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Multi-Way Conventional loudspeakers with crossovers

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Old 4th July 2009, 07:56 AM   #1
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Default please give a hand

I recently bought a pair of woofers and a pair of tweeters to replace my old ones on a hand made pair of 14lt sealed boxes made of 19mm MDF..the woofers are Peerless 830657
http://www.tymphany.com/datasheet/printview.php?id=20

and tweeters are vifa BC25SC06-04
http://www.tymphany.com/datasheet/printview.php?id=220

i tried to cross them at 3.7Khz using two Audax Coils one is 0.34mH and the second is 0.69, and my caps are MKP inox Gold plated 5.6mF and 2.2mF...

The sound is terribly bad..very shallow bass, extremely loud tweeter...
Please suggest me what box should i use for optimal sound using these speakers and materials for my cross.
If i can use the current boxes its ok, if i have to build new, its no problem at all. My current box is about 13,5lt sealed
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Old 4th July 2009, 09:38 AM   #2
bjorno is offline bjorno  Sweden
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Hi Sifis,

This morning I played with an on-line calculator :

http://ccs.exl.info/calc_cr.html#second

Maybe you could pad down the tweeter a little bit more by increasing the serial 1.5 Ohm resistor and recalculate the filter if necessary.

b

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Old 4th July 2009, 10:43 AM   #3
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What about the box?
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Old 4th July 2009, 11:52 AM   #4
bjorno is offline bjorno  Sweden
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Quote:
What about the box?
Hi,

For a sealed application IMO, the SLS driver requires a box volume of Vas to about 2 x VAs.

b
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Old 4th July 2009, 01:03 PM   #5
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that means that i need a Vas=23,1 x 2 = 46,2lt enclosure???!
Woah its way too huge for my needs..any way i can use them in a smaller enclosure?!
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Old 4th July 2009, 01:32 PM   #6
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i downloaded Eminence designer program and made some tests..it seems that a sealed box of 14.24lts should be optimal for high fidelity, but the program suggeste a sealed box of 5.063lts for high output!..now i am confused..can someone please calculate the ideal box as small as possible?..something around 10-15lts must be ok as speaker size but i dont want something huge..
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Old 4th July 2009, 05:55 PM   #7
Ron E is offline Ron E  United States
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Your box is fine, with some stuffing your Qtc is probably around 0.65, which is perfectly acceptable. Focus on the crossover.

3.7k is way too high for that woofer, You will need a zobel and probably a notch filter when taking the woofer above 2kHz, and the tweeter needs ~6-10 dB of padding. The crossover picture by Bjorno has a 2kHz crossover, which is too low for that tweeter - 2.7-3kHz is your sweet spot, or get a woofer that can go higher or a tweeter that can go lower.

You will need some Baffle step compensation, that is best accomplished by making the inductor in the woofer crossover larger, but you really just have learned that it is difficult to make a good sounding speaker without measurement gear.

You can try using SPLTrace and FRC from the FRD consortium to create measurement files from the Manufacturer data - several people have tutorials on how to do this and then use Speaker workshop to design your crossover.
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Old 6th July 2009, 10:21 AM   #8
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Quote:
Originally posted by Ron E
3.7k is way too high for that woofer, You will need a zobel and probably a notch filter when taking the woofer above 2kHz, and the tweeter needs ~6-10 dB of padding. The crossover picture by Bjorno has a 2kHz crossover, which is too low for that tweeter - 2.7-3kHz is your sweet spot, or get a woofer that can go higher or a tweeter that can go lower.
Good points. For a start on BSC, "the Edge" would be great with the front panel dimensions. Those 2 speakers are impossible to mate. Unless working on them 4ever, I would start with a ?kef? xover, 3order on the woofer. The tweeter seems to be very gentle in high frequency though.

sifis_samos post your last xover and thoughts. (this is if you made any change yet?)
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Old 6th July 2009, 10:38 AM   #9
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For the box , I would build a 1/4 wave horn for that woofer . It is pretty normal that you can't pretend big bass from 16 cm diameter drivers. It is easier to add a tweeter in this way because woofer cone movement is more controlled and matches with air surrounding it in a more natural way. Sorry to all the forumers that I apply a less mathematical approach , but my way of thinking -philosophy?- it is not to throw always a driver to a defined volume chamber.
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Old 6th July 2009, 10:45 AM   #10
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Quote:
Originally posted by picowallspeaker
For the box , I would build a 1/4 wave horn for that woofer . It is pretty normal that you can't pretend big bass from 16 cm diameter drivers. It is easier to add a tweeter in this way because woofer cone movement is more controlled and matches with air surrounding it in a more natural way. Sorry to all the forumers that I apply a less mathematical approach , but my way of thinking -philosophy?- it is not to throw always a driver to a defined volume chamber.
From what you say I don't think it would change anything, in the xover band, but adding a new version of the speaker (different box) to the first post and duplicate problems.
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