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Multi-Way Conventional loudspeakers with crossovers

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Old 14th October 2004, 04:57 PM   #1
Baronty is offline Baronty  United Kingdom
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Default First Build (3way)

*deep breath* here goes:

im about to finnaly get my *** in to gear on build a pair of 3way floors standers.

The drivers in have in mind are

Woofer - Peerless 831857 12"
Mid - Seas H143 MCA11FC 4.5"
tweeter - peerless 831830 soft fabic dome

im looking to cross them at 500Hz and 2KHz

Using Winisd the woofer will be in a 280l vented cab with a 10cm dia port 10cm lond tuned to 22Hz. This gives nice low bass extention.

The mid will be in a separte 17L closed enclosure.
The Tweeter will also be isolated (possibly pod mounted if i can manage it)


Now for the fun part - Xover.

I am looking to use a parallel 2nd order 12dB/octave Linkwitz Riley xover. With an impedance / zobels network on the woofer.


This is where i am having difficulty - i have calculated the values using the equations in Weems and subsequently using an online calculator and have managed to get different values.

Could someone have a look and see whats going on???
these are based only on book values as i dont have the drivers or means to test at the moment. The caps and resistors also represent the values required not values of actual resistors/caps that will be used to make the values necessary.
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Old 14th October 2004, 05:02 PM   #2
Baronty is offline Baronty  United Kingdom
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Top online calculated values

bottom my values for xover ( calculated from weems)


Note for some reason i cant get a descent size image up - but if you save thet one then open it it seems to work.

- so how dumb and i on a scale of 1 - 10 (1 = einstein 10 = Bush)
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Old 14th October 2004, 06:12 PM   #3
Baronty is offline Baronty  United Kingdom
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ignore me ignore me - please subsitute resistor in above posts for inductor and ignore the schematic. I'll drink some more coffer and repost it
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Old 14th October 2004, 06:29 PM   #4
Baronty is offline Baronty  United Kingdom
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right

this time the should

a) make more sense (what with having indutors instead of resistors )

b) should be readable
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File Type: gif xovers design.gif (26.9 KB, 301 views)
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Old 14th October 2004, 09:37 PM   #5
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Just by giving it a quick look, I would say your calculated values look more like it. The other values seem too low for the frequencies you state. On another note, I would recommend a higher crossover frequency for the mid to tweeter crossover. 2Khz puts the crossover point right in the middle of the ears most sensitive point. Raising it above 4kHz will give you a great midrange, with the 1 midrange driver covering the most critical range.
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Old 14th October 2004, 09:54 PM   #6
gary f is offline gary f  Canada
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I agree with Hornlover, cross the tweeter at least above 3000hz is a better idea IMO
F
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Old 14th October 2004, 10:20 PM   #7
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I am assuming that you dont have a problem with huge speakers but here are my few coins worth.

Right instead of the 851837 use the 850146.

This is the 10" CSX driver. Put it in a 65 litre box tuned to about 22hz. This will give you an F3 of about 30hz, in a real room probably flat to 20hz. Port wize depending on your box, 7cm diameter 30cm long or 8cm dia 40cm long. Both of these keep windspeeds acceptable, but id use the 8cm over the 7.

Then either use the peerless HDS 850488 or the SEAS CA15RLY as a midrange in a sealed box.

Swap the peerless tweeter for the SEAS 27TFFC.

This may sound like a lot of difference but should have almost the same bass reach as the one you suggested and will probably sound better then the drivers you originally posted about plus it costs less and is lots smaller. Two 300 litre boxes are HUGE! in any room. Assuming internal height of 110cm and an internal width of 30cm you speakers will be 90cm deep internally. This doesnt include the mids enclosure either. Think what two of these in your room will look like.

If you dont have measuring software using a mid/bass as a midrange driver should give you more predictable results because the impedance peak due to resonance will be lots lower and therefore less of a problem.

The SEAS 27TFFC is one of the best tweeters around for the price.

Edit, xovers around 300hz and 3000hz. give or take depeding on your personal preference.
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