Full Range Super Speakers

zingo

Alright ladies and gents, here are the first set of plans for my new "Super Speakers". They are a three way MTM WW design with two separate cabs, but a single XO (it will use a set of binding posts on the back of the HF cab and top of the LF cab connected by jumpers). I have always wanted to make a speaker that uses a compression/horn, and this will be an unusual application. The sensitivity of the two cabs should be about 99 db and they will be decoupled from the floor with fatty spikes. The bottom is your regular square ported box, but the top was originally designed as a modified D'Appolito design where the mids are slightly angled towards each other to provide a sweet spot about 7 feet away. All the drivers I chose are from B&C speakers who make MIDFI pro drivers. I hoped that by using the same company for all drivers, the voicing would have coherence. Please help me correct any issues and revise my design, and the more questions the better. (I just hope I can answer them :eek:)

Tweeter: B&C 1" Polyimide DE250-8 Horn Driver

Mid Woofer: B&C 6PEV13 6-1/2" Midrange

Woofer: B&C 12HPL76 12" Neodymium Woofer

Horn: B&C ME10 1" Hyperbolic Cosine Horn

ben62670

I don't know if I would go 4th order on the mids, or even the highs. It would make it tough to correct any bumps or irregularities. I am not an XO expert for sure, but horns in general don't need to be sloped too hard to handle power.

ShinAce

Who designed the crossover?

From the graphic alone, it looks like the tweeter is 8 ohm while the mid and woofer are 4 ohm. Since you're doubling up on the 4 ohm drivers, I expect them to be in series, yielding 8 ohm for each 'band'.

Likewise, the efficiency is stated 1 watt/m instead of by voltage. It's too bad I can't remember the formula to find efficiency based on thiele-small specs.

zingo

I used a value of 4 ohms for the XO since I knew I would be doubling up on the 8 ohm woofers. Was that a poor assumption?

ShinAce

You have:
-one 8 ohm tweeter
-two 4 ohm mids
-two 4 ohm woofers

To keep the system impedance equal, you should go 8 ohm total. Wiring the mids in series and doing the same with the woofers.

Your crossover is now just a 3-way 8 ohm crossover. Actual impedance meaurements are needed to improve the exactitude of the design.

I doubt the real world efficiency of the drivers will match up, so look into setting up something to measure specs. You can derive the true efficiency from this(Vas, Fs, Qes, and some others). Or if you have a Rat Shack SPL meter, measure the loudness on the back porch using a sine wave(make sure your DMM is accurate at the frequency used) and a constant voltage from the amp.

zingo

I am making this confusing!

The design is one 8 ohm tweeter, two 8 ohm midwoofers, two 8 ohm woofers. Wired up, this load would appear as 8 ohm tweeter, 4 ohm midwoofers, 4 ohm woofers.

I'm looking a getting a good design for the cabinets and a decent XO for the drivers, but I have an electronic XO, so I will do the tweaking and tuning with that before building the final passive XO.

ShinAce

My bad, I looked at the PE pages and yes, individual drivers are all 8 ohm.

zingo

ben62670 wrote: »

I don't know if I would go 4th order on the mids, or even the highs. It would make it tough to correct any bumps or irregularities. I am not an XO expert for sure, but horns in general don't need to be sloped too hard to handle power.

B&C recommends a 12db slope on that tweeter, so wouldn't that be accomplished by the second order crossover?

Face

Yes.

http://www.partsexpress.com/resources/crossover-component-selection-guide.cfm

zingo

I've never seen that chart before; good stuff! The only problem with these speakers right now is they cost about $1200 for parts not including materials. They can't be as much as Ben's monsters, but still pricey for the time being.

Does anyone have any objection to the cabinets, besides the "duel ports"?

zingo

New question: I've been looking at sound deadening materials and we all know about the dynamat, Quiet Kote, Sonic Barrier, etc. I like the idea of using a brushable material as it will be easier to apply and less messy than a spray. I was at my local hardware store and I found a product called Skid-No-More. It's a acrylic latex with ground rubber in it. Has anyone used this product before or have any thoughts on whether it would work?

http://www.evercoat.com/productDetail.aspx?pID=167

ben62670

I used a rubberized latex driveway sealer with excellent results.

ShinAce

If you're trying to deaden box vibrations, the dynamat or driveway sealer is fine.

If you want to absorb the treble bouncing around the inside of the box, get some carpeting mat or polyfill or mineral wool and line the walls.

zingo

I was thinking a combo of the deadening liquid, plus a foam or polyfill would be a good combo.

zingo

Since these speaker are VERY ROUGHLY based upon the Wilson Audio MAXX, has anyone ever used or have experience with the inverted dome tweeter? The one Wilson uses is made by Focal, and they claim that the inversion lets the dome be more closely coupled to the voice coil. Any experience?

ben62670

ShinAce wrote: »

If you're trying to deaden box vibrations, the dynamat or driveway sealer is fine.

If you want to absorb the treble bouncing around the inside of the box, get some carpeting mat or polyfill or mineral wool and line the walls.

I don't know if you saw what I did, but I used a couple coats of driveway sealer, and on the last coat I applied Poly batting to the wet sealer. This essentially glue the batting in place. I only used 2" think material, and added some loose fill after. Also mixing some sand into the sealer is another trick I learned after I had built my speakers:(

zingo

ben62670 wrote: »

I don't know if you saw what I did, but I used a couple coats of driveway sealer, and on the last coat I applied Poly batting to the wet sealer. This essentially glue the batting in place. I only used 2" think material, and added some loose fill after. Also mixing some sand into the sealer is another trick I learned after I had built my speakers:(

I have heard of doing that, except using roofing felt as the attached dampener. What does the sand do?

ben62670

The sand adds another density of material to the dampening. Its kinda like having DIY TT pads for vibration control. If you make them with a few different types of material it reduces vibrations from traveling all the way through. Each material has a different resonating frequency, and using a couple different types of material will reduce any resonant frequency. Some of the suggested material for DIY TT pads are stacking mouse pad(neoprene), vinyl floor tile, and cork in a few different layers.

ShinAce

ben62670 wrote: »

The sand adds another density of material to the dampening. Its kinda like having DIY TT pads for vibration control. If you make them with a few different types of material it reduces vibrations from traveling all the way through. Each material has a different resonating frequency, and using a couple different types of material will reduce any resonant frequency. Some of the suggested material for DIY TT pads are stacking mouse pad(neoprene), vinyl floor tile, and cork in a few different layers.

The sand adds mass. It's basically an attempt to make a wooden box look like a concrete box to the speakers.

I've tried various filling schemes many years ago. It started with polyfill/fiberglass mixes to optimize small sealed box size. I only later discovered it helped with internal reflections, and that's my main reason for using it nowadays.

jcaut

You have an active XO and you're going to try to get the sound you want with that and then try to arrive at roughly the same response with a passive XO-- Am I understanding that right? I'm not trying to be negative on your project, but I don't think you can get there using the crossover formulas. I think you'll end up having to go with the active x-over or come up with a way to measure your drivers' response and impedance. Or have someone who can design the crossover for you. You can sometimes get by with the crossover formulas for a simple two-way if you've got very well behaved drivers and you use impedance compensation, but for a 3-way I think it'd be next-to impossible to get right. That's my opinion anyway.

I like your idea though.

Not the same thing, but I built these (or something pretty similar, though mine look different) a few years ago and I use them for occasional light duty PA/DJ applications.

http://www.parts-express.com/projectshowcase/indexn.cfm?project=Blue

They sound a lot more "hi-fi" than most any other PA speakers I've heard, and they're really not fatiguing to listen to. They'll also handle several hundred watts and because they're about 97db/watt, they're plenty loud. I got both the woofers and the mids on PE's "Deal of the Day" at a substantial discount so I don't really have much money in them at all. Highly efficient speakers are fun. It was funny when I used them outside one day at a birthday party and powered them with a little T-amp. People couldn't believe it.

SlowcarIX

i had something that look like it awhile back