Input on SBA-941 + bass cab build

Hi All,

I am about to embark on a major upgrade project to my hifi system by building some new speakers. I’ve got a pretty good idea of what I want but would appreciate some input / checking over from folk with more experience.

I am planning to build the SBA-941 by Troels Gravensen and pair these up with two 15” Ciare NDH15-4S at 150-200Hz using a first order active filter.

CIARE NDH 15-4S NEO 15 1000 watt 8ohm PA Subwoofer

The rationale here is that I like larger diameter drivers. I am currently using a 12” in a closed box and enjoy the spacious and effortless nature of the lower notes. I am hoping to place the SBA-941 on top of the subs / bass cabs so they are about 50cm off the floor as recommended by Troels. From what I understand having the 15” driver close to the floor at the frequency range I am planning on using it should not be an issue. I can correct for any floor gain using DSP. I am not sure though if placing the SBA-941 on top of the bass cabs would create baffle step issues for the woofer?

Let me also explain why I chose the SBA-941. In general I was drawn to the 3 way classics by Troels as I have had positive experiences with a smaller driver to bridge the woofer / tweeter gap. The SBA-941 looks easy to construct and is within budget. Further, these seem like a good value proposition compared to the other speakers 3 way classics and are within budget. I did consider the SBA-741 and adding the bass module. However, the bass module only has a 10” driver which is not what I am looking for and the 741 is more difficult to construct.


There are also a couple of options with the 941. It is available with either the TW29RN-B-8 or TW29BN-B-8 (Beryllium dome version). I am leaning towards the TW29RN-B-8 as the Beryllium tweeter would add 300 euros to the cost. To me it seems like we are very much in diminishing returns territory here… Any thoughts on this?

Also, Troels can coat the edges of the MR13P midrange driver to smooth out the mids. This costs 100 euros and I was planning on doing this.

The Ciare NDH15-4S has the following parameters: Fs 27.9 Hz, Qms 11.19, Qes 0.26, Xmax 11.5. It will have a q value of 0.56 in a 60l sealed enclosure. Having something relatively compact is key and I do prefer a sealed enclosure for its controlled transients and ease with which it will enable me to implement any equalisation using DSP. If anyone has suggestions regarding an alternative driver that would be helpful but I was unable to find any other 15” driver that would go into a relatively compact enclosure with similar.

I will power the Ciare drivers with a Hypex PSC2.44 which delivers 2x 400 watts into 4 ohms.

Tony Gee also uses this driver in the Galactica speaker. I noticed that he has it a good 50-60cm off the floor and slightly angled. I guess to reduce gain off the floor as there is no DSP with which to correct here? Homemade Hifi_Galactica.pdf Homemade Hifi_CAD_Galactica.pdf
I am not sure though if placing the SBA-941 on top of the bass cabs would create baffle step issues for the woofer?

There is no impact by placing the speakers on top of woofer cabs though you will find them cleaner sounding physically separated.

the Beryllium tweeter would add 300 euros to the cost. To me it seems like we are very much in diminishing returns territory here
Sounds like you haven't heard any Beryllium highs before? Best to have a listen and see if its life changing like it was for me.

If you can't, dont sweat it, the TW29RN is a faultless tweeter with very good highs. You can always upgrade to the Be one later.
Joined 2005
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I agree (with you, not fishball) about the beryllium, I would not worry about floor gain or baffle step issues. I would consider a higher order crossover and I would be inclined to do 2x10”, or 2x12” in dual opposed configuration to minimize vibration since it or are putting the speakers on top of the subs.
Just my 02
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Thanks for the responses guys!

That clears up the baffle step question for me.

I've not heard any Beryllium tweeters so I might pop into a hifi shop to listen to some. There's a shop near me that has high end Focal stuff who use Beryllium domes. Gut feeling is still I'll probably go with the TW29RN.

2x10”, or 2x12” is an interesting option. Any suggestions in terms of drivers here?

I was going to build some pretty sturdy cabs for the bass out of 18mm MDF and 8mm ply so I suspect vibrations won't be much of an issue.

The crossover order is something I can play around with of course. My initial idea was to go with a 1st order to keep more of the impact of the woofer a bit lower down. Don't know if this makes sense.
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Joined 2005
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The 15”ers will probably not be very taxed during most music so they probably won’t move around much. since you’re using dsp you can cross them low easily which I prefer for subs.
I have used 4 subs with dual opposed xls 12’s before and the were great. If I were to do it again I would probably use the Dayton ref 12’s or if I had more money to burn the css 12’s or the some of the new SBA 12’s.