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angeloitacare 7th August 2008 11:37 PM

Tapped Horn for 18" bass
hi all

i am moving to a new house. I am thinking to make a Tapped horn for a Aura 1808. Has someone any plans for a TH for 18" woofers ?


JLH 8th August 2008 09:17 PM

Let's start with the T/S parameters to the woofer. Please post the T/S parameters you have for your woofer. From these, we should be able to come up with a solution for you.

Rgs, JLH

zlast 8th August 2008 09:51 PM

Unless you all ready own the AURA driver (which are rather expensive) I would recommend finding a more affordable driver to make a tapped horn. IN any case you will need to provide the exact model number of the driver or T/S parameters to design any proper enclosure. You can find less expensive drivers that will give you a better frequency response.

angeloitacare 8th August 2008 11:48 PM

t/s parameters
i have already the Aura 1808. In the new listening room, i have a height of 2,5m , and want to make the TH with 2,4m total length.

these are from the thiele/small database, but they list only the nrt 18.8
i guess only the cone mass is slightly different :

Nom. diamerer [inch] 18
Vas [Liters] 475
Qts 0,26
Qes 0,28
Qms 4,4
Fs [Hz] 25
Sensitivity [dB] 96
Max Power [W] 800
Power definition RMS
Lower freq [Hz]
Upper freq [Hz] 2000
Rec. Filter freq [Hz]
xmax [mm] 18
Moving mass [g] 186
Disp area [m2] 0,124
Disp Vol [cm3]
xdamage [mm]
Air gap [mm] 50
Coil height [mm] 25
Coil diameter [mm] 99,1
Cms [mm/N] 218
Rms [N*s/m]
Magnet weight [gr]
Magnet height [mm]
Magnet diameter [mm]
Magnet material -
Re [ohm] 5,6
Z [ohm] 8
L [mH]
Bl [Tm] 24,5
Magnetic flux [Wb]
Flux density [T]
Outer diam. [mm]
Bolt circle [mm]
Nr of bolts [Nr]
Cutout [mm]
Weight [Kg] 13,5

GM 10th August 2008 02:26 AM

2 Attachment(s)
FWIW, the Aura 1808 specs I have are considerably different:


angeloitacare 10th August 2008 03:28 AM


using your spec's, i get following SPL response :

what are the dimensions of the TH , to get this response ?

i am thinking of two possibilites :

a copy of the DTS20 , adapted for the Aura :

since it will be only for personal use, i don't think there would be any problem, if i build it.

or a TH similar to Volvotreter :

anyone has a idea, what might be better ?

GM 10th August 2008 04:04 AM

Yes, that's the response I got.

All the critical dimensions are in the S1, etc. input fields, though of course you will have to figure out how to fold it up. As large as it is though, it needs to be built into a false wall IMO. Anyway, you really need to measure your driver's specs to get an accurate design, not to mention you can make it considerably smaller with a conic flare.

Right, you can build a patented design if for personal use only.


angeloitacare 10th August 2008 04:11 AM


i intend to use it as sub, to cover up to 50hz.
i will not use a false wall, it will just stand in the middle of the system, close to the wall. How would that be with a conic flare ?

any picture or drawing ?

davygrvy 10th August 2008 07:36 AM

2 Attachment(s)
Cms doesn't look right to me. If the T/S params are right, the following looks good

N.B.C. 27th March 2009 11:31 AM

The Aura 1808 Overature?
Anyone want to help revive this thread?

I have two original style Aura 1808's that I'm wondering if might work well for TH's..?

I have a SET/front loaded midbass horn and compression driver based system and, as the saying goes, "it takes a horn to catch a horn".

I'm very early in the learning curve about TH's, so it would be great if someone can discuss the suitability of the Aura 1808 for a TH and offer cabinet plan suggestions, so I can quickly build a proof of concept to see what the TH hubbub is all about (and perhaps invite my experienced horn buddies over for a listen).

I can measure the actual T/S parameters if needed.

(The only other woofers I have on hand are Altec 416-8C, JBL 12" 2202A, Gauss 18" 4882 and EVM-15B.)


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