Help Newbie Design X-over Step-by-Step

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I'm hoping that someone can help me make a x-over for my new speakers. I'm a very poor student so I can't afford expensive measuring equipment or many components which needs to be constantly changed to reach the goal.

This is what i've got: 3 (or 2.5 way speaker) using ss9700 tweeter, Audiotechnology Flexunit 4 H 52 06 13 (4 inch mid) and a ss 21w8555-01 bass. I'm aiming for low Q around 0.5-0.6 which yields 43 liters for Q=0.5 for bass and 27 liters for Q=0.6. Looking for a midsized speaker 43 liters seems a bit too much so i'll go for a Q=0.55 which gives 33 liters. For mid I get for Q=0.55 9 liters.

I've been looking around the net for someone using the specific mid and found just a few. The reason for me doing so was to get some x-over points and from my "research" and through email back and forth with Skaaning (audiotechnology - they really were nice and answered all my mails) i have chosen 4800 Hz and 250 Hz. It has been recomended to use 1st order filters on both upper and lower x-over points with the flexunit. Looking at the frequency response curves for the mid this makes perfect sense to me. I have also been recommended a 3rd order filter for the tweeter. I don't exactly know what to do with the bass. Perhaps active crossing?

I have never designed a crossover before. I don't really know what i should do - i have been checking the design calculators around the net, but i'm not sure about the results. And i'm not sure exactly what i need... Do i need an impedance correction (have been recomended) and does this affect the rest of the crossover?

My question is then does anyone have any suggestions - that be design suggestions (changes to what i already have), suggestions to what i should do know and last but not least finished designs.

Please help :D
 
FRom one newbie to another

> bass. Perhaps active crossing
I’m no expert, but active I believe with the extra amp is usually better controlled bass, but if you’re not wanting to spend a lot, perhaps start passive.

Have you modelled the bass, eg in Unibox?
Which design calculators have you used? I believe that Speaker Workshop is the best of the free software; the learning curve is not small, but there’s a comprehensive manual at http://www.audiodiycentral.com/
(Though when I try to unzip the manual (with WinZip 9.0), - it doesn’t work – with two downloads: “the 32 bit CRC header stored in the local header for this file is nit the same as the 32 bit CRC stored in the central header”)

There are a few theories/ philosophies about what slope XO is best. Probably it’s best to model some, and see which gives the smoothest response.

One rule of thumb for a mid, is about three octaves is a good range. Any less, particularly with shallow slopes on the tweeter and bass, and you may get some unwanted overlap.

I outlined what I believe are the overall steps to get a good result in post 5 here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=46019
:dead:

Got to rush, hope this helps
 
How about active?

Is it easier to make a good-sounding active crossover than a passive? It seems to me that there are fewer problems with active crossovers - don't you just have the crossovers and some sensivity correction when using active or do you have impedance correction as well?


It would of course call for 6 channels of power but i have a few old amps lying around that i could use for now and upfrade to something better later (perhaps buy some krell ksa50 clone boards - i have some massive heatsinks and some 500va toroids all ready so i'm guessing it wouldn''t be that expensive)...


parts also seem cheaper when using active... even expensive opamps aren't as expensive as a single high quality high cap for passive x-overs...
 
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