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1850 horn measured plots

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Rog View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rog Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2009 at 5:23am
You place the speaker on the ground and then place the mic 2 meters away from the front of the speaker pointing at it. The mic must be on the ground with the capsule touching the ground. If you then feed the speaker 2.83 volts (presuming its an 8 ohm load) you will get a 1w/1m reading.
 
The mic must be at 2 meters as you gain 6dB from halfspace loading, but lose this 6dB by the mic being double the distance away from the speaker.
 
It dosen't take much of a distance to effect the reading if the mic is rasied of the floor, even at LF. The mic in some the the pics from the 1850 horn measurements looks like its about 1 meter from the floor, which would still effect the reading.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pfly Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2009 at 7:06am
The point wasn't being really scientific, but to test out the equipment (1850s and the measuring software) I wanted to see how different ways of stacking affects the response.
As I said we didn't drive them hard. Amp was bridged because it was wired that way already.

Thanks for the info though, we'll try to be more accurate next time Thumbs Up


Edited by pfly - 11 May 2009 at 7:07am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pfly Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2009 at 7:26am
Rog

Would that 60-70hz dip be there because of some cancellation stuff going on between the ground and the mike?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jake_Fielder Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2009 at 12:17am

If the height of the mic makes so much difference, wouldnt it be more usefull to have it the same height off the ground as an average persons height??

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2009 at 5:37am
Read back Jake.. the mic is on the ground so that its loading conditions are the same throughout the frequency spectrum.  If were at a given height, it would couple with the floor up to a given frequency, but not above that frequency.  The idea is to take a groundplane (halfspace) reading.
That's the way I got it anyway.
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schiller View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote schiller Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2009 at 7:31pm

I just saw your plots , thanks a lot for sharing your efforts with us. Really a pity you didn't put that mic on the ground, but i believe the difference under 100 Hz wouldn't be much-if any.

This is the only 1850 measurement available in the universe :-)  

What i see from the plot, is that in case of a single horn per side and in a room (yes there are people using this designs for hi-fi)  bass from 50 Hz will be awesome. Maybe the 186 can better this, because of higher Qes driver, which loads better down low. 

Does the peak at cutoff indicate a smaller than needed back chamber, a larger throat or both??

Thanks again,

greetings from Athens (Greece)

Konstantinos

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vaso_Bobinata Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2018 at 11:59pm
Only ifi could see that graph the links are broken.


Thanks
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