A new reason to use an isobaric enclosure

[lindermat]

Traditionally isobaric enclosures were used for subwoofers to make the enclosure smaller (with trade offs for efficiency and such)

I was in a store recently an listening to the large crop of portable bluetooth speakers. some of which have pretty good sound! (generally the bigger the better) Anyway, most of these used passive radiators and it got me thinking that since enclosure size is high up on the list of requirements for this type of speaker, wouldn't an isobaric configuration be a good choice?

Yes, I know more power equals shorter battery life, but wouldn't you be able to get better bass with half the size enclosure?

It seems though that most of these use small full range drivers. Would an isobaric configuration still work for full range drivers?

Thanks,

 

[Greebster]

Doubling woofers, doubling power requirement and halving the battery life for the same spl. Add in cost of filter (minor, only midfi output). Only gain would be how low? Is upto an extra octave worth it?

Better to use a larger, more effecient driver in a bigger box.

Looking back at the '70's as a kid with our 3.2w/ch car radios and large effecient full range drivers, was a real task just to overcome road noise 😉

 

[lindermat]

That's kind of the point though, using a bigger box isn't really an option....

 

[chrisb]

as greebster suggested, being able to actually hear that extra bottom octave or so could be a lot harder than you think with road and wind noise factored in

just for fun, download one of the free RTA apps for smart phone or pads to give you an idea as to SPL and spectral content of road noise - it could be very eye opening

 

[sreten]

Hi,

There is no difference really between a single driver
ideal for purpose and two drivers repurposed at all.

Isobaric is about changing the purpose of a pair drivers.
A single driver can always have the same parameters.
Consequently a single driver is better as its cheaper.

So no, as a principle it doesn't work any better
than a nice driver ideally suited for the purpose.

rgds, sreten.

Isobaric works better for say repurposing two
PA subs for domestic use, or cheap drivers.

 

[lindermat]

I disagree. The difference is the SIZE. That's the whole point of this
(and an isobaric configuration) Assuming the cost of the additional
driver is within budget and one of your design goals is to make the
enclosure as small as possible (fit in the palm of your hand lets say)
I think an isobaric might make sense.

 

[xrk971]

I used two low cost $5 woofers in isobaric setup and it reduced volume of sealed sub and tightened up impulse response - reduced ringing significantly. However it really cut response as the back side of driver doesn't let as much HF through compared to front of cone. For cheap drivers it was worth it but not sure I would do this with expensive drivers as it doubles cost. Just get a lower Qts driver lower Vas driver.

 

[lindermat]

The problem with getting a lower Qts/Vas driver is that I don't know that would work with a enclosure volume of say 0.1 liters! Hence the interest in isobaric a driver could be used that would normally require a enclosure TWICE the size (a whopping 0.2 liters!) 🙂

 

[xrk971]

Ok you are talking tiny little mp3 Bluetooth type speakers. Most compact way to get bass is a passive radiator. That won't ruin your HF response like having to listen to the backside of fullrange driver.