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Multi-Way Conventional loudspeakers with crossovers

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Old 28th April 2012, 10:40 PM   #11
boris81 is offline boris81  United States
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The best solution will be to add an extra woofer. Look up 2.5-way designs where the boost from a second woofer is used to make up for the loss from the baffle step.
As an added bonus you could build it so that the middle point between a pair of 10" woofers will be 11.6" from the floor.
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Old 28th April 2012, 10:44 PM   #12
boris81 is offline boris81  United States
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You can use the free XDir program to simulate the vertical lobe.
Xdir
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Old 28th April 2012, 11:43 PM   #13
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I don't want to go to a 2.5-way or 3-way because my initial challenge is to mate a 10" to a tweeter.
As my need is to listen no more than ears height and favouring to avoid midbass floor cancellations, I will build my speaker with an offset of 15.2" and steep slopes at Fx to minimise vertical beamwidth issues.
Anyway thanks to all for your comments.
Hope I will remember to give you some news about this matter after completing of this speakers.
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Old 29th April 2012, 04:09 AM   #14
boris81 is offline boris81  United States
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When designed correctly a two woofer configuration can be much more effective against floor bounce than a single woofer solution. It's one of the advantages of a 2.5-way
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Old 16th May 2012, 08:12 PM   #15
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Some news from my almost finished project using a tweeter (SB29) placed far away from a (close to floor) woofer (SEAS CA26RE4X)...
Finally it turned out to be quite interesting in term of listening results, with a lot of dynamics mixed with a very good level of details and smoothness; obviously the challenge was not only to control V directivity issues but also to design the filter without measuring close (usually 1 or 1.5 meter) to speaker_yes phase cancellations are huge at this distance...So I decided to measure at 3M, window 300Hz and smoothing things at 1/3octave for sims; this process gave great results; however the filter design was a lot of work, 2 x 4th order aren't easy to design right, particularly in these conditions! Transfert functions are particularly clean.

Room bounces didn't give me the possibility to measure the reverse nul, but it can be view on sims; non-windowed measurement at listening position gives an almost linear range (+/- 1.5dB) slightly decreasing (no screen capture, sorry).

Almost no BSC and some 91dB/2.83V are partly due to the woofer placed close to floor; all in all I would say that this drivers combo and filter doesn't need any mid-driver; the tweeter doesn't undergo any form of stress in spite of the 1.1kHz Fx and listening stays quite acceptable even if I stand up at listening position...

Click the image to open in full size.

the drawing, to remember drivers placement:
Click the image to open in full size.

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Old 17th May 2012, 01:59 AM   #16
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by crazyhub View Post
Room bounces didn't give me the possibility to measure the reverse nul,
Reverse the polarity of the tweeter, use a real time analyser and pink noise. Hold the mic in your hand and sweep it up and down in front of the speaker, maybe a few feet away. You should be looking to see that all frequencies around the crossover region are reaching their minimums close to on axis.

You'll also need to do something about C5, it really shouldn't be there.
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Old 19th May 2012, 01:11 PM   #17
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what is the problem with C5 AllenB ?
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Old 19th May 2012, 01:27 PM   #18
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C5 Z=0 at high frequency. It is clearly a short circuit. You should never do this.
As you can see the impedance of the speaker becomes low above 20kHz.

Your crossover is really a LR8 ? Not a LR6 instead ?

Congratulations for the project
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Old 20th May 2012, 05:09 PM   #19
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Allen and jerome,

I thought such low impedance at so high fr wasn't important ?!...
A screen shot with R10ohm in series with C5 and without the R:
Click the image to open in full size.

jerome, thanks for your congratulations!
I do never analyse the filter topology I design, so LR6 or 8 ?:
Click the image to open in full size.
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Old 20th May 2012, 07:12 PM   #20
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You see the difference 1.5ohms and 4.5ohms. Fortunately you don't push the test higher.
Yes it is important because some (bad in general) amplifiers can have high frequency oscillations and can overheat. It could reduce stability of the amp. with such low impedance at high frequency. The third reason i see, is you can amplify radio frequency and it's not good for the (very good) amplifier to drive 0.5ohms at 100kHz.

I see near 8th order (45dB/oct.) for the tweeter and near 6th order (36dB/oct.) for the tweeter. But in fact you have a LR2 near the crossover region
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