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Old 29th September 2013, 01:43 PM   #11
sreten is offline sreten  United Kingdom
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Hi,

Online calculators will never give the right x/o.

The x/o in post #8 is at 2.5KHz as shown.

rgds, sreten.

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Old 29th September 2013, 01:45 PM   #12
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As i wrote in my previous post, it is NOT the Mite's x-over, but the one in it is VERY similar to it. If not almost the same..... The x-over freq. shown is 2.5k, it is the same as of the Mite. I cannot help you more, but you can play with slightly different values, according to your personal sonic preference.
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Old 29th September 2013, 02:06 PM   #13
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Thanks for the help guys.

I've never built a 2 way speaker before. I did build a set of fullrange speakers. They were 'The Derwent' cabinets with CSS EL70 drivers, great sound. I did add a supertweeter which I designed the crossover myself. As for 2 way speakers, I better keep reading


Edit:

I've tried several online crossover calculators and I don't get values anywhere near what the diagram in post #8 shows. Can someone explain it? Thanks
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Last edited by portreathbeach; 29th September 2013 at 02:15 PM.
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Old 29th September 2013, 03:19 PM   #14
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For example, using this crossover design calculator Crossover Design Calculators and inserting the crossover frequency at 2.5KHz

4ohm woofer:
Linkwitz - 7.96uF and 0.51mH
Butterworth - 11.25uF and 0.36mH
Bezzel - 9.12uF and 0.44mH

8ohm woofer:
Linkwitz - 3.98uF and 1.01mH
Butterworth - 5.63uF and 0.72mH
Bezzel - 4.56uF and 0.88mH

How do you get the values in the diagram? Also, is there a calculation for working out the crossover frequency being given the inductor value and the capacitor value?
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Old 29th September 2013, 03:36 PM   #15
AllenB is offline AllenB  Australia
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It would seem from what I'm reading that if you use the crossover in post 8 you'll probably be within tweaking distance of a good crossover.

Anyway, filter components are essentially chosen to work with the driver impedance, which varies. In other words if you take a text book set of values and combine them with appropriate impedance compensation, you'll no longer need separate compensation but the filter will seem to have weird values. It's all good.

Quote:
Originally Posted by portreathbeach View Post
is there a calculation for working out the crossover frequency being given the inductor value and the capacitor value?
1/(2*pi*sqr(L*C)) will get you the resonance frequency of the filter. This may be close to the actual crossover point but it will be dependent on such things as the driver response, and the Q of the filter.
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Old 29th September 2013, 03:46 PM   #16
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That gives 1299 for the woofer and 4238 for the tweeter! Surely the driver impedance needs to be in the calculation!

Also, regarding one of the links Dizzi posted http://www.speakerlab.gr/papers/totem_REB.pdf. Here the guy has replaced the 4ohm driver with the 8ohm version. How could the 8ohm version work in the same box? As mentioned earlier, all of the values for the two version of the driver are different. The 4ohm version needs something like a 5.6l box and the 8ohm version needs about 10 or 11 l box.
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Old 29th September 2013, 04:46 PM   #17
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In the real world crossover design is much more experiment- based, because calculated values work only with constant impedance drivers, and the real ones are more than far from that. I happen to know this, because I did it for about 20 years. Also different impedance drivers with different T-S data can fit into lots of different size boxes, as it is splendidly demonstrated in an old Speaker Builder issue by Ralph Gonzalez (titled: Quasi-Monotonic vented alignments). Speaker design software are a good starting point, but usually have limited use when it comes to real-world drivers. SBB4, B4, C4 (the most commonly used alignments) are limited to only one box size each with a given driver, while QM3 gives you much more versatility by tuning the box to different frequencies.

Last edited by dragonweed; 29th September 2013 at 04:48 PM.
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Old 29th September 2013, 05:04 PM   #18
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OK, there seems a lot more too it than it first appears.

Dragonweed, would the crossover shown in post #8 work with the GDN 13/40/2 8ohm or 4ohm version and as for the tweeter, should I use the GDWK 11/100 (8ohm)

Sorry for all of the questions, thanks again

I still don't understand the box volume staying the same when using the 8 ohm version of the driver instead of the 4 ohm version in the link Dizzi posted.

I also found this build using the same drivers:

http://diyaudio.pl/showthread.php/14...-8-gdwk-11-100

How would you work out the crossover frequency in his crossover design
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Last edited by portreathbeach; 29th September 2013 at 05:13 PM.
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Old 29th September 2013, 05:43 PM   #19
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Use the GDWK 13/40 8 ohm version in a 5.6-6 liter box. Don't worry it will work well, because it uses QM3 alignment in the reflex tuning-("undertuned"). I do not work for Totem since 2000, I designed most of their products, but I have no right to publish the details of their designs, and I wouldn't do it anyway.......). Just suggesting, the values in post#8 are quite useful , so you can start from there.
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Old 29th September 2013, 05:53 PM   #20
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Thanks very much

I'll stick with a 5.6l box and the same port as the Mite and use the crossover shown and see what happens. I can always tweak them afterwards. This will be a nice stereo setup paired with my DIY amp.

I was looking also at the Totem Sttaf, as a friend of mine has a pair which sound great and he said I could take some internal measurements from them. These use the same drivers also, so I want to eventually build a pair of Sttafs and a single Mite to use in my home cinema set-up. Would the crossover described earlier work well, or should I redesign it?
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