[dprimary]

   
If you're recording something with a stereo pair of microphones, then, if those microphones aren't exactly matched in terms of frequency response, distortion, and phase, the image is going to "pull" to the left or right. Since any product, including microphones, is going to vary over time and production runs, if you want two microphones to be identical in all these characteristics, then they're going to need to be matched (and it most certainly won't hurt anything). Even if you had two microphones that were flat to a fraction of a dB (which would be pretty rare), if one has a peak where the other has a dip, they're not going to image perfectly. (Even if you buy two with sequential serial numbers, which many people seem to consider important, they could be made with the last capsule produced from "batch 11" and the first from "batch 12", which could be made with some slightly different part, or some production run change, or one could have had a part replaced during production testing which could be slightly different, so it does make sense to buy two that are actually matched.)
 
Now, if you're going to do full milti-tracking, where you aren't going to use a pair of stereo mics in stereo anyway, then it shouldn't matter nearly as much.At that point, it's simply a matter of consistency. However, as someone doing recording, even just being able to assume that two of your microphones that are supposedly the same really sound identical without having to confirm it or adjust anything would still make life easier.

Pulling a calibration file for one of my earthworks measurement microphones if only varies +- .2 dB out to 30kHz.
I know one that we just had checked  was off a few dB starting around 26kHz but it has dropped a few times, I let the butterfingers techs keep using that one.
 
I don't think earthworks can meet the temperature rating of a type 1 microphone.
 
BK's have even better specs and stability but you have add a zero to the price.

 

[bigshot]

When I record, I usually use Neumann U87s. They are VERY consistent, but I would imagine that the companies that provide them keep close watch on them to make sure they keep in calibration.

 

[dprimary]

  Would it be better to use a 1kHz test tone or pink or white noise in SPL matching? My intuition tells me pink is the best bet.

Test tones. A sweep would be best, but good luck getting the response the same. Pink noise is random the level varies some as well. When you slow the averaging down far enough to average the variations out you are taking a few minutes.

 

[dprimary]

  When I record, I usually use Neumann U87s. They are VERY consistent, but I would imagine that the companies that provide them keep close watch on them to make sure they keep in calibration.

For U87's I would want a matched pair. They have been making them for something like 30 years at least. Two random ones could very a large amount. 

 

[Steve Eddy]

I thought it has to have oil around the copper to make a difference? :confused_face_2:

(I couldn't resist :atsmile: )

se

 

[sonitus mirus]

  How would I go about connecting a laptop to an outboard DAC that only takes Coaxial, XLR and optical without any loss in fidelity?

 
I think you are looking for a USB to Coaxial converter.
 
Something like this product: http://www.amazon.com/Signstek-Coaxial-Converter-Decoder-Analogue/dp/B00FEDHHKE
 
There are versions that can convert 24-bit/96kHz.
 
I was looking to eliminate a nasty ground loop with my powered speakers, and I opted for cheap solution that worked out great for me.  I use a chromebook to stream music and output with USB to a Peavey DI box with XLR outputs.  The DAC specs are not wonderful, but it gets the job done.  Again, there are similar products that measure better. 
 
If you are looking to connect to an amplifier with XLR inputs, you could go the DI box route.  This is what I am using: http://www.amazon.com/Peavey-USBP-USB-Audio-Interface/dp/B004A4PSEU

 

[uchihaitachi]

   
I think you are looking for a USB to Coaxial converter.
 
Something like this product: http://www.amazon.com/Signstek-Coaxial-Converter-Decoder-Analogue/dp/B00FEDHHKE
 
There are versions that can convert 24-bit/96kHz.
 
I was looking to eliminate a nasty ground loop with my powered speakers, and I opted for cheap solution that worked out great for me.  I use a chromebook to stream music and output with USB to a Peavey DI box with XLR outputs.  The DAC specs are not wonderful, but it gets the job done.  Again, there are similar products that measure better. 
 
If you are looking to connect to an amplifier with XLR inputs, you could go the DI box route.  This is what I am using: http://www.amazon.com/Peavey-USBP-USB-Audio-Interface/dp/B004A4PSEU

Thanks for the response.
 
Basically, I managed to get hold of a Benchmark DAC1 (classic the one without USB) at a crazy low price.
 
So I am trying to figure out a way to get my laptop to have a coaxial output. I would like an option that wouldn't damage fidelity in anyway. Would be grateful for further feedback!

 

[sonitus mirus]

  Thanks for the response.
 
Basically, I managed to get hold of a Benchmark DAC1 (classic the one without USB) at a crazy low price.
 
So I am trying to figure out a way to get my laptop to have a coaxial output. I would like an option that wouldn't damage fidelity in anyway. Would be grateful for further feedback!

 
This will do the trick for $14.  
 
http://www.amazon.com/Syba-External-Adapter-Optical-SD-AUD20101/dp/B006SF68P2
 
One of the reviewers was specifically using this product to do exactly what you are trying to accomplish.
 
http://www.amazon.com/gp/customer-reviews/R3BB4BZHSZVFXT/ref=cm_cr_pr_rvw_ttl?ie=UTF8&ASIN=B006SF68P2

 

[uchihaitachi]

   
This will do the trick for $14.  
 
http://www.amazon.com/Syba-External-Adapter-Optical-SD-AUD20101/dp/B006SF68P2
 
One of the reviewers was specifically using this product to do exactly what you are trying to accomplish.
 
http://www.amazon.com/gp/customer-reviews/R3BB4BZHSZVFXT/ref=cm_cr_pr_rvw_ttl?ie=UTF8&ASIN=B006SF68P2

Slight problem, I will need it to support 192khz (I know there is no sound difference), but I wanted it to run some tests!
 
Also, am I correct in thinking that a USB to Coaxial output is strictly digital, and therefore unless the product is completely faulty, there shouldn't be any degradation in the fidelity?

 

[StanD]

  Slight problem, I will need it to support 192khz (I know there is no sound difference), but I wanted it to run some tests!
 
Also, am I correct in thinking that a USB to Coaxial output is strictly digital, and therefore unless the product is completely faulty, there shouldn't be any degradation in the fidelity?

Yes it is digital. If end up with a ground loop, optical can solve that.
Another option, I got one of these last year:
NuForce U192S Asynchronous USB to SPDIF Converter

1. USB 2.0 audio to S/PDIF converter
2. Coaxial S/PDIF output and Optical TOSLINK output
3. 16 or 24 bit resolution
4. 44.1, 48, 96, 176.4, and 192 kHz sampling rates supported
5. USB-powered; no external power supply required

 

[uchihaitachi]

Yes it is digital. If end up with a ground loop, optical can solve that.
Another option, I got one of these last year:
NuForce U192S Asynchronous USB to SPDIF Converter

1. [COLOR=111111]USB 2.0 audio to S/PDIF converter

1. [COLOR=111111]Coaxial S/PDIF output and Optical TOSLINK output[/COLOR]
   
2. [COLOR=111111]16 or 24 bit resolution[/COLOR]
   
3. [COLOR=111111]44.1, 48, 96, 176.4, and 192 kHz sampling rates supported[/COLOR]
   
4. [COLOR=111111]USB-powered; no external power supply required[/COLOR]
   

[/color]

Could you possibly explain what you mean by it's ground loop and optical can solve that?

I presume the other USB to Coaxial output that is selling for crazy amounts is purely snakeoil?

 

[MacacoDoSom]

-sorry wrong post!

 

[dprimary]

  It is "questionable" what linear is. For high frequencies, it will mean SMALL diameter diaphragm - or else polar pattern will be anything but good - more important than a few dB off on axis in real life. 
 
Microphone measurements are the most tedious and expensive. TBH - only manufacturers - and their agents (in case of Bruel & Kjaer/DPA ) are truly qualified to measure them. In the whole history of the home audio press, there was 1 ( in a word : one ) comparative review of microphones published in England - early 80s IIRC. 
And that one review blew the budget of the magazine for all measurements for one year... - no wonder there were (next to ?) none repetitions I am aware of.
 
Earthworks are supposed to be very linear - I would not mind owning a pair. Or Bruel & Kjaer/DPA 4006/4003 - or ...
 
With microphones , it will never be ABX thing to be decisive - place/orient it a bit different, the tables will turn. What counts is how well one can use the tools - provided both tools are about equally matched in various qualities. 
 
It is also NOT desirable for microphones meant for recording from greater distance to be linear - because linear mic from great distance produces VERY DULL recording. That is why Sanken mic has its response lifted above approx 10 kHz - and no matter how strange this looks to a "flat or nothing" guy, it IS proven in practice.
By judicious use of frequency response and polar pattern, it is possible to use Sanken mic in many ways - producing the desired effect. Which would be both unnatural and impossible with completely neutral flat response mic.

I have always A-B'd microphones in recording to select which will work best, then make finer adjustments on the ones I select. Often I am surprised at the ones I chose. I few times I ended with ones I would have never picked. But in that certain room they worked really well. 
 
Some recording microphones have a boost starting around 10kHz. above 8kHz the sound pressure losses can start to be a problem even in a small concert hall. 22C air at 15% RH has a 1dB loss at only 4kHz at 10 meters.  4k is .105 dB/m 20k is .333 dB/m 30k is close to a half a dB per meter at .450 dB/m. At 10k with microphones only 10 meters away you are already down 2.5dB and 3.3dB at 20kHz. This does not count the reduced reverb time in the higher frequencies.

 

[dprimary]

  Thanks for the response.
 
Basically, I managed to get hold of a Benchmark DAC1 (classic the one without USB) at a crazy low price.
 
So I am trying to figure out a way to get my laptop to have a coaxial output. I would like an option that wouldn't damage fidelity in anyway. Would be grateful for further feedback!

Here is a list of them
 
http://www.thewelltemperedcomputer.com/HW/USB_SPDIF.htm

 

[uchihaitachi]

Here is a list of them

http://www.thewelltemperedcomputer.com/HW/USB_SPDIF.htm

Sadly not many reviews and even less specifications. Any advice on making an educated choice?