Home Theater Forum and Systems banner

1 - 20 of 53 Posts

·
Registered
Joined
·
150 Posts
Discussion Starter #1
How come no one seems to do IsoBarik builds? It seems with the large boxes in home theater it would have a big benefit.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #3
I just see threads all the time asking for deep bass in small cabs and wondering if there is no disadvantage besides cost it is not more popular.
 

·
Elite Shackster
Joined
·
1,506 Posts
Most people looking for deep bass are also looking for LOTS of deep bass :R. The only real advantage is smaller box size, while the disadvantages are double the cost for the driver with performance about 1/4th of what would be possible with a different design, and a bit more complicated to make. It does seem to be a design that gets forgotten about but I just don't think the demand is there for it.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #5
How would the performance be 1/4?

Would not the performance just be the same as one driver?
 

·
Premium Member
Joined
·
1,941 Posts
I think it is the same. I guess such a design would be nice with cheap drivers :)
 

·
Elite Shackster
Joined
·
1,506 Posts
How would the performance be 1/4?

Would not the performance just be the same as one driver?
With two drivers sealed you gain 6db over a single driver. Porting gains at least another 6 db and depending on the design can be much higher at tuning.

The point is for the same cost, much higher performance can be had with a different design.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #8
With two drivers sealed you gain 6db over a single driver. Porting gains at least another 6 db and depending on the design can be much higher at tuning.

The point is for the same cost, much higher performance can be had with a different design.
IsoBarik can be used in a ported design right? I am not trying to argue it is just I have never seen an IsoBarik on these forums and am wondering if there is some fundamental reason beyond cost.
 

·
Elite Shackster
Joined
·
1,506 Posts
You could port an Isobaric though it would still be 6db shy of a dual woofer ported design.

I don't think there's a fundamental reason people don't build isobaric subwoofers. There are several reasons. I guess if you could say that most DIY'ers are after performance they cannot otherwise affoard so in a way cost is a big factor.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #10
Yeah I agree, I guess if there is no increase in distortion or other things above my head, then the biggest reason is "If I had 2 drivers and 2 amps I could have WAY more bass."


My feeling is most people with a house probably paid $150 to $200 per square foot of covered space. a 24" sono-sub takes up over 3 sq.ft.

Personally I am interested because my current DIY sub is about 7 cu.ft. It is fun to think about having the performace of a 18" large ported box in the same space. :)
 

·
Registered
Joined
·
154 Posts
My first real subwoofer was an Isobaric push-pull using Audio Concepts AC12 woofers. It was essentially an imitation of their original Titan subwoofer, in a different shape box.

To this day, I still think it was one of the best sounding subwoofers I've heard, though by today's standards, the output capabilities would be pretty meager. When operated in push pull, you can reduce harmonic distortions. If I recall correctly, Audio Concepts also claimed that you get slightly more linear excursion than a single driver, and slightly lowered F3. I probably have their subwoofer design manual around somewhere. Of course, you also get double the electrical power handling. You might want to ask Mike Dzurko over at Audio Circle though, he'd be the one to know. :)

I'd love to have the same performance of my current subwoofer with a box half the size (and yes, not use more power). But, woofers are uber expensive these days. Back when I bought my AC12, they were only $60 each. Then again, my Tempest-X does offer more swept volume per dollar, 20 years later. Still, it's $120 vs $400...

My impression is that now, woofers offer so much lower distortion to begin with, that the slight distortion cancelling benefit of push-pull is outweighed. So, it really comes down to box size. These days, power is cheap and people have seemingly no qualms about using as much as they can, so box sizes just keep getting smaller. Plus, if you went for a ported isobaric, I can see there being major issues fitting the ports inside the box.
 

·
Elite Shackster
Joined
·
1,506 Posts
My impression is that now, woofers offer so much lower distortion to begin with, that the slight distortion cancelling benefit of push-pull is outweighed. So, it really comes down to box size. These days, power is cheap and people have seemingly no qualms about using as much as they can, so box sizes just keep getting smaller. Plus, if you went for a ported isobaric, I can see there being major issues fitting the ports inside the box.
Agreed on both counts. I just complete a build that intended to make push pull, but in the end I decided the extra cubes would have a bigger effect on performance. Perhaps this is also why we don't see as many Isobaric. Better drivers with higher power handling + bigger amps = different solution for small box performance.
 

·
Registered
Joined
·
185 Posts
I think it is the same. I guess such a design would be nice with cheap drivers :)
Two drivers isobarically mounted do have the same sensitivity and output as one. The only advantage is the halving of the cabinet volume, achieved at the doubling of the driver cost. Doing so made some sense with driver technology as it existed 20 years ago and more, when very high Vas figures were commonplace while very long Xmax was not. Modern driver technology has rendered the isobaric alignment obsolete, and that's why they aren't seen much anymore.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #14
Two drivers isobarically mounted do have the same sensitivity and output as one. The only advantage is the halving of the cabinet volume, achieved at the doubling of the driver cost. Doing so made some sense with driver technology as it existed 20 years ago and more, when very high Vas figures were commonplace while very long Xmax was not. Modern driver technology has rendered the isobaric alignment obsolete, and that's why they aren't seen much anymore.
Thanks for that Bill.


It is good news that the tradeoff is so simple with no other factors being involved.
 

·
Premium Member
Joined
·
1,941 Posts
Agreed Bill.
 

·
Premium Member
Joined
·
14 Posts
Jamo has in the past build a lot of Puss Pull subwoofers.
Isobarac can be jused for a closed cabinet. To reduce te size of a big cabinet 400 Liters to 200 liters.
 

·
Registered
Joined
·
150 Posts
Discussion Starter #17
Jamo has in the past build a lot of Puss Pull subwoofers.
Isobarac can be jused for a closed cabinet. To reduce te size of a big cabinet 400 Liters to 200 liters.
you are saying it cannot be used in a Vented enclosure? Why do you say this?
 

·
Registered
Joined
·
2,431 Posts
Isobarick doesn't make sense in ported enclosures though. The main limitation is usually fitting enough port area to properly handle the driver and get a low tune with a non peaking FR. When you halve the enclosure volume for a given basic FR, but you will then need a huge port to get the same tuning as you would with double the volume. You can't cheat that part because it's related to the resistance and mass of air in the port related to the air space in the enclosure.
 

·
Premium Member
Joined
·
14 Posts
When you will have a low resonant Frq you can use isobarac. not to make the cabinet smaller. Only to get a lower bass.
Exsample normal cabinet size is 40 liters. Whit second woofer mounted you can add a
little mass to your woofers. your resonant Frq is droping douwn. Te cabinet get a lower - 3 Db output in the same 40 liter cabinet.
 
1 - 20 of 53 Posts
Top