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Lab horn USB crossover and general advice

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snowflake View Drop Down
Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 11:28pm
it's designed to be used in stacks of six which raises the impedance minimum slightly. most speakers have minimum impedance dips below the nominal impedance. the labhorn impedance is high enough to treat the box as a 4 ohm load for amplifiers in the band of operation 28Hz-100Hz.

that Tom Danley isn't a wally Wink
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gen0me View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2017 at 5:10am
Thats why I pasted imp curve for 4. To lose all doubts. This horn gets even worse than usually. It has second valley so low.
Didnt read it all but impedance in horns just has this valleys. And they are worse than in brs or open air. Its just not true!
I recommend 3 speakers on 2ohm channel.
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snowflake View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2017 at 8:53am
how could a driver possibly have lower impedance loaded in a box than in free air?

as someone who has built and operated labhorns (as well as reading all the design process documentation and the Marshall Leach paper) this is not a real problem. they operate as 4R boxes.
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tv00 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2017 at 9:25am
BPH also has this, a stack of 6 of mine are above 2 ohm impedance from 34-160hz
www.facebook.com/babysoundsystem
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gen0me View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2017 at 6:12pm
Originally posted by snowflake snowflake wrote:

how could a driver possibly have lower impedance loaded in a box than in free air?

Originally posted by gen0me gen0me wrote:




2ยท2.27ohm<5ohm
You can clearly see on documentation (http://www.eminence.com/pdf/LAB_12.pdf) that free air impedance is higher than 5 ohm
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snowflake View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2017 at 8:05pm
well you are comparing apples and pears. simulate the lab12 driver in free air in hornresp and you will see it gives a minimum impedance of 4.33 ohms - less than the 5.26 ohms per driver when loaded on the horn. maybe that graph is wrong, or scale is in dbohms rather than ohms or something


Edited by snowflake - 29 March 2017 at 8:06pm
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gen0me View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2017 at 11:38pm

Right. Looks like they added something in measurements...Ouch
Nice one!Embarrassed
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