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passive crossover

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godge View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godge Quote  Post ReplyReply Direct Link To This Post Topic: passive crossover
    Posted: 10 February 2016 at 10:20am
Ok so this isn't PA its a hifi build but I haven't got the greatest idea on passive crossover builds.

Here's some info on my build specs.

6.5inch driver - B&C 6ndl38

Fountek Ribbon NeoPRO 5i ribbon tweeter.

Box dimensions 380 (h) 220 (w) 300 (d)

It's a rear ported design, Looking at having the 6.5inch tuned down to about 45hz with the box design. The ribbon will be crossing over at the recommended frequency of 1500hz with a 18db slope, and thats about as far as I've got, I don't have any real idea on the building of the crossover to achieve this.

Any help would be greatly appreciated
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote all bass Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 9:18pm
There are some crossover calculators on the net, they should get you in the ball park. After that, it's a lot of measuring and tweaking.

Calculator, in German though...
https://www.instagram.com/my_modular_journey/
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godge View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godge Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 9:28pm
My main worry is that I don't want to ruin the ribbon tweeter accidentally but hopefully the calculator will put me in good stead. Been a while since I've done a build but looking forward to it again
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Steve20131 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steve20131 Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 9:33pm
Use an old speaker to test first
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 9:39pm
I would use a 1.5Khz 18dB Butterworth design assuming a 7Ω impedance and you should be fine (for the ribbon).

The B&C will probably require a notch filter at 4.2Khz, in addition to the 1.5Khz crossover.

I don't think the 72hz Fs will like being tuned to 45hz very well.


djk
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godge View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godge Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 10:30pm
How low do you reckon I would be able to achieve with port tuning etc
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Andy Kos View Drop Down
Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andy Kos Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 10:50pm
Crossover calc to get you in the right region:

http://www.speakerwizard.co.uk/1st-and-2nd-order-crossover-calculator-and-response-simulator/

plots frequency response too.


If you need help with any components drop me a PM

just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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godge View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godge Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2016 at 11:12pm
Cheers Andy I'll keep you in mind when looking for components. Already got the b&c drivers from you a while back
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stevie Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2016 at 10:51am
Somebody needs to warn you that it is impossible to design a decent passive crossover without a lot of knowledge and experience. You will also need proper measuring equipment - otherwise you're working completely in the dark. If you're just going to mess about for fun, fair enough. But the idea that you can design a crossover using an online calculator is ridiculous.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2016 at 11:27am
put a zobel on the woofer and an l-pad on the tweeter and you can assume fairly constant impedance to design the crossover. 4.5kHz is way above the tweeter resonance so you could cross a bit lower so the rising response of the woofer isn't such an issue. getting a notch filter right without measurement is tricky - unless the response is terrible you could just correct it with a bit of eq - most rooms and source material will need eq anyway.

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stevie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stevie Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2016 at 11:51am
This is a sure way of making £600 worth of drive units sound like garbage. Seriously - get a miniDSP and another power amp and go active.
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godge View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote godge Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2016 at 11:55am
I have though about going active the more I look into this, passive crossover seems like far too much work and research, but then it is also such a hassle having a separate dsp etc, ultimately I do want a nice sounding pair of bookshelf speakers that I can just run off my amp at home
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