Advice for Si HT15 cabinets


Active Member
Hi guys,

Just looking for some advise - I have two 15” dual opposed sealed cabinets loaded with 4x Si HT15 drivers. Measuring the volume of each cabinet I get roughly around 90l, those cabinets are awesome build quality but were designed with different drivers in mind that didn’t require as much volume as the Si’s.

Here are the parameters of my drivers:

15" D2

Re: 3.7 Ohms
Fs: 18.5 Hz
Qes: 0.37
Qms: 6.3
Qts: 0.35
Le: 3.5 mH
Sd: 80445 mm^2
Vas: 220 l
BL: 18.9
Mms: 309 g
Cms: 239
Sensitivity (1W/1M): 87.4 dB

I have never used WinISD and I don’t have a pc, so couldn’t even try - just wondering if any of you had a minute to run these and see what would be a good box volume for a single driver? I’m leaning towards splitting them as that would allow for larger volume per driver (don’t fancy having massive dual boxes), and would offer more flexibility with sorting out the in room response too.

At the moment the subs have a good response in my living room, I get flat 120-15Hz but I am battling some huge room gains and nulls and have kinda almost decided that I’d be better off having 4 rather than 2 boxes to help flatten out the response instead of using huge amounts of EQ - not a fan of it but without it my graphs look scary… Plus I just fancy a change :).

Thanks in advance!

Edit: just realised I’ve made a rookie mistake in calculating my boxes’ volume - they’re actually around 120-125 l rather than 90 🤦🏻‍♂️

Considering that, is it worth pursuing this, will I have any real benefits from 4 boxes with roughly around 80 l volume each?
Last edited:


Distinguished Member
Have you tried playing around with Rew room sim and plugging in your room dimensions etc to see what four spread around your room might get you at MLP?

Increasing the size of the box/es will gain you a bit of free output, but depending on your amp, power/eq can overcome this just fine.


Active Member
Thanks for your reply,

I did, however I’m not sure how accurate the results were because changing the values for walls, floor and ceiling surface absorptions has a big effect on the response, the room is not treated but has furniture - couches (main one being up against the rear wall which REW cannot account for), bookshelves, table and so on. Plus, my room is oddly shaped - the left wall is like this /-\ (if that makes sense, like it has a half octagonal shape where the window is) so I’m not sure how exactly to plot for that.
I’ve ordered 4x 80 l sealed boxes with Gordy and I guess it’ll be a trial and error kinda job :).

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