Expanding the Zaph B3S-B3N into a sound bar with sub

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eusubius

Member
Joined 2018
#1
Hi fellow audio geeks.

I bought a couple B3N Drivers on sale awhile back. Now I'm trying to decide if I just build a couple boxes for them, ala Zaph. OR, do I buy a couple more, and make a sound bar with 2 + 2?
There's a 6" alum Airborne subwoofer on sale too, so I can use that. it's smooth past 1khz, so it would tie nicely close to the B3N's with a 200hz cutoff.

I haven't designed or built a crossover in EONS, so I'm looking at Zaph's parts list:
http://zaphaudio.com/audio-speaker18.html

QUESTIONS:
1. What kind of wattage is needed for these components... especially resistors? I see R5 is parallel with 2 others... so 3-5W ? but 30ohm... would 250mW be enough? I imagine most of the current there would flow through LF & C3, correct?

2. I'm in Canada, and the Inductor cost on Solen.ca is $9 each! makes the total parts for each speaker as much as the driver itself. I'm looking here: https://store.walectric.com/electrical/ but they have too many options... Any recommendations as to crossover parts? I'd be willing to order from US too.

I'm tempted to buy a couple more drivers, and put 2 in each side of a soundbar, with the sub in the middle (facing up or down, obviously a deep sound bar). If I paralleled them, this would change the impedance to 4ohms. Obviously, I could go to 16ohm in series too.
3. If I did this - what values would change for the crossover? Would a 4 or 16ohm load make for more affordable crossover parts?

thanks in advance!
 
#3
Use two of these upfiring wired in series…..

https://www.parts-express.com/Dayton-Audio-LW150-4-6-Low-Profile-Woofer-4-Ohms-295-255?quantity=1

I‘ve used them all the way to 800hz with a second order low pass when facing up…..the off axis response is perfect in that application for a sound bar…..then you don’t have to compensate for baffle loss with the narrow face of the cabinet and the little 3” drivers……all the low end body of voices comes to life from boundary gain of your screen and dialogue sounds real and immediate

I’m working on another now for a family member with an 85” screen and I’ll be using 3 of the subs in an upfiring system with one dedicated for center channel duty…..phantom falls apart with such a big screen in my opinion.
 
#4
#6
Yes, with two drivers and a wide enough top panel/baffle you can avoid BSC……don’t forget the subs will be using the TV screen for boundary gain acting like a baffle extension and I would assume that the soundbar will be on top of a media console of some type so there’s boundary gain there too.
 
#7
ok. I won't actually have a TV on it though... my wife likes the look of the soundbar, (minimal wires & boxes) - but my big speakers are already in the basement with TV.

This will be on the wall most likely, but perhaps mounted as a shelf... maybe she'll throw art or flowers on top ?
 
#8
Ok, from looking at filter calculators, it does appear that speaker R makes no difference on components. In that case I'm considering the possibility of doubling up on B3Ns just for the added efficiency compared to the woofer. Though it is always nice to have headroom in the bass!
 
#9
Just DO NOT add the additional drivers side by side……this will cause a large reduction in horizontal directivity and destroy off axis intelligibility. If your going to wall mount it, make it shallow with a wider baffle and place the B3s over and under
 
#10
ahhh you are right! I designed a pair of MTM's years ago, I do recall how the directivity works.
I'll stick with one driver per channel, spaced as far apart as I can get them... 3-4' maybe.
Oh you mean making the baffle say, 4' by 8" high, then vertical orientation for each pair of B3s ?

Then I could keep the sub on the front baffle, and center it. I'm not sure that would be ideal for the WAF... we'll see!

I'm going to have to learn Sketchup to start getting my designs "approved" for living room placement before I start construction...
 
#12
No, because those horizontal drivers are NOT playing the same frequency bandwidths. That is a properly designed center channel.

You are talking about using 2 drivers horizontally full range adjacent in a STEREO setup. Horizontally placed, full range signal drivers will induce comb filtering, have good vertical dispersion and awful horizontal dispersion. You still get comb filtering in the vertical arrangement too, but good H and bad V. For a soundbar or center, you want good H for various seating positions. Comb filtering will roll off the treble by path interference. In a proper center channel, the outer woofers like the OS Center, will rolloff sooner on top than the more central units which play higher to meet the tweeter. Horizontal MTM centers aren't great H dispersion compared to average 2way stand mount speakers either, but having a lower xover from mid to tweeter and a close center to center spacing improves upon this issue.

These are essentially very different in operation.
 
#13
ahh, ok I didn't look at his design, but if the outer M's in that center are rolled off at high freq's that makes sense.
Do they just use an R-C Low-pass for the outer woofers in an MMTMM center?
I imagine you'd do one LPF for all 4 woofers, (as the inside drivers crossover to the tweet), then additional R-C for outer woofers? Does that shift phase between woofers at all?
 
#14
According to the video, the outer drivers have a different filter. Generally, this means the outer woofers have a larger inductance involved than the center drivers do, and likely all 4 play in the bass range. Usually, the RC of the inner drivers is also used for the outer units in a cascaded 2.5way setup. The larger L factor is a smaller L cascaded in addition to the lowpass of the inner units. I'm not certain the MMTMM is public design, so this is an educated guess and I did not look it up.
 
#15
that makes a lot of sense.
I know the Focal Twin Be monitors looked like MTM, but in all lit it was a big deal that only 1 woofer did the mids, while both woofers shared the bass. Hence preserving directivity.
Studio monitors are often placed horizontally, so that made sense. In my first speaker design book, MTMs were always shown vertically, and the vertical dispersion control was the key benefit, though I had no idea what all that meant back then... I just thought an MTM sounded like the ultimate!
 
#16
Nah…..the MTM or mmtmm or however many m’s you wanna add is terrible for off axis listening. Studio monitors use it in specific situations to reduce channel overlapp and reflections from side walls but the listener is always on axis so it works in that application.

A single B3n crossed over to a woofer in the 200-500hz range would be enough for rational volume in a small room in a center channel. The Faital Pro 3f would be a better choice though…..handles more power and more efficient. It also has better off axis performance using the large dustcap to aid.

if you’re crossing low as I suggested, you can mount the drivers horizontally, the wavelengths at that point are so long that comb filtering isn’t an issue. A pair of those 6” dayton woofers I suggested mounted this way on the front of a slim wall mounted center would be a good choice with the Faital 3” driver. Male voices will sound nice and full with body and depth. Small woofers have a hard time in this regard even though they ‘can’ play low……….there’s things we can’t measure and this is one of them…small woofers always sound….well…..small.
 
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