Calculating volume enclosure for 2 speakers

[ribolovec2]

Hello and Merry Christmas to all! I have found a few online enclosure volume calculators but they only work for loudspeakers consisting of 1 driver. My aim is to make a common cabinet for 2 drivers of the same kind. Can you help me? Should I double some parameters and calculate with them as if it was a single driver?

[Dr.EM]

I believe you can take the result given for one driver and double it when using 2. ie, a suggested single driver volume is 20L, to use with 2 drivers assume 40L

These are sealed boxes I presume?

[planet10]

You can double the Vas, halve (or double) the Re and work with that. Most calculators don't need more.

Martin King has an article on his website that goes into it in greater detail.

dave

[joekraska]

If you are designing your own speaker, you should get, and learn how to use, WinISD. It is free, and not hard.

Joe.

[Scottmoose]

It's also not particularly representative, unless you know exactly what you're doing. Although I still use it for quick checks etc. so I certainly wouldn't be without it.

Short version =
With drivers in parallel, Vas & Sd double. Re, Le /2.
With drivers in series, Vas, Sd, Re, Le & B*L all double.

Vb doubles with two drivers, as noted.

[joekraska]

Originally Posted by Scottmoose

It's also not particularly representative, unless you know exactly what you're doing.

Why do you say this, and what would you regard as better?

Joe.

[Scottmoose]

Any number of reasons, and 'better' is dependant on exactly what it is you want to be doing, to say nothing of your own background knowledge. It's a neat little piece of software (with a few bugs), but it's also very basic, and does not take many issues into account. Standing waves are not considered (its BR calculations are pure Helmholtz resonance, and life is rarely so simple -if you're planning a tall, thin floorstander it's unlikely to be accurate). It also provides anechoic data, & therefore, you have to take this into consideration. For e.g., a QB3 anechoic alignment in practice is likely to end up anywhere from +3dB to + 6dB below 100Hz in practice due to room-gain. Baffle-step loss is also not taken into account, nor is edge diffraction & host of other issues.

All of which makes it sound as if I'm down on it -I'm not, it's useful, & many other packages have similar issues, but it's limited, and like any software, it's just as important to know what it doesn't do as what it does.

[chris661]

I suppose the knowledge of how it will interact with your room is part of experience.

I found, for Visaton users only, Boxsim was quite good - it does baffle step, frequency response, and seems to take into account the tall, thin floorstander idea. It also has sliders for stuffing in different locations. Like I said, it's only for Visaton speakers.