How's this for a center ch. solution

Taurus574

Ok, finding a CS400i is getting pretty hard or expensive. I want to upgrade my CS175 for a better center so I was thinking of picking up another CS175 for cheap somewhere and wiring the two in series or parallel (probably in series since I still want to keep it at 8ohms and not blow up my receiver). I might have to tone the treble and levels down since i'll end up having 2 tweeters. What do you all think?

Dennis Gardner

Some use 2 centers with success. BTW, you will see 16 ohms wired in series. This isn't a problem as long as you compensate with your center channel volume to calibrate.

Taurus574

Are you sure about that? I thought running in series would keep it at 8 ohms and running parallel would drop it down to 4 ohms making the reciever work harder then normal.

BjornB17

Taurus574 wrote:

Are you sure about that? I thought running in series would keep it at 8 ohms and running parallel would drop it down to 4 ohms making the reciever work harder then normal.

i dont know the ohm rating on those speakers, but i'll assume its 8.

when you wire two resistors in parallel, resistance cuts in half. when you wire in series, resistance doubles.

so two 8 ohm speakers in parallel would be 4 ohms nominal, but it will dip lower than that during normal use.

two 8 ohm speakers in series would be 16 ohms nominal.

Taurus574

Darn, and I thought I could just wire them up.

aaharvel

sorry but that doesn't make any sense to me. Combining two mediocre speakers in parallel doesn't double your sound quality. it just doubles the mediocre sound you already have. Sell the 175- save up and buy a cs400i.

amulford

Gonzo will sell you his 400i. You;d have to buy the box and packaging, and pay for the shipping. Check the thread and PM him to work out the details.

http://www.polkaudio.com/forums/showthread.php?t=36284

That way you don't have to compromise.

seo

BjornB17 wrote:

iwhen you wire two resistors in parallel, resistance cuts in half. when you wire in series, resistance doubles.

Wiring two resistors in parallel, R1 and R2, the equivalent resistance seen by the circuit is (R1*R2)/(R1+R2). If you have two loads of the same resistance, the result is the resistance is cut in half.

Resistors wired in series are additive.

BjornB17

seo wrote:

Wiring two resistors in parallel, R1 and R2, the equivalent resistance seen by the circuit is (R1*R2)/(R1+R2). If you have two loads of the same resistance, the result is the resistance is cut in half.

Resistors wired in series are additive.

Yes you are 100% correct. The end result is the same for 2 speakers though. Now if you have 3 speakers, i'd recommend they follow your advice!

Taurus574

Ok, new idea... two cs175's BUT I only wire one set of crossovers instead of both and I run the tweeters in series AFTER the crossover and do the same with the woofers. Wouldn't that bring me back to 8 ohms?

BjornB17

Taurus574 wrote:

Ok, new idea... two cs175's BUT I only wire one set of crossovers instead of both and I run the tweeters in series AFTER the crossover and do the same with the woofers. Wouldn't that bring me back to 8 ohms?

Sounds like an ambitious project To be quite honest, i dont know the answer to that one

BjornB17

Taurus574 wrote:

Darn, and I thought I could just wire them up.

Well there is no harm to wire them in series. I actually had a psudo 7.1 setup with my 5.1 reciever, in which i wired 4 surround speakers... 2 on each of the surround channels. I wired them in series for 16 ohms, and it worked perfectly.

Dennis Gardner

Forget about messing with the crossovers.................(series wired) 16 ohms nominal won't hurt a thing. In theory, you lose 3 db with the 16 ohm load compared to the normal 8 ohm single center, but you gain that much back by adding the radiating area of the second center, so I would call it a wash and you shouldn't have a problem using them this way.

Now thats just theory, so go for it and report back to us.

aaharvel

why in gods name are you still entertaining the idea of two 175's? It's doesn't make any sense.


do what you want to do it's your money.

Larry Chanin

aaharvel wrote:

sorry but that doesn't make any sense to me. Combining two mediocre speakers in parallel doesn't double your sound quality. it just doubles the mediocre sound you already have. Sell the 175- save up and buy a cs400i.

Hi,

I completely agree with Andrew here.

However, I should add that I run two center channels in my home theater.
I'm running a pair of vertically stacked SDA-CRS+'s for centers over and under my projection screen. They are a perfect timbre match for my SDA-1C mains.

The big difference is that the CRS+'s are fine speakers in their own right and each is powered by it's own amplifier channel, so there's no **** around with dubious wiring in schemes.

One other issue regarding dual centers is that the experts will generally tell you to avoid this arrangement because when you play the same mono signal on two speakers different distances from the listener, there will be constructive and destructive interference between them when they arrive at the listeners ears with a slight delay. This is called comb filtering, and it may hurt imaging and timbre. For example here's an excerpt from Rives Speaker Placement white paper that discusses the subject.

Many people like the idea of 2 center channels because there is a lot of sound coming from the center channel, and 2 channels can handle that better than one. It is estimated that the average movie soundtrack has 60% or more of the sound directed at the center channel. Also, many people with projections screen TVs do not like the notion of sound coming from above or below the screen, and therefore try a speaker above and below. All of this may seem well and good, but in most cases 2 center channels are more problematic than they are worth. Typically you wind up with interfering wave patterns between the two speakers that cause areas where certain frequencies are cancelled out and other areas where they are doubled. If this seems difficult to understand imagine dropping a pebble in a pool of still water. The ripples radiate from where the pebble entered the water. Now drop a second pebble in the water in a different location, and you can see how the two ripple effects interfere with each other. This is similar to what happens with two center channels. It is not a problem with stereo channels, because their signals are different and designed to function in a stereo mode. But with two center channels the signal is the same and thus the interference pattern. In general we recommend avoiding 2 channels, and rather than buy 2 center channels, and the necessary amplifiers, buy one better center channel.

So why am I using two center channels? Well, in addition to the benefits described by Rives in the first three sentences there is a couple of additional benefits to having a second center channel mounted high in a home theater with two rows of seating. One big benefit is Dialog Intelligibility. When you have a single center channel mounted in the typically low position under a screen, or even behind an acoustically transparent screen, the sound attempting to reach the second row of listeners is obstructed by the seating and listeners in the first row. This destroys dialog intelligibility. A center channel mounted high has an unencumbered direct shot to the second row of listeners. The other reason is that having a large screen between my mains forces them to be 13 feet apart. That's a very large sonic hole to fill with just one center channel.

So in summary, unless you have very specialized needs such as in a home theater with a big screen, that out weigh comb filtering distortion problems, then as Andrew and Rives stated, there would probably be more problems with trying to wire two average speakers together than to simply bite the bullet and buy a more capable single center channel speaker.

Larry

Dennis Gardner

Yeah Larry, uses two center the only way I see it as useful, to center the voices on a huge screen.

Hey Larry, I have never asked, but are you LarryB on other HT sites?

Taurus574

aaharvel wrote:

why in gods name are you still entertaining the idea of two 175's? It's doesn't make any sense.QUOTE]

Cause it's fun to talk about and theorize. :cool:
Cause Ebay only has 2 CS400 and not the CS400i versions.
Cause advice from the forum and Polk tech support suggested that the CSi5 would not match well with my discontinued RT1000i. :eek:
Cause I can't find any other good center to match what i have. :mad:
Cause I want better sound from the center. :cool:
Cause I'm **** and alway trying to find another solution to the problem. :eek:

The CS175 from what I read and of course my own personal experience lacks in mid-range. My towers over power them and raising the db levels on the center doesn't give clarity either. I figure, 2 of the same centers and the ability on my receiver to adjust the frequency and the db levels I might be able to acheive what I want. If the CSi5 matched with what I have, i would've had ordered that sucka last week. i really wished it did match.

aaharvel

have patience.

Larry Chanin

Dennis Gardner wrote:

Yeah Larry, uses two center the only way I see it as useful, to center the voices on a huge screen.

Hi Dennis,

Yes, I also believe that vertically stack centers, while still subject to comb filtering, will have less problems than horizontally oriented dual centers. There's a couple of reasons for that. First, it may be possible to locate the two speaker equidistant from the listener's ears. So in theory at least you can't have comb filtering if the signals arrive at the same time. With vertically stacked centers all the members of the audiences ears are pretty much located equidistant if the center location is equidistant. However, for horizontally oriented dual centers, the more off-axis the listener is, the greater the delay.

The other reason horizontally oriented centers is a dubious idea is because it is sort of opposite of the basic intent of a center channel. A center channel is supposed to pin point the sound, usually dialog, in the center of the sound field. Dual horizontal centers do just the opposite, they smear the central sonic image over the distance between the speakers. The greater the distance the greater the smearing.

Dennis Gardner wrote:

Hey Larry, I have never asked, but are you LarryB on other HT sites?

Do you mean this LarryB?


No, I'm this LarryC


Larry

Taurus574

aaharvel wrote:

have patience.

Yes Obi-Wan Kenobi.. I agree... I must practice patience.

SKsolutions

Larry,

As I see from just a quick glance at your system, you have tried to reduce the filtering effect by careful measurement and positioning. I don't think that most HT's have this much sophistication or latitude. I am jealous though. It's quite a fete of accomplishment.
Taurus:
Buy the 400i or even the 245 can be had for 120-ish on the bay or less and are very underated.

Sean

Taurus574

SKsolutions wrote:

Taurus:
Buy the 400i or even the 245 can be had for 120-ish on the bay or less and are very underated.

Sean

I think your right and so is aaharvel. I was watching Matrix 2 and 3 last night and it wasn't all that great... at low volumes I couldn't hear dialogue well so i raised it up and then when action sequences came up it was two loud. It's bad enough I've got 1 POS center.. if I wired 2 of these together... that's twice the POS.

The CS245i huh? I'm gonna look into that also.

Larry Chanin

SKsolutions wrote:

Larry,

As I see from just a quick glance at your system, you have tried to reduce the filtering effect by careful measurement and positioning. I don't think that most HT's have this much sophistication or latitude. I am jealous though. It's quite a fete of accomplishment.

Sean

Hi Sean,

Thanks for the compliment.

Larry

Dennis Gardner

I like the old CS350 for center clarity. 4-4.5 inch mids really helps deliver the vocals. The Tri-liam tweeter matches your 1000s also.

beardog03

I have the 245i, and now run the 400i..
the 245i is anexcellent center IMO..

or you can get ahold of Gonzo and get his 400i

I may have an extra 245i..
I`ll have to look..!!

Taurus574

I already PM'ed Gonzo already.. just waiting for his reply. He's probably busy with his HT/mini club he's got now. :cool:

Taurus574

beardog03 wrote:

I have the 245i, and now run the 400i..
the 245i is anexcellent center IMO..

or you can get ahold of Gonzo and get his 400i

I may have an extra 245i..
I`ll have to look..!!

Ok, i've got a question for you beardog03, what major difference did you find between the 400i and the 245i..... this sounds more like a BMW question then anything else.

Dobermann

There are several 245i and 400i on ebay right now. Pretty reasonable price-wise.

Drumingman

I run 2 center speakers R50's and R50 mains.
The centers are about 4.5 ft. apart, both sides of entertainment center.
No problems and I think the sound is great.