# A good kit for a set of DYI surrounds?



## olddog (Dec 21, 2008)

My fronts are Warfdales and I would like to wall mount the two surrounds. The sofa is against the wall I would mount on so they need to be forward and side firing I would think? Driving them will be a Denon 2808 in a 15X26 room.
Thanks


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## olddog (Dec 21, 2008)

I guess what I mean is a good kit or plan for a set of rears. I think DYI is the way to go as it is a unique application and that is one of the things DYI is all about. I am thinking it would have a forward driver and a side-firing driver dedicated to right and left as the sofa is on the 15ft. wall. 110-Watt amp. Audyssey correction,matching Mirage subs on front. A cabinet with a flat front with a 30 to 45% cut on each side with drivers that have a center mounted tweeter small and efficient. Just my thoughts, and I have never built a speaker before so maybe I am way off base? Let me know. 
Front and center channel specs.
Nominal impedance 6 ohm (suitable for 8 ohm amplifier) 
Sensitivity (for 2.83v at 1m) 90dB 
Frequency range at -6dB: 75Hz to 29kHz 
Crossover frequencies at 2kHz and 7kHz 
They have a rear loaded tweeter, and a rear loaded mid horn, with Dual 6.5” polycarbonate laminate bass drivers, all in each of the 3 cabinets. 
Your input is as always appreciated.


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## Owen Bartley (Oct 18, 2006)

Mike, here's the rear centre I made a while ago. Most of the info is in the thread, but if you have any questions, fire away.

http://www.hometheatershack.com/forums/diy-speakers/2805-dipolar-rear-surround-speaker.html


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## olddog (Dec 21, 2008)

Thats a good looking speaker! It's close to the shape of what I had in mind. I caught your building thread and will study it. Thanks.


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## olddog (Dec 21, 2008)

I saw these and believe I have found the style and form :help:shape I want. Anyone with any good ideas of where I should start in order to build a set?



QS8 v2 Surround Speakers 

Specs QS8 
Enclosure: Acoustic Suspension 
Max Amp Power: 400 Watts 
Min Amp Power: 10 Watts 
Freq Resp +/-3dB (Hz): 95 - 22 kHz 
Freq Resp +3dB- 9dB (Hz): 65 - 22 kHz 
Impedance (Ohms): 6 Ohms 
SPL in Room1w/1m(dB): 95 dB 
SPL Anechoic 1w/1m(dB): 91 dB 
X-Over 2.5 kHz 
Tweeter: Dual 1" 
Woofer: Dual 5.25" 
Sub Woofer: - 
Dimens. H W D (inches): 8.25" x 11" x 6" 
Dimens. H W D (mm): 210 x 280 x 152 
Weight (lbs) each 13.5 lbs 
Weight (kg) each 6.123 kg 


Twin Titanium Tweeters 


Dual Aluminum Woofers, top and bottom 


Anti-Standing-Wave Cabinets 


Quadpolar Technology 


24 karat 5-way gold-plated binding posts


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## fbov (Aug 28, 2008)

You saw them where?

Judging by your description, the only place to start building a set would be at the manufacturer's employment office. This does not appear to be a DIY loudspeaker...

Frank


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## olddog (Dec 21, 2008)

Axiom on the web. They are a ID company. I just thought I could take there shape and incorperate my own selection of drivers? It's just an idea but gosh where do you start?:huh:


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## Mike P. (Apr 6, 2007)

Driver selection and a crossover would need to work with the specific volume of the cabinet.


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## fbov (Aug 28, 2008)

If this is what you're looking for, I can only suggest you reconsider. 

Bipole/dipole designs like this are poor performers in surround applications. Think about the way those two drivers will interact in the seating area. If wired bipole (in phase), you have interferenece patterns in the seating area at each point that's 1/2 wave farther from one driver. If wired out of phase, dipole, you have a big null at any spot that's equidistant from the drivers. 

I'm just finishing a set of surrounds for a similar-sized room using Vifa TC14wg and D25ag components. It's a simple MT in a 0.25 cu ft box with small drivers that give wide dispersion to minimize frequency response variation in the seating area. I'll let you know how it works.

HAve fun,
frank


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## olddog (Dec 21, 2008)

Please do Fbov, I look foward to it. I just thought the form factor fit my situation on those as the sofa is against the wall with the speakers. I currently am using a pair of high end Polk outdoor 2way speakers each slanted in 30% and then facing down 90%. There has to be a better way!:gah: Iam pretty certain I am not the only one with this sort of problem and I cannot gracefully put in celing speakers.


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## Bent (May 24, 2006)

Paradigm's ADP's (adapted dipoles) work slightly differently, they do generate a diffuse soundfield but reduce the center "null" considerably by using the mid-bass drivers in phase. They call it an advanced crossover design, but it is merely that they wire the tweeters out of phase with each other, but one mid-bass is wired in phase with the other.

A side benefit is more usable low frequency extension.


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## olddog (Dec 21, 2008)

How about the form factor on a pair of these? Har to build? Definitive Technology BPVX


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## fbov (Aug 28, 2008)

I've built the Madisound Recession Buster in a sealed, rectangular 0.25 cu ft box. Right now, they're set up as mains and work nicely, so I'm sure they'll make good surrounds. The XO is an in-wall design (no BSC) and would sound fine in a corner surround application. You could build a corner box with an angled baffle. 
Frank


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## olddog (Dec 21, 2008)

Thanks for that info! Do I just go to Madinsound and look it up? I am new at the DYI but not scared to try. Any hints or upgrades to that kit you can suggest?


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## fbov (Aug 28, 2008)

http://www.madisound.com/catalog/product_info.php?products_id=8525

There are application notes, including driver specs, schematics and box designs. For surrounds, I'd build the smaller sealed box, with the baffle angled so drivers point to your listening area. If ceiling mounted, put the woofer on top. but maintain driver spacing.

Have fun,
Frank


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## olddog (Dec 21, 2008)

fbov said:


> I've built the Madisound Recession Buster in a sealed, rectangular 0.25 cu ft box. Right now, they're set up as mains and work nicely, so I'm sure they'll make good surrounds. The XO is an in-wall design (no BSC) and would sound fine in a corner surround application. You could build a corner box with an angled baffle.
> Frank


Hey I looked that one up and the price is RIGHT ON:clap:If I kept the sealed incloser volume to specs but did it with the drivers facing a right and left config with the box tapering back to the wall?:dontknow: Would it still perform?


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## fbov (Aug 28, 2008)

The only performance issues are design related; driver size limits how loud they can play and the crossover design results in poor bass in free-standing applications. However, surrounds don't normally play as loud and they're normally wall mounted, so one could reasonably describe these as "designed" for surround use. They seem a little bright perhaps, and there is a 1.5dB rise in output above 10KHz in my simulations, but I also find that attractive in a surround, especially in my well-cluttered listening space and with my aging ears.

At $100 for the pair, it's hard to beat.

Have fun,
Frank


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## Bent (May 24, 2006)

if a common midbase chamber run in bi-pole, they would prolly work, but if used di-pole, there would be no bass what-so-ever - plus you might risk hitting the excursion limits due to one driver always pushing the other driver and vice-cersa.


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## olddog (Dec 21, 2008)

So both sharing the same chamber/box. Kept to sq ft. specs. If you can picture? A ramp to jump a motercycle??? Jump side flat to wall and ramp running to wall. Right and Left dedicated--why? because the tweeters are on top and off center? To the outside or inside on top? Outside I would think. What do you all think? Would this be better than my Polk Aturim 45s?


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## celsing77 (Aug 15, 2008)

Fbov how do you think the Madisound Recession Buster is a good project for someone who has never built a speaker before? I've looked at their website and for just a little over a 100 bucks it seems like a great deal.


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## fbov (Aug 28, 2008)

I think enough of them that I bought 2 sets, one for me, one as a gift. What sold me was the driver quality; not the best Vifa makes but good none the less. It's a very servicable speaker kit, and the boxes can be as easy or hard to make as you'd like. Speaker building isn't hard if you have some basic woodworking tools and there's very little you can do with the provided designs that would sound bad, save for expecting strong low bass out of the sealed box. 

Have fun,
Frank


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## keelay (Dec 11, 2008)

I have been eyeing the Encore for some time. I built a pair of Natalie P's  and absolutely LOVE them. The Dayton tweeter and midwoofers offer exceptional bang for the buck. The Encore uses the same tweeter and a smaller mid woofer. It looks like a pretty straightforward project too. Here's the link to my Natalie P Build thread. 

- Kyle


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## fbov (Aug 28, 2008)

Given what you're doing to integrate the NatP's into your room, any proven design will likely be straightforward for you. It then becomes a matter of philosophy. The Encores are a nice design, and if you like them, you may like these even more
http://www.eldamar.net/audio/rs150mtm/

From a practical standpoint, there's no advantage to an MTM over an MT unless you plan to play very loud, but some folks might like to maintain a consistent configuration. Again, I went with the RB's based on low cost and a desire to learn more about sound and speaker design, not necessarily for the sonic match you get form common driver/driver family. 

Have fun,
Frank


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## keelay (Dec 11, 2008)

Just checked out the RB at madisound. That is a smoking deal. I may just have to pick up a pair just to try.

Thanks,

Kyle


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## keelay (Dec 11, 2008)

Update. I just ordered a pair. If they check out I'll order another pair and round out my surround speakers.

Kyle


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## celsing77 (Aug 15, 2008)

Well I took the plunge and bought set of the Madisound RB's. They should be here in the next couple of day's. I just went to HD and picked up the MDF and cant wait to get started. I also picked up a router yesterday. I have a feeling I have just started down a very slippery slope, I can see where this leads to just one more project and then another and then another......


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## keelay (Dec 11, 2008)

celsing77 said:


> Well I took the plunge and bought set of the Madisound RB's. They should be here in the next couple of day's. I just went to HD and picked up the MDF and cant wait to get started. I also picked up a router yesterday. I have a feeling I have just started down a very slippery slope, I can see where this leads to just one more project and then another and then another......


Very slippery. I just finished my third speaker project. When my RB comes in that will be the fourth!

Kyle


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## fbov (Aug 28, 2008)

Why are you waiting? The RB plans are accurate; the only thing I'd wait on parts for is cutting the tweeter recess, so you get it flush with minimal gap. The rest is straightforward, assuming you have a table saw or circular saw. 
Frank


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## keelay (Dec 11, 2008)

I got my RB-Kits and built a pair. Put them in an MDF .5CF box tuned to 48Hz. I'm very impressed for $60 a pair. They are clean detailed sound. The top end is airy and crisp, the midrange is clean, and the bass was very surprising. These little guys in this box do nicely down to 50Hz. Both female and male voices performed well. I A/B tested them against my Natalie P's as mains and while the Natalie P was better in every category, the RB-Kit speakers held their own. I A/B tested them against a single Onkyo HT-in-a-box SKM-520S surround. It wasn't even close. The Onkyo speaker which at one point in my life, I thought were great, sounded muddy and dull by comparison. 

This was a compromise for me. My original plan was to build 4 encores or Modula MT's for the surrounds, but that was going to cost 4x what these cost. In the end though, I really think I'll be happy with them as my rear surrounds. I have two more RB-Kit speakers to make and My 7.1 will be complete. I'll be soon posting my build thread for the speakers. They are in a custom box for ceiling mount.

Kyle


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## Owen Bartley (Oct 18, 2006)

Can't wait to see the build thread. And yes, you are in trouble now. You know its bad when as soon as you finish your current project, you don't even take the time to enjoy it before thinking about the next one.


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## keelay (Dec 11, 2008)

So I have started my RB-Kit Build Thread. This was a fun project and have to build 2 more, which I will likely do this weekend. Then I just have to ceiling mount them. 

Kyle


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## mosconiac (Jan 31, 2009)

I just completed the obligatory Recession Buster build and was pleasantly surprised by the results. They will be my surrounds in an upcoming HT build. Fronts will be Murphyblaster CAOW1's with a Shiva-X sub.

http://www.hometheatershack.com/for...oniacs-recession-buster-build.html#post179045

Here's a little teaser...


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## Mario (Jun 2, 2009)

Hope people don't mind me resurrecting the thread since I've started work on my HT and in need of four surround speakers. Two of those will be dipole and serve as left and right surround and two will be bipoles and will be in the back. I know some people don't recommend dipoles since they produce a null perpendicular to the driver axis, but that's the whole point of surrounds. You do not hear the speakers, you hear reflections which helps create the illusion of being surrounded by the source. If you are able to close your eyes and point to the surround speakers as the source of sound, they are not doing their job properly. 

Anyway, I was thinking if I can adapt an existing design to my purposes since there are zero DIY designs out there that mimic commercial surround speakers similar to the Axioms mentioned in this thread. My knowledge of crossovers are pretty limited. I understand I'll need to remove any baffle step compensation and modify the crossover to handle twice the number of speakers. Also, I have no slightest idea how to simulate dipole speakers in a program like WinISD. Can the drivers even share a single chamber in this configuration? Any input would be appreciated.


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## mwmkravchenko (Jul 11, 2009)

Never say never.

There are some designs that are available.

A very good design basis is a multiple point source design using full range drivers.

A second very good design guideline is a half cardioid pattern. It creates the most convincing surround effect according to Floyd Toole.

As for simulating the design it is not easily done with free software. But thre are ways to measure a design using free software like REW etc.

Mark



Mark


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## gibroni (Sep 25, 2010)

http://www.gr-research.com/index.asp?PageAction=VIEWPROD&ProdID=113

Similar drivers as the MurphyBlaster. I have a pair of MurphyBlasters and the sound great. I'm using them as surrounds in my 5.1 and would like to build the cabinets in the link above.


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## GranteedEV (Aug 8, 2010)

mwmkravchenko said:


> A second very good design guideline is a half cardioid pattern. It creates the most convincing surround effect according to Floyd Toole.


Do you mind elaborating on a "half cardioid"? I've always thought cardiods make sense for surrounds but what's a half cardioid? Can you give an example of an existing design?


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## mwmkravchenko (Jul 11, 2009)

http://www.hometheatershack.com/for...ns/26846-el70-surround-speaker-show-tell.html

A bit more explanation.


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## Mike P. (Apr 6, 2007)

mwmkravchenko said:


> http://www.hometheatershack.com/for...ns/26846-el70-surround-speaker-show-tell.html
> 
> A bit more explanation.


The "Kravchenko Kantaloupe", an interesting design indeed! Wish I had the time to build them.


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## mwmkravchenko (Jul 11, 2009)

It's easier when all the pieces are pre-cut.

It hangs on a wall and is the closest thing to an ideal surround I have ever seen.

And it will never become a commercial product. To complicated to cut out!

Mark


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## gibroni (Sep 25, 2010)

Actually mark I don't see it as too difficult to cut for a commercial product. Most commercial speakers manufacturers are using CNC routers and cutters so it's a piece of cake. I actually think that if a company wanted to put this in Best Buy it would use a molded baffle. I've actually seen it a decade ago. It might have been Infinity, and the speakers were rotated 45 deg.


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## gibroni (Sep 25, 2010)

I thought the Infinity QPS-1 was quadrapole but it's actually just bipole.


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## mwmkravchenko (Jul 11, 2009)

Even with a CNC this is not an easy box to cut out. I have worked as a consultant and speaker designer off and on since 1989. The angles in this box are the problem. They are not the normal "V" groove cut and fold type of layout that favors the CNC method.

But unlike all the other boxes shown in the preceding pictures this one actually does behave as a proper dipole and has a true half cardioid null at the listener's position. The reproduced signals are wide enough in bandwidth to cover all the range of hearing that is concerned with spatial recognition. The sources are laid out in a symmetrical pattern that creates a dead zone very near the imaginary apex of the pyramid. So correctly positioned in a home theater setup this is one way to get an almost ideal surround speaker. The drivers are not all that expensive either. 

Mark


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