Isobaric push pull

[Music is life]

Hope I spelled that right lol.
I was contemplating a project of getting the most out of 2 3015lf drivers in push pull Isobaric to make the enclosure as small as possible with a decent f3.
[That would be speaker cones facing each other with reversed polarity]

I realize the expense. What would be the draw backs?
It would be now 4 Ohms.

What would the 1 watt sensitivity be as compared to a single driver?
While thermal power handling will double will it reach it Xmax quicker?
Thanks in advance.

[billfitzmaurice]

What would be the draw backs?
The sensitivity, response and displacement limited power will be the same as with one driver.
Isobarics had some utility 30 years ago and more, when extremely high Vas drivers often required 10 cubic foot and larger cabs, so using two drivers to get a more WAF sized speaker for the home made some sense. Spending twice as much for drivers to get a smaller cab never made sense to the pro-sound crowd, so it didn't catch on then, and with today's drivers it makes even less sense now.

[badman]

The sensitivity, response and displacement limited power will be the same as with one driver.
Isobarics had some utility 30 years ago and more, when extremely high Vas drivers often required 10 cubic foot and larger cabs, so using two drivers to get a more WAF sized speaker for the home made some sense. Spending twice as much for drivers to get a smaller cab never made sense to the pro-sound crowd, so it didn't catch on then, and with today's drivers it makes even less sense now.

"Sensitivity" is referenced to voltage and will remain the same. Efficiency will be 3dB lower. You can't shrink a box without giving up efficiency. The other part of isobaric is the even-order distortion cancellation. The value is debatable and varies with driver quality. If you're willing to have 2 drivers, (and 2x the nominal single-driver box size) you can just face one magnet in and one out and achieve the same distortion cancellation.

[Taterworks]

People that spell the term 'Isobarik' make me grind my teeth. 'Isobaric' is the correct spelling.

One of the first companies to popularize an isobaric design was Linn, which sold a model known as the "Isobarik", but one of their 'things' is to add K's to the names of their models where you would expect a C, like the Kan loudspeakers, Magik and Sondek turntables, Akurate power amplifiers, and Klimax speakers. That's why the 'Isobarik' misspelling has persisted for so long.

[Music is life]

Thanks for the info, it was very helpful in considering such a project.

Since thermal compression usually sets in at about half the rated power handling quite significantly it would seem that a small but true to life sensitivity could be gained back over the efficiency loss of the larger box with one driver. Maybe 1 to 2 db? (whether or not I've confused sensitivity and efficiency)
Also another .5 or so may be gained through additional power handling. But at the risk of overreaching Xmechanik (lol) without properly set high pass and limiters.

None of which if true make the design "worth it". Such a design might only be worth it in very specific situations.
Just thinking.

[hectorloshuk]

Bob you can close this, Ive only had 2 people E-mail for pictures. It is still for sale, guess this must be a bad time to try to sell. Ill post again latter. Im in no hurry to sell it. It looks good setting right beside my 79 Black Push/Pull