Isobaric reflex sub

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   So, I am not exactly a newbie, but I have never tried to use an Isobaric arrangement. My question is, if wired properly and the drivers are face to face, I feel like it should be OK to bolt them in without a baffle between them, since the pressure between drivers should not be all that high, as they are moving parallel to each other, as opposed to a PPSL where they are moving against each other. Am I wrong in thinking this or should I put a spacer baffle between?

For the record, this is a dumb car sub, and I know people hate those on here. The space issue is my concern for this project, and my understanding is that isobaric arrangements allow for an enclosure of half the size with the same frequency response as a single driver BP6, but a loss of efficiency (which is not a huge deal in a car cab). Has anybody else tried an Isobaric BP6 and have any warnings or observations, or votes that it is a waste of time? I feel like it could be a fun problem solver for a small project design one off.

Edited by b grade - 22 July 2016 at 2:28pm

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b grade Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337	Post Options Post Reply Quote b grade Report Post Thanks(0) Quote Reply Topic: Isobaric reflex sub Posted: 17 July 2016 at 4:03pm
	So, I am not exactly a newbie, but I have never tried to use an Isobaric arrangement. My question is, if wired properly and the drivers are face to face, I feel like it should be OK to bolt them in without a baffle between them, since the pressure between drivers should not be all that high, as they are moving parallel to each other, as opposed to a PPSL where they are moving against each other. Am I wrong in thinking this or should I put a spacer baffle between? For the record, this is a dumb car sub, and I know people hate those on here. The space issue is my concern for this project, and my understanding is that isobaric arrangements allow for an enclosure of half the size with the same frequency response as a single driver BP6, but a loss of efficiency (which is not a huge deal in a car cab). Has anybody else tried an Isobaric BP6 and have any warnings or observations, or votes that it is a waste of time? I feel like it could be a fun problem solver for a small project design one off. Edited by b grade - 22 July 2016 at 2:28pm

b grade Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337	Post Options Post Reply Quote b grade Report Post Thanks(0) Quote Reply Posted: 17 July 2016 at 4:10pm
	The reason I prefer not to do a spacer baffle is that it seems like I would either need a second access door or else some kind of circular spacer piece that seems annoying to make and kind of weak structurally. Bolting the drivers together and then placing them on one side of the baffle just seems easiest. Edited by b grade - 17 July 2016 at 4:11pm

Pasi Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 25 April 2010 Location: Knutsford Status: Offline Points: 2732	Post Options Post Reply Quote Pasi Report Post Thanks(1) Quote Reply Posted: 17 July 2016 at 5:17pm
	Do it like OHM HD-BB which has 12mm plywood/MDF ring between the drivers. One baffle but still enough spacing between the drivers to avoid any issues from high excursion.

b grade Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337	Post Options Post Reply Quote b grade Report Post Thanks(0) Quote Reply Posted: 17 July 2016 at 5:52pm
	Kinda what I figured too, but I wish sometimes the coin flip came up the easier way. Not real hard at all though. Just an extra little piece. Thanks.

b grade Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337	Post Options Post Reply Quote b grade Report Post Thanks(0) Quote Reply Posted: 19 July 2016 at 7:32pm
	In case anybody cares where I am going with this, I have decided that an Isobaric Bass reflex will satisfy the requirements, sound better and be a much lazier build, which is my natural inclination anyhow. Boring, old, lovely and simple reflex.

b grade Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337	Post Options Post Reply Quote b grade Report Post Thanks(0) Quote Reply Posted: 22 July 2016 at 2:26pm
	The final speaker came out sounding pretty awesome. I cut all kinds of corners and slapped it together in like half a day. No paint. No screw filler. No frills of any kind. Nobody on here wants to see that. Sounds really nice though. The chamber is about 55 liters so its still big, but I swear it sounds much bigger. The reason I veered away from a bp6 is that the reflex was just simming much better, except for a small band below where I would ever use it, for excursion concerns. I would have thought the increased motor strength in an isobaric pair would have been ideal for BP6 though. But I am not working harder for worse results. The computer says go simple, I go simple. Edited by b grade - 22 July 2016 at 2:27pm