3-way center-channel using SEAS 7" coax and 7" woofers

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I currently have a Vandersteen VCC-1 center-channel speaker. Generally I like the sounds of it, but it sounds rather thin—bass-shy--compared with my Vandersteen 5A left/rights. V’steen rolls off the bass to improve voice intelligibility, but I want it to sound more full-range. My goal is NOT to have bottom-octave energy from the CC, but it is to have good energy into the mid-bass octave.

I planned initially to build a 2-way based on the current, 7" version...
Madisound Speaker Store

...of the SEAS 6-1/2" coax V-steen uses, but I’ve gone perhaps-stupid and decided to build a 3-way by adding a pair of SEAS H1215 7" woofers...
Madisound Speaker Store

I’ve scratched out a plan for a 2-cavity, tapered-2-ways box with volumes of c. 0.6CF for the coax and c. 1.2CF for the woofers. Both will be ported, and I’ll add some resonance-damping material such as BlackHole-5 and some asymetrical bracing internally.
JBCC2_1280w.jpg


I plan to use 1st-order x-overs with no high-pass filter on the coax and with a rather low...maybe 50Hz...low-pass filter on the woofers which will be wired in parallel. Probably I’ll use 2 inductors in series on the MR driver with the smaller one switch-outable to create a presence bump for dull-sounding soundtracks. I’ll have full-range and also c. 70Hz-high-passed signals from the poweramp, the latter if there’s too much bass for the CC from some soundtracks.

I’ve build several speakersystems previously, with, of course, mixed results. I’ll have this box built by someone lots more skilled than I. I’ll cut the holes and do all the rest. I have some measuring equipment such as sinewave and noise generators, SPL meters and a third-octave RTA.

What do you think? Too much for me to hope for excellent results?

What should I be careful to DO? Or NOT do? All constructive advice appreciated.

TYVM.
 
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Hi,

I don't understand why you didn't simply try adding a a further sealed
box with a single driver in it, with a big inductor on it to your current
centre to see if works / gives you want you think you want.
Is the proximity switch set to off ? Near wall should be plenty of mid-bass.
Seems that the VCC-1 has capacitor coupled bass, so set it to
small to reroute the low bass to Left and Right (set to large).

I don't like your plan much. You say you don't want low bass but then
say your going to put a 50Hz (!?) low pass filter on the bass units.
I think your going to struggle to get near what you already have.

http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_USB Mk-II_copy.pdf

I can't see a way of adding two bass units without a complete redesign.

rgds, sreten.
 
Hi,

I don't understand why you didn't simply try adding a a further sealed box with a single driver in it, with a big inductor* on it to your current centre to see if works / gives you want you think you want. I don't have a bass driver or inductor to experiment with, and I don't feel like building a throw-away box.

Is the proximity switch set to off? Yes.

Near wall should be plenty of mid-bass. The rear of that system is about 5 feet from the front wall.
19Arp2012_roomfrontfloor_1000h.jpg


Seems that the VCC-1 has capacitor-coupled bass...Yes, it was. I removed the 'permanent' portion of those caps and left some in to effect the Proximity filter. I 'never' use the Proximity compensation..
...so set it to small to reroute the low bass to Left and Right (set to large). Been there, did that initially. Music and voice coming from the CC sounded thin enough for me to start this project.


I don't like your plan much. You say you don't want low bass but then say you're going to put a 50Hz (!?) low-pass filter on the bass units. The 50Hz point is to get some bottom-2-octaves bass from that pair of higher-sensitivity drivers while rolling off their energy relatively early to avoid making the sound too thick, since there will be no hi-pass filter on the bottom of the 'MR' driver. I believe any output in the bottom octave will be way down in respect of mid- and upper-bass energy.

I think you're going to struggle to get near what you already have.

http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_USB Mk-II_copy.pdf

I can't see a way of adding two bass units without a complete redesign. That's what I thought mine was, or I don't understand your question.
rgds, sreten.

* I have too much 'junk' lying about and gave away all my speaker-building supplies.
 
Hi,

Zaph|Audio

Its pretty clear your going to have no fun trying to high pass them at 50Hz.
Which will have to be active as a passive arrangement is nigh on impossible.
Low bass and its management shouldn't have much to do with the centres
tonal balance, and setting the centre to small so its bass is sent to L+R
should sound pretty much the same at it having extended bass itself.

If your centre is 5ft from a rear wall that is very untypical. Line level EQ
if can be arranged could have worked. Another box with a single driver
to match your current centre and an inductor is hardly throwaway,
it probably would of worked to add richness quite well.

Unless you build baffle step into your "new" centre its going to sound
very thin. x/o the coaxial to the two bass units in the midrange will
give some form of automatic baffle step compensation.

rgds, sreten.
 
Hi,

Zaph|Audio

It's pretty clear you're going to have no fun trying to high pass them at 50Hz. LO-pass, s, LO-pass.

Which will have to be active as a passive arrangement is nigh on impossible. Low bass I keep writing that I'm trying to get little if any LOW bass out of the new system. What I want is a good-sounding bass system with a little bottom-octave energy and great-sounding mid- and upper-bass and that does NOT make voices sound thick.

and its management shouldn't have much to do with the centre's tonal balance, and setting the centre to small so its bass is sent to L+R should sound pretty much the same at it having extended bass itself. You may think so, but that's not my experience.

If your centre is 5ft from a rear wall that is very untypical. Maybe so, but that's where all the front speakers are.

Line-level EQ if can be arranged could have worked. Am already using a 31-band eq to recover some bass, but the VCC-1 can handle just so much power, and the eq doesn't sound very good.

Another box with a single driver to match your current centre and an inductor is hardly throwaway; it probably would have worked to add richness quite well. See below.

Unless you build baffle step into your "new" centre it's going to sound very thin. x/o the coaxial to the two bass units in the midrange will give some form of automatic baffle-step compensation. I don't understand that, but it doesn't matter, as I'm NOT willing to add a bunch of capacitance in series with the MR driver; I just removed some when I rebuilt the VCC-1's crossover.

rgds, sreten.

You have given me an idea, tho, to build a bass system about identical to what I've already planned--using two 7" SEAS H1456 drivers wired in parallel and with a lo-pass inductor, but in a separate box that the VCC-1 can sit on. The online calculator indicates I need c. 1.3CF in a vented box. I'll build it just tall enough to get the drivers in it so that it's low enough to accommodate both the VCC-1 and the screen above it.
 
http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Black Box_copy.pdf

Hi,

The above gives some idea of what the bass capacitor coupling is supposed
to do. I've played with it in a SIM and it works quite well, and it does improve
overall bass power handling by helping reject low frequency cone movement.

If your going to drive the VCC-1 fullrange in parallel with the new box, I'd
be tempted to put them back (assuming a bunch of parallel caps is used).

Sorry I missed the 50Hz high pass bit. Seems a fair enough plan.

rgds, sreten.
 
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