SDA-2B Consensus on Modifying the Crossover's

audiocr381ve

Hi guys, after auditioning the Monitor 10's last week, I found a guy about 10 minutes away selling an almost pristine pair of SDA-2B's. So, I auditioned them and took them home last night! They are being powered by my vintage Marantz 2245. So far, I've been enjoying my vintage system, but I'm oddly missing the resolution and "punch" of my Monitor Audio RS6's, which is weird only because I bought this vintage setup to not care about that type of stuff (I understand placement and amplification are two things that can help with the mid-low end). I'm a fickle man. :redface:

The only alteration to these speakers were the tweeters (upgraded to the RDO-194).

Their are to many threads on successful modifications to ignore. My goal is to get them sounding as good as I can afford to get them sounding. I think I have just enough "modding" and solder experience to take on the task of rebuilding or updating the crossovers.

I was wondering if anyone would be willing to walk me through the process who has a pair of successfully modified SDA-2B's either by phone or email. Or if there is a step by step guide/thread that someone could refer me too as well.

Thanks dudes.

On3s&Z3r0s

Welcome to the club, and congrats on the score. I loves my 2B's!

If you don't mind spending an extra $100 in doing the mod, send a PM to Gimpod to purchase a couple of the custom crossover PCB's he had made. (http://www.polkaudio.com/forums/showthread.php?t=118187)

These, together with the materials he has put together at gimpod.com make a crossover upgrade to the TL a slam dunk. I think most guys who have done the TL upgrade would say it is definitely worthwhile. It involves replacing stock caps and resistors on the board, deletion of a couple unnecessary pieces and addition of a 5.8uF cap and upgraded tweeters.

You can do it without the custom boards gimpod made up, but it's not a trivial exercise to get high-quality capacitors to fit on the stock boards. I wouldn't have wanted to attempt it without the customs. Check out the 3rd and 4th pics on the first post of this thread for a comparison of the custom vs. stock boards. That 4th pic is wickedly glue-licious.

As I said, the gimpod.com site makes it crystal clear how to perform the upgrade. But if you did decide to go with those, I'd be happy to walk you through my recent experience upgrading my 2B's with them. If you use the stock boards there are others who could give better input as I haven't ever attempted that.

Joe08867

I was going to suggest Gimpod also. I wish I had used his boards originally. The finished product with his new boards is much cleaner than the Polk originals. Especially with the Caps most of us use in the upgrade.

Go Sonicap or Clarity. You won't be disappointed.

audiocr381ve

Thanks Ones,

Just to clarify, what exactly is the "TL" mod?

The custom PCB's look like they'd make life a whole lot easier. But more importantly you've gone through it with that board and are willing to walk me through this. That's worth the purchase alone as far as I'm concerned.

Do you have review of what happened after the upgrade? Would love to read it.

Also what's the best way to keep in touch? I'm going to check out the thread you linked now..

audiocr381ve

I just emailed Gimpod. I'll let you know as soon as the transaction goes through.

On3s&Z3r0s

audiocr381ve wrote: »

Just to clarify, what exactly is the "TL" mod?

Polk used the TL designation in the model numbers of their later model SDA speakers. TL referred to their tri-laminate tweeters which had a mellower sound than their earlier tweeters. Prior to the TL's the SDA's generally used the SL2000 tweeter which spikes louder at a certain frequency, I think around 12kHz. (Incidentally, the RD0-194's already in your speakers eliminate that spike.)

Anyway, because the TL's were so much nicer, I understand Polk made available some kits for DIY'ers to use in modifying their speakers. By tweaking the crossover the TL tweeters could be used in place of the SL2000.

One model that had new schematics drawn up for the tweak was the SDA CRS+. It used the same tweeters, MW drivers, and crossovers as the 2B, just in a different cabinet with a different PR. So, it's possible to apply the same mod to the 2B to allow the use of a TL tweeter (SL3000), or its current replacement, the RD0-198. Here's that schematic. (There's sticky threads for schematics at the top of the Vintage Speakers forums.) So, that's why people generally refer to this mod as a "4.1 TL" riffing on Polk's model number scheme, or just a 2B TL.

Since, you already have the RD0-194 replacment tweeters, if you didn't want to do the full TL mod, you could just replace the stock caps and resistors on the board (no extra caps and keep the tweeters you've got) and get an improvement out of it. But again, some folks have actually started with the 194's and then done the TL mod and felt it was worthwhile. Here is the orginal and still the best thread on the sonic improvements of the upgrade.

The thread reminded me that some older 2B's aren't as easy to upgrade this way. If you have the serial numbers handy or at least know whether your interconnect cable is the pin/blade or blade/blade style that would help determine what version you have.

I'm still burning-in my upgraded speakers (just finished them last week). But, I'll do as decent a review as I can manage when I'm done in a couple weeks. Already, I can tell it is a bigger improvement than I guessed it would be. Using Sonicaps for shunts gives some crazy bass over the stock electrolytics, and the highs are waaaayyyy smoother and more detailed.

If you want a quick response, feel free to PM me any time. But I'll watch this thread and possibly start one of my own like CincyCat did with my personal lessons learned.

On3s&Z3r0s

audiocr381ve wrote: »

I just emailed Gimpod. I'll let you know as soon as the transaction goes through.

Cool. Again, you should double check that you have a later version 2B with the pin/blade IC and single crossover board. Gimpod's boards are made to replace that later single crossover. Sorry I forgot to mention that earlier.

intangible

If you are on a budget, I would skip the new PCBs. They look very nice for the more complicated crossovers, but the original 2B boards are pretty easy to fit everything on.

gimpod

Replied to audiocr381ve by PM.

On3s&Z3r0s wrote: »

Cool. Again, you should double check that you have a later version 2B with the pin/blade IC and single crossover board. Gimpod's boards are made to replace that later single crossover. Sorry I forgot to mention that earlier.

As far as I know (and I could be wrong) Polk only made 2 versions of the 2B's both used the single crossover board and the only difference being the early ones use a Blade/Blade IC that only uses the narrow blade for a connection the other blade is not connected to anything. So if his crossovers are of the single board style he's good to go.

BTW: Thanks for the plug.

On3s&Z3r0s

gimpod wrote: »

As far as I know (and I could be wrong) Polk only made 2 versions of the 2B's both used the single crossover board and the only difference being the early ones use a Blade/Blade IC that only uses the narrow blade for a connection the other blade is not connected to anything. So if his crossovers are of the single board style he's good to go.

Good to know, thanks G! F1's thread reminded me that some of the blade/blade CRS+ had the 2 boards, and I remembered something else I had seen about crossover differences in the 2B's could make a difference in whether an AI-1 was usable (not that it's relevant here). But that was probably just referring to the IC plug too. In retrospect, my inference that early 2B's couldn't be TL'd was unwarranted. :redface:

audiocr381ve

My 2B's are the pin/blade version. Is their a difference between mine and the other interconnect (pin/pin?)?

Also, the gentlemen who sold me the speakers suggested I build new crossovers on a thin wooden plate and use hot glue. He's a speaker builder/designer as well, so I've decided to save some dough there.

I want to leave the original crossovers as they are and build new ones to swap and compare (keeping the inductor).

I want to build a crossover that has been successful around here. Would ordering all the parts from Gimpod's website be all that I would need to build new crossovers? http://gimpod.com/parts2b.html

This would be the first time I've attempted doing something of this caliber! The most I've done is a swap some caps and resistors in my DAC. I'm very excited. So far my SDA-2B's paired with my Marantz 2245 have been a super fun combo.

On3s&Z3r0s

It sounds like the only difference between the pin/blade version and the blade/blade version in the 2B's is the plug, so nothing to worry about there. Doing the crossovers point-to-point would be a little bit beyond me. I'm sure I'd end up telling you to put the two 20uF shunt caps in series and then we'd all be sad. I'm not sure if anyone else has done this with the 2B's but I've seen several pics of crossovers done that way, so I'm sure someone has some applicable knowledge.

txcoastal1

It was a long time coming as Gimpod engineered the boards and us Polkies watched every step of the way....the boards are not fly-by-night search the threads....not an SDA owner but the reviews and reads have been nothing but spectacular ask "cincycat13"

audiocr381ve

Hey TX, I'm sure they're awesome. Just tryin' to cut corners where I can afford too.

nspindel

hi audiocr381ve. you'll enjoy those 2B's. i had the 2b's (i've since sold them) and did the crossovers in sonicaps. here's a link to my thread with photos:

http://www.polkaudio.com/forums/showthread.php?t=62106

+1 for not replacing the board if you're operating on a budget. I'm going to be doing a pair of CRS+'s, and have Tony's boards to use. But the stock crossover boards are workable, it's just that you may need to perform some gymnasics with the larger caps and resistors. Sonicaps are on the higher end of the price scale, there are less expensive caps that you can substitute. The resistors are cheap enough, definitely stick with Mills.

The binding post upgrade isn't a bad move, as I've documented in the thread. I used Cardas. Again, there are less expensive alternatives.

Definitely pay attention to swapping the sda connection out for a single binding post, which the pin/blade version is capable of. You can then use any speaker wire of your choice in place of the sda-connection wire, which can give you quite pleasant results.

Joe08867

Don't get me wrong. You can perform all the upgrades on the stock boards it is just easier with Gimpod boards. I wish they were available when I did mine.

The next set I own will get these for sure.

nspindel

Forgot to mention that I've gotten great results doing the inductor as well. The crossover mounts on top of the large coil. For about $60 for the pair, you can bypass those with Erse inductors, as I've done in the photos in that thread. Those are iron core. In my CRS+ upgrade I'll be using Solen air core inductors, but they are more expensive.

audiocr381ve

nspindel wrote: »

hi audiocr381ve. you'll enjoy those 2B's. i had the 2b's (i've since sold them) and did the crossovers in sonicaps. here's a link to my thread with photos:

http://www.polkaudio.com/forums/showthread.php?t=62106

+1 for not replacing the board if you're operating on a budget. I'm going to be doing a pair of CRS+'s, and have Tony's boards to use. But the stock crossover boards are workable, it's just that you may need to perform some gymnasics with the larger caps and resistors. Sonicaps are on the higher end of the price scale, there are less expensive caps that you can substitute. The resistors are cheap enough, definitely stick with Mills.

The binding post upgrade isn't a bad move, as I've documented in the thread. I used Cardas. Again, there are less expensive alternatives.

Definitely pay attention to swapping the sda connection out for a single binding post, which the pin/blade version is capable of. You can then use any speaker wire of your choice in place of the sda-connection wire, which can give you quite pleasant results.

Hey cspindal, thanks for linking me up. What I want to do is leave the orignial crossovers intact in case the upgrades do more harm than good. I've gotten mixed opinions on the upgrades actually being "upgrades." So, this is kind of an going to be an experiment slash hopeful upgrade.

I asked a question earlier and provided a link. Will the link on Gimpod's site for crossover parts be all that I need to build new crossover's if I'm keeping the original inductors?

gimpod

audiocr381ve wrote: »

I asked a question earlier and provided a link. Will the link on gimpod's site for crossover parts be all that I need to build new crossover's if I'm keeping the original inductors?

To answer your question, Yes and the mounting hardware on this page, This will cover everything but the inductors. You can replace the big 16mH inductor but then you'll have to figure out a different way to mount the board. Replacing the board level inductors is basically a bad idea because you can't find them with the right DCR, wire gauge and shape. If you want some more info on this I suggest you check out this thread by DarqueKight he does go into some detail about the inductors.

Hope this helps.

Face

audiocr381ve wrote: »

Hey cspindal, thanks for linking me up. What I want to do is leave the orignial crossovers intact in case the upgrades do more harm than good. I've gotten mixed opinions on the upgrades actually being "upgrades."

From where?

Here's another link that may help you. http://www.polkaudio.com/forums/showthread.php?t=87121

heiney9

audiocr381ve wrote: »

Hey cspindal, thanks for linking me up. What I want to do is leave the orignial crossovers intact in case the upgrades do more harm than good. I've gotten mixed opinions on the upgrades actually being "upgrades." So, this is kind of an going to be an experiment slash hopeful upgrade.

If you don't think it's an upgrade then you should probably leave this hobby alone..........I'm just saying.

There really aren't mixed reviews..........just a few crackpots trying to justify leaving them stock and most of those people have never even heard these after they have been refreshed.

IMO, you are way over thinking it. Refresh the parts on the original boards and enjoy. Inductors can be left stock or if you really want to "mod" them they can be replaced, but it isn't cheap.

H9

Toolfan66

heiney9 wrote: »

If you don't think it's an upgrade then you should probably leave this hobby alone..........I'm just saying.

There really aren't mixed reviews..........just a few crackpots trying to justify leaving them stock and most of those people have never even heard these after they have been refreshed.

IMO, you are way over thinking it. Refresh the parts on the original boards and enjoy. Inductors can be left stock or if you really want to "mod" them they can be replaced, but it isn't cheap.

H9

Agreed!!!! Refresh and Enjoy!!!

On3s&Z3r0s

To be completely fair, I was in much the same boat. Mine were pure stock (SL2000's) and studio cabinets, and they were good enough I was afraid to mess with them. Having done the TL, I can definitely say it is an upgrade. But the upgrade changed the balance of the speaker dramatically. The highs are way more mellow and laid-back, which is good. But the bass presence is a little overwhelming on some stuff. Has anyone ever listened to CCR's Bad Moon Rising and heard that out-of-tempo thumping? I've notcied it before, but after the TL you can't ignore it.

Maybe that'll tame down a little with burn-in, or maybe the TL mod just made these a much more revealing (and less forgiving) speaker. But if the tweeters have already been replaced, and audiocr381ve likes them the way they are, I can see why there would be hesitation.

If you want a pair of stock XO's to be able to go back to, I'd say look for a pair on Fleabay. You can buy ones that came out of a CRS+ or 2B. It'd be a lot cheaper than buying all new inductors for sure.

Toolfan66

Not all of it is due to crossover upgrade, your gear plays a big part of it as well. I have said it many times lately but it is one of the biggest things I have learned here and that is everything matters. IMNSHO one upgrade can really showcase your weakest link as well as your strongest..

The more Clarity, more Seperation, more Blackness,and Deffinition you chase the tighter the straight jacket becomes..

audiocr381ve

heiney9 wrote: »

If you don't think it's an upgrade then you should probably leave this hobby alone..........I'm just saying.

There really aren't mixed reviews..........just a few crackpots trying to justify leaving them stock and most of those people have never even heard these after they have been refreshed.

IMO, you are way over thinking it. Refresh the parts on the original boards and enjoy. Inductors can be left stock or if you really want to "mod" them they can be replaced, but it isn't cheap.

H9

Really appreciate the thoughts from you all.

H9, my reasoning for this along with playing it safe, is to just preserve the original. It's almost like swapping an engine in a classic and keeping the the original that made it what is was in the garage just because you can. I will keep the original inductors for the new XO's, unless it can't be done? Again, your thoughts are appreciated.

Maybe that'll tame down a little with burn-in, or maybe the TL mod just made these a much more revealing (and less forgiving) speaker. But if the tweeters have already been replaced, and audiocr381ve likes them the way they are, I can see why there would be hesitation.

You see Ones, that's why I'm a tad hesitant to touch the original XO's. After performing quite an extensive mod to my DAC which everyone was raving about at the time, (replaced caps, resistors, binding posts, added a transformer), I actually thought it came out WORSE after giving it tons of time to burn in. It undoubtedly lost dynamics, and there was hardly any change when A/B'ing between that and my NAD DVD player. I just don't want a situation to happen like that again, so why not have a plan B? These speakers right now are unlike any others in that it can play anything I throw at and for the first time they gave real definition to the term "non fatiguing" to the point where my wife even pointed it out. So why mod at all? Lol, I'm hard wired to build and create and explore!

Gimpod, thanks for the links!

heiney9

audiocr381ve wrote: »

Really appreciate the thoughts from you all.

H9, my reasoning for this along with playing it safe, is to just preserve the original. It's almost like swapping an engine in a classic and keeping the the original that made it what is was in the garage just because you can. I will keep the original inductors for the new XO's, unless it can't be done? Again, your thoughts are appreciated.

But it's not at all like swapping an engine in a classic car. It's like putting in new spark plugs, air filter and oil filter and perhaps adjusting the timing. Same value parts, in the same positions, using the same speakers. Adding a new breath of life.

The RD0's tweets are leaps and bounds better than the sl2000's and POLK did the R&D on them and got them right and improved them alot.

H9

audiocr381ve

heiney9 wrote: »

But it's not at all like swapping an engine in a classic car. It's like putting in new spark plugs, air filter and oil filter and perhaps adjusting the timing. Same value parts, in the same positions, using the same speakers. Adding a new breath of life.

The RD0's tweets are leaps and bounds better than the sl2000's and POLK did the R&D on them and got them right and improved them alot.

H9

If we're taking it a step further, swapping the spark plugs, air filter, oil filter, and adjusting the timing would cause me to be hesitant only because they have worked for several decades and have no foreseen time of expiring. So what would I do? Keep the old **** in the garage! Haha

Thanks for the help by the way. I'll keep you all updated. I'll be able to order parts next Friday.

On3s&Z3r0s

heiney9 wrote: »

But it's not at all like swapping an engine in a classic car. It's like putting in new spark plugs, air filter and oil filter and perhaps adjusting the timing. Same value parts, in the same positions, using the same speakers. Adding a new breath of life.

The RD0's tweets are leaps and bounds better than the sl2000's and POLK did the R&D on them and got them right and improved them alot.

H9

I think it's stretching things a bit to say that replacing the stock electrolytic shunt caps with Sonicaps is like-for-like. People wouldn't switch to film caps if they weren't different and I haven't seen pics on this thread of people putting new NP electrolytics on their stock boards. Put another way, there are threads here on modding LSi crossovers. Why would you need to "refresh" a 2 year old speaker's electronics? People do these mods because they are hoping for an improvement. They will definitely get a change and different people may like/dislike various aspects of that change.

heiney9

On3s&Z3r0s wrote: »

I think it's stretching things a bit to say that replacing the stock electrolytic shunt caps with Sonicaps is like-for-like.

Yeah well, not what I meant in that analogy. I don't understand anyone's apprehension at doing this. It's been documented several hundred to a thousand times and only a minuscule portion of people had anything negative to say about it.

But it's his decision and his speakers so he can do things any way he wants. I've given my input.

H9

heiney9

On3s&Z3r0s wrote: »

Put another way, there are threads here on modding LSi crossovers. Why would you need to "refresh" a 2 year old speaker's electronics? People do these mods because they are hoping for an improvement. They will definitely get a change and different people may like/dislike various aspects of that change.

This thread isn't about 2 year old LSi's............it's about 20 year old SDA's and it is called "refreshing" more than modifying since other than a film cap being used we aren't altering anything in the basic design. Unless we are talking about the TL mod and even that was a Polk approved change that never made it to production because SDA's were killed before Polk had the chance to implement it into production.

H9

audiocr381ve

heiney9 wrote: »

This thread isn't about 2 year old LSi's............it's about 20 year old SDA's and it is called "refreshing" more than modifying since other than a film cap being used we aren't altering anything in the basic design. Unless we are talking about the TL mod and even that was a Polk approved change that never made it to production because SDA's were killed before Polk had the chance to implement it into production.

H9

The TL mod is what Gimpod listed for parts right?

Refreshing, modifying, tomatoes, tamotoes. Again, just because Polk approved it doesn't mean it sounds better to me. I'm not sitting on the fence here trying to see who liked and who didn't. I'm actually going to do it, and play it safe. Am I not making that clear? I'll trust your ears when my ears believe you...(attempt at being clever but it turned out being weird)