SDA2A RDO198 Upgrade??

[JPSmario]

I'm a new SDA owner; got a fairly clean pair and was lucky to have a Polk expert friend help fix the problems I didn't know I was buying

I've been getting ear fatigue much sooner with these than my old speakers (B&W 602 S2), and my friend tells me it's probably the SL2000's. We had listened to both the SL2000's and the RDO194's in a couple pair of his Polk's and he remeber's me preferring the replacements.

After looking through several threads, there seems to be a consensus that the RDO198's are cleaner and clearer than the RDO194's. But I'm not clear on whether there's a clear mod plan for upgrading the SDA2A's with the RDO198's.

Is there a plan that most people have had success with?

Thanks!

[Toolfan66]

"Nope" you have to use the RDO-194's they are the replacement for the SL2000's

Welcome to the club by the way..

[comfortablycurt]

You'll have to go with the 194's. Don't worry though, you'll be more than happy with them. They're a big improvement.

[cnh]

WELCOME TO CLUB POLK!

That's an improvement I'm hoping to hear myself on my 'return'!

cnh

[george daniel]

Have you considered upgrading the crossovers with better caps and resistors? I think that you will be pleased should you perform the upgrade and install the RDO 194's.

[JPSmario]

Thanks, everyone for your comments and advice. I have a pair of RDO194's on the way.

I looked through a couple of the related threads listed below; was that a good parts list from Reagan on 11-7-09? no offense, just want to verify it before spending the money. Other than mic and speaker cable ends, I haven't picked up a soldering iron in seriousness since I assembled 2 Dynakits almost 40 years ago. Does the x-over upgrade have any tricky steps?

Thanks!

[F1nut]

Wait a sec, you can upgrade your crossovers to use the RD0198-1 tweeters. You'll have remove the 2.7 ohm resistor in series with the 0.4mH inductor. Then follow the documented upgrade for the 2B TL, which simply adds a 5.8uF cap in parallel to the remaining 2.7 ohm resistor.

[george daniel]

JPSmario-- I am curious,, do you have the p/b or the b/b interconnect?

[george daniel]

If he has the SDA 2A B/b,, it can be upgraded to the tl?

[TNTsTunes]

Sure you can it's just a matter of some crossover rework.

[wayne3burk]

I'd love to have a pair of MK IIIs if you have a couple of extras :) thanks in advance

[JPSmario]

I have the b/b IC.

[george daniel]

If you can solder,,you can do what is necessary to the crossovers,, schematics are posted here,,and there are plenty of folks willing to help.Good luck,and keep us posted.

[F1nut]

If he has the SDA 2A B/b,, it can be upgraded to the tl?

Yes.

[Toolfan66]

Yes.

That is good to know..;)

[chandler9a]

Yes.

wow! for some reason I thought this could only be done with the 2B's. So I am assuming the MW's also have to be replaced to make it a TL model or can they stay 6510's?

Also, is it worth it if I have already put RDO-194's in? Would it make more sense to just do the xovers and keep them moded 2A's?

[george daniel]

I too, was under the impression about the 2B's being the only candidate for the tl upgrade,, so,, in the very near future,, I am going to be upgrading,helping another polkie perform the mod.I'll let you know how it turns out,as it appears to be a fairly easy task,,I'll post more when I know a little more about the specific speakers. :)

[comfortablycurt]

Wait...what?

I've asked on here before if 2A's could be TL'd, and my question was met with a resounding "NO".

Is there any reason that a TL'd 2B would sound better than a TL'd 2A? I know they used different MW's.



Also...+1 to chandler's question. I've got some 2A's with 194's...would it be worth it to upgrade to 198's? I've been contemplating whether I want to upgrade the XO's in my 2A's, or hold off for a pair of 1C's. If I decide to upgrade the XO's in my 2A's, it probably wouldn't be much extra work to TL them really.

[Disc Jockey]

The 2BTL mod is the only "officially sanctioned" mod in the SDA2 series because the crossover is the same as the CRS+ model that that mod was originally done on. Since the mod only affects the tweeter, it should be able to be done on the 2A as well. No mids would need to be changed. It is to be done at your own risk. Since this is not a change that was signed off on by Polk, it does approach frankenpolk status. And Jesse, I think that 2.7 ohm in line with the inductor would have to stay, otherwise the balance between the mids and tweeter would be off.

As to whether it's worth it to change from 194s, only a person who has had his ears on them both ways could tell you that, and that isn't me.

[chandler9a]

Well, it sounds like it "could" be done but I am thinking I might just try the xo mod since I already have the 194's and be happy with that... They really are good speakers. I like the TL's but this might be just fine unless Polk suggest they could be better.

Just my opinion but I could be wrong and those with more experience may want to chime in.

[F1nut]

Since the mod only affects the tweeter, it should be able to be done on the 2A as well. No mids would need to be changed.

Yep.

And Jesse, I think that 2.7 ohm in line with the inductor would have to stay, otherwise the balance between the mids and tweeter would be off.

Can you explain why you think that? I'm not disagreeing with you as you may be correct, just curious.

As to whether it's worth it to change from 194s, only a person who has had his ears on them both ways could tell you that, and that isn't me.

I have on the CRS+ and 2B. The RD0198-1 is a major improvement, IMO.

[Disc Jockey]

Can you explain why you think that? I'm not disagreeing with you as you may be correct, just curious.

Well, here's my take on it: The purpose of the inductor there is to draw the low frequencies down to the mids. The resistor's purpose is to limit current, and therefore output of the mids, to achieve proper balance between the tweeter and MWs. The TL mod was designed to just address the tendency of the 198 to roll off at higher frequencies without affecting the rest of the crossover. I believe by taking out that resistor, you would be affecting the rest of the crossover balance and the mids are going to run hot.

[Face]

It's my understanding that a resistor in that position will affect the driver's Q and will steepen the roll off at the crossover frequency. I'm assuming that the RD0-194 and 198 behave similarly at low frequencies, so it's possible that this resistor may not be doing any harm if left in place during the TL mod. The only way to know is to model it with the appropriate software, measure it, or maybe get some feedback from Polk.

I was going to attempt to model this in LspCAD, but I just discovered that I lost all my saved work and have more important things to worry about at the moment.

[Disc Jockey]

I'm assuming that the RD0-194 and 198 behave similarly at low frequencies

That is my understanding.

[F1nut]

Well, here's my take on it: The purpose of the inductor there is to draw the low frequencies down to the mids. The resistor's purpose is to limit current, and therefore output of the mids, to achieve proper balance between the tweeter and MWs. The TL mod was designed to just address the tendency of the 198 to roll off at higher frequencies without affecting the rest of the crossover. I believe by taking out that resistor, you would be affecting the rest of the crossover balance and the mids are going to run hot.

Hmmmm...entirely possible. Perhaps someone willing to mod their 2A's to use the RD0198-1 would be willing to let us know what happens with the resistor in and out........or we can wait for Face to quit fooling around. ;)

[Conradicles]

Try it Curt!!! If you don't feel comfortable (hehe) with soldering, I'll do it for free.

[inspiredsports]

I'm a new SDA owner; got a fairly clean pair and was lucky to have a Polk expert friend help fix the problems I didn't know I was buying

I've been getting ear fatigue much sooner with these than my old speakers (B&W 602 S2), and my friend tells me it's probably the SL2000's. We had listened to both the SL2000's and the RDO194's in a couple pair of his Polk's and he remeber's me preferring the replacements.

After looking through several threads, there seems to be a consensus that the RDO198's are cleaner and clearer than the RDO194's. But I'm not clear on whether there's a clear mod plan for upgrading the SDA2A's with the RDO198's.

Is there a plan that most people have had success with?

Thanks!

Welcome to Club Polk. F1 hit it on the head.

Study the schematics for the SDA 2A and SDA 2B posted here and you will see what F1 is describing . . . http://www.polkaudio.com/forums/showthread.php?t=55888

I've owned SDA 2B's since 1987 and there is no comparison when you upgrade the crossover to accommodate the RDO-198. Results with the 194's will be good, with the 198's, superlative.

I can't speak to the removal of 2.7 resistor (the one in series with the .4 inductor) as the 2B circuit does not have that configuration, but the 6.5" drivers in your 2A's are all MW6510's (where the 2B uses 1 each MW6503 & MW6511) but my guess is leaving the "extra" 2.7 is probably OK. I'm also guessing the extra 2.7 may be there more to match characteristics of the the 6.5 mid drivers than for the tweeter.

As posted prior, only experimenting both ways would allow you to be sure, but leaving the extra 2.7, listening, and removing later would be a logical path.

[ben62670]

Do your SDA's have the side by side tweeters?

[inspiredsports]

Hi Ben! You doin' OK?

There should be one tweeter per cabinet if they are SDA 2A's -- http://www.polkaudio.com/forums/atta...3&d=1186345413

(real similar to 2B's http://www.polkaudio.com/forums/atta...4&d=1186345413)

[JPSmario]

if Ben's question is for me, no, I have single SL2000's.