SDA-2A vs 2B identification...

AFEuphman

Good morning! I'm actually kind of embarrassed to ask this, but I need a little help. There is a fellow selling a pair of SDA-2(?)s near by. We are close on a price, but he can't ID them as A or B models. The picture on the ad shows the larger wood "cap" at the bottom, which makes me think "A," but I know how the transitional models get a bit "muddied." (He THINKS they are B's, BTW)

So, I don't want to annoy the guy too much, but I really want B's. What is the most foolproof way to ask him to check. Would it be to pull the passive and look at the crossover (or pull the terminal cup?). I've got a pair of CRS+ and could send him a pic of the big air core inductor. Am I correct in thinking the A model doesn't have that?

If he pulls the MW's, is it guaranteed that they should be different on a "B?" Or is that a "transitional" issue?

Anyway, thanks so much for the knowledge. Have a great weekend!

John

westmassguy

There are two models of the 2B, the Studio, and the regular. The studio looks almost identical to the 2A, with walnut vinyl. The regular 2B has a slab top and bottom, with a wrap-around grill. You can't go by the IC socket either. Some early 2Bs used the blade/blade socket. If he's willing to pull the Passive radiator, you'd be able to tell immediately. 2As have the 3rd generation two piece crossovers, while the 2B will have the 4th generation single, large crossover.

TennMan

A less technical way to tell is if there is a large B added to the upper right corner of the label on the back of the speaker. I'm not sure if that was done on all the 2Bs but mine has it.

Emlyn

If the SDA connection is pin-blade they are 2Bs. If they are blade-blade, they could be either 2A or transitional 2Bs. If the speakers are blade-blade and if the owner is willing to remove one of the mid-woofers, confirms it is a correct original driver, and sees it's anything other than a MW6510, the speakers are transitional 2Bs. The mid-woofers will most likely also be date stamped and if they are original and stamped after 1986 they should be 2Bs.

Unless you're planning on doing some major modifications to the speakers or running a non-common ground amp, I wouldn't be too concerned myself with the distinction between whether they're 2As or 2Bs. I actually prefer my 2As over the 2Bs I had, in part because they didn't have the glued on cloth side panels.

I'd be more concerned with confirming that the mid-woofers don't make scratching sounds when they're manually moved in.

AFEuphman

Hey, thanks so much for the info! I had forgotten about the studio edition! I thought they were always black? At any rate, I'll write the seller and see how much he's willing to do. He's just a LITTLE too far for me to drive out to do it myself.

Thanks again!!! I'll let you know how it goes!

John

gimpod

There's basically 2 ways to tell if there SDA 2B studio's,

1. Look at the SDA interconnect socket, If it's a Pin/Bade there 2B's, If it's a blade/Blade they could still be 2B's (see #2)

2. Pull the dimensional driver (Facing the speaker, The right one for the right speaker and the left one for the left speaker) if it's a MW-6511 there SDA 2B's and if it's a MW-6510 there SDA 2A's.

As far as I know there are 4 possible different SDA 2B studio's (they came in both black and wood grain vinyl)

1. one SL-2000 tweeter, one MW-6503 stereo driver, one MW-6511 dimensional driver, one SW-121 passive radiator, a dual board style crossover with a blade/Blade I.C. socket
2. one SL-2000 tweeter, one MW-6503 stereo driver, one MW-6511 dimensional driver, one SW-121 passive radiator, a dual board style crossover with a Pin/Blade I.C. socket
3. one SL-2000 tweeter, one MW-6503 stereo driver, one MW-6511 dimensional driver, one SW-121 passive radiator, a single board style crossover with a blade/Blade I.C. socket
4. one SL-2000 tweeter, one MW-6503 stereo driver, one MW-6511 dimensional driver, one SW-121 passive radiator, a single board style crossover with a Pin/Blade I.C. socket

The crossovers for all SDA 2B's should be the same component wise,
1 Polyswitch.
1 2.7 Ohm resistor.
1 750pf Silver Mica bypass Capacitor.
1 12uf Polyester Film Capacitor.
1 20uf Electrolytic Capacitor.
1 40uf Electrolytic Capacitor.
1 0.4mh Inductor.
1 1.25mh Inductor.
1 2.50mh Inductor.
1 16mh Inductor.

Also keep in mind that Polk sometimes (depending on stock I think) replaced or recommends replacing a blown MW-6503 with a MW-6510.

With early SDA's (pre 1988), especially the SDA 1's & 2's you really don't know exactly what you have until you open them up and look.

AFEuphman

Wow, I've never seen a more complete explanation. Thank you so much! So, any reason I should I be staying away from the studio version, in general? And is there an easy way to tell if he has the studios?

You all have been so helpful already. Many thanks!

boston1450

Pictures.. Studio SDA's tend to be valued less.. Whats his price ? But then again without knowing what they are-doesnt help. If the price is right - dont walk--RUN & GET THEM

AFEuphman

Duh! Ok, so here is the shot from Craigslist. They need tweeters (I have a pair). They are listed at $175. Can you tell by looking if they are the studios?

westmassguy

Look like 2As to me

On3s&Z3r0s

I'd definitely give the seller a call or an email to ask about pin/blade vs. blade/blade question. If the answer starts with a P sound you should already be on your way to the car by the time he finishes his answer. If they are blade/blade you could ask to pull a driver, but honestly I would say statistics are not with you. I own and have seen other black 2B studios, but I think the wood ones must be pretty rare. I'd assume they are 2A's without direct evidence to the contrary.

I also have a pair of the regular 2Bs with the "wraparound" grill effect. I've listened to both in the same spots with the same components installed, and I can't hear a difference. I think it's all about cosmetics (which I admit is why I bought the non-studios). The black vinyl is less pretty, but with the wood grain I would definitely get those if they are 2Bs!

BKphoto

westmassguy wrote: »

Look like 2As to me

this...

AFEuphman

Ok, sent the seller a note with the ID directions. Hopefully I'll hear back soon!

F1nut

westmassguy wrote: »

Look like 2As to me

Agreed

AFEuphman

OK everyone, thanks again for all the help. The consensus was correct: The seller replied back and says they are 2A's. So now, it seems that while the upgrade train (TL, etc) may not be in the cards for these speakers, that they are still great. A couple more questions:
1) He's listing them with non functional tweeters. Think they are blown, or could this be a poly switch issue?

2) Listing is $175 in their current condition. If I replace the tweets, am I getting behind? This is PRETTY close to an impulse buy... You know: "Boy, I've had these SL2000's sitting around for a while... HOLY COW, somebody's got some Polks that need them!" I should make sure I can get my money back out of them, or at least close...

I've always wanted the 2B's. Ugh. I'm having a tough time here.

Thanks guys, I don't post often enough., but I love reading and learning. Thanks again!

westmassguy

The 2As can be TL'd just like the 2Bs, so don't let that stop you.
The one caveat, is the 3rd generation 2A crossovers are more expensive to upgrade than the 4th generation 2Bs

chandler9a

I had 2A's for years up until two weeks ago when I traded them for a pair of SDA SRS II's. The 2A's are a great sounding speaker but I would honestly either hold out for a nicer pair or offer him $125 tops with non working tweeters. Based on your location, you should be able to find some better SDA's in time. Don't get me wrong, those are great speakers but you will need to do some upgrades and who knows if the correct woofers are even in there (6510 I believe )

Just my .02

BKphoto

Don't buy IMO, I paid 100 for a mint pair (although no cable)

have to be patient..

AFEuphman

Thanks for the help guys. I searched my soul and knew that it just wasn't what I was looking for. Next time!

On3s&Z3r0s

FWIW, you made the right call. Much better to wait for the pair that is what you're looking for than invest a bunch in what's available now and have to figure out how to recoup that investment when the right pair comes along.