So far SO GREAT

littlewoodboats

Thank you to everyone for all of the help with my SDA 2B's.

New RD0-194's that have been running for almost three days now. It is a good thing I was warned they would get worse before they got better. Yesterday it sounded like someone had swapped out the silk for wet sponge. :eek: Somewhere in the neighborhood of 50 hours now and they show great promise.

The new gaskets came in along with the dynamat extreme (I had the wrong stuff). Having never heard a healthy set without the dynamat I cannot say if there is a difference. Sealing the cabinets was huge. Every original gasket other than the tweeters was toast. Both cabinets now pass the leak test with flying colors.

I did notice that I put one of the mids back in clocked 90 degrees out from the original orientation. Is this a problem that should be put back or does it matter with the old drivers?

I have been trying to use the search function to find crossover threads with little success. When I opened my cabinets I found the two round board crossovers where the threads I am finding address a different style. Could someone direct me to the correct place?

Great forum.

drumminman

Found this thread: http://www.polkaudio.com/forums/showthread.php?62106-Oh-my-something-magical-has-happened-to-my-SDA-s&highlight=sda2b+crossover

Do a search with this: sda2b crossover. You'll get lots of threads.

rromeo923

When I swapped my sl2000's for the RDO 194 it was awesome. Immediate improvement. I have done most upgrades to my 1C's including Armacell, Larrys Rings, New Interconnect cable, spikes, New Caps and Resistors etc. The RDO 194 upgrade was the most drastic improvement in sound that I noticed of all upgrades. IMO

littlewoodboats

I found some threads showing that particular board but mine are the round type and I am sure I read here somewhere that the mods are done differently.

What is Armacell?

falconcry72

littlewoodboats wrote: »

What is Armacell?

Armacell is a foam insulation material that can be used to replace the stock gaskets on these vintage Polks. Search "Armacell" in the Vintage forum and you'll find some how-to guides, specifically by Darqueknight (sp?).

People who have tried both Mortite and Armacell tend to prefer Armacell, which makes sense because it's more similar to the original gasket material, and it isn't as messy. I've never used either, so I'm no help there.

drumminman

falconcry72 wrote: »

Armacell is a foam insulation material that can be used to replace the stock gaskets on these vintage Polks. Search "Armacell" in the Vintage forum and you'll find some how-to guides, specifically by Darqueknight (sp?).

People who have tried both Mortite and Armacell tend to prefer Armacell, which makes sense because it's more similar to the original gasket material, and it isn't as messy. I've never used either, so I'm no help there.

I've used both mortite and armacell. They both work well, with armacell being easier to use. It can be purchased at Home Depot. One box is enough to do many speakers.

inspiredsports

Post #54 in my thread SDA 2B thread at http://www.polkaudio.com/forums/showthread.php?74945 may help.

I've added the 5.8uf cap to accommodate the RDO198-1 (called the "TL" mod), but everything else should pretty much match what you have.

littlewoodboats

Thank you for the link. I seem to lack the touch to make the search function work well.

I appreciate everyone's assistance with my new to me speakers.

evhudsons

a great tip I use all the time now for searching on particular websites, such as this one:

sda2b crossover, site:www.polkaudio.com


copy/paste that into your google search and you will have no problem finding anything.

littlewoodboats

Thanks for the tip. I never thought of searching the site from the outside.

evhudsons

Another polkie posted that tip and I've been using it everytime.

VR3

Best way to use the search tool in site is to put " " at the beginning and end - of course you can refine further to find specific posts by specific people, etc etc

gimpod

littlewoodboats wrote: »

I did notice that I put one of the mids back in clocked 90 degrees out from the original orientation. Is this a problem that should be put back or does it matter with the old drivers?

Most likely not, But if it was me I'd put it back.

littlewoodboats wrote: »

I have been trying to use the search function to find crossover threads with little success. When I opened my cabinets I found the two round board crossovers where the threads I am finding address a different style. Could someone direct me to the correct place?

Great forum.

Now this makes me wonder if you really do have 2B's or could they be 2A's. If they are 2B Studio's they are very early one's as I've never seen or heard of a set of 2B's with the dual board crossovers now this doesn't really mean any thing as Polk use to use leftover parts from the previous model when they came out with a new one. Case in point the first 1C studio's used the dual board crossover design with a Pin/Blade IC and 1B cabs. I think this is how the Studio versions came about.

The easiest way to find out is to check the model number on the back of the drivers, If there both MW-6510 there 2A's, If one is a MW-6503 and the other one is a MW-6511 there 2B's.

Now as far as what parts you'll need that all depends on what model SDA 2's you have and how much your willing to spend. Check the crossover board for the part values to be sure. But before we can help you spend your money we really need to know which SDA 2's you have 2A's or 2B's.

Hope this helps

evhudsons

I know it's apples and oranges, but I discovered my CRS+ speakers were slightly different. One was 6511/6510, but the other one was 6511/6503. Was there the same kind of differentiation between the 2a and 2b? I bought mine at the same time but Polk Elders have said that speakers were sometimes sold individually. I just want to make sure the clarification in order to help make sure he makes the right determination on what he has and for all the reasons you stated. I wound up putting both mine to 6511/6510.

Rock on Polk SDA Brothas!

littlewoodboats

Unless I happen to have the only funny set they are 2B's. Two mw's, single tweeter with the blade/blade interconnect. The interconnect is not in the binding post cup but higher next to the bolt holding the second board in place. And they say the name on the back. From what I have seen I do think they are early production with the built on base and vinyl wrap wood grain. Grill only on the front.

I will open them up tomorrow and get some images.

gimpod

evhudsons wrote: »

I know it's apples and oranges, but I discovered my CRS+ speakers were slightly different. One was 6511/6510, but the other one was 6511/6503. Was there the same kind of differentiation between the 2a and 2b? I bought mine at the same time but Polk Elders have said that speakers were sometimes sold individually. I just want to make sure the clarification in order to help make sure he makes the right determination on what he has and for all the reasons you stated. I wound up putting both mine to 6511/6510.

Rock on Polk SDA Brothas!

This does not surprise me as Polk made 3 models of the CRS+'s that I know of.

1. 1986 - b/B IC, SL-2000 tweeter, 2 x MW-6510 driver, SW100 Passive, Dual board style crossover.
2. 1987 - P/B IC, SL-2000 tweeter, MW-6503 driver, MW6511 driver, SW102 Passive, Single board style crossover BE1807-B.
3. 1989 - P/B IC, SL-2000 tweeter, MW-6510 driver, MW6511 driver, SW102 Passive, Single board style crossover BE1807-B.

Both the 1987 & 1989 versions used the same crossover. And to make things even more confusing sometimes if Polk was out of MW-6503's they would use MW-6510's as a replacement and vise a versa as both drivers are almost identical spec wise.

So I think what happened here is one of the drivers went bad and Polk replaced it with ether the 6503 or 6510 or you got a mixed pair one 1987 version and one 1989 version.

As far as the differences between the 2A and 2B they used different drivers, As I've said before the 2A's used two MW-6510's and the 2B's used one MW-6503 and one MW-6511 (even the 2B's with the b/B IC and Single board style crossover), The crossovers are completely different animals and are not compatible with one another.

littlewoodboats wrote: »

Unless I happen to have the only funny set they are 2B's. Two mw's, single tweeter with the blade/blade interconnect. The interconnect is not in the binding post cup but higher next to the bolt holding the second board in place. And they say the name on the back. From what I have seen I do think they are early production with the built on base and vinyl wrap wood grain. Grill only on the front.

I will open them up tomorrow and get some images.

This makes me think there 2A's even more, But hey I could be wrong they could be 2B's, Polk did a lot tinkering back in those days and didn't keep very good records of what they were doing. As far as the name on the back that doesn't really mean squat, My SDA 1C's just say SDA 1 on the back. This is part of what makes some SDA's fun you never really know what you've got until open them up and look to see what drivers you have and what values the caps and resistors are on the crossovers. Pics of the crossovers will help a whole lot in figuring out what SDA's you really have. The higher res pics the better. Now keep in mind Polk made at least 3 versions of SDA 2B's that I know of and if yours are 2B's then that will make 4 versions.

1. 1987 Studio with b/B IC and a Single board style crossover BE1807-B, One SL-2000 tweeter, One MW-6503 driver, One MW-6511 driver and One SW121 Passive.
2. 1987 Studio with p/B IC and a Single board style crossover BE1807-B, One SL-2000 tweeter, One MW-6503 driver, One MW-6511 driver and One SW121 Passive.
3. 1989 Wood end caps, cloth sides with a p/B IC and a Single board style crossover BE1807-B, One SL-2000 tweeter, One MW-6510 driver, One MW-6511 driver and One SW121 Passive.

littlewoodboats

It did not rain as forecast today so I spent my day mowing instead of inside doing something productive like playing with speakers.

I pulled the drivers from the Left cabinet before I discovered my camera batteries are dead. I will describe what I found and get the images here ASAP. On the back of the cabinet it only says SDA-2 with the interconnect cable just below the binding post cup. Both of the mw drivers are mw 6510 dated Dec 2, 1986. The passive radiator is a SW-121 dated Nov 17, 1986 and initialed by a S. G.

So I have SDA 2A'a with the wrong radiators? I noticed the fabric has come loose from the back of the foam on the radiator. I think I read this is fixed with Elmers School glue?

gimpod

Yea I thought they were 2A's and yes you DO have the right radiators 2A's used the SW121's and Elmers School glue should work just fine.

littlewoodboats

Thanks for all of the info gimpod. It is funny in a way as I bought these from the original owner.

I was not sure about the glue. I had seen a thread where the fabric had ripped and that was the advice given. Is there a preferred method?

littlewoodboats

Here are the images of the crossover boards.

Lots of hot glue but does not like look like a difficult upgrade. I can see that the crossover is different and the 2A uses the same drivers but I was wondering if there were any major differences between the 2A and 2B from a listeners standpoint?

gimpod

The difference sound wise between the 2A and 2B i can't say as I've never heard them, I've got 1C's and CRS+'s

The hot glues not really bad on those I've seen a LOT worse, you can use alcohol to remove it from the caps but leave it on the inductors. From this point it doesn't look to hard to do but just wait till you get those new film caps and try to get them to fit on those boards especially those 130uF one's. Here's some tips and link for parts.

First: mark and label all the wires that connect to the crossover paying close attention to the wires for the IC socket as they are wired different for each speaker.

Second: Only do one crossover at a time.

Third: Do NOT clip the leads on the caps and resistors until you sure everything fits and is wired correctly.

Forth: That little brown thing on the yellow caps are 750pF Silver By-pass caps and are not need with the new and better caps you can get today.

Here's a link to the schematic for your 2A's SDA 2A Sch.pdf

Here's the parts you'll need.
Parts Express
Solen 130uF (2.45" x 2.76") @ $48.17 ea x 4 = $192.68
Solen 20uF (1.26" x 1.77") @ $9.25 ea x 4 = $37.00

Sonic Craft has a 20% off sale going on right now. (There listed prices don't reflect that but the discount will be applied when you request a quote)
Sonicap 12uF (1.17" x 1.74") @ $22.50 ea x 2 = $45.00

Mills MR12 2.7 Ohm @ $4.15 ea x 4 = $16.60
Mills MR12 0.1-0.5 Ohm @ $4.15 ea x 2 = $8.30 Note: these are used to replace the polyswitch (that little blue thing) but ONLY if you can keep from cranking the crap out of the volume control other wise I suggest you leave them in. The value really depends on taste, the lower the value the brighter the tweeters. 0.22 Ohms seem too be a good place to start.

While your at it you should get some good solder like Cardas Quad-Eutectic 24ft for $7.00 is more than enough to do those.

And some new binding posts
Vanpire BPHEX @ $14.35 a set x 2 = $28.70
Or Cardas CCBP S @ $26.25 a set x 2 = $52.50

Hope your sitting down as that's around $300.00 + just for parts more if you need a soldering iron (a 40 watt), Hot Glue gun, Solder sucker or wick etc..

BTW: On that glue for the passives just make sure it wont eat the styrofoam.

littlewoodboats

That should pretty much cover it. Thanks gimpod.

I have all of the tools and supplies and I can solder. I have built several Velleman kits over the years but those are the electronics equivalent of paint by number. I did a tube amp and passive preamp. I try to be methodical and also take pictures for reference.

Funny you mentioned the binding posts as my first thought when I put them into the office was how much nicer the SDA's were over the crap Sony speakers I had in there before. I had read here where it was on the list of things to change and had looked at the Vampire set and planned to order those.

It will be next week before I can order the parts but will post some images for critique once they are finished.

I used the Elmers on the passives as I had some. One was completely loose and the other was close behind. I went in from the side and applied a coating of glue with an artists brush then gently pushed the fabric down into its original position. Once I had done that I used the brush again and put glue around the outside hitting the foam and fabric. The drivers are back in the cabinets so after a nights curing time for the glue (as per package instructions) I will see how they sound. I am not running much in the way of power so I had not noticed any sound issues but discovered the problem when I took them out to get the shots of the crossovers.

Thank you again to everyone who has helped since I came here.