Help with crossover design for 18" PA Cabinets - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st May 2005, 04:09 AM   #1
diyAudio Member
 
Join Date: Apr 2005
Location: providence, ri
Default Help with crossover design for 18" PA Cabinets

I'm thinking of making a pair of 3-way cabinets for mobile dj'ing.

The drivers I'm considering (on a budget) are as follows:

Eminence Sigma PRO-18A 18" Cast Frame Driver

http://www.partsexpress.com/pe/pshow...90-427&scqty=1

Eminence Beta-8A 8" Midrange Driver

http://www.partsexpress.com/pe/pshow...90-404&scqty=1

Eminence ASD1001S 1" Compression Driver

http://www.partsexpress.com/pe/pshow...90-525&scqty=1

They will be powered by a QSC 2450 Amp: 500w RMS x 2 into 8 ohms

In photoshop I overlayed the frequency response curves as you'll see in the posted image (sorry about the crappy resolution, best I could do grabbing graphs off the web).

I'm pretty sure these drivers should work well together, please let me know if you think otherwise. I'm sure I could do better with more expensive components, but I'm on a budget.

Do you guys see any problem with these components being used to gether?

Assuming the components work ok together, I really need help designing the crossover. I suppose I could use a premade one from parts express, but I'm worried that they won't level out the sensitivities well.

Would one (or more) of you be so kind as to recommend a design? Assume I know next to nothing about how to design a crossover...but I DO know how to read a basic schematic, and I'm pretty slick with a soldering iron.

Obviously I need the crossover design to not only attenuate at the correct frequencies, but also to level out the sensitivities (as you'll see from the graph the sensitivities of the drivers vary substantially).

It would be super extra nifty if you could also include the exact names of the components, and out of this world spectacular if you could also provide the Parts Express part numbers.

I realize this is no small task, and I would GREATLY appreciate the help. In return, if you need any graphics work done I'd be happy to help you out...I'm very good in photoshop.
Attached Images
File Type: jpg 18 inch pa graph2.jpg (89.3 KB, 192 views)
  Reply With Quote
Old 1st May 2005, 05:34 AM   #2
diyAudio Member
 
Join Date: Jan 2004
Location: chico CA
Default sigma 18

There are some problems that occur when trying to apply conventional hifi approach and making a threeway speaker for live or dj sound.The optimum is to be able to dedicate an amp for bass and bass only.The bass consumes the vast majority of the power in a pa setup.By activly filtering out the bass at a line level you will decrese distortion and eliminate heatproblems in the crossover. etc etc etc yada yada yada...
I think you will be more sucessfull making a dual 15 and a horn rather than this configuration.that would make for only one crossover point at a less strained part of the spectrum.
However threeways have been done and and one example is the hurricane from adire audio.That one design crosses the bass at 400hz and the tweeter at 2400.I think selenium have some monster speakers with similar setups on their website.
It would defenitly be alot easier if the sensitivities of the elements are as close as possible.But be prepared to see that the compdriver have quite alot higher sensitivity,witch is ok because you will have to attenuate it anyway.But try to match the mid and lo freq drivers within a db two.
__________________
thanks for reading.
H.Honda Chico CA Land of the fooled
  Reply With Quote
Old 1st May 2005, 05:25 PM   #3
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
Default Re: sigma 18

Quote:
Originally posted by holger honda
I think you will be more sucessfull making a dual 15 and a horn rather than this configuration.that would make for only one crossover point at a less strained part of the spectrum.
I agree with you HH. Two way with one or two 15" and a horn.

Cal
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 26th September 2005, 07:48 PM   #4
jsn is offline jsn  United States
diyAudio Member
 
jsn's Avatar
 
Join Date: Sep 2004
Location: The Atomic City
Here is the Hurricane - pretty big indeed:

http://www.adireaudio.com/Files/HurricaneBassCab.pdf

For me, the typical 15-plus-horn PA speaker sounds horrible. The highs are usually so screeching that any distortion from the amplifier is emphasized, and the bass typically doesn't go much lower than 100Hz. I don't think you can expect a 15" midwoofer to handle strong bass and clear midrange. The solution seems to be to stretch the tweeter/mid horn way down into the midrange, which forces it to do things it is not good at. Add a power amp that is less than awesome and you have a recipe for certain doom.

I like the idea of a 3 way because you let the mid play mids! you can cross the tweeter over much higher, and the woofer much lower.

Of course you need a more complex crossover, which might be tough to do. Starting with that hurricane crossover might make it easier.

I like the idea of using the Aidire 10.1 kit for the high end, but maybe in your case, you could do it with the 8" coaxial driver - although you would be giving up a bit of efficiency.

This is just my two cents since I haven't built any PA systems. I have heard a lot of them though, and they are mostly horrible. I appreciate you trying to get a result that actually sounds good!

I have heard that the bottlehead straight-8 line arrays with a higher power slot-loaded tweeter make good PA speakers. They have fantastic midrange as hi fi speakers, so they should sound great for live sound.

jsn
  Reply With Quote
Old 26th September 2005, 07:56 PM   #5
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
lunchmoney seems to have left us. He hasn't been online for 144 days.
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 2nd October 2005, 05:42 PM   #6
Notax is offline Notax  Montenegro
diyAudio Member
 
Notax's Avatar
 
Join Date: Jun 2004
Location: Belgrade
Default calculation

Bass. Equivalent port diametar 5". Vb = 7 cu. ft. Fb = 36 Hz, port lenght 15 ".

Mid. Closed box, Vc = 0.5-0.6 cu. ft.

x-over

bass - high pass 12 dB/oct. - at 230-260 Hz -6 dB point. Something like 6,8 mH (ferro)and 60 uF (4x15 uF MKT block 250 V)
mid - low pass 6 dB/oct. - at 450 Hz -3 dB point. 45 uF (3x15 uF MKC block 250 V)
mid - high pass 6 dB/oct. - at 1350-1450 Hz -3 dB point. 1.5 mH (air, 1.6 mm wire or more)
tweeter - low pass 12 dB/oct. - at 4-4.5 kHz -6 dB point. atenuation: paralel - 11 Ohm (2x22 10-15 W each), in order 7.5 Ohm (2x15 10-15 W each) and in order 2.2 uF , paralel 0.39 mH
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
are ultraflex cabinets "tuned"? asiquis Multi-Way 1 14th July 2009 10:44 PM
Looking to re-house Tannoy 10" DC and 10" woofers in to other cabinets speedysteve Multi-Way 15 30th September 2008 03:27 AM
Dayton Cabinets used in a "high-end" design?? sbrtoy Multi-Way 5 21st September 2008 02:46 PM
15" Woofer Cabinets HKC Multi-Way 7 5th November 2007 11:30 AM
How might one design Karlson-type cabinets? freddi Multi-Way 6 24th November 2006 12:56 PM


New To Site? Need Help?

All times are GMT. The time now is 02:56 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2