Should all the speakers of a surround system be of same size?

I'am not a guru, but I just went through this also. Some things I found was it depends on your use. For strictly home theater, they ussually are different sizesThe surround and back speakers don't have to be big to put out movie sounds.. You want to be sure and buy the same series of a brand for at least the fron center and front left and right so they are tembre mached (they sound the same). If you are going to play more than 2 channel music (maybe all speakers), then I would get adaquate speakers all around.

I've got a friend who's got a 7ch system, using LaScalas all the way around.

 

It's staggering to listen to.

 

If you have the room and budget to do it, I'd say go for it however, I would also agree that it might not be as necessary to match the surrounds since they might be more for ambiance rather than focused sound.

 

Meaning...  the movie makers want your eyeballs on the screen (front) not turning around to "see" what just happened behind you so the most important sound would be up front.

 

That's my take on it.

The mantra that surrounds only carry ambient sounds is simply false. Modern soundtracks can, and do, contain equal content/dynamics/SPL in all channels. If your priority is accurate, uncompressed reference level reproduction of a soundtrack then all speakers need to be capable of playing 105dB without compression. Identical speakers all around is ideal IMO.

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So, what if you use towers upfront?

For most people, in most rooms, the main thing is to have front speakers that are large enough and powerful enough to go down to below 50 Hz and provide decent power and bass. This usually requires a minimum of a 5.5 inch main driver or larger. The subwoofer should be set for operation below 60 Hz only. They can be monitors or floorstanders.

Center speakers do not need to go very low or high, and only need to go from 120 hz to 5 khz, so they can be much smaller and do a very good job. Too many people confuse larger with better in a center speaker, which is wrong.

Other speakers should be capable of going down to 80 Hz, but the need for anything below that is questionable.

Now you're messing with that pea I call a brain. Home Theater bass management has everybody rolling bass off to the subs at 120Hz so the bass of the subs won't argue with the bass of the mains; bloating. We have bass management set, all speakers small, mains set to roll everything off at 120Hz and the center channel set to 60Hz so we can casually listen to television programming dialogue without need for subs. Because the subs and the mains aren't fighting at the lower 120Hz level (LFE tracks are mastered <120Hz), there's no boomy or bloated bass.

Use matching brand and model line but you don't have to use the same speaker for the fronts as you would for surrounds or vice versa. There is a lot of information mixed into the center channel so its important not to skimp on it and it should be close to the performance of you mains.

I don't use the same speaker all around I use Arx A2s for Fronts and center with the planar tweeter rotated for vertical use and the smaller A1 bookshelf for surrounds. Have them all crossed at 60hrz and its a really seamless soundstage, although you can cross over what ever you like 60, 80,100,120 ect. Its room dependant and what sounds best to you, no absolute rule.

60hrz for mains is a good crossover point IMO for the mains, saves them from trying to produce the bass from movie soundtracks. I think by crossing the mains to low you lose some dynamics in the upper midbass and distortion can rise at higher volumes, let the sub handle everything below 60-70hrz its much more capable of producing bass than the towers.

Centers do need to extend at least to 80hrz even lower, the male voice can go to 80hrz. Also with modern movie soundtracks the center is a very important speaker, theres so much information being mixed to the center channel. If you've taken time to listen to a good large center channel than you wouldn't make such a claim.

Not too important for surrounds to be crossed low but DVD Audio and other surround sound music mixes recommend that all speaker be of full range.

All speakers should be crossed over to match the sub. If your crossing the sub at 60hrz than all the speaker should be X at 60hrz.

Disclaimer: I do not claim to be a guru.

I have heard systems with all speakers the same and with significant differences. To me, having them all the same sounds best, given good speakers (I heard a system using B&W 802's all the way around), but it is rare that the surrounds/rears/center have as much LF content as the mains, especially with a subwoofer set at the typical 80 Hz suggested by THX (and many other folk). It is also rarely practical to match all speakers; there is usually not space or finances, and seating (chairs/couches) often requires the surrounds/rears to be higher than the mains, a problem for most floor-standers. From a sound standpoint, in my experience, there is not enough full-range surround content to justify the space, cost, and set-up hassle.

I have had a variety of speakers in my system and prefer them reasonably matched, but since I have dipoles (Magnepan) I may be more sensitive than a typical system. I had less an issue when I had Infinity L/R/C (Alpha or Beta, I forget) and little Mirage Nanosats as surrounds. I would prefer to buy the same manufacturer and line, but see no special reason to force myself if there are other, better alternatives. I do think having the center match the L/R speakers reasonably well is important since you want a seamless (or as near as possible) across the front as dialogue and other sounds pan across the front. I find that less important in the surrounds. As always, YMMV.

I have noticed a significant amount of energy seems to go to the center if it is capable, so prefer a little deeper response than the surrounds. However, having additional LF response can complicate set-up since the placement is fixed more by aesthetics and concern for proper surround sound field than bass response. It may be hard to find the best compromise with a full set of full-range speakers versus a sub or three you can move around to optimize in-room response. I also tend to think a 60 Hz crossover is too low for most speakers since most surrounds (and many mains) do not handle large bass excursions. Big L/R speakers can often handle 60 - 80 Hz with aplomb, so I would not set all crossovers the same unless I had to. My mains go to about 35 Hz on their own and I have them crossed around 50 - 60 Hz. The surrounds are rated to 80 Hz and I have them crossed at 80 Hz. My little Nanosats I crossed around 100-120 Hz.

So, for me, having different surrounds provides cost- and space-savings and makes it easier to set up the system both physically and aesthetically. I prefer timbre-matched L/R/C since the sound needs to flow smoothly across the front; less so the surrounds/rears. The loss in sound quality is minimal and not noticeable to be unless I compare one after the other.

I do not think there is really a “right” answer but this is what I have found for myself.

HTH, IMO, FWIWFM, YMMV, etc. - Don
Edited by DonH50 - 8/11/12 at 7:42am

In direct answer to the OP question, no. If you note manufactures don't always match speaker sizes in their packaged surround systems. Some do, some don't, it's not a requirement.

No. You do not need to have matching size surrounds in a setup. You want the majority of your budget to focus on your left, right, and center main channels and your subwoofer. While it is often recommended to timbre match your surrounds with your mains, I don't find this to be a hard requirement. That said, you do want to timbre match your left, right, and center main channels.

THX, Audyssey, and most trusted subwoofer companies recommend using bass management in your receiver and setting crossover to 80hz and adjust from there. Human ears cannot localize bass below 80hz, so that is a good place to start, but you can adjust from there.

FWIWFM = For What It is Worth From Me

I do not think bass localization stops at 80 Hz for everybody, at least IME and per tests run back in the 80's. In the tests I participated in, virtually 100% of listeners could localize at 100 Hz, no-one at 50 Hz, but there was a range between. That said, in agreement with posts above, 80 Hz is a great starting point and good enough for most, again IME.

What some haven't include in their conversation are bass sound wave conflicts set about by competing emitters. When the subs and the mains reproduce bass notes, the bass notes fight each other; adding and subtracting as they will as the bass notes bounce off walls, furniture and ceiling. This bass note fighting creates boomy and bloated bass notes (lack of tightness in bass note quality), hence the need to manage bass emitters; mains and subs.

In 5.1 sound tracks, the people on the mixer, mix <120Hz to the 0.1 LFE channel. And if sound at this level is allowed to go to the mains such as is the case of dialogue or what ever, as an example, the mains reproduce their 100Hz sounds and the subs reproduce their 100Hz sounds and the bass note sound wave fight is on as both mains and subs are blasting competing sound waves all over the room; so messy.

The way this is handled is bass management, which is to port all <120Hz to the subs so only the subs are reproducing <120Hz sound as now <120Hz sound of the mains are not fighting with the <120Hz LFE channel when 5.1 tracks are decoded and ported to the sub channel. I do make exception for the center channel as I set the crossover or LPF to 60Hz so as to maintain some musicality of the male/female dialogue.

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Edited by BeeMan458 - 8/11/12 at 2:04pm

Having speakers that are identical are really the best way to go...as long as you are using quality speakers (no bose tin cans). Say, two ft tall 3-ways and a couple of subs. Like the decade old JBL PT800s or the current Revel Gem2.

Now with that said, can you improve those systems? Yes, but the case of the Revel Gem2 you then have to go with the Studio2 towers or the Salon2 towers for the mains. You're talking big bucks for a pair of either.