IB driver in sealed enclosure

[presscot]

I’m planning to start a new project of large bookshelf speakers recently. I have a pair of old-school 10” MB Quart woofers (model QM250TX). It seems they’re infinite baffle type drivers as they are also used in a car audio three-way system (QM340CX). I would like to know if there is anyone using an infinite baffle woofer in a SEALED enclosure? How about the result? Is it good or bad?

I have gathered information about the enclosure sizes of home audio 10” bookshelf speakers, this configuration is so old school as it was found in the 80s-90s speakers such as ADS L880, Braun LS100, MB Quart 390, etc. I found the volume of the sealed enclosures, in the market, varies in the range of 1-2.25 cubic foot. I wonder which side we should use between small or large volumetric, i.e. lean towards 1 or 2.25 cubic foot, for the IB drivers.

I don’t have the T/S parameters of these drivers (QM250TX), I have its successor’s (QM250SUB) though, hope they should get closer. Here is the data:

Impedanz 4 Ohm
Re 3.4 Ohm
fs 44.2 Hz
Qms 8.51
Qes 0.77
Qts 0.71
Le 0.89
Vas 55.8 Liter

 

[planet10]

using an infinite baffle woofer in a SEALED enclosure?

An IB is a LARGE sealed box.

If the volume of the aealed box ia not as large as the Q_t & V_ast.√ like, then ,ake it aperiodic… leaky sealed box.

dave

 

[Moondog55]

Vb = Vas is a pretty big bookshelf speaker

 

[jerome69]

I don’t have the T/S parameters of these drivers (QM250TX),

If you have a soundcard and a know mass(10-30g) it is easy to measure with the headphone output 😉
Measure Thiele Small parameters using free software
You cannot make speculations, you should know the actual T/S. You can have some surprise like the drivers have not the same specs.

 

[Sonce]

I wonder which side we should use between small or large volumetric, i.e. lean towards 1 or 2.25 cubic foot, for the IB drivers.

Larger, with a good amount of stuffing with mineral wool.