Monitor 40 as center?

Drew_veloce

I'll be splitting my time between movies and multichannel music, so I wonder if I shouldn't put Monitor 40s all around, including the center, or use another center instead (the CS2?). What do you guys think?

RuSsMaN

40's all around.

MacLeod

Wouldnt a dedicated center like the CS1 or 2 be better Russ?

RuSsMaN

No it wouldn't, especially if he's into the multi-ch music scene. That being said, even for HT, if you want seemless imaging side to side, front to back - all your speakers should be the same. EXACTLY the same.

Dedicated center channels were built to appease the masses, so they could have a horizontal speaker to 'lay' on the TV - it's hardly the best option for true timbre matching.

I've always wondered why Polk has never done an LCR speaker, and ditch the 'dedicated' center speakers all together. The 40 would be the LCR for the Monitor line, the 9 for the LSi series. They'd need to do a MTM for the RTi line.

Cheers,
Russ

Polkersince85

I agree with RussMan. I've used three (3) M10b on the frontend and two (2) M7b on the backend. No sidewinders here. Give it to me straight-up.

VR3

A speaker standing vertical will have a much wider soundstage than one laying on its side. There are all kinds of ill-effects of having a horizontal center channel. Plenty of companies do what they can to get rid of these effects, but they are - indeed hard to get rid of.

A good thread to view to get more information on this -

READ ME BEFORE REPLYING TO THIS THREAD
http://www.soundandvisionmag.com/idealbb/view.asp?topicID=28298&forumID=37&catID=1&search=1&searchstring=

MacLeod

OK, I get it. So center channel speakers like the CSi3 are strictly for cosmetic reasons.

aaharvel

sure the monitor 40 would work great as a center. It's got 2woofers- Russ tell me why you don't need 2woofers in a center channel speaker. I mean with your advice I should have gotten a RTI4 as a center channel. Why?
I would think a csi3 would better center dialogue between the 2 side speakers thanks to it's 2nd woofer. Where am i going wrong?

RuSsMaN

RTi4's all the way around would be great. A 'center' doesn't NEED 2 woofers any more than any other channels does.

Read the article.

Cheers,
Russ

VR3

Yeah for real, read the link I posted above...

It explains why a second midbass is not always a good thing.

aaharvel

sid's article- ok.
(edit) very interesting...

Mike682

Cool...very interesting article. Gonna have to give it a try

MacLeod

This is kind of along the same lines as in car audio and rear speakers.

Rear speakers are usually looked down on for the same reason, cancelation. Having the same sound hit your ears at different times due to the different distances causes cancellation and smears detail and clarity not to mention pulling your stage to the rear.

Kinda makes an argument for not having a center channel at all.

VR3

I kind of look at center channels in a few variables.

Variable 1) Why do they even *REALLY* exist? I mean, I understand that a center channel allows for multiple people in the room to enjoy a center imagine. But why exactly do center channel, large horizontal based speakers exist? What kind of technology warrants their existance for a specific name.

Lets look at what we get with a center channel, in most cases a standard enclosure, 3/4" thick MDF, two midbasses, a port (or two), a tweeter, and of course the crossover. A center channel usually ranges from $200-$500 (Polks that is). What in the world can warrant a price tag so large for something that offers so little. At one time I had the CS245i and the RT25i, the RT25i used the same exact drivers, had a larger enclosure, used more wood, veneer, more tweeters, more crossovers, more ports - yet costed the same.

Center channels just don't have a value, a single bookshelf or a pair will do as much or more for alot less!

Variable 2) Do you really need one? As it has been said in this thread, the perfect match for your mains is the same exact speaker all around. Well this makes sense, but I have yet to hear a center channel that sounded similar to the mains - even when they use the same drivers, technology, the works. Its close, but never the same.

So you are never getting an exact match. Ever. So when you combine this fact with the high price tag - center channels look less and less appealing.

Variable 3) Why would you need it in a system...?) Well this is really simple, like rear speakers in a car, it is based around you having more than you in the room/car. It is so people off axis/out of the sweetpot can hear dialog clearly, and in the center - where the vocals are supposed to be... Or like in a car, so people in the rear can enjoy the music just as much as you are, because lets face it - front speakers in a car do not sound that great in the back seat...

I do own a center channel, but it is a CLR and makes for an AWESOME pair of mains. I really enjoy their sound as a main speaker. I think when you design a center channel around the fact it could double duty as mains in a musical enviorment, you hear the benefits during movies in a horizontal or vertical configuration. Not to mention you could save costs due to the fact you wouldn't really need a dedicated center or bookshelf line if you thought it out well enough ya know? You just include two sets of grills with the speakers, vertical and horizontal configuration and let it go...

Center Channels have their place, but have absolutely no real benefits as far as sonic improvements go. Yes - they provide that center image for off-axis listeners, but a 2-way bookshelf setup in a vertical configuration can do the same exact thing with less costs! So the whole purpose behind center channels we will have to assume is purely marketing and feeding the customers what they want - or what the wife wants, a discrete, easily hidden horizontal speaker that can go below or above the TV. Makes sense to me.

DollarDave

How do LS-90's resolve this problem? Are each of the mid-base drivers crossed-over at different frequencies? It seems with four in vertical alignment that things would be a mess as you went from sitting to standing. Does the tappered cabinet cancel out this affect?

BTW, I read threads a lot but seldom feel the urge to comment. I have a pristine set of LS-90's anchoring my HT system.

KrazyMofo24

If you use a bookshelf vertical for the center channel wouldn't the tweeter not be at ear level? I'm just guessing, but doesn't the Csi3 use the same 5.25 woofer and tweeter as an rti4? The csi5 same woofers and the tweeter as the rti6? I barely had my speakers for a few weeks so I may be totally wrong.

VR3

You can always turn it upside down and tilt the speaker downwards...

You have to do this with center channels as well, just because you set it on top or below your TV dosnt automatically set it at ear level. If anything, setting the bookshelf upside down will bring the tweeter closer to you.

And if you would read the article I linked you to - you would find that there is MUCH more to it than drivers.

KrazyMofo24

Read the article gonna try putting my center channel like that.

aaharvel

the article was interesting- but i like my csi3 and the way it's horizonal placement (aesthetics first) IMO it does better than just for off-axis. And with Logic7 music mode it does great.

not to mention (ahem) movies.

Eman

I understand the logic behind this line of reasoning but there are those who listen and prefer the sound of loudspeakers be it in stereo or two pairs in a surround set up. In this case a center loudspeaker is not a realistic solution so a voice matched center channel is the best and a dual woofer design will in most cases produce a wider frequency response. Most multichannel music dedicates the center channel to dialogue so you loose nothing by not having a fifth loudpeaker. In a small sub sat combo sometimes the center channel is not enough to accurately produce a good movie track so going with a larger speaker sometimes yields positive results. For example there are no monitor bookshelves with a 6 inch driver so going 40s alll around with a CS2 could potentially sound better and still be voice matched. I wouldnt label the center channel speakers as useless - they do have a purpose. As for a dedicated design and price - Is not the CS1 priced at $180 and so is the pair Monitor 30s both of these include a pair of 5 inch drivers. The CS1 also has the ability to be aimed upward if placed below the screen and most upright bookshelves wont fit in standard hometheater TV stands etc...

Eman

The article does not state that this cancellation effect depends also on the distance between the speaker and the listener if the distance between the two speakers is d and the distance between listener and speaker is D. As long as D>>d you are fine.


Also this analysis does not take into account the effects of the reflected sound waves at all boundaries - so its really crude and I wouldn even pay too much attention to it - dont believe me ask any other physicist at your local university.

RuSsMaN

:rolleyes: You guys are doing great, keep over-thinking it.

Mazeroth

RuSsMaN wrote:

:rolleyes: You guys are doing great, keep over-thinking it.

I agree with you 100%

The ONLY reason for incorporating dual woofers is to run the 2nd woofer as a 0.5 woofer. Here's what this does:

Sound does not radiate perfectly straight out of the woofer. The low frequencies actually radiate almost 50% BEHIND the speaker, and when you finally reach the high frequencies up to 20k, then they radiate almost perfectly straight out at you. What does this mean? Well, from roughly 1hz to 500hz you are losing 6db-1db of sound. The way to counter this is to run the 0.5 woofer all the way up to 500hz, then cut it off. Normally this is done by placing a single inductor before the 0.5 woofer, which rolls the woofer off at 6db per octave. The speaker I'm working on now has a 0.5 woofer (actually 12, but let's pretend it's only 1 hehe). At 1hz it's down 6db, at 150hz it's down 3db, and at 500hz it's back to playing full volume because sound waves above 500hz radiate almost straight out. I place a 5.25 mH inductor before the woofer which lets the woofer play full volume at 1hz, drops it down 3db at 150hz and drops it down 6db at 300hz. Since it drops it down 6db per octave, after 300hz it will be down 12db at 600hz, 18db at 1200hz, 24db at 2400hz and so on. I think I'm getting a little too technical here (sorry) but hopefully you guys get what I'm saying. Since this woofer will be down 18db at 1200hz, the lobing effects will be minimal because a woofer playing at 118db is much more powerful (almost 3x) than a woofer playing at 100db.

Here's a pic of me using The Edge, a program used to simulate box size and speaker placement, which shows you the bass roll-off due to the baffle size and shape. The graph in the top left shows how the woofers will behave without using a 0.5 woofer or a baffle step compensation circuit, which many good speakers use that don't have a 0.5 woofer incorporated. What a baffle step compensation (BSC) circuit does is "muffle" the higher frequencies so the bass and highs "blend" better. This does, however, significantly drop the speakers sensitivity, usually by 4-6db/watt.

Ok, I'M DONE!

MacLeod

I think Sid has a point. Im running a pair of bookshelf speakers right now with no center and due to our living room size, Im sitting a little off axis in either the chair or my couch. In both spots, the center image still seems to be coming from right smack in the middle of the TV.

Maybe you can save the extra $300 you would put in a center and get a pair of RTi6's instead of 4's!

VR3

COF (The guy that wrote that article) was sticking to basic principles of how a speaker radiates and what is caused and why it is caused. It is NOT wrote around every aspect, just basic understanding that everyone can comprehend.

No need to complicate this whole subject.

Mazeroth

Vr3MxStyler2k3 wrote:

COF (The guy that wrote that article) was sticking to basic principles of how a speaker radiates and what is caused and why it is caused. It is NOT wrote around every aspect, just basic understanding that everyone can comprehend.

No need to complicate this whole subject.

I thought that would get a reaction

MacLeod

Mazeroth wrote:

I thought that would get a reaction

It gave me a headache!

VR3

Mazeroth wrote:

I thought that would get a reaction

I was actually responding to EMan...

I didnt even read yours, No offense