# If not limited by size what would you use for surround speakers?



## justforthesoundof (May 8, 2012)

With no limits on your design, what type of cabinet, crossover (or not), size, number and type of drivers and of course, the why of it. The goal is the most natural sound and clarity of voice, music and sound effects, based on your experience. This is not for arguments sake, just what you would enjoy.


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## tonyvdb (Sep 5, 2007)

Ideally the same speakers as you use in the front but I would be surprised if anyone could really tell if you used some good sized bookshelves like I do. The space your theater is in would be a challenge if you used full sized towers.


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## justforthesoundof (May 8, 2012)

I'm not experienced, just going by what I've read, using different speakers would cause a change of voice as it moves between speakers. I thought that maybe you could use the same woofer/mid range for all and add a large woofer (not subwoofer) for each of the front. As I understand, a crossover changes phasing, so I wondered if that would work. I understand that some 9.1 systems can use two channels for bi-amplification. Maybe that would prevent the difference of phase shift in adding the larger woofers for the stereo pair. Again this is reading and thinking, not experience.


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## justforthesoundof (May 8, 2012)

Let me seed this for discussion 
•	6 ½” 2 way for the 80 Hz up on all and add a 12” to the fronts. (LFE would go to a sub). 
•	8” 2 or 3 way all the way around with below 60 HZ to the sub with the LFE. 
•	Full range all the way around with 100 Hz and below going to the sub with the LFE. 
•	???:huh:


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## fusseli (May 1, 2007)

The biggest gain of a 3-way is high power handling ability. MTMs are far superior for sensitivity and maybe even better polar response. If you want to preserve the signal you are trying to reproduce, simpler is definitely better. If you want simple and good performance then you need the best drivers. But, you can still waste the best drivers on a poorly executed design. No matter how you slice it better quality requires more time and more $$. 

A well designed full-range (single driver) would probably be the easiest to pull off, but it would have performance limitations like low power handling and narrow off-axis performance.


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## colofan (Aug 30, 2013)

From what I have read on surronds in movie theaters the frequency range typically is 65-16Khz plus or minus 3 dB in frequency response. also power response is what you want not on-axis performance. A very wide polar response of at least 100 degrees (plus or minus 50 degrees) for drop off of no more than 3 dB.

I have seen those specifications in THX certified systems.....good luck


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## Tonto (Jun 30, 2007)

I used to think that floor standers all around was the best solution to timber matching. But nowdays with speaker evolution, bookshelf speakers are just superb. Matching them to the main speakers is all that is necessary. Not that much loudness needed out of them, so it becomes less of an issue. And you can save some dollars as well.


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## justforthesoundof (May 8, 2012)

When you say "bookshelf" are you thinking 5", 6" or 8". full range or two way. When you say 65HZ, would that suffice for the front as well and send below 65 (80) Hz to the sub. Or is there a true advantage in using full range for the left and right front. I will be building these into a large crown moulding. I have a cathedral ceiling, so even though the room is average length and width, up is wide open. I just have to make it look like it belongs there.


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## Tonto (Jun 30, 2007)

Bookshelf just refers to the general principle of being able to sit them on, well, a shelf. You can also hang them on the wall. Floor standers are just that, too big for the same (even though some of us here have hung them on the wall!!!). Size of the driver is up to the manufacturer. All speakers & rooms are different. You will have to experiment with setting the crossovers and see what measures out to be better. It is not uncommon to cross fronts @ a frequency that is different from the surrounds or rears. Or just let the room analysis software take care of it (Audessey).


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## colofan (Aug 30, 2013)

justforthesoundof said:


> When you say "bookshelf" are you thinking 5", 6" or 8". full range or two way. When you say 65HZ, would that suffice for the front as well and send below 65 (80) Hz to the sub. Or is there a true advantage in using full range for the left and right front. I will be building these into a large crown moulding. I have a cathedral ceiling, so even though the room is average length and width, up is wide open. I just have to make it look like it belongs there.


Depends on the output level you want to what size you want to use. I am using a 8 inch mid-bass, 6.5 inch midrange and horn tweeter for a really high out. 

The 65Hz specification came from a certification process that they use to mix the movie down to on the surrounds. The LCR in the front I still maintain a 30Hz woofer mostly in case the producer want to add some "punch" in special effects on the front channels. The LFE channel takes care of the res. It depends really on what processing you have in house to decide on how much lower bass your fron mains are going to use.


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## justforthesoundof (May 8, 2012)

Does this give you a natural sounding voice and instrument, your opnion compared to other setups you have experienced? What frequency range are you sending to the 6.5? Are you using the sound processor to limit the low frequencies on the surround speakers?


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## redrider_99 (Mar 9, 2010)

My dream would be to modify a DIY design into an in-ceiling speaker with some kind of angled baffle to direct the axis toward the seating area.

Plain round in-ceilings are boring to me and I like to make things harder than they need to be.

Even though you're asking regardless of size limitations, the setup of my room isn't going to let me use the floor or wall-mount so ceiling it is for me.


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## fusseli (May 1, 2007)

Aim for something that can reach to 80Hz either sealed or IB. Consider a design with flat power response rather than flat frequency response since they will be surrounds.


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## robbo266317 (Sep 22, 2008)

fusseli said:


> Aim for something that can reach to 80Hz either sealed or IB. Consider a design with flat power response rather than flat frequency response since they will be surrounds.


Russ, can you elaborate on what you mean by "flat power response" 

-Bill


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## fusseli (May 1, 2007)

Power response is like an average of the off-axis performance of the speaker. When doing DIY designs for your typical L/R mains, you usually go for flat frequency response since the "sweet spot" is usually where you listen. PA speakers used for mains may have optimized power response instead, as might surrounds, since your listening position is rarely right on axis. Either is chosen in the crossover design process.

Does that help?


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## robbo266317 (Sep 22, 2008)

Yep, thanks for that.
To use an analogy it's like an antenna can be very directional eg:








or it can have the same power spread over a larger area.


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## fusseli (May 1, 2007)

And to further complicate the concept, the polar response of a multi-way speaker is also frequency dependent. That's a tougher one to model though.


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## justforthesoundof (May 8, 2012)

I "kinda" understand the off axis of the speakers, though my learning curve hasn't reached a point that I know which types of speakers offer the widest angle of sound. Thanks to these last recommendations, I will make sure to get a pattern that is wide enough to cover my sweet spots. 

In my present situation, I have a surround system that is about 13 years old. The surround speakers are in ported boxes, though the "woofer" in each has a capacitor inline with it to limit the low end. I have them set "small" in the receiver to cut off at 100 Hz. Male voices have always been awful, booming. I will DIY a new system and want to make sure my thoughts are correct. From what I've read, using a larger woofer, size ?, in a sealed enclosure will give a more natural sound to the male voices. 80 Hz comes up more often than not as an ideal cutoff point. The 65 Hz was a new one to me. Should that be in my design. I can't go high dollar and I don't want to go oversize. I look at the specs on some 6.5 raw woofers/mid-range drivers and they appear to have a starting point of around 70 Hz, sealed box. 8" appears to be and easy fit in the frequency, but is pushing the envelope in terms of real estate on the wall. They will be designed into the crown molding that I will put in my living room. It has a cathedral ceiling that starts at about 9.5', so the speakers can be larger that the average. I have not been exposed to many systems so I do welcome any comment. Brainstorming.


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## fusseli (May 1, 2007)

To get into the 70-80Hz range, you could easily do it with the right 5-6" driver in a small ported box. It will be harder to do that sealed, even with an 8". The boomy sound you are experiencing is just from cheap poorly designed speakers and you shouldn't take that sound as typical for the driver size!


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## crazydiamond (Apr 3, 2012)

Parts Express CBT36. For surrounds line arrays are ideal, because they minimize intensity differences for off-center listeners.


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## morca (Aug 26, 2011)

I would buy the same as the front,s.
If possible i would buy the same center to.

5 the same speakers give,s a awesome sound bublle.


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## lcaillo (May 2, 2006)

I agree, match the speakers if possible. The seamless sound, with the same voicing and linearity is hard to beat.


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