# How can i calculate the enclosure volume for two parallel fullrange drivers

#### noyan

##### Member
Hello,
I want to build ported loudspeakers using two parallel Visaton BG20 drivers in each cabinet. How can i calculate the necessary volume of the enclosure?
Thank you for your help
Noyan

#### GM

##### Member
Greets!

Well, one way is to design for one, then make it 2x as big internally and if vented, use 2x its vent design. Another way is some programs allow you to choose the number of drivers or if inputting the driver specs, then input 2x Vas.

#### Galu

##### Member
I will back GM's post up thus:

The Vas doubles so you should double the box volume.

Then you should calculate the port dimensions that tune the doubled volume to the desired frequency.

#### noyan

##### Member
Greets!

Well, one way is to design for one, then make it 2x as big internally and if vented, use 2x its vent design. Another way is some programs allow you to choose the number of drivers or if inputting the driver specs, then input 2x Vas.
Thank you

#### noyan

##### Member
I will back GM's post up thus:

The Vas doubles so you should double the box volume.

Then you should calculate the port dimensions that tune the doubled volume to the desired frequency.
Thank you, doubling the volume is the answer

#### GM

##### Member
I will back GM's post up thus:

The Vas doubles so you should double the box volume.

Then you should calculate the port dimensions that tune the doubled volume to the desired frequency.
Hmm, just so we're clear; if inputting the specs for a program to calculate a box alignment, then 2x Vas will automatically double box volume (Vb).

1 user

##### Member
Paid Member
Hello,
I want to build ported loudspeakers using two parallel Visaton BG20 drivers in each cabinet. How can i calculate the necessary volume of the enclosure?
Thank you for your help
Noyan
Not only doubling the volume. Ideally, you should divide the internal space by the wall. Just like bose did with nine identical fullranges. You do not want one affecting the cone of the other. Ideally.

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#### GM

##### Member
Yeah, I debated about mentioning it, but I've done a lot of multiple driver vented boxes using unmeasured same-same drivers with no issues, not even in prosound where any issues multiply seemingly exponentially.

That said, as good a way as any to add bracing with minimal Vb loss.

As for your example, they apparently had to based on some of the measured specs I've seen.

#### noyan

##### Member
Not only doubling the volume. Ideally, you should divide the internal space by the wall. Just like bose did with nine identical fullranges. You do not want one affecting the cone of the other. Ideally.
Ok. Thank you

#### xrk971

##### Member
Paid Member
I have not had a need to separate the two drivers into two chambers. Especially if you want to only use a single vent. For a TL you can approximate the two drivers as a single driver at the midpoint between them and double the volume by doubling the TL cross sectional area.

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#### noyan

##### Member
I have not had a need to separate the two drivers into two chambers. Especially if you want to only use a single vent. For a TL you can approximate the two drivers as a single driver at the midpoint between them and double the volume by doubling the TL cross sectional area.
Thank you

##### Member
As an aside, a pair of 8" 'full range' drivers next to each other is going to make a hell of a polar response mess.

#### GM

##### Member
True, my presumption is it will either be used at a long enough listening distance or one will be rolled off as a 1.5 way to 'taste' ............

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#### cracked case

##### Member
I once tried both stereo channels in one, undivided ported box with no problems. I've made a few speakers with two identical full rangers, if they're wired in series just a cap ( 1.5 uf works well ) solves any problem with beaming, one cap even worked with four drivers in a square.

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