# Surround design options



## f0zz (Dec 1, 2011)

What is "the best design" for surround speakers for my 5.1 system?

I'm building these speakers myself. Originally I was going to build a set of Dipole surrounds, but I've read that Dipole is actually not the design of choice for HT. up until now, all the speakers I've built have been direct radiating.

I have access to more raw drivers than I can count so no problems there. My fronts and rears are all using the same matched drivers, just not sure if I should stick with a standard design?

The speakers will be mounted in wall about 2ft above the listening position aimed slightly down @22.5 degrees)There are two rows of seats for this room with the back row against the rear wall. 

John


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## Zeitgeist (Apr 4, 2009)

What are you running for L/C/R?

In an ideal world, you'd have all speakers using the same drivers. That would give you matching timbre, sensitivity, dispersion, etc.

How big is your room?

From the conversations that I've read, the ideal surround is direct radiating (if you have the room). Dipoles can be used successfully - but they're not used when doing the mixing - direct radiators are. I was thinking about building some switchable bipole/tripole speakers like M&K sells, but decided that it's better to have a very good direct radiator.


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## f0zz (Dec 1, 2011)

All of my speakers are being built by me. They will all use identical (matched) speakers. The fronts are a three way design using one 8" two 5" and one tweeter. 

The room is fairly small. About 15 ft x11 ft with a ceiling height of about 6'-6". I live in a 100+ year old house, so I'm lucky to have a basement at all!

My concern and reason I considered dipole was due to my limited space. 

John


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## Zeitgeist (Apr 4, 2009)

Got it. I think I misunderstood your question. I think you are asking what the best configuration is for the surrounds ? Such as, Woofer, midrange, tweeter? IE, a traditional 3 way with drivers stacked on top of eachother? WMT. My thinking is the 2nd midrange is probably less important on the surrounds.

Awesome you have a basement. I can't imagine HT without it. 

Ive built a set of 3-ways, using a WCW configuration (so coax in the middle) - with 12" woofers. I'm planning on building surrounds with 8" woofers and the same coax for mid/tweet (partly due to cost, but mostly due to size)


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## f0zz (Dec 1, 2011)

Not really the configuration, rather the design type. Is dipole or bipole a viable option? Or would a standard monopole (regular type) speaker be the best option for my small room?

If it helps, I have about 20 of the 5" mids remaining. So if adding more speakers will help, I can do that.


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## Zeitgeist (Apr 4, 2009)

My room is effectively 10'wx15'l and I sit about 3' in front of my rears which are direct. I'm personally very very happy with the configuration. 

I've been skimming through Holman's book "Surround Sound Up and Running", I'll see if there are any dipole mentions.

I have to think that at a CERTAIN size room - that dipoles have to have some advantages, given their diffuse nature.


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## f0zz (Dec 1, 2011)

That's my thinking exactly. Just not sure if my room qualifies as direct or dipole?


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## patchesj (Jun 17, 2009)

This might be a silly suggestion, but if you have the drivers/time/materials why not build some test mules both ways? I think this is one of those extremely grey areas and in the end it all comes down to your preference. You'll never know unless you can demo them in the room back to back.


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## Prof. (Oct 20, 2006)

Why not have the best of both worlds and build a tripole or quadpole surround!?


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## f0zz (Dec 1, 2011)

patchesj said:


> This might be a silly suggestion, but if you have the drivers/time/materials why not build some test mules both ways? I think this is one of those extremely grey areas and in the end it all comes down to your preference. You'll never know unless you can demo them in the room back to back.


I agree that this is probably the only real option. I think I will star with the dipole and go from there.

Thanks for the input guys


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## Owen Bartley (Oct 18, 2006)

f0zz, welcome to the Shack from a fellow Ontarian.

If you're going to be placing the surrounds in-wall, and you don't have any weird constraints on where to locate them, it seems to me that direct radiating may be the best. And I say this knowing that I like a nice diffuse surround field. I think that in a small room, you don't need as much "fill" in the surround channels. I'm also kind of wondering how you would build the baffle. There are quite a few commercial options that do this, but it seems like it would be a fair challenge to build yourself.

With that said, I'd still love to see it if you do go the dipole route!


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## f0zz (Dec 1, 2011)

Building the isnt a big deal. It was which design that was giving me trouble. I have changed my mind several times but am now back to direct radiating. 
I've also changed the set up to a 9.1 system. Not because I need it, but because I bought a reciever that had the extra channels and they wouldn't have been used otherwise. 


Cheers, 

John


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## Owen Bartley (Oct 18, 2006)

I think that will sound great for you. In my plans for a future basement theatre I'm going with direct radiating in-walls too. I think it was mostly an issue of ease of setup, cost, and the finished appearance in the end. Although now that I'm thinking about it, if I had an option for dipolar in-walls at a small price premium, I might just take it. Sorry, not trying to send you back to the drawing board!

Have you decided on what 9.1 layout you'll be using? Front height or wide channels?


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## f0zz (Dec 1, 2011)

Im going the front height route. The speakers will actually be slightly further out ( further from centre) than they are technically supposed to be, but it should still work just fine.


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## Owen Bartley (Oct 18, 2006)

Is there a way you could set up the speakers in a temporary location to try out height and width individually to see whic you like better, before installing them permanently, or do you have to settle on one before you set things up? I'd probably go with height if I had to choose too, but I guess if I had a very wide room I might go the other way.


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## f0zz (Dec 1, 2011)

I don't really have many choices. There is only one location available! 

Makes decisions easier when there is only one option.


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## Owen Bartley (Oct 18, 2006)

Yes, it certainly does!


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## gmannel (Jan 16, 2012)

Continuing w/ surround design advice - I am new to DIY but have about 1/2 way completed my sub build and have started gathering parts for the main LR speakers. These are to be linear arrays wall mounted at listening level. The room is basically a long rectangle about 18 x 50 ft w/ a lowish ceiling at about 5 ft at the side walls peaking to 9 ft in the center(roofline). The HT area will be about 1/2 of the length of the room, w/ a planned FP and ceiling hanging screen. So there will be the other 1/2 of the room open behind the HT seating area, rather than a wall. So surrounds would more or less be at listening level and at or just behind seating area. I could do 2 each side, or one each side. I could add a center rear all the way at the back wall as well. AVR will be 9.1 at minimum. I don't see any space options for front height or front wides given the room shape.
Thoughts?


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## GranteedEV (Aug 8, 2010)

f0zz said:


> Not really the configuration, rather the design type. Is dipole or bipole a viable option? Or would a standard monopole (regular type) speaker be the best option for my small room?


In my opinion, mixing rooms use monopole speakers. It stands to reason that a well designed monopole speaker will most accurately reproduce discrete surround effects and, with with four (in a 7.1) should provide excellent envelopment.

It's also my opinion, to use dual concentric type drivers for surrounds, because they maintain their phase accuracy in the crossover region even well off axis, leading to minimal localization, as well as an even power response, assuming good design.



> I have to think that at a CERTAIN size room - that dipoles have to have some advantages, given their diffuse nature.


The nature of those so-called dipole speakers, is that they throw the sound forward (to the front of the room) and backward (to the rear of the room), and minimal signal sideways (towards you).

Now all that I have ever read, says that we don't want surround information arriving from in front of us.

Compounded with the fact that there is discrete info (IE a car crash) in surround channels, now being "diffused", and I feel dipole surrounds are artificial.

Bipoles are essentially the opposite effect. They create phasy-ness that makes the surround speaker MORE localizable than a monopole. There's less diffusion IMO, albeit not IME as I have no experience with such surround speakers.



> I've also changed the set up to a 9.1 system. Not because I need it, but because I bought a reciever that had the extra channels and they wouldn't have been used otherwise.


I would scrap the extra channels as they will just put unnecessary burden on the receiver's amps and processing.



> So surrounds would more or less be at listening level and at or just behind seating area. I could do 2 each side, or one each side. I could add a center rear all the way at the back wall as well. AVR will be 9.1 at minimum. I don't see any space options for front height or front wides given the room shape.
> Thoughts?


Do side surrounds and rear surrounds, monopoles! :bigsmile: [/QUOTE]


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## tshifrin (Nov 24, 2011)

Check these out for surrounds: http://www.diysoundgroup.com/speaker-kits/small-kits/osmtm-flat-pack.html 
The word on various forums is that they're pretty fantastic, and at this price, a steal.
G'luck,
Tom


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## gmannel (Jan 16, 2012)

How would an adequately long line array work as side and rear surrounds? And maybe even trying to do them w/ a single line of a full range 2-3" drivers?http://www.parts-express.com/pedocs/specs/290-210-dayton-audio-nd90-8-specifications.pdf I imagine 95+% of the surround info would be covered by full ranges with the realtively non directional low end coming from the sub? Maybe filter out 150Hz on down?


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## gmannel (Jan 16, 2012)

Or other driver ideas?
These would be a cheap experiment at $8 each - thinking 12-15 per line?http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-113
For such an array w/ only one type of driver there is no xover right? just a notch filter if needed?


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## maxmercy (Apr 19, 2008)

I plan on using those TB 3" drivers for a rear speaker in a 6.1 setup.

My L&R surrounds are these:



















Made from some peerless 2" buyouts http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-271and are vented boxes tuned to 100Hz, I cross them at around 120Hz. They sound good, and though I haven't measured them, I know they will likely not measure as well as a fully optimized design, but for $80 total for both surrounds (not counting wood, stain, lacquer, wiring, terminals and pvc pipe for vents), they are hard to beat.

In a group of 8 (wired for 8 Ohms), they reach near 91dB sensitivity prior to any boundary loading, which drops off like all arrays do higher up in frequency. They are set by my receiver's Audyssey at -4.5dB, and begin to show audible strain at -7dB Reference. Since my LCRs also start to strain at the same level, I usually listen at -10dBRef for movies.

According to WinISD, they should hit 105dB at Xmax with 30W in. Since the listening distance is around 3 meters, that means a level of around 96-97dB at the listening position. Since the most ever asked of a surround at -10dBRef is 95dB, they stay within Xmax at all times, and never see more than 30W... 

I wish I would have bought more of them, thay are nice sounding little speakers.


JSS


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## gmannel (Jan 16, 2012)

Do you see any downside in those TBs? At $8 each seems like a safe try. I was thinking a straight line array but I could curve it like those, but would have to be floor up in my particular room. Thinking 12 -15 per array?


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## maxmercy (Apr 19, 2008)

There are compromises to any speaker design. For instance, in my little surrounds, I knew I was giving up LF due to driver size, I knew I would have lobing issues throughout the dispersive field because I did not shade the array (needed every dB I could get), and beggars cannot be choosers. The drivers were cheap and available, and I did not have adequate surrounds at the time.

Any fullrange solution will beam and have grating and lobing issues in an array. But again, budget and space requirements sometimes do dictate terms.

I plan to do a curved array with 9 of those TBs. 

JSS


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## gmannel (Jan 16, 2012)

Design flaw here? What do you think?
As side surrounds at listening height, 8 of thesehttp://www.parts-express.com/pdf/295-342s.pdf, 4 above and 4 below this WGhttp://www.eighteensound.it/index.aspx?mainMenu=view_product&pid=262, or 6-8 of the LFs w/ the WG on top. Top of speaker can be no more than 58" due to slanted ceiling. Crossover would be miniDSP.
Front LRs planned now as MCLAs and center is Econowave Deluxe, sub is Tuba HT


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## gmannel (Jan 16, 2012)

Was thinking that the line array idea would be better horizontally than a basic MTM


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## maxmercy (Apr 19, 2008)

You'll need a 2.5 way crossover for that, with the 6" drivers closest to the horn doing bass+midrange duty, and the further ones doing bass-only duty.

Why not do a MCLA for center and surrounds? Use an acoustically transparent screen and bingo, done. No need to timbre match.

BTW, with a slanted ceiling, MCLAs will not use floor and ceiling bounces to act like infinite lines. Show us a diagram or picture of the room.

Also, 2 THTs make for more good seats than one, unless you get lucky. Also gets you 6 more dB below 20Hz.

JSS


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## gmannel (Jan 16, 2012)

How do u do an MCLA for a center(no corner)?
What about these drivers for full length MCLAs?http://www.madisoundspeakerstore.com/approx-3-fullrange/aurasound-ns3-193-8a1-3-black-cone-wide-range/
Xmax looks great, price is right!


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## maxmercy (Apr 19, 2008)

It looks like the Dayton ND90 and the Aura NS3 are essentially the same driver. Just modify the enclosure for on-wall loading and go for it. First, I would build just one and listen and measure, though... 

JSS


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