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Multi-Way Conventional loudspeakers with crossovers

NEWBIE: Seeking 2 or 3 way SEALED DIY project!
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Old 11th January 2018, 02:47 PM   #11
boswald is online now boswald  United States
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NEWBIE: Seeking 2 or 3 way SEALED DIY project!
You can make an excellent sealed speaker with woofers with Qt of .4-.6
Outside of that, you can still do it but you will find it much more sensitive to placement. High Q will want to boom. and very low Q will have little bass, best used with a sub.

It will not affect your crossover as any bumps or dropoffs are below your low(non sub) cross point, just keep baffle width and driver placements from top the same as the ported version. Get any extra volume you need going down and/or back.

mh-audio.nl has graphing on its sealed calculator that will let you see what different sealed alignments look like at the bottom(w/o room or baffle effects, keep them in mind).

Last edited by boswald; 11th January 2018 at 02:51 PM.
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Old 11th January 2018, 04:09 PM   #12
Paul Vancluysen is offline Paul Vancluysen  Belgium
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Originally Posted by boswald View Post
You can make an excellent sealed speaker with woofers with Qt of .4-.6
I completely agree, sealed box Qtc = 0.5 – 0.6, and a low system resonance frequency fc ( = large driver and large cabinet), I have the best experience with it. To play louder I prefer the woofer in a ported system, because of the reduced excursion. Then a 4-way system with a woofer in a ported enclosure and the midwoofer in a closed box, crossing at about 120Hz, becomes interesting. The crossing frequency with the midwoofer cannot be chosen too low, otherwise the excursion limit of the midwoofer becomes an issue while playing loud. I don’t like the ported system up to a few hundred Hz, because of the lack of enclosure filling at low medium frequencies.
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Old 11th January 2018, 05:03 PM   #13
andy2 is offline andy2  United States
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Originally Posted by boswald View Post
best used with a sub.
.
as a last resort I would think.
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Old 11th January 2018, 05:20 PM   #14
Keruskerfuerst is offline Keruskerfuerst  Germany
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When using ported system in bass range, the cone excursion is not damped.
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Old 11th January 2018, 07:09 PM   #15
SONDEKNZ is offline SONDEKNZ  New Zealand
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Wow! You guys have surely done me proud.

Many thanks for all these thoughts. Much to consider.

Special thanks to you - Paul Vancluysen - for your very kind offer to work with me on a brand-new plan.

The truth is that many of you are speaking a language that is beyond my current understanding, hence my preference to run with a proven recipe.

I can also see that there is - as always - a strong preference for a ported design, but this is not for me.

I will wade through all of this detail and the many options and give it all a think.

Once again, many thanks for your kind and generous suggestions. What a great global community. So very impressive.

Sincere thanks.

-Tony (SONDEKNZ)
Auckland, New Zealand.
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Old 11th January 2018, 07:14 PM   #16
Paul Vancluysen is offline Paul Vancluysen  Belgium
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Quote:
Originally Posted by Keruskerfuerst View Post
When using ported system in bass range, the cone excursion is not damped.
For a ported system, the cone excursion as a function of frequency has a notch at the tuning frequency fb. This is typical for of a ported system. Below the tuning frequency the excursion becomes higher again and is even larger at very low frequencies than the excursion of the same driver in a closed box system. But in the frequency region of interest for music, the excursion of a basreflex system is lower than a closed box system with the same driver. I a way you can play louder with the basreflex.
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Old 11th January 2018, 08:04 PM   #17
PeteMcK is offline PeteMcK
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IIRC, the Peerless 10" woofer models well in a sealed cab; if no size restrictions, use two (can't recall the model no)... Prob is I don't think there's much available in NZ, you may have to import?
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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 11th January 2018, 08:41 PM   #18
fatmarley is offline fatmarley  England
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Originally Posted by PeteMcK View Post
IIRC, the Peerless 10" woofer models well in a sealed cab; if no size restrictions, use two (can't recall the model no)... Prob is I don't think there's much available in NZ, you may have to import?

I'd Imagine you mean the one used In the Tarkus? The Tarkus could also be used without a port.
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Old 11th January 2018, 09:53 PM   #19
Paul Vancluysen is offline Paul Vancluysen  Belgium
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Originally Posted by fatmarley View Post
I'd Imagine you mean the one used In the Tarkus? The Tarkus could also be used without a port.
In the Tarkus the Peerless 830668 is used.
For this driver Fs = 32Hz, Qts = 0.55 and Vas = 73L.
Placing it in a cabinet of 70L, the system frequency fc = 55Hz and Qtc = 0.77. With one such woofer the overall sensitivity will become 82dB. With two of them in parallel it will be 88dB.
In my opinion Qtc = 0.77 is rather high, 0.5 to 0.6 would be better, at least Qtc should be equal or less than 0.7. fc = 55Hz is also rather high. The -3dB frequency F3 will be about 55Hz in such system.
Better is to use a driver with a lower Qts and a lower fs.

Maybe the 11 inch Eton 11-212?
Placed in a 60L cabinet fc = 39Hz and Qtc = 0.56. F3 becomes a little higher than 40Hz and the overall sensitivity will become 85dB with one such driver and 91dB with two drivers in parallel.

The above numbers are first estimations, not computed accurately, only to have a first idea.

As an example, 2x Eton 11-212 in a 120L cabinet, combined with the Accuton C173-6-096E midrange and the SB Satori TW29BN Be tweeter, a system 40 – 40000Hz with a sensitivity of 91dB can be realized.
It is just an idea, there are so many good alternatives.
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Old 11th January 2018, 09:59 PM   #20
SONDEKNZ is offline SONDEKNZ  New Zealand
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The cabinet for the TARKUS project would be beyond my capability.

For ease of fabrication, I'd much prefer to make a mostly classic rectangular box speaker - similar in proportion to the AUDIO NOTE / DEVORE . 8008-CORNER models, the images for which I included in the my post.
(I far prefer their look also...)

Regarding availability, here in New Zealand we fully expect to import almost everything. It is the norm. No problem.
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