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Lab horn USB crossover and general advice

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Kieranearth View Drop Down
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    Posted: 26 March 2017 at 2:01pm
Right I've just prurchased 5 lab horns(eminiamce lab loaded), 2 USBs with celestion Ftr's, and a turbo tms4. I've got a couple questions. Basically at the moment I want to use 4 labs one USB and get some different tops to go on top (recommendations would be handy), so am I right thinkikg that I should cross the labs from 30-80 and the USBs 80-180) or the drop from the tops. I'm also not sure how the impudence would work, they are 6oms drivers wired in parallel so that's 3ohms a cab and could wire them in series parallel to an amp to get a 3ohms load 2 cabs a channel. Is that correct? And will most amps run 3ohms? Should probably add that I'm probably going to get 8 or 12 labs in total to sit under the 2 USBs, what would be good for the top end?
Thanks

Edited by Kieranearth - 26 March 2017 at 2:02pm
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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: 26 March 2017 at 7:12pm
tms4 doesn't need subs and kicks below it. forget about the USBs.

labs are designed to be a four ohm box - impedance is greater than the dc resistance.
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Mark James View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2017 at 10:54pm
series parralel would be 6 ohm load not taking into account what the horn may add.
so youd have between 6<8 ohms if you series parralel 2 cabs [4 drivers series parralel]
30-80 labs and 80-180 with the usb would be about right I should think.....
if your going to ha ve 8 labs you will need more than 2 usb i would think
as for tops..... flood light ? seems a combo people have been using a fair bit.....

If you want people to feel the bass then a reflex design is probably best as you get the most air movement per decibel from those.      errrrr yes wtf?
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Kieranearth View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kieranearth Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2017 at 11:14pm
yes the tms4 are full range but I am going to get some dedicated tops to match the power of the bottom end. The USBs are 2000rms a cab so I don't think I'll need more, and on the tops I was thinking xtro's
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Kieranearth View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kieranearth Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2017 at 11:17pm
What do you mean labs are designed to be a 4 ohm box? How could this be when the drivers are 6ohm and there are two In the cab?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 12:08am
Nominal impedance of a driver in free air is not the same as that driver loaded in a box. It's also a curve that varies with frequency not a fixed number. You should ideally measure the impedance plot of a loaded box. It isn't hard to do with REW and a resistor there's a guide here even
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Kieranearth View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kieranearth Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 12:35am
I understand that the impemdence will be different loaded into the box, I don't quite understand what you mean there working out the Impendance plot but if you could link me to the post I'd appriecate that and can then educate myself. Been looked for the specs of the cabs loaded on ProSoundWeb but I just can't seem to find any.
Thanks for your advice,

Edited by Kieranearth - 27 March 2017 at 12:36am
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toastyghost View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 12:49am
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Kieranearth View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kieranearth Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 2:53am
Thanks mate I apreachate that, I'll have to look into it all when I've got a bit of time.
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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 1:11pm
"What do you mean labs are designed to be a 4 ohm box?"

literally that. the lab horn was designed by Tom Danley with input from people at ProSoundWeb. They wanted a 4ohm nominal impedance box, the horn and driver paramaters (including Re) were then calculated to give a 4 ohm box, and then Eminence were asked to produce a driver with those specs.

Re is not the same as impedance whether driver is in a box or not.

http://leachlegacy.ece.gatech.edu/papers/HornPaper/HornPaper.pdf
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Kieranearth View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kieranearth Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2017 at 6:46pm
Thanks i didn't realise the cab could make such a difference in resistance but I've saved that paper thanks.
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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: 27 March 2017 at 8:49pm
Sorry to disappoint you.

Thats from above page simulation.
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