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Isobaric Cabs - will they be loud enough?

F

fivespoke

Feb 16, 2011
37
0
Poole, Dorset, UK
#1
I'm in the market for a new rig, with a mind to portability and have been looking at the Orange 2x12 isobaric cabinets.

Does anyone have any experience playing through these? I'm looking at 2 cabs with a terror bass 500w head to replace my ageing (and heavy) 300w Trace Elliot 2x10 combo, which i run with a 15" extension cab.

I'm slightly worried that being a fairly small rig, it won't be loud enough to compete with a loud drummer and a Boogie-using guitarist. Any thoughts?
 
#2
Iso cabs have half the output one might expect. An Iso 212 will be as loud as a 112. You also loose sensitivity, as it will take twice the power to reach the same level of volume, albeit your power handling is doubled due to the extra driver. They also weigh more than other cabs in their SPL range as they have an extra driver.

All that said, they do have good low end extension. If they fit your volume and tonal needs then they could be a good choice. IMHO there are better ways to get all the effects of an iso cab in a lighter, louder, more economical package.
 
#3
I agree to disagee, my SP212 is every bit as loud as the 410 I got rid of. CL400Peavey and I have debated this before, but I actually use an isobaric 212 on a regular basis, and it puts out tons of low end at plenty of volume. I didn't believe it myself until I tried one. Any member of my band will attest to the fact that my Orange TT and the SP212 is more than enough for almost any gig. By the way, both my guitarists play through Boogies, and I have no trouble competing.
 
#5
Isobaric cabinets have two drivers mounted one behind the other, with a sealed chamber between them, so a 2x12 looks like a 1x12. As far as i understand it the idea is that the two drivers work together to provide added bass response from a smaller cabinet.

I've not played through one but like the idea of using smaller cabinets, as long as they're going to be loud enough!
 
#8
Mr. Foxen said:
Isobaric means you pay for and carry a second speaker that is doing the work that the back of the other speaker would do otherwise.
Click to expand...

+1

I dont doubt CB007's experience. He is getting similar volumes from his iso as he was through his old 410.

That said there is not a balance in frequency response, sensitivity, power handling, and total SPL.

The iso wins in low end, clearly from his testament. I do doubt how hard he has pushed either cab, and wonder what SPL levels he is playing at.

If he is pushing a lot of low bass then yes his Iso cab may have more volume than a very mid voiced 410 or 212. Low end extension is only part of the game when it comes to volume though (I know who would have ever guess I would say that). If we are talking more mid voiced bass, the standard 212 or 410 will go louder, with the same power, and a bit louder with more power.

How much louder? That is tough to say, since the specs needed to make that comparison are almost never available from manufacturer.

Iso designs target low end extension with out using more specialized woofers.

IMHO its a raw deal to trade sensitivity, SPL, and weight for a bump in the low end when there are other options out there.
 
#9
Mr. Foxen said:
Isobaric means you pay for and carry a second speaker that is doing the work that the back of the other speaker would do otherwise.
Click to expand...

+1. The design sacrifices increased cost and complexity with lower efficiency in order to get the usual bass response of 1 driver in a smaller cab. If you NEED a 212 in the volume of a 112, it's 1 way to get there. As far as volume, physics dictates that an isobaric 212 will be as loud as a 112 with the same driver in a larger box. As far as people saying the isobaric 212 is louder than some other 410.....well..... must not have been a very loud 410:p......and were they tested side by side with the same amp/bass and settings (really the only true way to evaluate them for respective volume)?

Seems to me if one has already paid for a pricey orange 212, there'd be a massive bias in wanting to believe it's as loud as a 212. I have recently heard the isobaric 410, and it didn't strike me as very loud.....certainly nowhere near as loud as an efficient 410.
 
#10
i actually purchased My Tiny Terror Bass before I bought the SP212. It worked great with my Boogie 118, my GK212NEO, my SWR 210 and 410 cabs. When I heard it through an SP212 I was amazed at the sound level and tone. The SP212 also sounded great with my SWR and Boogie amps. I sold my GK and SWR cabs because the Orange sounded better. So, yes I did side by side comparisons, and the SP212 won. I don't expect to convince anybody who believes otherwise, but the Isobaric are great cabs, and worth the price.
 
#11
Just to throw a monkey wrench in this thread, what about that 2x12 by Glasstone that gets raved about once in a while? That's the size of a 1x12, and purportedly goes much louder and full range-er than it has any right to. 2nd driver is hidden, but no mention of isobaric. What's _it's_ parlor trick??
 
#12
There is a lot of chatter about this very old design.
The isobaric concept is detailed in Harry Olson's book 'Acoustical Engineering' with first copyright of 1940.
He calls it a "compound" configuration.

Here is a WIKI Link that gives a good explanation.

The sole purpose of the isobaric is reducing the cabinet internal volume to half that required for a single driver.
It is not intended to be lighter, louder, or lower, or anything else other than smaller. That's it.

The ideal configuration is the clamshell, where the fronts of each driver face each other with the baffle board in between.
This produces the smallest air volume between the two cones.
It also keeps the motor assemblies of both drivers exposed to air, rather than a tiny sealed chamber. Read: they cool better.

The isobaric design reduces the efficiency by -3dB compared to a single driver.
However, a parallel wired pair draws an additional unit of power, so the acoustic output is probably a wash.
I am tardy on getting my BP102 isobaric ready for RTA, so I have no hard facts at this time.

The sole use for isobaric is making small boxes out of big ones.
For example, it is pointless to use an S2010 (0.93 cubic feet) in isobaric.
Delta 15LFa at 22 cubic feet could be reduced to 11 cubic feet internal volume. A significant savings in size.

The design is very simple to prototype.
For BP102, build a simple box with 2.0 cubic feet internal volume.
Cut the baffle to front mount a BP102 driver.
Mount two BP102 face to face, and front mount the unit to the baffle.

Cut a vent hole in the box that will accept a 4.20" ID PVC section sticking outside the box.
Cut PVC to length to get the exact tuning.
The external PVC length does not change the box volume, so tuning is easy.

After you achieve the correct tuning, you can calculate the effective end correction factor for this specific vent and box.
 
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#13
It was worthwhile when they couldn't make decent speaker motors, but now you can get a decent speaker motor on a single cone for less than the price of two mediocre ones that would otherwise need a giant box. Now the space taken up by another driver, isobaric chamber, and the necessarily larger port takes up a significant amount of the space saved.
 
#14
If it works well--that's the bottom line. I have pretty much experience building and experimenting with them. With an isobaric you really have a super 112 in this case. I don't know the woofer they're using ---maybe they got 12's with super long excursion. But with an isobaric the amount of air moved is still limited by the cone area of the single 12. You can get better control, smaller box,etc. but the amount of air moved is still the same as the single 12. Now if they're using the highest excursion pro sound 12 (the Eminence Kappalite 3012lf) it has a vd (cone area x excursion) of about 500cc. Now if you use a typical not-so-great 10"er that is used in lots of pedestrian 4 x 10's you get a vd about the same. Now if they are OEM'ing a long excursion 12 I could see it competing with a 4 x 10. And the fact that it would likely have a better low end might give it an edge. I kindof doubt that they're using that expensive of a 12---but maybe so. But----in that case---the single 12 mounted in a standard reflex enclosure would do the same thing---although the isobaric would give better low end control---albeit at a higher price and weight.
 
#16
rhopper said:
You need to try a SP 212 cab before you make judgement. Most critical comments are from those who are strictly judging the cab on specs alone without actually trying one.
Click to expand...

How do you know which cabs people have played through?

Not everyone has access to every cab. Understanding of specs and designs let people gauge and compare products. You may have never have driven a Bugatti, but you can look at specs and understand that it has a faster top speed than a Mustang.

Or maybe you have to drive every car on the market to truly understand whats available.
 
#17
I have played through them, and I don't find them to be particularly remarkable. They are loud, but without a ton of bottom end. 4x10" killer I think not. You would be far better off with one of the new "Super 12's" on the market. Audiokenisis TC12, Baer ML-112, or even a Fearful design 12"(might be a bit larger than you were looking at though).
 
#19
It's a gimmick. It was useful decades ago, but not now.

A cabinet maker that has connections to a driver manufacturer could design a single driver with the same specs as two drivers in isobaric configuration. You can have the same theile small parameters in one driver as you can have in two.

Alas, Nobody would by such a drivers in general, because they wouldn't the best use of materials and they'd be expensive.

Even then drivers are better these days, they have the best design of materials to performance.
 
#20
I experimented with this concept about 10 years ago. The idea was to produce a line of amps that had a neutral sound (as far as possible) and had excellent low end extension. I've always been of the opinion that most bass amps didn't have enough bass - real low end - and that most of their output was in the upper - mid bass. The neutral sound would allow the use of cabinet emulators without additional coloration from the existing cabinet and amp. I worked with driver designers at Eminence and had three drivers designed; a 12", a 15" and an 18". I put together a prototype using four 15" drivers mounted in pairs - the isobaric, push - pull.

I have to say that it worked but yes, it was far less efficient than conventional cabinets. The iso - push pull design subtracts approx. 6 dB from the driver's efficiency and this particular design had to have a very low free air resonance and a very large Xmax - other factors which also detract from efficiency. The prototype had excellent low end extension - down only 3 dB at 27 Hz. It shook the dust off the rafters in the shop. But when used with a full band I got comments like "When are you going to turn that thing up?" The high end was great, using three 8" drivers with matching horn loaded, carbon fiber dome tweeters in a conventional closed box alignment.

But the deficiencies of the low end were the drawback. It was large, although about half the size of an enclosure with a conventional design, and not as powerful as one would expect a rig that size would be. It was a little larger than an SVT rig. I gave up the idea for the reasons that it would have taken too much time and money to get the driver design right (the sample drivers make excellent home subwoofers) and the marketing aspect was iffy at best. Set up two amps side by side in a music store and most of the time the amp that plays louder wins. Bass players are in general used to (conditioned to) the sound of conventional bass amplification with it's inherent resonance peak in the 80 - 150 Hz region. Anything else sounds "odd." I was trying to solve a problem that didn't seem to be a problem to anyone else. This would have been more of a high end amp aimed at pros who would have used it in the studio and as that it was too big. For stage use you have to consider the factor that such an amp has no advantage for professional players. Their amps simply function as monitors with most of their house sound being channeled direct through the PA. At the time I did not have the wherewithal to invest the resources to develop the product to a higher level of perfection and the rather limited market did not seem to justify the expenditure. Quite frankly I'm glad that someone seems to have worked out some of the bugs. I'll have to check out the product.
 

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