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Multi-Way Conventional loudspeakers with crossovers

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Old 22nd January 2013, 06:59 AM   #11
system7 is offline system7  United Kingdom
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bart-dood, I get used to going over people's heads at this forum, and taking a lot of flak in the process. But if you want to get the best out of that Peerless 830875, it is important to equalise out the peak at 4-6kHz.

These peaks represent energy storage, best exemplified by the waterfall plot of aluminium Visaton AL170S driver below. The Nomex (paper) driver has similar issues, though not as dramatic.

The two phase plots are for the circuit I posted for the Peerless 830875 circuit. The first is with the essential tank, the second without it. I could do this another sort of notch, but you get the idea I hope. It's the difference between an average speaker and a very good one. We are, after all, PROFESSIONALS.
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File Type: jpg Visaton_AL170_Waterfall.JPG (75.0 KB, 46 views)
File Type: jpg Phase_With_Tank.JPG (62.6 KB, 44 views)
File Type: jpg Phase_Without_Tank.JPG (60.8 KB, 45 views)
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Old 22nd January 2013, 11:24 AM   #12
Dissi is offline Dissi  Switzerland
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Quote:
Originally Posted by bart_dood View Post
Think I'm getting the hang of this a bit more now, Dissi I modelled up your Xover in PCD7.0 and then my crossover. Here's the comparison, yours is about 86db and mine about 90db.
It's very interesting to compare my simulation with the results of PCD. I see not much difference above 400 Hz, great. But the question is: what is below 400 Hz? Assuming a vented box tuned to 54 Hz, my simulation predicts a woofer sensitivity of 86 dB. For that reason my design is matched to 86 dB.

To answer your question regarding phase matching of woofer and tweeter: Proper phase matching is achieved, when the sum at the crossover frequency is 6 dB higher than the individual spl of woofer and tweeter. Reversing the tweeter polarity then gives a deep notch of -20 dB or more.

Concerning crossover frequency: Google yourself, but some people do not recommend to use that tweeter below 2 kHz.
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Old 22nd January 2013, 11:39 AM   #13
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Hi Chris,

Quote:
Concerning crossover frequency: Google yourself, but some people do not recommend to use that tweeter below 2 kHz.
Concerning the woofer, The Elsinore and the Nomex 164 are crossing the 830875 at ~3 Khz.

Concerning the level of the woofer, take a look at the section concerning BSC at the link below.

Introduction to designing crossovers without measurement
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Old 22nd January 2013, 08:21 PM   #14
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Quote:
Originally Posted by Dissi View Post
It's very interesting to compare my simulation with the results of PCD. I see not much difference above 400 Hz, great. But the question is: what is below 400 Hz? Assuming a vented box tuned to 54 Hz, my simulation predicts a woofer sensitivity of 86 dB. For that reason my design is matched to 86 dB.

To answer your question regarding phase matching of woofer and tweeter: Proper phase matching is achieved, when the sum at the crossover frequency is 6 dB higher than the individual spl of woofer and tweeter. Reversing the tweeter polarity then gives a deep notch of -20 dB or more.

Concerning crossover frequency: Google yourself, but some people do not recommend to use that tweeter below 2 kHz.
I guess I'm more confused now regarding the sum at the crossover, shouldn't PCD sim show me what the expected response is? The plots I'm getting out of it show a relatively flat sum between the tweeter and woofer but the individual values aren't 6db below the sum. Does this mean the responses from PCD should not be taken as accurate? If it were it should show a peaking at the crossover point?

I didn't sim the vent and box with PCD, I used winISD to figure out the port tuning and box volume, hence why it is missing from my plots.
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Old 23rd January 2013, 02:58 AM   #15
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Default I think I got it now..

Linkwitz Riley, 2nd order (woof/tweet), zobel on the woofer, reversed tweeter polarity so smooth transition.
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File Type: jpg linkwitx Xover.jpg (118.1 KB, 39 views)
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Old 2nd March 2013, 02:53 AM   #16
fakeout is offline fakeout  Canada
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Uh, where these built? Any pics and listening impressions?
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