Home sub build ATC 15" ULTRA enclosure help required


Standard Member
Hi all, first post in this section. Im after some help designing a box for an Atc ultra 15" sub that will work well in my front room with my current setup. Ive got a pair of Dynaudio BM15's running off a Belcanto S300iu getting 300wrms each. Ive got a BK electronics 500wrms plate amp to run the sub. I know theres a few people out there that understand room acoustics and enclosure design alot better than I do, and was wondering whats the best way to go about it. I want a well balanced setup that hits hard on the lows aswell as intergrating well with the Dynaudios, basically hits every note. Its gonna be mainly for music, Im not to worried about HT. I was thinking ported over sealed to maximise output.

Heres some specs on the sub

Fs: 23Hz
Qms: 1.6
Vas: 486L
Cms: 0.474mm/N
Mms: 101.1
Rms: 9.131
Xmax: 25mm
Xmech: 37.5mm
Cone Diameter: 329mm
Overall diameter: 390mm
Sd: 850 sq cm
Vd: 2.125L
Qes: 0.3
Re: 8 ohms
Z: 8
BL: 19.74
Pe: 150
Qts: 0.253
SPL: 95dB/1w/m

Anyone out there got the time to help would be much appreciated. :)

Member 639844

Former Advertiser
Te power rating in your specs says 150 watts power handling. Its that correct? seems a little low. Are you after a ported or sealed enclosure, and do you have any size restraints?


Standard Member
Hi I believe all that infos correct, Im looking to buy this sub off another forum, the members been giving it 600wrms and says its rated at 400wrms @ 8ohms. Im definately after ported to maximise output, and size can be negotiated with the misses I suppose.

Edit: I really just want to get the best out of it taking the room size and shape into consideration. Or be told theres a better/cheaper option than this sub.
Last edited:

Member 639844

Former Advertiser
I dont know much about this driver specifically. It looks like a proper sub driver in the specs, but looking at the ATC site they seem to specialize in pro audio drivers, which would indicate its not for really low HT style output.

Anyway, I modelled it in a ported enclosure and it seems to work well in 200 litres tuned to 15 z with about 400 watts input power. A slot port 200mm wide and 75mm deep at 900mm long would give you the required 15hz tune.

It doest give massive output, and whether its a bargain or not depend on the asking price really. Something like an Fi Q15 driver would be a much better driver though.


Standard Member
I was looking at them also quite recently, Ive been running a Dayton reference 12" in 2.4cuft ported off the Bk amp and was quite happy with it but Im after more output and a flatter response. When I bought the Daytons I bought 2 of them so Im either looking at putting them in my deck room, or maybe making a box for them for the lounge. Too many choices really, Im just after more bass in both rooms. What sort of power do the Fi q drivers need to work best?

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