Compound or Composite Isobaric

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Morning all, I have the following drivers which I want to build an isobaric enclosure for -


Check out the Fs!

Now they question I want to ask is this -

Should it be built Compound (push pull)

OR Composite (push push)

I have been reading that there may be differences but does anyone have the knowledge to explain this further. This is going into a car and is a pure SQ system, not interested in boom boom.

The Subs will be driven by a Soundstream Class A 10.2 amp.

Thanks, Rod.
BTW, there's a parameter that is wrong on this spec sheet.

I guess it's Fs.

Fs calculated by WinISD using Vas, Qms, DCR, BL, Mms and Sd give me a Fs of 40.27 Hz.

I hope that doesn't break your design, but I hope you expected this also.

A Fs of 11 Hz with an Mms of 60g is suspicious :D

If I use the Fs of 11 Hz instead of using Vas to calculate parameters, then either you get a Vas of 600 liters and a Qts and Qes of 0.1.

Good luck !
It depends on what you want, the bigger the better usually, but most normal people have size constraints ! :)

The volume is critical for a vented enclosure, but I guess you are going sealed. Those drivers seem to be better for vented OTOH, but since Fs is so high, they are hard to tune lower than 40 Hz.

In a sealed enclosure, you can achieve 0.707 alignment with 9 liters, 0.6 with 15 liters, 0.577 with 18 liters and 0.5 with 32 liters.

So it will be ok in a sealed box between 9 to 32 liters ( 1/3 cu.ft to 1.15 cu.ft internal net volume )

Good luck !
Hi again,

0.5 will achieve deeper bass but some people prefer 0.707 because it has more punch (louder midbass), some take the compromise with 0.577 or 0.6.

I'd go with 0.5 but that's me !

I also suggest you to connect those drivers in parallel (2 ohms load) and bridge your amplifier (2 ohms bridged) so that you will be able to use 500W. OTOH, this will get quite hot hehe !

Isobaric is not very efficient so better use as most power as possible.
WOW! A fake certificate of fake T/S parameters... And the "engineers" at Soundstream had such a good understanding of T/S parameters that they did not even manage to make the lie consistent with itself :D

This can only happen in car-audio!!! :D:D:D

I bet all the parameters are wrong and don't come from any real measurement. This is quite easy to do with a computer and a printer by adding a random component to base values. Then again, they give you such a piece of paper to fool you into thinking that you are buying an exclusive speaker, not to inform you about real T/S parameters... (Who cares about these? :D:D:D )

You should rather measure the parameters yourself. Search the forum or the web on methods to do it.
Hi Eva,

You're right that he may be better measuring the parameters himself but since he's designing a sealed enclosure it might not be a too big issue.

Also, when putting the Fs at ~40 Hz, all others parameters quite line up with each other. I also checked the SS-10R normal edition and Fs was rated at 35 Hz, each other parameters were close to that matched pair limited edition of SS-10R. So maybe the lie is only on the Fs.

Since they can lie about Fs, you're right that maybe they lied on everything else... as you said, typical of car audio. If there was less ******** in audio, it would be a better world...

The Rug Doctor :
If you want to measure the parameters yourself :
Most significant issue in regards to exposed motor structures is, IMO, mechanical noise from the driver + noise from the movement of air in the vented pole piece (if it has one). Aside from all of that, it's just cosmetics.

:edit: Usually, however, it's always been my experience that these audible annoyances aren't nearly as noticable in a vehicle as they are in a home.
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