# Crossover help, first build idea



## STRDB2000 (Oct 29, 2009)

Hi all,

So I'm almost finished my DIY sub thanks to all the info I've found here, and think I understand all the principles involved in subs. Have to say from the test enclosure it has far exceeded my expectations :unbelievable:

So I've decided to try and build some bookshelf speakers so I can learn and practice my woodworking skills etc. The goals for this are to give me an idea of the processes involved, specifically so I can start to learn about crossover design and driver selection, not really to build a high end design, so I'd be happy with a reasonable sounding result to start with...

I have two tweeters already, the HiVi K1's http://www.swanspeaker.com/product/htm/view.asp?id=30
and I was thinking of using these drivers here http://www.jaycar.com/productView.asp?ID=CW2194&keywords=woofer&form=KEYWORD to go with them to keep the costs down. 

6.5"-
Nominal impedance:8 ohms
• Power nominal: 60WRMS
• Frequency response: 44Hz - 7kHz
• Sensitivity: 89dB ([email protected])
• Qms: 2.02
• Qes:0.567
• Qts: 0.443
• Fs: 49.52Hz

K1-
Nominal Impedance (Z)(Ω) : 5 
Resonance Frequency (Fs)(Hz) : 800 
Nominal Power Handling (Pnom)(W) : 15 
Sensitivity (2.83v/1m)(dB) : 92 
Weight (M)(Kg) : 0.9 
VC Diameter (mm) : 25 
DC (Re)(Ω) : 4.6 
Recommended Crossover Frequency(Hz) : >2500Hz 

Does this driver look like an ok match? How do you gauge if they are or not?

Now crossover, I have found a few crossover calculators, however I'm unsure what type of crossover I need eg 1st order, butterworth etc etc I've read about them but really don't understand which and when to use each.

Can anyone suggest a good read that might cover all this as I'm keen to learn!

Must mention I currently don't have any test equiptment to measure the drivers or T/S specs, so given the drivers are cheap and the posted specs are probably incorrect to a degree I thought I might do a sealed design as the tolerances are less tight? Think I worked out EBP was 86. At some point in the future I will look to get some kind of measuring kit as finances allow, but not for the moment unfortunately.

Hope someone might be able to help especially with the crossover stuff, or point me towards some reading material, or both!

Thanks


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## dyohn (Apr 17, 2008)

Hi there. The rule of thumb I usually go by when choosing components is to start with the tweeter. You will want to cross it over at no lower than approximately 2X the fs of the driver. In your case, the tweeter fs is 800Hz (which is quite good) so you'll need a woofer with decent response up to about 1600Hz, and you want to design your Xover with a 1600Hz target knee. 

While I know nothing about the woofer you linked too, judging from the rather incomplete published data it might be a decent choice as far as FR goes. So, design a 2nd order (or higher) crossover @ 1600Hz for these two speakers. Pay attention to the fact that the tweeter is a different average impedance than the woofer. I suggest trying a Linkwitz-Riley 2nd order for these drivers.

Next you'll need to pad the tweeter to match the lower sensitivity of the woofer. Again based on published data the tweet needs about -3db of attenuation.

There are other issues we can deal with once you have your enclosure designed but that's my recommended starting point. 

I suggest reading the passive crossover component selection guide in the sticky section, and choosing good quality components. Your crossover parts cost will likely far exceed the cost of these two drivers.  And most of all, have fun!


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## STRDB2000 (Oct 29, 2009)

Great, thanks for the reply, it's good to get a rough idea of where to start! 

Yes I read your crossover guide, great info there, will be refering back to that once I get to that point.

I've also spent a few hours now reading up online about crossovers and didn't realise how complex it was, however I'm determined to get the hang of it and have also started reading the loudspeaker design cookbook.

I think I'll invest in something like the Dayton WT3 as I think more accurate/realistic T/S specs would help alot- everytime I try and model the above woofer in Winisd or BBP it gives me errors or really weird enclosure recommendations :hissyfit:

I found more detailed woofer specs here, but they still don't seem to be correct http://www.electusdistribution.com.au/products_uploaded/CW2194(W-178PII)%20parameter.pdf


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