https://www.htguide.com/forum/ en Wed, 26 Aug 2026 15:16:59 GMT vBulletin 60 https://www.htguide.com/forum/images/misc/rss.png https://www.htguide.com/forum/ https://www.htguide.com/forum/mission-possible-diy/design-studies-theory/961242-how-high-can-an-isobaric-midwoofer-pair-reasonably-be-used Sun, 09 Aug 2026 03:05:50 GMT Is there any inherent reason a pair of 6.5–7" midwoofers in a conventional isobaric arrangement can't be run cleanly to around 2 kHz?

Assume both drivers individually work well to 2 kHz. I am specifically wondering whether the isobaric arrangement itself — trapped air between the drivers, coupling, spacing, cavity resonances, etc. — creates problems as frequency rises, and what determines the practical upper limit.

It has obviously been done. The Totem Mani-2 reportedly ran its iso pair to around 3 kHz, and I just found the Dellichord FR6, a current 6.5" two-way using two identical SB Acoustics midwoofers isobarically, a passive radiator, and a 1.7 kHz crossover.

I am going to build a test box and compare a single driver directly against the iso pair, but I would be interested in any measurements, experience or technical explanation of what happens to an isobaric pair as frequency increases.

Please keep this to the question of using an isobaric pair into the midrange. I understand the usual iso tradeoffs and alternatives. “Use a different driver,” “use DSP,” “there's no reason to use isobaric anymore,” etc. may all be perfectly reasonable advice, but aren't the question I'm trying to answer.

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https://www.soundstageaustralia.com/...s-fr6-speakers]]> DaveFred https://www.htguide.com/forum/mission-possible-diy/design-studies-theory/961242-how-high-can-an-isobaric-midwoofer-pair-reasonably-be-used