SDA 2B Proper Resistance Values

Jasper67

I recently purchased a pair of SDA Studio 2B's and I want to make sure everything is in working order. I downloaded Raife Smith's SDA Handbook (very informative) and there is a section describing how to check everything out using a Volt/Ohm meter, however the 2B's are not listed with values. Any thoughts? Here is a link to the handbook if you don't have a copy. The section I am referring to begins on page 34. Thanks...

http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

F1nut

That information was supplied by Polk Audio and since they didn't list the 2B's it must not have been available. Do you have a reason to believe something is wrong with your speakers?

Jasper67

No not at all, just having fun with my new speakers and trying to learn as much as possible.

F1nut

Very good sir. All you need to know is the TL mod along with all the other standard mods will take your speakers to a level you won't believe.

Jasper67

Before I consider the TL mod, I should probably address my power. I am currently powering them with a Yamaha surround amp. (RXV-671) I listen to them in pure direct mode, but my amp is my weak link right now. I am so psyched to have these, I remember as a kid listening to the SDA SRS in a local stereo shop and I was completely blown away.

F1nut

That's a good plan.

Jasper67

F1, Would I reap any benefits if I made some of the minor mods first? For example, dynamat, hurricane nuts etc... Save the crossovers and tweeters for later. I appreciate the advice...

agfrost

I imagine all of those would be helpful towards increasing clarity and cohesiveness. Add installing spikes to that list as well.

Jasper67

Any idea how much dynamat is needed for the project? I checked online and it is a bit pricey and I don't want to buy more than I need. I have hardwood floors do I don't think my better half would be cool with the spikes...

agfrost

The "wedge pack", I believe is sufficient for your needs.
Some spikes come with cups/disks that they sit in that will protect floors. In theory, one can slide them around until you find the ideal placement, then add the spikes/disks. It's the solution for hardwood floors, if you decide to go that route.

There was a thread about these recently...

Ah, here we go: LINK

RandyCroissant

Hello Jasper and welcome to the forum, you made a great choice with the 2bs, I have the same ones as you bought them new back in 88. I just went through rebuilding the crossovers with new caps and resistors also new rdo198 tweets and the TL mod. I believe these mods will give you the biggest bang.. Funny thing I also have the same receiver as you so we have something in common. Have fun with those old polks they are awesome. PS F1 and others on the forum were a huge help to me.

leftwinger57

I have told this before.If you don't mind scrounging a bit most audio installation shops use Dynamat Extreme . I asked if they had any and they said they just did an entire trunk and have some scraps and let me have it, and there was enough to do 4 2Bs. Why spend cash if you don't have to. You do not use it as sheets anyway only strips on the baskets and just throw them some coffee money as appreciation factor. Black Hole-5 is fairly expensive I did find my sheet on C/L for $15, bargins are out there. Also a roll of Armacell/Armaflex gasket tape was about $8 at Home Depot if you need new gaskets.

F1nut

F1, Would I reap any benefits if I made some of the minor mods first? For example, dynamat, hurricane nuts etc... Save the crossovers and tweeters for later.

Sure, it's a cumulative effect.

Definitely add spikes and get the floor discs to protect the floor. They make a bigger improvement than most folks realize.

gimpod

Jasper67 wrote: »

I recently purchased a pair of SDA Studio 2B's and I want to make sure everything is in working order. I downloaded Raife Smith's SDA Handbook (very informative) and there is a section describing how to check everything out using a Volt/Ohm meter, however the 2B's are not listed with values. Any thoughts? Here is a link to the handbook if you don't have a copy. The section I am referring to begins on page 34. Thanks...

http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

If you look on page 36 you'll find values for the SDA CRS+ (New Connector) which uses the same electrical components as the 2B with the exception of the stereo driver (MW-6503 (6.54 Ohms) for the 2B and the MW-6510 (6.57 Ohms) for the CRS+), This should get you well within the +/- 10% tolerance.

Jasper67

Thank you to all for the input. I need to spend some time going over all this info. In the meantime, is there an optimum floor to bottom of speaker cabinet dimension for best results? When I purchased the speakers, the sliders on the bottom of the cabinet were broken so I replaced them with new sliders I bought at Lowes.

Jasper67

Has anybody documented their TL mod on YouTube? I would need a lot of help with this since I am such a newbie. Also, what is the approximate cost of the crossover rebuild? I gotta say, this stuff is making me feel like a kid again!! A revival of my love for Music!!!

RandyCroissant

Yes!! I can tell you all about it since I just did mine last month. I have a pair of 2bs I bought new back in the day 88 to be exact they started to sound dull and lifeless, so I looked em up and found CP. With a lot of help and suggestions from members here I purchased my caps sonicaps from sonicraft (they may still be on sale) as well as the mills resistors those items plus some solder and chassis wire will set you back about $250 or so that includes the caps for the TL mod for the RDO198 tweets. Get them from polk, they will set you back another $100 bucks. These upgrades were easy to do the TL mod is simple, you can find out all you need to know from Vr3 and others here. Once the mods are all complete give them some time to burn-in and you will NOT regret jumpin into the fish bowl with the rest of us...

Jasper67

Update, I reached out to Vr3 and the response I got back was that they are booked until October and what are my goals. I asked them about just buying the board for the crossover and I haven't head back as of today.

Jasper67

Thought I would give you all an update. All baskets and been "dynamatted" however I used a product called extreme Road kill that I got from a local car stereo shop. (thanks for the tip leftwinger57). Hurricane nuts and spikes ordered. I am also talking with the folks at Vr3 mods about the crossovers.

TennMan

Westmasguy did a great job on my 2Btl crossovers. You don't need new boards but they might make it a little easier. Check with westmasguy before you order any parts.

Jasper67

I'm considering letting Vr3 build my boards with new inductors and new plates with binding posts and new SDA connection. It's expensive, but I have never done anything like this and I'm concerned that I might screw it up. Does anyone have experience with their complete mod? This is the spec they quoted.

Tweeter Circuit -
Clarity Cap ESA 250V
Mundorf Mox Resistors

Midbass Circuit -
Clarity Cap ESA 250V (Not Pictured)

Upgrade Features -
GIMPOD Circuit Boards
Drop in replacement

Faustin

Many members have had c/o's done ny vr3 and seem quite happy with them. Many have had wessmassguy (Dave) do c/o's, including myself and have been pleased as well.

Jasper67

Just ordered the RD0198-1's today from polk. $98 for both, free shipping and discount because of being a forum member.

KJM

Hello, Polk SDA enthusiasts! I just joined the forum, after a recent update/upgrade of the crossovers in my SDA-2b speakers. The date stickers on them revealed that the left and right cabinets were manufactured 18 months apart! (I always wondered why the serial numbers on the enclosures' backsides were so far apart.) I have not changed the tweeters; I eliminated the protection varistors and their accompanying tiny parallel caps from the signal path between the tweeter and its high-pass capacitor. And replaced the large resistor with a newer one of identical value. I believe both of those things are the correct procedure, but I noticed one other oddity, with regard to the factory connection of the massive inductor. The leads attach to the board at 'P' and 'R'. But the inductor leads on one crossover are reversed, compared to the other. I don't know if the "polarity" (inner-beginning of winding, versus outer-ending of winding) really matters, with respect to an inductor. Can anyone here tell me if there are benefits to reap, by matching the inductors' connections? Or perhaps one channel's inductor is connected "in-reverse" BY DESIGN for desired out-of-phase reasons? Thanks; I will now attempt to attach a photo of my finished work below ...

agfrost

Someone can correct me if I'm wrong, but the inductor is 'directionless', much like a resistor or nonpolar capacitor, and unlike a polarized capacitor.

westmassguy

Inductors don't have polarity, they can be wired to either terminal

F1nut

I'm going to recommend you start again. Order the RD0198-1 tweeters and add the 5.8uF cap to the crossovers to "TL" the speakers using something better than Solen. Replace the 12uF Solen with the same something better you use for the 5.8uF. Is the 20uF a mylar? If so, replace that as well. You need to remount the 40uF Solen. Stand it up on end using 3M VHB tape to secure it to the board at the bottom and to the inductor on the side. Run a zip tie through the inductor and around the cap to further secure it. Cut off the excess tail on the zip tie. You will have to extend the one lead from the top of the cap to the board, use 18 gauge solid wire.

Solen caps used in a high pass result in an grainy/edgy sound.

Freeridesnomore

F1 do you recommend silver wire or copper wire to complete the connection?

F1nut

The cap leads, board traces and everything else is copper, so definitely copper wire.

KJM

@ westmassguy, Thank You, i kinda figured that inductors were entirely non-polar. @ F1nut, also Thank You, a couple things to explain. No money was spent here, I have been out of work long-term, all the parts were a birthday gift from a fellow audiophile. So I won't be buying the upgrade tweeters. Besides, I enjoy the extra brightness of my new sound, finally able to set the treble knob to 'flat'. The 12uF high-pass to the tweeter is not a Solen like the others, it is a Dayton Audio 1% tolerance cap. Yes, the 40uF Solen should have been stood on its end, but it took me several hours to manage the required soldering as it is; didn't want to try splicing an extension wire from one end, and I don't have a hot glue gun or equivalent. You can see that the monster cap is zip-tied in place; I did not tighten them until the crossover was remounted and I squeezed the audio connector in place (which unfortunately has zero clearance, pushes slightly against the cap!) Whenever I find steady work again, I will consider purchasing the upgrade tweeters and associated caps. Meanwhile I am debating a newer form of SDA cable, pondering a single run of solid copper the same large diameter (8-gauge maybe?) as the pin of that silly proprietary connector, just buy a 10-foot piece at Lowe's, strip each end and jam it in the holes ... Poor-Man cable upgrade.

westmassguy

An alternate to Jesse's mounting method, is to use dual belly-bands plus the 3M VHB tape. You'll need to drill an additional hole on the edge of the circuit board for the 2nd wire tie.