# Skinny, thin speaker design



## Anthony (Oct 5, 2006)

Well my plan on building the Zaph B3S speaker fell through. His box is just too big for for the wall mount area constraint.

So I started looking into pre-built small speakers and the wife likes the Gallos and Orbs, but we talked and decided to give a couple of DIY designs a chance first.

I have a bunch of B3N's, Dayton RS 8" drivers (too big for this), BG Neo3PDRs, and NEO8. I may even have a Tang Band 3" driver in the box and some Dayton ND28's.

I'm not averse to buying something new to make a design work, but I'd like to use some of the stuff I have on hand.


Speaker has to be skinny 6" wide max, thin, 6" deep max, but can be 12 to 18" tall if necessary. Will be mounted flush to wall (pre-wired). Ideally, I'd like a design that I could eventually make into a center channel, but L/R is fine for now. There will be a small ported sub up front with the speakers. I can cross it as high as 150 if necessary, but I'd like to go 120Hz or lower. High SPL is not a consideration since this is just a family room system (and I was looking at the B3S single driver before, so you can get an idea of how loud I was considering).


Right now I'm looking at the following:
Dayton RS125-4, Neo3PDR MTM arrangement (might be too low impedance for my receiver).
Dayton DA115-8, Neo3PDR MT arrangement
Same in a MMTMM.

Some Neo3/Neo8 combo with a small woofer section (again, what?)

All ideas appreciated. I'm just now getting back into the swing of things with speaker building so the rust is coming off slowly.

Thanks!
Anthony


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## tonyvdb (Sep 5, 2007)

Just remember if you crossover a sub higher than 80Hz you start getting into the range where you can localize where the sub is.
Have you looked at the Axiom M3 v3's?


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## Anthony (Oct 5, 2006)

Yeah, but it will be up front with the speakers, and quite frankly, physics is not on my side to get down to 80 Hz with such a small size constraint (and I am aware of that).


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## fbov (Aug 28, 2008)

If you have a bunch of B3N's consider a set of these, used vertically. 
https://sites.google.com/site/undefinition/updates/overnightsensationcenterchannelbipolewhatwhen

This is 5 1/4" tall/wide using 1/2" stock, so it fits, and being a 2.5-way MMTMM, it should have very good lobing properties, especially used vertically. Plus there's the B4N based ONS for elsewhere, where the size isn't an issue and drivers aren't in stock!

HAVe fun,
Frank


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## Anthony (Oct 5, 2006)

Ding ding ding, we may have a winner. I searched for B3N designs, but didn't see that one.

I think I have six B3Ns, but I'll have to count. If it's 8, I will model it up and see if I have the MDF or ply on hand to build a test box.

I'll also try the Neo3 as a tweeter and the 28ND to see how they look (obviously the X over would change).

Thanks -- good find.


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## fusseli (May 1, 2007)

From my experience, Xovering in the sub as high as 100-120 Hz can be doable without locallization. Continously variable phase adjustment on the sub would help out a lot I think, to get it dialed in perfect with the LR. There should be 3" and 4" drivers that can reach to the 120 range in a reasonably small size. Sorry I'm in a rush at the moment, I'll get back on later.


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## Anthony (Oct 5, 2006)

Looked into it and that design for the B3N LCR is just a tad too big. Close, though.

For size and space reasons, I'd love an MTM with the Neo3, if I can get the bass extension to 120 Hz or so.

I'm going over all the PE offerings. I threw a thread up on their board and got a couple of recommendations, but again -- just a bit too big.

Nothing like painting yourself into a corner


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## Anthony (Oct 5, 2006)

How about this one:
Dayton ND105-8 in a 0.17ft^3 box and a Neo3PDR tweeter? I'd have to cut down the Neo3 with a pad or straight resistor, but for impedance reasons anyway, I would have to do that.

Hmm . . . (wheels turning).

Then I could do a horizontal pair of the 4 ohm version with the Neo3 as a center, when PE finally gets them back in stock (late July/early August).

I need to model these to find out if this will work.


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## fusseli (May 1, 2007)

If you want help modelling let me know.

Two ND65-4 in a tiny (.05cuft) sealed box will get an f3 of about 100Hz with a high Q and handle plenty of power. I actually have those modelled up, I was going to build an mp3 player dock slash portable computer speaker set at one point as a gift but never got around to it. For full BSC it took an LCR notch and zobel of sorts to model "flat."


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## Anthony (Oct 5, 2006)

I was just looking at the 65. That moved to the front in an MTM arrangement, sealed with a small tweeter or, if won't look too comical, the ND28 or Neo3 (since I already have them). ND20 is on the table as well.

What were you notching to make it work? Is there a nasty breakup mode in there?


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## fusseli (May 1, 2007)

Ah no, I guess it was more of a contour than a notch. Single driver, no tweeter, not sure how it would sound (though I'm quite curious). Kinda almost makes me curious of doing a "1.5-way" with them and making the box slightly larger :yes: and of course then making two speakers

This is as far as I got (intending on stereo operation with both in a stuffed .05cuft box): http://img210.imageshack.us/img210/867/61832089.png


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## Anthony (Oct 5, 2006)

Ah, single driver. My receiver can only handle 6 Ohm minimum, so I may need to either use the 8 in a larger enclosure or 2, 4 Ohms.

Hmm. I think I need to get an order together this weekend.


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## fusseli (May 1, 2007)

I would venture the guess that a 6-ohm stable receiver would run L/Rs that are 4 ohm nominal just fine before going into protection... I've been running my 4 ohm center on my receiver for about 7 years now, which have been through hundreds of blasting movies together. It's up to you though.


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## Anthony (Oct 5, 2006)

I had the opposite experience. I was told Magnepans were an "easy" 4 Ohm load and ran them for a couple years on my Marantz and then one day . . . POP! Two channels smoked. Easy fix for the repair shop (two new output stages). That being said, that receiver was rated to 8 Ohms and my Sherwood is rated to 6, so it is probably okay. I'm just a bit gunshy on that front.

I got turned onto a B3N MTM design on the PE forums. It's interesting if I can reconfigure the cabinet, but I like your single driver small cabinet better. I may be building both and see which we like better. They aren't too expensive and I have a TON of crossover components (and scrap poplar and MDF)

Thanks again!


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## Anthony (Oct 5, 2006)

Russ,
Just to be clear, did you model that as a single driver or two together? I have an order ready at PE and just wanted to confirm.

Plan is to build a B3N speaker and the single driver speaker and test them both out. I have a ported sub design with a RS225-8 in a 50L ported and tuned to 30Hz. Should be able to play pretty high. Again, a driver I had laying around.

Thanks,
Anthony


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## fusseli (May 1, 2007)

Anthony said:


> Russ,
> Just to be clear, did you model that as a single driver or two together? I have an order ready at PE and just wanted to confirm.
> 
> Plan is to build a B3N speaker and the single driver speaker and test them both out. I have a ported sub design with a RS225-8 in a 50L ported and tuned to 30Hz. Should be able to play pretty high. Again, a driver I had laying around.
> ...


What I posted was two ND65s sharing .05-.06cuft (my secret plan lol, paint from the inside). A single one in .05cuft would be good also, with less peaked response near 100Hz. The baffle I planned for was 4"x7", so if that stays the same and it's a sealed alignment then the crossover I posted would still work. Definitely plan on stuffing the box, that will be pretty much mandatory to keep the midrange clean.


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## Anthony (Oct 5, 2006)

Cool, thanks. I'll add two more drivers to the cart. I like your idea of the 2.5 way as well. 

Once I get something up I will probably start tinkering.

Thanks again.


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## fusseli (May 1, 2007)

Coolness. Let me know what you decide to build, I will be happy to model whatever.


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## Anthony (Oct 5, 2006)

Prototype boxes mostly built last night. 4x5x8, 1/2" maple ply (scrap). Still need to do the front baffle. Gonna run them without a crossover (but stuffed) for a few weeks of music and movies to break them in, then measure in box, both drivers together and design the crossover from there. It probably won't look too different from your design, Russ, but who knows with manuf. changes and actual box response.


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## Anthony (Oct 5, 2006)

So, box built, baffle made and I started breaking them in. Originally the box was unstuffed and there are no crossover components as of yet. Boxes are scrap maple plywood, 1/2" with a 3/4" MDF baffle. I had to router the back a lot to allow the driver to vent into the box. I need a bigger chamfer bit. Ply is glued and brad nailed. Baffle is just tacked with brad nails. I plan on taping the seam so there is no leakage.

Some initial thoughts:

These are pretty good little drivers. Since there is no bass and I had the receiver cross at 80Hz, I focused mostly on acoustic guitar music. Very clean and crisp and no breakup that I could hear. I also got them pretty loud.

Before stuffing the bass just disappeared completely, male midrange was throaty and muted, and female midrange rang and resonated. After stuffing bass magically appeared and the upper mids settled down. I still get a hint of the male voice being muted, but I'll reserve judgment until they are broken in and I get a crossover (well, filter) for them.

These are two 4Ohm drivers in series. One presented a 7.7 Ohm DCR and the other was 8 Ohm exactly. I might mix and match the drivers to get the overall DCR even on both sides because one did sound louder. Again, though, all decisions like that reserved for after break-in.


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