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Multi-Way Conventional loudspeakers with crossovers

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Old 15th January 2013, 03:49 AM   #11
dijaam is offline dijaam  Australia
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Quote:
Originally Posted by PeteMcK View Post
re:"**could anyone suggest my best option still using the jaycar parts?**" - Download ARTA, make a simple jig, & measure the driver parameters.
Download Unibox, type in the parameters & design the box,
Read up a bit on crossovers, & ask lots of questions here, & design a simple 2nd order LR crossover with some baffle step compensation built in.
It'll take a few weeks, but you'll be well on the way to being an expert.....
Thanks for that, i'll have a look

Quote:
Originally Posted by Moondog55 View Post
Read this thread too, as it has lots of information about the choices you need to think about making

diyAudio reference speaker project

Pete gave me a pair of those 8inch woofers a while ago, I'm of the opinion that they need to be crossed low, no higher than 400 or 500Hz. One thing you might consider is what is known as 2.5 Way speaker, pick a driver which has a good midrange reproduction and add a woofer using just a first order roll-off down low. I push this option rather than a dedicated 3-Way as it is much easier to get sounding OK without too much trial and error.
Where are you located??
What is your budget??
Other questions also need to be asked; such as how big is your room, how loud and which types of music do you listen to and is the room full of soft furniture or is it open and bare with hard wooden or tiled floors??
I would say tho that using that tweeter may make your job just a little harder and trying to match those 2 drivers without a midrange very hard indeed.
are there any good guides for 2.5 way? I'll look into it but sometimes theres a gem of a source that i'll miss in the process

Quote:
Originally Posted by PeteMcK View Post
ah...THOSE woofers... they're good for a bit of woof, but not much else...
(get a bit rough in the mids when you push them)
if I've got the model right, measured parameters (after burn in) will be approx:
Jaycar CW2196#1
Fs 37.00 Hz
Re 6.00 Ohm
Qms 2.38
Qes 0.32
Sd 187.0 cm2
Vas 36.5 l
Le 0.29 mH
I used them in pairs in 48L tuned to ~ 40 Hz (so 24 L for a single driver)
haha yeah, they were sitting there in the shop so I couldnt resist just buying something and having a crack! thankyou so much for those numbers btw! how do you think one in as a smallish floorstander (maybe 40-50L?) would fare? assuming id want some decent bass.

Thanks again!
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Old 15th January 2013, 04:30 AM   #12
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That's too big for a single woofer, you'd get a bad sounding bass peak
- mine sounded OK as 3 ways, IIRC I crossed then over 2nd order at ~ 300Hz, they'd be OK as party speakers, but TBH, use them as a learning experience, & then buy some good drivers....
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 15th January 2013, 04:34 AM   #13
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To help out has any-one used the smaller Jaycar drivers

The best of the bunch looks on paper to be the 5inch as a midrange

5" Paper Cone Woofer/Midrange - Jaycar Electronics

While adding another driver adds to the cost and total complexity; midrange clarity is the focus of most of us.
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Old 15th January 2013, 04:34 AM   #14
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Here's a little "Light" reading.



Understanding Cabinet Diffraction ? Audioblog
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Old 15th January 2013, 04:40 AM   #15
dijaam is offline dijaam  Australia
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Quote:
Originally Posted by PeteMcK View Post
That's too big for a single woofer, you'd get a bad sounding bass peak
- mine sounded OK as 3 ways, IIRC I crossed then over 2nd order at ~ 300Hz, they'd be OK as party speakers, but TBH, use them as a learning experience, & then buy some good drivers....
ok thanks, yeah that was the idea, keep it cheap for a bit of fun and once i understand the process better, spend money on good parts.


Quote:
Originally Posted by Moondog55 View Post
Here's a little "Light" reading.



Understanding Cabinet Diffraction ? Audioblog
thanks
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Old 15th January 2013, 04:48 AM   #16
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Quote:
Originally Posted by dijaam View Post
are there any good guides for 2.5 way? I'll look into it but sometimes there's a gem of a source that I'll miss in the process
Thanks again!
Do the arithmetic on the baffle step -3dB frequency ( some people use the -6dB ) F3 = 115 / WB (Width of Baffle) then select a coil for the woofer that acts on the woofers impedance at that frequency. If making a 3-Way then that frequency is often used as the XO frequency.
So for you baffle width of 300mm the answer is 383 Hertz and I don't think plus or minus 10% is going to make much difference.
300 to 400 is often suggested as an appropriate place to put the XO

More light reading

Baffle Step Compensation
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Old 15th January 2013, 08:04 AM   #17
dijaam is offline dijaam  Australia
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It seems trying to use the 8'' in a 2-way will be average at best so id consider using jaycars 5'' woofer in a 3-way as id get better results.

Using the 8'' woofer and crossing over at 300-400Hz like suggested would id be recommended i design for a 5000Hz crossover for the mid? (jaycar specs list a difference in frequency response between 2kHz and 7kHz for the tweeter and mid).

Also, unless anyone has a simple calculator, jaycar has a diy crossover building table which suggests capacitors and inductors depending on what crossover frequencies you use (form their range of parts) and to keep it a budget learning project, should i just follow that guide? It also accounts for wiring in a 'tweeter atenuation' from 0- -4dB. Alternatively this would help me build a junk crossover and I should follow something else..

thanks
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Old 15th January 2013, 09:52 PM   #18
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re:"jaycar has a diy crossover building table" - NOOOOOO!!!! these tables are based on the nominal impedance of a driver, which is nothing like the ACTUAL impedance of the driver at the crossover frequency you're using. To find that, you need an impedance graph of the driver, (I'll see if I can dig mine out for that driver, may take a couple of days), then use that value in a crossover calculator such as this:
Crossover Design Calculators - that'll get you a much better crossover
To work out tweeter attenuation use this: L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
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Old 15th January 2013, 10:01 PM   #19
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I have been thinking about this on your behalf (when I should have been plastering and painting LOL) perhaps you could return the tweeter and use the money to purchase a halfway decent 3 inch full range. Then all you need is one crossover in the range 300-400 or so.


3 inch drivers have a reasonable top end and the woofer you have will fill in the bottom quite well.

http://www.fostexinternational.com/d...s/pdf/fe87.pdf

eBay Australia: Buy new & used fashion, electronics & home d?r

There are many other good cheapish 3 and 4 inch fullrange drivers around
I see lots of cheap computer speakers at our local recycle centre going for $5 or $10- a pair and some of them have quite reasonable little drivers in them
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Old 15th January 2013, 10:32 PM   #20
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Building a pretty decent sounding speaker system isn't too hard, with a little trial and error experimenting. Building a really good one is much more complicated. Internal cabinet shape and damping, and external listening room acoustics have a huge influence on what you will hear in the end. After reading the advice others have given you, I noticed several cases where the advice is actually quite complicated (Get ARTA and use to measure impedance, for ex.).

For a newbie, I'd actually recommend a closed box woofer, perhaps with a passive radiator made from a regular woofer so you can short the voice coil out for better damping if that works better. I've had great luck with that. It pumps up the low end in the least complicated way. For midrange, I'm thrilled with the $12 Peerless 3 inch drivers I've been playing with lately (check Parts Express or Madisound websites here in the US). They're great from about 200HZ to 12kHZ+. I'd put in a 3/4 inch dome tweeter crossed at 7kHZ or higher for the top end.

It's true that nominal impedance of any driver and actual impedance at the frequency you want to cross it over at will be way different. That's one of the reasons to keep a passive crossover simple. If you can figure out how to measure the impedance at these frequencies, you can be more accurate. For a newbie who can't find a published impedance graph, I might suggest assuming the driver has about twice the nominal impedance at the frequency you want to cross it over at (based on my experience), build a crossover based on that, and then vary the values if necessary until it sounds the best to your ear. Many people out there will condemn me for saying that, but in the real world, that may get you closer to accurate than any other approach, if you're a newbie. And yea, going from an 8 inch to a 1 inch tweeter will have pretty substantial off axis problems. Difficult to listen to over time. Too much upper midrange. There is a lot to be said for having good tone controls in you preamp. Those who hate tone controls are fools, or have had a very bad version of them. Hope this helps.

Check out my audio hobby website if interested. It's pretty advanced, but perhaps relatively understandable to a newbie. My "Aurium Waveguide" speaker project has a lot of discussion that you could learn from. Bob's Website
Bob's Website
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