SPL President Posted May 21, 2003 Share Posted May 21, 2003 Hi Folks, now iám testing a system with 2 center speakers. i added the same center speaker to my system. i though.... the fat problem is often that, in the middle of the screening the sound is "very small and emty" i mean there is often a "sound hole". i have a projector with a screening size of 300inch so the main problem is when a car or music reproduction is playing or you play "Audio DVD" , there is often a "hole" in the screen and the sound presence is... i testet with some DVD stuff, when the singer or in a movie, somehing goes from the left to the right side "effects" through the center, i think there is something missed... often is a sound hole, between center and the speakers (Left/Right) side. so i buy an 2nd center speaker to fill in, to get out the sound hole. and..... perfect !! works nice ! ok ok, in cinema there´s the same system. that be used while the screen is very large. so the voice/music is often in the middle and the sound presence is very stupid with one c.speaker. better be 2 center than one try it Quote Link to comment Share on other sites More sharing options...
STL Posted May 21, 2003 Share Posted May 21, 2003 Actually, using two center channel speakers is just going to mess up the center channel. It might make it sound wider but now you have two point sources (arriving at your ears at slightly different times) instead of one. That is just going to make things "fuzzy". What you really need is a full size center that is truly equal to your RF-3s. You would be much better off using a lone RF-3 rather than two RC-3s. With my setup using another KG5.5 wasn't and option, so I had to make a custom center channel speaker. Here is a picture: Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted May 22, 2003 Share Posted May 22, 2003 I don't have that problem I have a La Scala for a center channel - no holes or voids here for sure. Quote Link to comment Share on other sites More sharing options...
jzoz01 Posted May 22, 2003 Share Posted May 22, 2003 Wait wouldn't using 2 RC3's mess up your balance anyway. Depending on whether you wired it in parrallel or in series, it will either drop your impedience to 4 ohm or increase it to 16. One way would draw to much power and strain the reciever and the other would not draw enough. maybe I'm wrong here, but that just seems like it would be a problem. Quote Link to comment Share on other sites More sharing options...
j-malotky Posted May 22, 2003 Share Posted May 22, 2003 JZ - As far as impedance, it depends on the receiver and the range of Impedance it can run safely at. Usually 4-16 ohms is not a problem for most. SPL - Im curious how this is set up. Are the 2 centers side by side or are they spread apart a few feet to fill the sound gap? I always find its best to place the center especailly the mid and tweets right smack dab in the center to get the best imaging. Like STL shows in his nice looking center. JM Quote Link to comment Share on other sites More sharing options...
jzoz01 Posted May 22, 2003 Share Posted May 22, 2003 ---------------- On 5/22/2003 9:00:44 AM j-malotky wrote: JZ - As far as impedance, it depends on the receiver and the range of Impedance it can run safely at. Usually 4-16 ohms is not a problem for most. ---------------- He's running off a reciever, most recievers I've ever used tell you to keep the impedance between 6 and 16 ohm. I'm guessing it's not a huge deal seeing as it's the center and not one of the front mains, but I still wouldn't do it unless i had an external amp. Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted May 22, 2003 Share Posted May 22, 2003 OK, I broke the rules here, but this is what I'm up to. I'm running two Cornwalls as center channels in my HT as a trial. It is a 5.1 system using 6 channels of amplification. I split the center channel output on the pre into two amp channels, then to the Corns, to avoid any impedance issues. The Cornwalls are standard horizontal models, laid on their sides, tweeters and midranges on the inside. I did this because the alnico magnets on the mids and tweets do not mess with the picture tube, but the mud magnet woofers do if I place the mids/tweets outside. The "book" says this is uncool, but after careful placement, am getting VERY good results. On a wider screen, this would be a benefit, because it provides for a "washing over" effect across that screen. In SPL Pres's case, he cannot sonically fill the "hole" because his single center speaker cannot throw the image across a wide enough area. I have a different problem. I want the center speaker to be symmetrical. I cannot have an upright Cornwall at center. If I place a single Cornwall on it's side, the sound is less realistic, because I am somewhat close to the front array. The speaker is not symmetrical now, since the woofer is off to the side when the mid/tweet is centered. To solve this problem, I placed two Cornwalls at center as described above, between two Cornwalls as mains. I know it's not the book way to do it - I was told this could be problematic due to phase problems - but I am getting very good results. I have more listening time to do on this, but initially, I like how it is going. Eagles "Hell Freezes Over" - the ultimate justification for center channel overkill, sounds BTW, if one wanted to test for phase problems in the center using AVIA, what is the best method for doing this? Quote Link to comment Share on other sites More sharing options...
STL Posted May 22, 2003 Share Posted May 22, 2003 dndphishin, The reason you need two cornwalls is precisely because you are laying them on their sides! Rotating their horns 90 degrees like you have done has made their sound much more narrow. What you really need to do is buy a couple 10" woofers (because two 10" woofers have about the same cone area as one 15" woofer) and use them along with mid and high horns from the Cornwalls. The just build a new enclosure that has the horns oriented correctly and stacked in the center with a 10" woofer flanked on each side. That truly would give you a much better center image! Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted May 22, 2003 Share Posted May 22, 2003 OK, STL, but what if I placed a pair of vertical Cornwalls in the same way, so now the vertical horns are horizontal?? That's the next trial. Quote Link to comment Share on other sites More sharing options...
STL Posted May 22, 2003 Share Posted May 22, 2003 Just to clarify, looking at the specs on the Cornwall you can see both exponential horns are the 90°x40°. Rotating them like you have makes their horizontal dispersion become 40° which is a lot more narrow 90° it would be when oriented correctly. Furthermore, you increased the vertical dispersion from 90° to 40° which might help with them sitting down low, but that wide vertical dispersion also creating a lot of reflected sound that is just going to muddy things up. You would be better off building that a center (like I described) with a slight angle on the front baffle that aim the speakers up. If you look closely at my custom center channel you can see than the front in angled (about 10-12°) down to fire the sound directly down the the listener ear level. Quote Link to comment Share on other sites More sharing options...
STL Posted May 22, 2003 Share Posted May 22, 2003 dndphishin, Vertical Cornwalls should do the trick for you except you still have the one woofer problem. As far as placing them you will have to experiment. You really don't want the horns dead center because they would leave the woofer on one side (and thus skew the lower midrange to that side). You also don't want the woofer centered for the similar reasons. You probably want it centered somewhere between the woofer and horns with a slight weighting more towards the horns -- but you won't really know what is best until you experiement with it. Without two woofers though it still won't be optimal. I still say you need to build something! Quote Link to comment Share on other sites More sharing options...
dmk Posted May 22, 2003 Share Posted May 22, 2003 Hello, I am using a single cornwall with the famed vertical horns. It is laying on its side on top of my 55-inch. I placed it so that the tweeter is at the bottom (closer to listening height). I have a pair of cornwall II as the front speakers. Sounds great to me. Quote Link to comment Share on other sites More sharing options...
SCOOTERDOG Posted May 22, 2003 Share Posted May 22, 2003 I agree with STL. Having two speakers is not the best solution. I would either keep one and find a home (maybe rear cenetr) for the other or do a custom center like some of have done. Here is a pic of the center I just finished. Scooter Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted May 22, 2003 Share Posted May 22, 2003 My La Scala is laying on its side under my 43" Sony RPTV and it works beautifully. I think with the larger horn I get better dispersion than if I had a Cornwall. I certainly don't notice any gaps or voids whether it be a DVD or CD playing. It sounds alot better than the KV-4 that I had previously. The mains and center are fed off my DBX BX-1 running in the 3 channel mode. The center sees 400W and the Khorns about 100W, but the volume rarely needs to be above -45 to -40 to be quite loud. Quote Link to comment Share on other sites More sharing options...
SPL President Posted May 23, 2003 Author Share Posted May 23, 2003 WOW STL !! very biigg center i love that that must be a great hearing... Quote Link to comment Share on other sites More sharing options...
SPL President Posted May 23, 2003 Author Share Posted May 23, 2003 SCOOTERDOG you got a center! ,there where no problems with washing effects i think what do you think over 2 center speakers, i got a big screen (projection screen 300 inch). and what do you say, may solve that problem what i got? manny thanks Quote Link to comment Share on other sites More sharing options...
SPL President Posted May 23, 2003 Author Share Posted May 23, 2003 okay okay, folks, i buyed the 2nd center. Result: now it´s much better. the sound presence is biger, lifeness higher.. but... you got right STL. there are an another problem with the sound reproduction. but i solve that i placed the center(s) speakers in front off, not in the middle in under the screen. so i put one center 20 degrees left and the other one 20 degress right sidewards to the front L/R speakers. now i get louder the front speakers (+2 in my ampfiler) and it works nice! the impedance should be no problem. i solved to 8Ohms with an koupling procedure. in the next time, comes a picture from the System. Quote Link to comment Share on other sites More sharing options...
STL Posted May 23, 2003 Share Posted May 23, 2003 SPL President, I could not quite understand what you were trying to say, but I do know you really do not want two center channel speakers no matter what the circumstance are. Have two separate speakers producing the exact same audio is not a good thing. It might be better than what you had before, but it's still far from optimal. Take your new RC-3 back and trade in the old RC-3 you already had to get a lone RF-3 to be your center. It will sound better. You can't do better than using the exact same speaker for all three of the fronts channels! Quote Link to comment Share on other sites More sharing options...
j-malotky Posted May 23, 2003 Share Posted May 23, 2003 ---------------- On 5/23/2003 10:57:48 AM STL wrote: SPL President, I could not quite understand what you were trying to say, but I do know you really do not want two center channel speakers no matter what the circumstance are. Have two separate speakers producing the exact same audio is not a good thing. It might be better than what you had before, but it's still far from optimal. Take your new RC-3 back and trade in the old RC-3 you already had to get a lone RF-3 to be your center. It will sound better. You can't do better than using the exact same speaker for all three of the fronts channels! ---------------- I had the same problem when I did my HT. A single Heresy was just too small sounding in between my Khorns. Needed a big K400 and more bass to do the job properly. Try a single RF3 for a center between your RF3 mains. JM Quote Link to comment Share on other sites More sharing options...
DrWho Posted May 24, 2003 Share Posted May 24, 2003 "Have two separate speakers producing the exact same audio is not a good thing." wat's the physics behind that? cuz the vast majority of recorded music in mono most of the time...does that mean having 2 speakers during mono playback is also a bad thing? so why would you add a 3rd center channel? hehe, im just harping on ya a bit because even PWK felt a center channel helped a lot.. now back to some phsyics: the center channel is a mono signal, so 2 or 100 speakers they're all recieving the same signal. all that to say, having 2 speakers for a center is fine if you're sitting in the sweet spot (cuz it will sound mono to the person there...equal volume to each ear). the problems you start running into occur off axis where the waves start to interact with each other. this same thing happens though with 2 channel listening, but can be resolved by toeing in the speakers (waves at a 90 degree angle don't affect each other). so if the center speakers were alone, you could toe them in and solve that problem. HOWEVER, it's a center channel and you've got volume pumping out the LEFT and RIGHT too! toeing in the center would narrow that part of the stage as well as create the combing effect with the mains (yuck). the same thing happens when you toe it out so i guess you're left with pointing straight out then...but here's the problem with that: as mentioned before, you've got 2 point sources for the center channel. on axis, you prob won't be able to notice it, but as you move side to side, you're now getting the comb effect that would normally be fixed by toeing in the speakers. end result? by filling in the sound stage you are going to be muddying up the sound...audio is full of comprimises and you just gotta pick which problems don't bother you as much. i personally would have the mains toed in at 90 degrees and the centers at 45 if you end up with 2 centers. that way the muddy sound is more uniform throughout and then it's possible to make it sound clearer by over EQ'ing and stuff like that. OR, you could go for 1 center channel and work hard to obtain the timbre match and wide dispersion with enough output to get away from all these issues. however, that requires plenty of work and just another thing to note...these "problems" aren't really that audible. yes, just about every1 can hear the difference, but the difference in sound between 2 centers and 1 center doesn't really distract away from the enjoyment (unless you're anal rententive and dwell on every minor flaw in your system...but if that was the case, you'd need better speakers) lastly, with the 2 center deal...placement would become a huge factor and it's quite possible that the "muddying" sound which usually comes from the combing effect...aka waves interacting with each other) could be unnoticable at the listening positions. (remember, on axis or in the very center you won't notice a difference) sorry i rambled so much and just a word of caution: everything i say is my own understanding of how it all works...i might be wrong. also, i've never AB tested between 1 and 2 centers so im not speaking from my own experience. oh one more thing...i dunno if it'd be worth all the work to build a custom center IF you're mostly satisfied with the results of two centers...and yet again, i've never heard either so i shouldn't be talking Quote Link to comment Share on other sites More sharing options...
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