Isobaric Bass Cabinet?

[jeff_free69]

Just curious - any thoughts on this ?http://www.premierguitar.com/Magazine/Issue/2010/Jul/Orange_SP410_Isobaric_Bass_Cab_Review.aspx

Its (4) 10's in the space of 2. Could be an interesting idea with some lightweight neo's. But there appears to be a port, its that normal for an isobaric design?
What driver characteristics would make it appropriate for this application?

[Randy L]

I think I remember a discussion about IB designs for pro PA use a while back.
As far as the ORANGE company is concerned, I'm VERY leary of trusting a company that lists under their product Specifications page, just 2 things...

http://orangeamps.com/products.asp?Action=View&ID=111

Orange SP410
Features: 4 separated speaker compartments
Output: 1200 watts RMS

WOOOOOO....awesome! I'll order 14 of them!!! :cool:

[billfitzmaurice]

Just curious - any thoughts on this ?http://www.premierguitar.com/Magazine/Issue/2010/Jul/Orange_SP410_Isobaric_Bass_Cab_Review.aspx

Its (4) 10's in the space of 2. Could be an interesting idea with some lightweight neo's. But there appears to be a port, its that normal for an isobaric design?
What driver characteristics would make it appropriate for this application?It has the same output as a 2x10. That's why you don't see isobarics used by anyone else, and why those made by Orange will eventually fade away. Bass players have a tendency to want to get the most possible output for the least possible outlay, and these have the least possible output for the most possible outlay. Mag reviews are worthless, they love anything that generates ad revenue. Reviews without a single measurement of any kind are pure piffle.

Orange SP410
Features: 4 separated speaker compartments
Output: 1200 watts RMSYou'd think a speaker company would know that speaker output isn't measured in watts. :confused:

[hyperlite]

better yet...


Isobaric design using four ultra-lightweight Neo-Dineum 300 watt 10" loudspeakers.

That must be a super special kind of Neodymium! :cool:

Looks like they've been around for a long time though...

[billfitzmaurice]

better yet...



That must be a super special kind of Neodymium! :cool:

Looks like they've been around for a long time though...
In their defense they make fine amps. But as for their cabs, drivers stuffed in a box.

[jeff_free69]

It has the same output as a 2x10. That's why you don't see isobarics used by anyone else, and why those made by Orange will eventually fade away. ..


Yeah I was really just interested in the general design theory. But after a little reading, and as you confirmed, its only half as efficient! That sure makes it a lot less sexy!

Is this sometimes referred to as "push-pull" ? (about 20+ years ago I had a friend of a friend with a DIY system that totally blew me away ; I remember him referring to the subs as this)

[Randy L]

I too have seen this design, but never for pro audio. It seems to have gone by the wayside...maybe it was a "fad" or something.

[billfitzmaurice]

Is this sometimes referred to as "push-pull" ? (about 20+ years ago I had a friend of a friend with a DIY system that totally blew me away ; I remember him referring to the subs as this)Push-pull usually refers to drivers on opposite sides of the cab, placed that way to keep the box from dancing about.


I too have seen this design, but never for pro audio. It seems to have gone by the wayside...maybe it was a "fad" or something. It was semi-popular when Vas figures of 20 cu ft and more were the norm. Isobaric loading of two drivers give the same response and output as one, but with halved Vas, making a smaller cab possible. That's hardly an advantage with pro-sound drivers that typically have Vas in the vicinity of 2 cu ft.

[AMC]

better yet...



That must be a super special kind of Neodymium! :cool:

Looks like they've been around for a long time though...

I'm still trying to find some paleodymium speakers, for that real old school rock sound!

[AMC]

Is this sometimes referred to as "push-pull" ? (about 20+ years ago I had a friend of a friend with a DIY system that totally blew me away ; I remember him referring to the subs as this)

This is the best example of a push pull design I can find. This is an M&K unit that started production close to 20 years ago. The idea was that distortions could be reduced by putting the drivers in this orientation, making the distortion created by driver A, 180 degrees out of phase with the distortions of driver B. This was of course limited to 1 type of distortion, and in general irrelevant to sub bass production. This was however, an excellent sounding sub for it's size, about 10 X 10 X 16 as I recall from memory, used 2 8".

Side note, these drivers are available in the close out section right now at PE!

[Jeff B.]

It has the same output as a 2x10. That's why you don't see isobarics used by anyone else, and why those made by Orange will eventually fade away. Bass players have a tendency to want to get the most possible output for the least possible outlay, and these have the least possible output for the most possible outlay. Mag reviews are worthless, they love anything that generates ad revenue. Reviews without a single measurement of any kind are pure piffle.
You'd think a speaker company would know that speaker output isn't measured in watts. :confused:


Well, you could measure it in Watts. But, given speaker power efficiencies it would take a lot of speaker and a lot of power to generate a dozen of them. Acoustic watts, that is.

[drwoo]

I'm also planning to design/build a vented isobaric speaker for my keyboard set. Contrary to a couple of previous posts, isobaric speakers are indeed more efficient, to the tune of +6dB (if wired in parallel) according to the 'loudspeaker design cookbook'. The drivers I'm planning on using are the goldwood GW-1058 10" woofers. These have an fs of approx 40 Hz, so they should cover the low end of my synths' range just fine. I'm planning on using 4 drivers/cabinet, so I guess that would actually be a twin isobaric configuration. I'll keep you guys posted as to my progress.

[billfitzmaurice]

isobaric speakers are indeed more efficient, to the tune of +6dB (if wired in parallel) according to the 'loudspeaker design cookbook'.No, they aren't. You have misunderstood what Vance wrote, if indeed he was referring to Isobariks at all.
BTW, one does not use dB to refer to the efficiency of speakers. Efficiency is stated as a percentage, that of acoustical watts output relative to electrical watts input.
Sensitivity is quantified in dB. When two identical speakers are parallel wired with constant voltage sensitivity will increase by 6dB; with constant power it will go up by 3dB. With constant voltage 3dB comes from the halving of impedance; in both cases 3dB comes from the doubled Sd. In the case of isobarik mounted drivers constant power sensitivity remains the same, because Sd remains the same. Maximum output also remains the same as one driver, because Vd is that of one driver.

[Jeff B.]

I'm also planning to design/build a vented isobaric speaker for my keyboard set. Contrary to a couple of previous posts, isobaric speakers are indeed more efficient, to the tune of +6dB (if wired in parallel) according to the 'loudspeaker design cookbook'. The drivers I'm planning on using are the goldwood GW-1058 10" woofers. These have an fs of approx 40 Hz, so they should cover the low end of my synths' range just fine. I'm planning on using 4 drivers/cabinet, so I guess that would actually be a twin isobaric configuration. I'll keep you guys posted as to my progress.


Well then, it looks like you are going to be 6dB disappointed.

[Ludo]

In the case of isobarik mounted drivers constant power sensitivity remains the same, because Sd remains the same...

Shouldn't the power sensitivity be reduced by 3dB since the impedance is halved?
Voltage sensitivity should remain the same, I think.

[billfitzmaurice]

Shouldn't the power sensitivity be reduced by 3dB since the impedance is halved?
Voltage sensitivity should remain the same, I think.Yes, you're right. I don't model iso's often enough...as in almost never... to have that at the tip of my tongue. You can model them in WinISD Alpha Pro and it will confirm that all you get for paying for a second driver is a halving of the net box volume. Voltage sensitivity, and more important maximum SPL, is the same as with one driver.