"New" SDA's needing work

yeahbuddy

Hey all,

I stumbled on some brilliant SDA speakers recently in my girlfriend's mom's storage room, and used all my powers of smooth talking to convince her that they'd fit better and go to good use in my living room. Despite my efforts to convince her I should give some money for them, she wouldn't hear it, so I'm sitting on two very lightly used SDA's for the price of being amicable with my girlfriend's family...not a bad deal!

Meanwhile, all that money that I'd give her now has no more noble purpose than to get the full ability out of these speakers, and the experience that I've read all about in these threads. I figured that instead of risking my job by reading every post ever written on the subject while at work it'd be best to post a few pics and ask for some direction on what I might need to do to get these babies rocking.

First order of business is to identify what model these speakers are. The back states SDA 1A, so I'd be inclined to believe that. See picture to verify. The funny thing is that the serial also includes a number "1981", which from my research is before any of the SDA's were produced. What's that about?

Second, I'll need to have a plan of attack on manufacturing the interconnect, which unfortunately was nowhere to be found...grumble grumble. The connector is definitely not blade/pin, as an RCA pin doesn't fit in either slot, and I have to insert speaker wire into both ports to get the dimensional drivers going. However, I don't recognize the interconnect port from any pictures I've seen on here. They're located below the main plate, and one blade is longer than the other...see attached pic. Can anyone shine some light on this? Can I maybe just buy some higher quality connectors to put in place of the stock ones?

Third, I'm currently running these with a paltry 65 W/ch from my Onkyo 5.1 receiver, any suggestions on what wattage is necessary for these to operate as they should? Any suggestions on pre-amp specs or modes is welcome, as I've never had nice enough speakers to justify getting one and am thus clueless.

I suppose that will do it for now...ready to get these things to the level they should be at to hear these for real! Thanks for any help I get get!

inspiredsports

Welcome to Club Polk. You'll get lots of great info here about how to proceed.

Wow, the price was certainly right! Nice Score.

Blade/Blade interconnect cables come up for sale here in the Classified's forum and on eBay from time to time for around $35, and you can find the male plugs at various parts supplies and build your own using even higher quality cable. Ben in the group builds a really nice cable for a few dollars more.

The 1A's are a very early SDA model where one of the tweeters in each cabinet is lnked to the SDA circuit. Polk later found only the midrange needed to be involved in the array so subsequent models did not have tweeters in that circuitry. There is a way to properly disconnect the SDA tweeter in each cabinet of the 1A, and some owner's find that to yield a sonic improvement.

Capacitors in 20+ year old gear tend to drift off value and a noticeable improvement can be made by replacing them with modern high quality caps. Adding new/quieter resistors and removing/bypassing the tweeter polyswitches also helps.

Conradicles

yeahbuddy

bsturgeon89

Nice score....can't beat that deal!!

What happens if you break up....LOL

F1nut

The grill cloth is not original.

The blade/blade cable can be purchased from Polk for about $35.00.

fishbones

Makes me want to go through all my wife's family's stuff!
Nice find :eek:

Welcome to the club...you'll get all the help you'll need on here.
Many threads on here about upgrading SDA's. Here's one that isn't exactly your SDA 2's, but has alot of the same info, and you will learn alot.

http://www.polkaudio.com/forums/showthread.php?t=97719

jimbo1421

Wouldn't "1981" be the serial number, not the manufacturing date? The actual date of manufacture should be stamped on the back of the individual drivers.

Have you done the "press test"? Gently push the passive bass radiator in and observe that the other drivers are pushed out by air pressure. Hold the PBR in and count off the number of seconds it takes to return to center. It should take several seconds. If they pop right back in you have an air leak and should reseal the drivers with Mortite rope caulk(do a search here). Another tweak is to line the steel baskets with Dynamat Xtreme, a sound deadening material that keeps the baskets from ringing slightly.

Welcome to CP,

Jim

F1nut

If they pop right back in you have an air leak and should reseal the drivers with Mortite rope caulk

Let's not be so fast with the Mortite thingy. An air leak can be caused by a number of things, such as gaps in the joints of the cabinet, tears in the surrounds or simply loose tweeter/driver/PR screws.

Fongolio

Great find. As for an amp, almost any dedicated amp will sound better than a receiver with a few exceptions. For solid state amps you want high current and common ground. My 1C's really came to life with an old Kenwood KA-9100 I used to own. They really started to sing when I put them with a Carver TFM-25 which put out about 225 wpc. I now have them mated with a Carver TFM-45 and they daily blow my mind with great sound. Mind you mine have almost every mod you can do to them. Tonight I was playing Yello's Say Yes To Another Excess on vinyl and the bass extension was so low it sounded like a subwoofer was attached. But very controlled bass. Fantastic. Many guys (and gals) here are fans of tube amps which can power SDA's very nicely on considerably less watts than a solid state amp with extremely pleasant results. Congratulations and welcome to Club Polk.

kelvin

cwilliams

You can also make the interconnect cable like I did for my 2A's -

http://tinyurl.com/23nvdlt

Bobsama

I'd suggest you listen to them without disconnecting the dimensional tweeters. Listen to them how they were designed to be listened to: if Polk found that those particular speakers sounded better without the dimensional tweeter, then they would have been disconnected or omitted from the factory.

Anyways, very nice speakers.

yeahbuddy

jimbo1421 wrote: »

Have you done the "press test"? Gently push the passive bass radiator in and observe that the other drivers are pushed out by air pressure. Hold the PBR in and count off the number of seconds it takes to return to center. It should take several seconds.

So I understand, I press in the passive radiator and hold it depressed while waiting to gauge the driver's response? Or do I press it in, release, then count how long until the drivers return to center? If it's the press, release, then count method then I'll have to do something about resealing them, they go right back to center without hesitation.

F1nut wrote: »

The grill cloth is not original.

Funny that this would have been replaced, maybe the reseller back in the day had some fun selling speakers more as a decorative item than sound reproducing machines...makes sense from my perception of her: more concerned about her appearance of wealth and style than actual substance. Can't complain though, I like the look and love the sound!

bsturgeon89 wrote: »

Nice score....can't beat that deal!!

What happens if you break up....LOL

Hoping that won't happen near future, but I'll have to ensure that I don't talk them up too much to her in case of that unfortunate scenario

Thanks all for the responses! Hopefully I'll have the interconnect up and running in a few days to experience the SDA effect I've heard everyone raving about.

F1nut

So I understand, I press in the passive radiator and hold it depressed while waiting to gauge the driver's response? Or do I press it in, release, then count how long until the drivers return to center? If it's the press, release, then count method then I'll have to do something about resealing them, they go right back to center without hesitation.

Push in and hold.

yeahbuddy

Got the speakers up and running, but now I'm looking to see if I can't get the correct power to them. Currently I think I might be risking damage from clipping trying to get them pumping from my pitiful receiver.

However, it'd be nice to not have to get an amp as well as an additional pre-amp, so I looked at my receiver to potentially play the pre-amp role. Problem is, my Onkyo 307 doesn't have any pre-outs for me to hook up to an amp.

Anyone have comments on whether I can manually add some pre-outs to this receiver? I've heard of such modifications, but may be a little ambitious for me.

F1nut

However, it'd be nice to not have to get an amp as well as an additional pre-amp, so I looked at my receiver to potentially play the pre-amp role. Problem is, my Onkyo 307 doesn't have any pre-outs for me to hook up to an amp.

Get a really nice integrated amp.

schwarcw

Nice speakers! Welcome to the Forum. Lot of good advice here. F1nut has given me a lot of good advice over the years.

Joe08867

Until you get the interconnect cable I would hold off on any upgrades. But I would suggest something stronger to run them or like you said you risk damage due to clipping.

I would listen to them stock when you get the cable and then try them without the Dimensional tweeter and see which you like more. I found the dimensional tweeter irritating and inorganic in sound to my ears. But you may not.

I wonder if the grill cloth was changed to match a decor? I did that on some old JBL's I had a thousand years ago. They don't look bad that way at least. Kind of like real thick Maggies.

yeahbuddy

The interconnect parts should be in this week for me to fab the cable, until then I've rigged some speaker wire into the ports to get a workable band-aid meanwhile. Hopefully the actual cable will improve performance greatly, as I stand right now my "sweet spot" is a pretty narrow spot right in the center and it'd be nice to not have to arrange my living room just-so in order to get the SDA effect.

As for an amp, I actually recently picked up a CS350 center to try out a 5.1 system using the SDA's as fronts with my R15's as rears. The R15's don't need any more than my receiver can give them, but the CS350 can handle 200W and obviously the 1A's much more than that. Any recommendations on what amp I'll want to send the right power to my fronts? I'm thinking a 3-channel would do fine, although I'd need to limit the wattage to the SDA's based on the center. What about a 5-channel that takes ~200W to the center and I can bridge the other 4 channels two each to the SDA's? Anyone else have a similar set-up?

Bobsama

Check distance; measure how far the speakers are apart and sit about the same distance away from them, and in the center of course. That'll be the sweetspot. If you like a narrower sound-stage, sit 1.5x as far back. Also, tweak where the speakers sit exactly. Closer to the wall means more bass response, further is naturally less. Try to keep them away from side walls. In addition, avoid putting anything in front of and between them. If you have a TV setup, your speakers should be sitting a few inches further forward than the TV, if at all possible

Joe08867

And whatever you do don't toe them in. Meaning: face them square into the listening area. If you toe them or angle them inward it will shrink the sweet spot and the SDA effect will get all weird on you.