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Re: more md comparisons

Subject: Re: more md comparisons
From: Dan Dugan <>
Date: Thu, 27 Jan 2005 21:40:45 -0800
Rich Peet wrote:

>Mic is a Senn ME-62.
>Pre a RME Quadmic
>A/D and Mixer a RME Multiface
>
>Signals sent to two Sony Minidiscs recorders.
>Minidisc #1 was analog line input MZR-55.
>Minidisc #2 was spdif input MZR-90.
>Then both were output through the same Minidisc at line level out into
>Multiface and recorded with the laptop using Audition. Then mixed to
>one stereo file with each machine having a channel. Levels were
>equalized between the two channels.
>Results show essentially the same results also by ear the results were
>about the same.
>This leads me to believe that maybe the spdif input still goes through
>the same a/d conversion as a line level input to a Minidisc.

I wouldn't be surprised that one good audio path sounds like another.
An S/PDIF input certainly doesn't get a/d converted again!

>Next I inputted the ME-62 into the Quadmic and Multiface and recorded
>to one Minidisc by SPDIF and direct to the laptop at 16/44.1. Each
>were given a channel in one stereo track and levels were equalized
>between the two.

I'm sorry I don't understand this patch.

>Of course there was some difference at 17,000 and above as well as 50
>and below.  So to be fair I resampled to 11,050 khz so that the sound
>would be closer to the same.

Just a low-pass filter would have been sufficient.

>Results were not the same.
>The left channel is the laptop and the right the MD.  As you can hear
>my house is not as quiet today as Robs was.
>During the first half of the recording there was a range fan on 25
>feet away in another room that I walked over and turned off.
>You can also hear a compressor running in the very distant basement
>that shows itself as the 60 cycle hum with harmonics above.
>
>Ok, I won't be yelling down the street artifact because I don't have a
>MD with digital output.  But note how the image of the clock moves
>from the right to the left sides during this recording. What I find
>strange is that the right side is the MD.  Looking at the numbers and
>graphs they are very close.  So I have a real hard time figuring out
>why the MD channel would sound louder during this distant fan (white
>noise) event.  Coloration or artifact?

Sounds like a delay pan to me. The result of significantly different
sample rates on L & R?

-Dan Dugan


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