Enclosure size confirmation.

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Hi all.

I'm re-purposing a pair of car speakers into desktops.
As such I've been playing with various programs to calculate an enclosure.
The bass drivers have some odd specs that make it hard for me to decide on sealed or vented.

I'm leaning towards 20 ltr sealed at this point.

ADS 6.5" (Proper ADS, not the newer stuff)
Driver free air specs as measure with Dayton DATS.

Re 4.098
Fs 53.16
Qts 0.7534 <-- this is why I'm here double checking enclosure style and size.
Qes 0.875
Qms 5.419
Le 0.3646
Mms 14.65 Grams (added mass for Vas test was 14.5 Grams)
Vas (added mass) 12.14Ltr

WinISD is showing 20 Ltr sealed or ported as being not a huge difference.
Obviously the closed box is showing far Superior group delay.

REW (5mm Close mic'd) shows a 20ltr sealed test box as having a smoother roll off than the same box ported with 6cm diam 15cm long port.

So, does anyone see anything that suggests I shouldn't go foward with a 20ltr sealed ?

Ta :)


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I take it that measurement is nearfield on the woofer. Shows tuning about 43Hz.
You need to do a nearfield on the port and add it in (vectorially) to do an apples-apples comparison. You will have a broad port resonance with such a high Q, so the peak above tuning will be higher and there will be a bump before dropoff.

If it were me, space would be a premium and I'd go with ~10L, but there is nothing wrong with your 20L decision. Here is your woofer with a 20L vented box tuned to 43, 20L sealed and 10L sealed.


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The rew sweep is indeed near field.
5mm from dustcap center.

I wouldnt mind a smaller box.
But when i built the current cabs yeeeeears ago, 20L ported seemed best. I've learnt a little since then ;)

10 L sealed looks pretty good to be honest.
I didnt think it would be such a small difference.
Applications may vary. Where you have a sub/woofer you need extension (larger box usually) and where you have a 3-way a higher Q might be useful. In a studio multy-way a good for transients with a sealed box. What's your project and xover? To be of any useful info...
They are a pair of car speakers.
ADS 6.5" two way with 1" tweeter. (AL6)
Once I have the box sorted out I will be doing measurements and building my own crossover for them.

End use will be 'desktop' speakers primarily for pc use - mostly tv/movies some music (outboard class a/b amp).

As per attached, not the best info.
So I'm going by actual real life measurements.

I keep coming back to the 20L sealed.
acceptable size with reasonable extension and low group delay.

the low group delay is something that others seem to think is really important.


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a/d/s (ADS)/Braun

20L sealed looks very good, F3-52Hz. High Qtc close to 1.
10L gives a Qtc = 1.16 and F3-58Hz.
Works fine sealed with a L/T (Linkwitz Transform) also.
Looks like making for a nice 2-way speaker.:)
Do your drivers look like this?
Whats the Sd (diam between the middle of the half rolls: I used 140mm)?
What is the history of ADS speaker company? - ecoustics.com
ADS L400 Speaker Review
A/D/S loudspeakers | Audioholics Home Theater Forums
Braun; Frankfurt manufacturer in D, radio technology from Ge
Lautsprecherbox L400e a/d/s Speaker-P Braun; Frankfurt
A/D/S line pecking order? | Audiokarma Home Audio Stereo Discussion Forums


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Looks like a 20ltr sealed is the way foward.
They always sounded really nice in the car.
But with their new 'desk' position I shall throw a bit of money at a true crossover.
yup, that the ones. :)
cone is 123mm
middle of the surrounds is 134mm
edge of surround is 140mm

Thanks for the links, I shall enjoy checking them out.

Many thanks for everyones help and advise. :D
He, he, yes, well said. Usually posts for a couple years more...:D

Seen that so many times here...Sometime you'll see project threads stop halfway through the project, then 5 yrs. after you see the thread being resurrected with a note saying how the OP went through a nasty divorce and the ex kept the enclosures as part of the divorce financial agreement and it took him 4 yrs. of negotiations with the ex to get them back.
ha, I went through my divorce 25 years ago :p

I shall indeed update as stages are passed.
Im now thinking about the shape of the enclosure and baffle as well as recessing the tweeter to get some sort of rough time alignment.
I dont want the typical, box with holes.

This wont be a quick build as I do actually have other things to do in life. Sometimes ;)

EDIT, this is as much a project as it is a learning exercise for me.
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