View Full Version : Timber matching center channel and SDA CRS
09-24-2002, 09:57 AM
I know this has been asked a bunch of times but my question is a little more specific. I have a pin/blade set of SDA CRS for fronts in my home theater and a set of blade/blade CRS in the rear. I dont have a center channel OR a sub. I DO NOT feel that subbase is omnidirectional - I have no trouble determining where the subbase originates from - particularly when it is off to the side - if you have stereo subs - it is better but there is still a "time" issue - it doesnt arrive as fast as the sound from the fronts and rears. Long story short - I want to combine the sub and center channel signals and build a center/sub speaker using polk components. I wish to use - 2 sl2000's and 4 - MW 65xx & 2 - SW 100's (side firing for a slim design) I realize this sounds a bit crazy but my actual question...
can you suggest what 4 drivers I should use?
Should the crossover design resemble that of the stereo portion of the CRS crossover?
What kind of insanity am I in for by employing a side firing design.
the idea is to put the speaker over the
Any help is GREATLY appreciated
Ken - if you have a minute...
09-24-2002, 10:32 AM
use the CRS's you are bidding on at Ebay for a center and a center rear :)
09-24-2002, 10:46 AM
That would be a big speaker, have you thought of using the CS1000 powered center?
I have played with the idea of buying a pair of monitor 10 (hoping for a pair with effed up cabinets on the cheap) and taking the parts from it and making a cabinet more suited for sitting ontop of a TV, you would want to keep the same cabinet internal volume, and use bucking magnets.
09-24-2002, 11:44 AM
yes the volume and bucking magnets are a must - (SDA CRS+ x2) which is the reason for using
possibly side firing PR's. considered a million different center channels speakers but I can build exactly what I want and have it match up better - asthetically and timber wise - for the same money. power is a non issue I have several Pro amps at my disposal.
When you live in a place with more than 1 room NATURALLY you MUST have more than one surround system! :lol: (good eyes on the Ebay thing)
09-24-2002, 11:51 AM
Ideally I want a 12 3/4" high by 32" wide baffel and whatever depth to make the volume work out - I am sure this makes speaker designers cringe by my blatent disregard for number fudging but - hey take your best shot! If we are good we MAY come up with something COOL! I have a few bucks to spend and the talent to work this out so hey HELP me out!
09-24-2002, 01:31 PM
I still think my C/L/R's match my 2.3TL's very well. Def tech's are made very close to the older Polks. Why is this? hmmmmm, I wonder. This was taken from Def Tech's "about" website.
In 1972, Sandy Gross and two classmates from Johns Hopkins University formed what was to become one of the world's largest loudspeaker manufacturers.
But Sandy wanted to take his dream to create the world's finest loudspeakers even further. In 1988, he left to pursue his ultimate dream and create truly affordable high end world-class loudspeakers dramatically superior in design, technology, sonic performance, construction quality and value to everything which had come before.
Definitive Technology was founded in 1990 and the rest is history. Definitive loudspeakers have become legendary around the world for unequalled sound quality and unsurpased value. Definitive Technology has twice been voted the nation's top loudspeaker manufacturer. Definitive has also been voted #1 for quality and reliability by top industry professionals in a nationwide dealer survey and officially authorized by the U.S. government to call ourselves "The Leader in High-Performance Loudspeakers®." Definitive Technology loudspeakers are truly the successful realization of Sandy's dream.
If quality sound is important to you, you owe it to yourself to visit an authorized Definitive dealer and experience the superior sound quality of Definitive Technology loudspeakers. Bring in your favorite CDs or movies and be prepared to be amazed by our speakers' unmatched musicality, lush spacious soundstaging, lifelike depth of field, razor-sharp resolution, pinpoint 3-D imaging, crystal clear highs, utterly transparent midrange, and taut powerful bass. You will hear for yourself why Definitive Technology is the USA's best selling brand of high-end loudspeakers for music and movie perfection.
09-24-2002, 02:13 PM
NICE - is there a fill in the blank version around someplace?
09-24-2002, 02:38 PM
doing some quick math, 34"Wx12.75"Hx12.625"D would be about the same internal vol. as two CRS+'s. 12.625" is most likely enough for side mounted PR's but why? Why not just mount them in the rear?
I just reread your first post, are you looking to build:
a full range center
a center and LFE subwoofer built into it?
As far as what mid-driver I would use the 6510 to match your front CRS's
09-24-2002, 02:57 PM
center and LFE signal would be combined at line level and sent to the amp that way to feed this thing.
full range center
I messed up the dimension - 32"w X 9" baffel. the low profile is desired. this makes it 19" deep and the SW100 wont fit on the back any more. what does this do to the dynamics of the speaker? my fear is the bass wont extend low enough but my hope is to achieve that 6 db overall gain by the drivers sharing the same volume. (compared to 2 speakers individually see bullock on boxes)
6510 is my first thought aswell BUT.
what contribution does the SDA driver make to the low end response of the CRS+? if this driver gets + signal from the left channel and - from the right channel (basically) I wonder if a box volume adjustment isnt in order or maybe some dampening material since all drivers would then be full range...
A Bi-Ampable solution isnt out of the question if any one has any suggestions
09-24-2002, 03:14 PM
LFE/center combo? on top of a TV? using the same drivers as CRS+'s? Are you asking too much? 6.5" drivers and a PR in a small cabinet will not make much of an LFE subwoofer I my opinion.
9" Lowprofile? that kills anything but top or bottom placement of the PR's.
That SDA driver has always messed with my head. If you remove the interconnect cable you now have ADDITIONAL drones (PR) to mess with the air spring, or how about this, if the SDA driver is the inverse of the other channel it is working against the stereo driver with the interconnecet cable hooked up. Almost seems like the SDA array would have needed to have been in a separate sealed enclosure? I know that did not answer anything.
09-24-2002, 03:42 PM
I have also played with building a subwoofer that would double as the TV stand, it had a place for the Center speaker to sit under the TV. This would have to be a heavy mother to minimize the vibrations to the TV. But the int. volume available is large up to (4) 12" downfiring drivers WOW.
09-24-2002, 03:50 PM
RIGHT! - piss on it - trial and error it is.
this is why I was hoping for some insights from polks tech staff...
What is a monitor 10 or an SDA 2 ? evva 1.2tl? these designs employ 6.5's right? - rhetorical
- my box would have 4 mw 6510's, 2 sw100's.
polk makes a living from small drivers and more of them. they have a faster more detailed response compared to large drivers and are quality enough to reproduce lower freq's than typical 6.5" drivers. it is possible but tough- hence the origin of this post.
09-24-2002, 03:59 PM
here is a thought - how about 2 SDA CRS+ for center channel - 1 top and 1 bottom. the imaging makes it seem like it is comming from DEAD CENTER to the screen! it works great but the space thing is ugly...
09-24-2002, 04:10 PM
The Polk staff ignores most of what goes on here, Ken will jump in on offering warranty work, but all opinion or insightful requests that I have seen go unanswered. Not kicking the folks at Polk, but I have never seen them jump in on something like this.
Would you agree the 9" profile kills your idea? I doubt the PR is usable in the up/down firing position. A cabinet 2-3 inches taller and it starts to work.
09-24-2002, 04:14 PM
"here is a thought - how about 2 SDA CRS+ for center channel - 1 top and 1 bottom. the imaging makes it seem like it is comming from DEAD CENTER to the screen! it works great but the space thing is ugly..."
Are we back to the beginning? This is a circle. Two CRS's is what was suggested before, but you wanted SUBWOOFER also.
09-24-2002, 04:22 PM
I dont completely understand PR's. I understand Low freq's eminate from them but arent they there primarily to back load (dampen or reinforce) the 6.5" drivers in this case? I dont see what difference it makes. I think there are some slim line designs that use side firing PR's arent there? I dont really know. the CRS+ are only 9 1/4 " deep - I just dont know the deal with side firing PR's. the air pressure situation is constant so why not?
09-24-2002, 04:23 PM
sorry about the tangent with the regard to 2 CRS center - has nothing to do with this project
09-24-2002, 04:38 PM
What I am saying is if the cabinet is 9" tall, a 10" PR can not physically be mounted on the front, sides or back, so it would have to be top or bottom mounted.
PR can not be up or down firing, it is passive and needs to freely move to work properly. if it is up/down firing the weight of the PR would keep it from moving as it should.
09-24-2002, 04:38 PM
Would a pair of 5jr+ not work out? At least as far as yanking the matching drivers out and building your own box. Not to mention the smaller pr......
09-24-2002, 04:43 PM
A pair 5JR+ parts would be great for a center channel, but the monkey wrench is he is looking to feed the LFE channel in here some how and I don't see the 5JR+ as a subwoofer, BTW how are you going to combine the two signals.
09-24-2002, 04:52 PM
Feed LFE? You mean set the center to 'large'? I think it could handle it....
09-24-2002, 04:55 PM
2 ch mixer down to 1 channel
09-24-2002, 04:58 PM
I see your point with regard to the up/down thing guess we will have to fix that...
09-24-2002, 04:59 PM
OH - I have individual access to each channel I am in a separete decoder and 5 ch. amp situation - love the flexability
09-24-2002, 05:05 PM
5 Ch Carver amp - AV 405
2 Ch Yamaha amp - P2100 (Sub Amp)
Technics digital decoder
4 - SDA CRS+ (L,R,LS,RS)
2 - RTi-15 (C)
1 - bulls*it sub - unpowered
09-24-2002, 05:11 PM
Just to catch up - I have to get a sub and a center. I have no good spot for my sub I think it needs to be right next to the TV. The idea is to have a Center/Sub speaker
09-25-2002, 08:48 AM
I wish you good luck on this interesting project, please keep us informed if you built it.
09-25-2002, 09:44 AM
thankyou for your time and input
09-25-2002, 01:35 PM
Seems to me you're complicating this beyond what it needs to be. You want a center speaker, you want a subwoofer, and you want the sub to be close to the TV because you believe you can locate the sub sounds, correct? But you're worried about the effect of the sub (vibrations) on the TV.. right? I don't see any need to combine signals just because you want the sub and center physically close to each other.
Build a sub as you want... make it no wider than the approximate width of your TV (or you could go a little wider to accomodate a larger TV in the future). Essentially it could be a box as deep as you need to make it.
THEN... build a TV stand with built-in or at least a location for a center speaker that sits OVER the sub box... essentially a "garage" for the sub box that doesn't touch the sub box, to do away with your vibration worries. The center speaker, whether built-in to the garage or sitting on as shelf, could be right above the sub and right below the TV.. or if you wanted the TV to sit a little lower, put the center over the TV (either built-in or sitting on a shelf).
You could still do the side-firing design on the sub, as well... just build the TV stand strong enough that you can leave adequate openings on the sides for the subwoofers to fire through.
This would eliminate the need to try to figure out how to design a combined speaker and would allow you to design each as best you could.
It would also mean the sub section was separate just in case you ever did want to move it, repair it, or replace it.
Usually, the simplest design that serves the purpose is the way to go. Set out your basic requirements and go with the easiest design that handles what you want. I think separate design and separate enclosures, combined in a single "set up" with the TV would solve the complications and leave you the most room for change in the future.
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