isobaric coupling configurations

Hi

I have 2 pcs of homepod subwoofer ready to bring them into duty in form of 4th order bandpass sytem. It will be using an isobaric setup. There were 3 types of setup available for isobaric ... face to face, back to back and front to back coupling

This is my first time dealing with isobaric system ... which configuration will be the best? thanks
 

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Danny,

Just a quick note that isobaric loading won't give you any more SPL (which seems to be a concern for you), but will allow the use of a smaller enclosure.

I'd typically recommend face-to-face mounting, unless the motor's wind noise is an issue. Face-to-face is the only one that allows useful air flow around the motors.

Chris
 
Danny,

Just a quick note that isobaric loading won't give you any more SPL (which seems to be a concern for you), but will allow the use of a smaller enclosure.

I'd typically recommend face-to-face mounting, unless the motor's wind noise is an issue. Face-to-face is the only one that allows useful air flow around the motors.

Chris
the face to face method i will need to create a spacer ring?
 
Danny,

Just a quick note that isobaric loading won't give you any more SPL (which seems to be a concern for you), but will allow the use of a smaller enclosure.

I'd typically recommend face-to-face mounting, unless the motor's wind noise is an issue. Face-to-face is the only one that allows useful air flow around the motors.

Chris
i dont think wind noise will be an issue since i will be running them in bandpass instead of ported/sealed .... the port will mask the noise away
 
Yep, a spacer ring will be needed. Alternatively, you could attach both drivers to the same bit of wood, using the wood thickness as the spacer.

Bandpass designs will filter most of the noise. It's difficult to predict as I don't know how noisy your drivers are. In most use cases, the rest of the music is covers the motor noise of the subwoofers well enough.

Chris
 
Why isobarik? Really only useful to make a box half the size. But with the overhead of the coupling chamber nd thw box material, gains in that respect can be very small. You also lose output. You are using one driver, and half your amp power to “fake’ a larger box with no output.

Given th edriver size and the probably box size isobarik makes little sense.

But to the question of how to arrange; the smaller the coupling chamber the better the coupling and would in theory, if you weren’t listening to the back of the driver, would have the greatest HF potential. The magnet to magnet is the largest coupling chamber and i se elittle application for it.

If you plan to use higher up in frewurncy the only thing thst makes sense is both drivers facing the same way (cone-side out), with as small a coupling chamber as possible.

dave
 
I did it for fun but it’s kind of a waste unless you already have a drivers.

Its like a brand new set of ts parameters, it works great. comparing it to anything else is kind of pointless though.
i bought those as pairs thus i have 2 of them ... i plan to integrate it as a piece of compact soundbar with the mids and tweeter so i wanted it small size without taking up too much space
 
Yep, a spacer ring will be needed. Alternatively, you could attach both drivers to the same bit of wood, using the wood thickness as the spacer.

Bandpass designs will filter most of the noise. It's difficult to predict as I don't know how noisy your drivers are. In most use cases, the rest of the music is covers the motor noise of the subwoofers well enough.

Chris
ok how about in this case? for this driver it still need spacer ring because unlike the homepod unit it was already spaced up
 

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I do not think isobaric is an option with those woofers, if you want to make a 4th order bandpass enclosure. It will make the ports impractically long.
any other options besides this ... i am thinking to try out passive radiators for such application (small enclosure reasonable bass SPL) ... now i am stuck to either 2 of these as the candidate for the bass unit ( not larger than 13L enclosure)
 

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and yes exactly ... WINISD shows that too :ROFLMAO:
That’s what always crushes my isobaric Fun. It’s off in such a small port cross section that it’s going to be an issue with turbulence ( at the least). However that’s with the MLTL idea saves the day(potentially). But shaped with a venturilike shape for the port so that the chuffing/compression/noise/ whatever issue is resolved(hopefully)?

The tang band w5 -1138 is like this. Small long port requirements

Either way it’s long and skinny, eating up your space in the soundboard design?