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In the Forum: Audio Discussions
In the Thread: Simpson Microphones thread.
Post Subject: Absolute polarity?Posted by Andy Simpson on: 9/19/2008
Hi Collin,

 CO wrote:
Hello Andy,

I like your recordings although i am listening on headphones which i normally do not use. My Main setup is not operational right now.
They do sound clean, clear and dynamic.


If you get your main setup operational, please post your impressions and perhaps we will see differences. I would generally consider the headphone as a direct-radiator, so if your main setup is horn you should hear greater performance there.


Can you let us hear a recording of the live vs playback? This would be very interesting i think. How educated are these people sound wise that they cannot tell the real from playback? I'm also curios as to what kind of horns you are using to fool them.


Next time I have the chance I'll try to remember to make a recording of the recording. I have done similar things on occasion, simply to illustrate that there is no fundamental loss in perceived resolution where acoustic impedance is maintained.

With regards to my testing, I use a pair of Mackie SRM450 speakers, which are portable, reliable and designed for 'flat' frequency response (not tuned to taste). They sound horrible with conventional recordings.

For choirs, orchestras & large sources, the speakers are located either side of the source/stage, so that the approximate height of the speaker is similar to the height of the source.

There are occasions where the 130dB @ 1m is not enough headroom (large room + loud orchestra), but for less extreme sources these are not too bad.

I also use these in the workshop or outdoor and they are more effective on smaller sources.

For example, piano, voice, guitar, drums, tambourine, etc will usually sit between the speakers and the comparison will be made with the speaker-height approximately the same as the height of the source. This kind of test has the best success rate.

In the workshop, the listening subjects tend to be anybody who happens to be around at the time - friends, family, musicians, engineers, etc.

On location, the tests are far less comprehensive and the subjects are anybody who is not playing at the time.


Also what distances are you using for mics to source ? are they right in front of the people that undergo the test ?
Are the musicians completely quiet before the jury is seated and blindfolded not to give away the reverberation of the venue?


Usually the microphone pair is setup where the subjects are seated or close by, so that the distance is similar. In the case of the location testing, this is rarely so formal as to require total silence between stimuli, and is not so critical as you might think in the larger venues.


It seems like my VLC player is reversing the polarity incorrectly. It sounds more spacious and less in your face, less harsh when i reverse the polarity on this player.
On two other players it sounds better in the regular position (these can not be flipped though)
Never tested it on headphones and did not know it was so apparent.. Perhaps because of the flat phase resp of the ribbon mics that it is so obvious ?


I have not listened to the recordings with reversed polarity - I will try it when I have the time.

I would expect that if you are sensitive to exact polarity, the improved mechanical performance would most likely make this more obvious, but since the sources in question are not particularly asymetrical (unlike the trumpet/trombone/etc), I would not expect a drastic difference in perception.

Also, the Model A is not a ribbon mic.


Do you always respect absolute polarity?


By design yes, but consciously in a recording situation no. I assume that polarity is maintained without checking!

Andy

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