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Multi-Way Conventional loudspeakers with crossovers

Isobaric frequency limits?
Isobaric frequency limits?
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Old 26th September 2017, 09:06 PM   #21
scottjoplin is offline scottjoplin  Wales
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Old 26th September 2017, 11:57 PM   #22
Andersonix is offline Andersonix  Sweden
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Isobaric frequency limits?
He's saying it has good bass!

I've always liked the idea of half the box size, plus it's an interesting way to use two 4-Ohm drivers and get 8 Ohm load.
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Old 27th September 2017, 12:46 AM   #23
Bill poster is offline Bill poster  Thailand
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He's saying it has good bass!

I've always liked the idea of half the box size, plus it's an interesting way to use two 4-Ohm drivers and get 8 Ohm load.
2x8ohm = 4ohm and same output (as single 8ohm driver)
2x4ohm = 8ohm and minus 3 or 6db output?

Last edited by Bill poster; 27th September 2017 at 01:07 AM.
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Old 27th September 2017, 12:53 AM   #24
Andersonix is offline Andersonix  Sweden
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Isobaric frequency limits?
Yes, you could also make two 8 Ohm drivers into a 4 Ohm driver.

This sub was smaller and cleaner than it had any right to be:
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Old 27th September 2017, 01:11 AM   #25
Bill poster is offline Bill poster  Thailand
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The satori WO24p is available in both 4 and 8 ohm, so if I'm only losing 3db output from 2 in series, I might do it that way.
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Old 27th September 2017, 02:21 AM   #26
Don Hills is offline Don Hills  New Zealand
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Try and avoid using isobaric configuration in a ported enclosure. You won't get the same excursion-limited SPL as you would with a single driver, due to the enclosure resonance changing the effective rear enclosure volume.
See the attached graph, showing excursion.
The red line is the excursion of the outer driver of a clamshell pair.
The black line is the excursion of the inner driver.
The green line is the excursion of a single driver with T-S specs equal to the combined clamshell pair.
Most of the time, the volume of the rear enclosure is much larger than the volume of the space in the clamshell, so the two drivers move almost together.
But at port resonance, the back-pressure of the enclosure resonance has the same effect as making the enclosure much smaller, and the ratio of the two volumes becomes smaller. The volume of the clamshell space becomes significant.
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Old 27th September 2017, 03:43 AM   #27
Bill poster is offline Bill poster  Thailand
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Originally Posted by Don Hills View Post
But at port resonance, the back-pressure of the enclosure resonance has the same effect as making the enclosure much smaller, and the ratio of the two volumes becomes smaller. The volume of the clamshell space becomes significant.
Is it best to create a slightly bigger volume between the two drivers?
In my design concept, spl is not a biggie, as the mid I want to use kind of compromises ultimate output. All the same, this is very interesting and thanks for posting
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Old 27th September 2017, 10:55 AM   #28
Nico Ras is offline Nico Ras  South Africa
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Those who knows, does. Those who don't simulate and advise.
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Old 27th September 2017, 11:43 AM   #29
john k... is offline john k...  United States
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Originally Posted by Bill poster View Post
The satori WO24p is available in both 4 and 8 ohm, so if I'm only losing 3db output from 2 in series, I might do it that way.
What ever the voltage sensitivity of the 4 ohm version is, if used in series as an isobaric, the voltage sensitivity would be reduced by 6dB. I'm sure that the sensitivity of the 4 and 8 ohm versions are different to start with.

Doesn't matter whether 4 or 8 ohms. You will always have 3dB lower efficiency for the isobaric compared to a single driver. But in parallel you double the power in (for a given voltage drive) and get the same SPL out where as in series you cut the power in by 1/2 and get 6dB lower SPL out.

If the 4 ohm driver is more efficient than the 8 ohm, that's something else to consider.
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Old 27th September 2017, 12:13 PM   #30
Bill poster is offline Bill poster  Thailand
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Originally Posted by john k... View Post
What ever the voltage sensitivity of the 4 ohm version is, if used in series as an isobaric, the voltage sensitivity would be reduced by 6dB. I'm sure that the sensitivity of the 4 and 8 ohm versions are different to start with.

Doesn't matter whether 4 or 8 ohms. You will always have 3dB lower efficiency for the isobaric compared to a single driver. But in parallel you double the power in (for a given voltage drive) and get the same SPL out where as in series you cut the power in by 1/2 and get 6dB lower SPL out.

If the 4 ohm driver is more efficient than the 8 ohm, that's something else to consider.
Ah ok, so if using the 4 ohm version rated at 91dB, i'd be looking at a 6 dB loss in output in series. For some reason I thought it was only a 3dB loss in output overall. Id better stick to the 88dB 8ohm drivers in parallel then.

Last edited by Bill poster; 27th September 2017 at 12:32 PM.
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