  #12
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Sounds Great's Avatar
 

Quote:
Originally Posted by MichaelPatrick View Post
There's a WAV CD audio version here for those who want to hear the organ lows more clearly.
Listening on my M50's. That is really beautiful. What a wonderful room, the recording sounds like you're there!
Old 20th February 2013
  #13
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boojum's Avatar
MP - Just lovely. Good room, good mics in the right place and good instrument well played. The sound is grand.
Old 21st February 2013
  #14
This could explain why my Josephson C700A sounds pretty darn good with a non-specialist type of mic preamp -- whatever Sound Devices packs into a USBPre 2.

I believe the 617 and C700 share identical innards, in terms of the internal mic amp that fits into the mic body (but I could be wrong).
Old 23rd February 2013
  #15
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Quote:
Originally Posted by MichaelPatrick View Post
It's quite common to terminate lower impedance sources into a high impedance input. A principle of modern balanced circuit design is to let source devices operate without loading, drawing little current from them.
Yes, and that goes for analog unbalanced signal transmission as well.


/Peter
Old 23rd February 2013
  #16
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Quote:
Originally Posted by MichaelPatrick View Post
MP3 reduces the organ's low end, but the rest survives well enough.
Very nice recording !
I could not hear any LF loss in the mp3 and would not commit in distinguishing the wav and the mp3 320 in blind test. Spectral analysis confirmed that the LF end is not affected by mp3 compression.
Old 23rd February 2013
  #17
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Originally Posted by didier.brest View Post
Very nice recording !
I could not hear any LF loss in the mp3 and would not commit in distinguishing the wav and the mp3 320 in blind test. Spectral analysis confirmed that the LF end is not affected by mp3 compression.
Didier,

That's good to hear because I flatly distrust MP3 to maintain spectral balance and phase. Images get blurred in the sound stage and LFs are sacrificed but, in this case, the kind of music played seems to make it of little effect in the end.
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