Let's design "The" SDA Center Channel Speaker

Conradicles

There was some talk of this a while back but it seems this project never developed.

With the Minds we have here on the forum, why don't we do this?

I was thinking of a TL model and a standard model with the two most common tweeters. Maybe two different sizes (one huge and one big)!

Ideas?

jimbo1421

Could a CRS+ be repurposed as a center? In my imagination the dimensional MW would become a regular driver and the IC jack would be plugged. I have no idea what to do with the crossover.

I also did some drawings of a center using the gubbins of a Monitor 10 with a box reshaped similar to the CS 1000, keeping the internal volume the same. The PR would be placed on top. The box ended up 36"W x 17.89"D x 7.25"H. Would the Monitor 10 crossover work in the same volume but a much flatter shape?

Jim

Dawgfish

jimbo1421 wrote: »

Could a CRS+ be repurposed as a center? In my imagination the dimensional MW would become a regular driver and the IC jack would be plugged. I have no idea what to do with the crossover.

I also did some drawings of a center using the gubbins of a Monitor 10 with a box reshaped similar to the CS 1000, keeping the internal volume the same. The PR would be placed on top. The box ended up 36"W x 17.89"D x 7.25"H. Would the Monitor 10 crossover work in the same volume but a much flatter shape?

Jim

That's my thought as well, a single CRS + would probably make an ideal center channel to match with other SDAs used as front mains.

Zentish

The vintage section of this very site calls the CRS+ a "Center Channel":

"SDA CRS+ Classic Polk Center Channel Speaker"
http://www.polkaudio.com/products/sdacrs

and

"The only center channel speaker worthy of SDA"

These statements confuse me since I thought the CRS was originally not a center channel but a Compact SDA.

westmassguy

nbrowser wrote: »

Maybe some real inspiration in the following thread ?

http://www.polkaudio.com/forums/showthread.php?150760-My-Center-Channel-Project

I do love my center, and so does everyone who's heard it. I plan on raising the tweeter at some point. It will require modifying the plastic bezel, filling and re-veneering however. If I'd allowed more room for the tweeter, I could have mounted it higher, and horizontally.

westmassguy

jimbo1421 wrote: »

Could a CRS+ be repurposed as a center? In my imagination the dimensional MW would become a regular driver and the IC jack would be plugged. I have no idea what to do with the crossover.

I also did some drawings of a center using the gubbins of a Monitor 10 with a box reshaped similar to the CS 1000, keeping the internal volume the same. The PR would be placed on top. The box ended up 36"W x 17.89"D x 7.25"H. Would the Monitor 10 crossover work in the same volume but a much flatter shape?

Jim

If you used an 86' CRS+, you could drop in a Monitor 10 crossover. The Later model CRS+ would require replacing the 6511 driver with another 6503. Problem is, where to find a single CRS+, unless two go in on the purchase.

westmassguy

nbrowser wrote: »

I bet it sounds good, a lot of thought and time went into it. I just had to link to the project cause well, it's cool and outside the box.

Thanks. I love it, and my surrounds are all timbre matched as well.

jimbo1421

westmassguy wrote: »

If you used an 86' CRS+, you could drop in a Monitor 10 crossover. The Later model CRS+ would require replacing the 6511 driver with another 6503. Problem is, where to find a single CRS+, unless two go in on the purchase.

This could work for me as I have a 1988 pair of Monitor 10s whose boxes are in poor condition. Would moving the crossover to a smaller box, but same drivers be OK or is redesigning the crossover necessary?

I could use the CRS+ center with my SDA-1bs, although in my set up I like the CRS+ pair better. I have been on the lookout for another set of the baby SDAs.

Jim

westmassguy

The 10s should be 6503s I believe. Transplant the drivers, crossover and tweeter from the 10 to the CRS+.

Mr. Bubbles

I'm thinking an RTA 15TL would make an awesome center. It is already MTM. lay it on it's side and now you've got a serious center channel speaker. Would just need to remove the tweeter deflectors.

jimbo1421

westmassguy wrote: »

The 10s should be 6503s I believe. Transplant the drivers, crossover and tweeter from the 10 to the CRS+.

But does the smaller box of the CRS+ have no effect on the design requirements of the crossover?

Also, why would I need to transplant the tweeters? They both had the SL-2000 until I put the RDO-194s in the CRS+. Also, if I find another pair of CRS+, is there any reason not to do the TL upgrade on all three?

Jim

Face

Mr. Bubbles wrote: »

I'm thinking an RTA 15TL would make an awesome center. It is already MTM. lay it on it's side and now you've got a serious center channel speaker. Would just need to remove the tweeter deflectors.

And you would also have lobing by placing it on it's side.

I had something in the works a while back, I'll revisit it this week.

westmassguy

jimbo1421 wrote: »

But does the smaller box of the CRS+ have no effect on the design requirements of the crossover?

Also, why would I need to transplant the tweeters? They both had the SL-2000 until I put the RDO-194s in the CRS+. Also, if I find another pair of CRS+, is there any reason not to do the TL upgrade on all three?

Jim

I didn't know what tweeters you had. The 86' CRS+ used two 6510s, which are close enough to the 6503s. The only thing you may have to do, is pad down the tweeter with a .75 ohm resistor instead of the .5 ohm used to replace the Polyswitch.
"TL"ing all three would be very good, that's what I have.

westmassguy

Mr. Bubbles wrote: »

I'm thinking an RTA 15TL would make an awesome center. It is already MTM. lay it on it's side and now you've got a serious center channel speaker. Would just need to remove the tweeter deflectors.

I think an 8T would be more manageable. It's ported, so no PRs. Plenty of room on the baffle to raise the tweeter up

Mr. Bubbles

Face wrote: »

And you would also have lobing by placing it on it's side.

I had something in the works a while back, I'll revisit it this week.

I absolutely agree. But hey it has lobeing now, just in the vertical plane and as all centers with multiple driver, it would also have lobeing in the horizontal plane. That is just the nature of any multi driver speaker unless it's a point source unit. A design like the Vandy VCC-5 would be awesome but there is no vintage Polk full range or point source driver to work with. On the 15 the drivers are already mounted in very close proximity to each other to reduce the effects of lobeing issues as much as would be present in another good ready made center like most other Polk centers. In fact the driver proximity would be much better than most Polk centers produced in the past creating less lobing than those models.

Conradicles

That is what I have always thought. The 8T and the 8TL may be the perfect choice with a slight redesign of the cabinet style keeping the internal volume the same.

Mr. Bubbles

Conradicles wrote: »

That is what I have always thought. The 8T and the 8TL may be the perfect choice with a slight redesign of the cabinet style keeping the internal volume the same.

In all matterof correctness, accuracy, and SQ i would agree with this. The reason i mentioned the 15 is just because it would be bad ****. kind of like the SRS and 1.2TL's. To me the most basic of the SDA's "sounds" the best. (maybe not in every single aspect but over all) This is primamrily due to the minimal lobing, fewer source points of radiation, etc. Much of it associated with the basic design and fewer components. However I wouldn't give up either my SRS or 1.2TL's for another set of SDA 2's. Another reason is that my HT is totaly seperate gear from my 2ch rigs. Rarely is HT the cleanest, most detailed sounds we will hear like in our 2ch listening. Again i just mentioned it because it would be bad **** for HT! My choice again would be a point source design or a full range design like the Vany VCC-5. This would give true center focus with no lobing at all other than the radiation pattern of the single driver.

Another thought would be to design a sort of progressive point source like the SRS tweets and bring the focus back to the center somewhat like a focused array.

Face

Or maybe a dedicated midrange above/below a RDO and flanked by a pair of MW woofers.

Conradicles

Bump to see if anybody wants to get this project finished. We need specs/dimensions of the ultimate SDA center speaker.

gudnoyez

Zentish wrote: »

The vintage section of this very site calls the CRS+ a "Center Channel":

"SDA CRS+ Classic Polk Center Channel Speaker"
http://www.polkaudio.com/products/sdacrs

and

"The only center channel speaker worthy of SDA"

These statements confuse me since I thought the CRS was originally not a center channel but a Compact SDA.

That's what I've read on the vintage sight, I guess I have 4 SDA center channels then. We're you spose to use per say 2bs as fronts and 1 CRS+ as a center with out the SDA cable, all I would need is a 5 channel amp And I could have a all SDA surround rig the rears would be without the SDA cable connected Correct?

westmassguy

If I were using a CRS+ as a center, I'd swap out the crossover with a Monitor 10 crossover, and change the MW6511 to the 6503 or 6510, to match the stereo woofer.

westmassguy

An alternate for using the CRS+, would be to keep the existing crossover. Disconnect and safe-off the dimensional woofers wiring. Install two MW6511 woofers, and wire them in Series off the stereo woofer's harness.
You would probable have to play with the value of the Resistor that replaces the Polyswitch. The Tweeter's output may have to be increased.

voltz

here is a link to a 1 speaker CRS being sold on ebay but it is not a CRS+
http://www.ebay.com/itm/Vintage-Polk-Audio-SDA-CRS-Compact-Reference-System-Right-Speaker-Only-Black-/231403168334?pt=Vintage_Electronics_R2&hash=item35e0b4224e

westmassguy

voltz wrote: »

here is a link to a 1 speaker CRS being sold on ebay but it is not a CRS+
http://www.ebay.com/itm/Vintage-Polk-Audio-SDA-CRS-Compact-Reference-System-Right-Speaker-Only-Black-/231403168334?pt=Vintage_Electronics_R2&hash=item35e0b4224e

It is a CRS+, note the pin/blade interconnect socket

voltz

Ah cool! I remember seeing this for awhile now and was thinking it may never sell by itself but now maybe it will.

bingmobo

Reviving this thread;
Definitely ant to make a Home Theater package pull of SDAs. To this day (though I', only 30) the SDAs are the best bang-for-the-buck sound of anything I've heard. I currently have a pair of Polk SDA 2B's and a pair of Polk CRS's and am dying to get some Polk SDA SRS 2.3's ;-)
Most of the links above are broken, what do you all think is the best setup for a 5.1 system using Polk SDA 2's or 1's as the front L/R stage?
Thanks in advance!

EndersShadow

I've seen a set of CRS used above and below the screen as a center before. Otherwise the CS400i is I believe the center of choice...

bingmobo

Is the CS400i TimbreMatched to Polk SDA's? It looks quite different (not to mention ugly IMHO ;-) )

boston1450

Yes it can be used on SDA's. I used one with my 2b's & they are wonderful

bingmobo

boston1450 wrote: »

Yes it can be used on SDA's. I used one with my 2b's & they are wonderful

That is absolutely awesome!
Thanks so much.

Conradicles

Bump for folks who want the best SDA Center ever made.