Isobaric - does it work vented?

[Guiria]

My bro-in-law has ordered 2 Dayton 10" DVC subs, the Dayton 240 watt plate amp, and the Dayton 10" passive radiator to build an isobaric sub.

He decided to go isobaric because the box size is considerably less vs. a normal ported enclosure. The F3 of the enclosure is 26 Hz. We plan on wiring the subs to an 8 ohm load.

So the big question is...will he realize any benefit (other than cabinet size) vs. running a single woofer + passive radiator?

Given the quote here from Annunaki's sticky (it references sealed designs)...do the same benefits apply for a ported enclosure?

Compound Compression Enclosures and/or Isobaric Enclosures: These types of systems are nice if slightly inefficient. The benefits are very small enclosures and extended low frequency extension. It essentially uses two woofers that act as one. They also only give you the output of one woofer. However, they typically will play much deeper and more accurate than a single woofer alone in a sealed enclosure. The accurace usually comes from the way the woofers are loaded cancelling any anomalies. The disadvantage here is having to use two woofers and get the output of one and the use of a lot of amplifier power. Given the circumstances the advantages can significantly outweigh the disadvantges.

 

[WmAx]

So the big question is...will he realize any benefit (other than cabinet size) vs. running a single woofer + passive radiator?

Only benefit is generally reduced cabinet size. If using a rather poor quality woofers that have poor incursion vs. excursion symmetry due to a poorly designed motor, then installing one woofer facing the other(clamshell type install) can effectively reduce this non-symmetry, thus reducing distortion.

-Chris

 

[Guiria]

Only benefit is generally reduced cabinet size. If using a rather poor quality woofers that have poor incursion vs. excursion symmetry due to a poorly designed motor, then installing one woofer facing the other(clamshell type install) can effectively reduce this non-symmetry, thus reducing distortion.

-Chris

Two things,

One, are you implying the woofers he purchased have the poor incursion vs. excursion symmetry you are talking about (go ahead say it, we're all grown-ups not to mention the woofers cost 30 bucks each so they can't have it all.)

Two, is it safe to say that reducing distortion is effectively improving SQ within the performance of the driver(s) ability.

 

[TLS Guy]

Isobarik and VAS

In isobarik configuration, the Vas of the Thiel Small parameters is halved. So you get an enclosure half the size with isobarik configuration for the same F3. However, there is no free lunch as the efficiency is also halved.
You can use any design with isobaric loading except horn or open baffle.
Why is he using DVC drivers? Is it to use two amps? The big advantage of DVC is to be able to apply eq in the crossover, as you usually use the eq to ameliorate the step response, but that would not be an issue in a sub

 

[WmAx]

Two things,

One, are you implying the woofers he purchased have the poor incursion vs. excursion symmetry you are talking about (go ahead say it, we're all grown-ups not to mention the woofers cost 30 bucks each so they can't have it all.)

Two, is it safe to say that reducing distortion is effectively improving SQ within the performance of the driver(s) ability.

I was not aware of the costs of the woofers, nor do I know the model, nor am I ware of the measured performance of these woofers. However, if they are $30 new priced units, it would seem that is more likely that they will have substantial compromises.

And yes, reducing distortion in such a case as you have implied would increase SQ, because at even moderate SPLs, such quality woofers will probably produce very high levels of distortion. But the specific nature and amount of distortion can only be guessed for your particular application. You would likely benefit more by using the woofers separately if the cabinet volume can be accommodated.

-Chris

 

[Guiria]

Why is he using DVC drivers? Is it to use two amps? The big advantage of DVC is to be able to apply eq in the crossover, as you usually use the eq to ameliorate the step response, but that would not be an issue in a sub

He is using the DVC subs primarily because of a price point. They model reasonably well for the application and are less than $30/sub.

Plus there is a DIY coolness factor of building something you don't see everyday (reason for isobaric).

 

[annunaki]

DVC won't matter as long as the final impedance with the drivers in parallel is at the proper impedance of the amplifier.