SDA System: Yesterday and Today

rncala

Hi everyone!

New to this forum / owned and loved SDA speakers since 1987 / not a DIY electronics guy

My SDAs are sublime, but if I could noticeably enhance their crispness / clarity / resolution that would be nice.

Looking for a fusion of yesterday and today's technologies to rock the house -- without burning it down.

Here's my vintage system:

Polk L SDA-SRS-2 1755
Polk R SDA-SRS-2 1756
Nakamichi STASIS PA-5/CA-5
Sony C77ES CD
MonsterCable Interlink M1000i (CD/CA-5)
MonsterCable Interlink Reference A Total Bandwidth (CA-5/PA-5)
MonsterCable MCX-2s w/Bananas (PA-5/SDAs)

Here are my questions:

1. Would I get much better sound with a new amp and if so, which one?
I looked into Krell's S-300i integrated amp, but Krell said not with interconnected speakers. Rotel's RB-1582 is also highly rated, but I don't know if it is compatible with my SDAs. I don't want to fry my speakers or amp! Jolida has some very interesting tube equipment, but I'm afraid that like a pet, tubes demand attention. I saw posts praising out of production amps and I don't want to refurbish an amp at this point.

2. Should I upgrade my SDAs?
I read posts about replacing cross-overs and other components. Can that be done by Polk? I'm in Maryland. I think Polk is too. If not, what components do I buy and who would install them? Should I just go to a high end store like Gramophone and ask what they can do?

Thanks for your patience

Rob

heiney9

Welcome to Club Polk

The Nakamichi is a formidable amp and I doubt the Rotel would better it.

You can upgrade your original sl2000 tweeters. In about 2001 or so Polk researched and developed a new replacement tweeter for the old sl2000 tweeters. Electrically it's a plug-n-play replacement, but it's a more modern version with a silk dome and sounds much smoother and more open than the original sl2000. It's less fatiguing and real pleasure to listen to.

Many of us have also refreshed the x-over capacitors and resistors. Electrolytic caps have a finite lifespan and todays poly type caps are much better and smoother.

H9

drumminman

Welcome to CP Rob!

As H9 said getting the replacement tweeters is a very effective mod. Getting your crossovers rebuilt with modern film caps and resistors would bring about a huge increase in performance as well.

There are folks here on the forum who would probably be willing to do it for you: VR3 comes to mind, and I think there may be one or two more.

There are other mods you can do that also make an improvement. Time to get your read on and raise the performance of those bad boys!

Schurkey

If those SRS-2s have the blade/blade interconnect cable, they can use the RD0-198 tweeter if the crossover in each speaker is modified by replacing a 4.4uF capacitor with a 5.8uF (5.6uF is close enough) capacitor when the rest of the caps are replaced with exact- or near-exact matches. A member here, inspiredsports, pioneered this modification along with a couple of other crossover tweaks for the SRS 2 blade/blade speakers.

If you have pin-blade interconnect cable, no-one has researched and performed the RD0-198 upgrade, you're probably going to want the RD0-192 tweeters. (I think the 198 upgrade is possible on the pin/blade SRS-2, but I'm not an electrical engineer so I can't prove it.)

bluecomet

SRS 2's came with SL2000 tweets. The replacement for them are the RD0-194's if you didn't want to do the crossovers. It would be a noticable improvement.

rncala

Thanks to everyone for such great information!

H9: Good to hear that Nakamichi separates hold their own after 25 years. The dimensional soundstage and spatial isolation of instruments is absolutely stunning. I feel the bass in my soul. Cymbals in Walking on the Moon dance across the room. Pat Metheny's Still Life (Talking) and Uchida's Debussy: 12 Etudes are amazing. I'll research those new tweeters; plug-n-play sounds like a quick-and-easy upgrade. X-overs may take a little more time to organize as a project.

Drumminman: Thanks for those contacts.

Schurkey: I'll check IC terminal configurations when I get home tonight.

DSkip: Probably won't need JoLida after all -- although they have an interesting tube CD to consider if my Sony ES dies. Only catch is I like a multi-disc carousel; so I'm not getting up to change discs all the time.

Have a great weekend!

Rob

F1nut

Ok, I'll be brutally honest.

Polk L SDA-SRS-2 1755
Polk R SDA-SRS-2 1756

Upgrade the tweeters, the crossovers, Dynamat Extreme the driver/PR baskets, upgrade the binding posts, install spikes and you'll wonder why you didn't do it years ago. If you can find a set of Larry's rings...well, they'll take your speakers to a place you never knew they could go.

Nakamichi STASIS PA-5/CA-5

Yeah, time to replace that gear. Consider a SS amp with a tube pre.

Sony C77ES CD

That's got to go.

MonsterCable Interlink M1000i (CD/CA-5)
MonsterCable Interlink Reference A Total Bandwidth (CA-5/PA-5)
MonsterCable MCX-2s w/Bananas (PA-5/SDAs)

They have to go as well.

There's only one question at this point, what's your budget?

chandler9a

Welcome to the Club Rob. A lot of good advice above, F1's advice may be brutally honest but it is exactly what you will want to do at the end of the day... I have done all of them as far as speaker mods can go and just now moving on to improving my gear. It ALL makes a difference, just take you time and enjoy the process.

Keep us posted!

Schurkey

Schurkey wrote: »

If you have pin-blade interconnect cable, no-one has researched and performed the RD0-198 upgrade, you're probably going to want the RD0-192 tweeters. (I think the 198 upgrade is possible on the pin/blade SRS-2, but I'm not an electrical engineer so I can't prove it.)

bluecomet wrote: »

SRS 2's came with SL2000 tweets. The replacement for them are the RD0-194's if you didn't want to do the crossovers. It would be a noticable improvement.

Yes, RD0-194, not 192. My mistake.

rncala

Schurkey/bluecomet: Looks like blade/blade IC termination. One 6mm wide blade + one 4mm wide blade (polarized?). Left channel has 6mm blade on bottom; right channel has 6mm blade on top. I have 2 Silver Coil Dome tweeters per speaker. Roughly how much will 4 RD0-194 Silk Dome tweeters cost? Does Polk provide installation instructions? Is it as simple as unscrewing and removing old tweeters? Do I need to solder contacts, or are they modular plugs like internal computer connections? I've built a few computers. Would it be a different tweeter w/blade-blade ICs if I replaced the x-overs? ". . . RD0-194's if you didn't want to do the crossovers." That wasn't clear.

F1nut: Finesse is overrated. I appreciate your honesty. I'm taking it one step at a time. Eventually all will get done. No particular rush as they're already quite amazing.

Thanks!

Rob

Schurkey

rncala wrote: »

Schurkey/bluecomet: Looks like blade/blade IC termination. One 6mm wide blade + one 4mm wide blade (polarized?). Left channel has 6mm blade on bottom; right channel has 6mm blade on top.

You have the early version. Same speaker as the SDA-1B but in a larger, nicer cabinet, larger passive radiator, and one different resistor in each high-frequency crossover board. Cannot be upgraded to use non-common-ground amplifiers without **** up the sound quality. (AI-1 interface can't be used)

rncala wrote: »

I have 2 Silver Coil Dome tweeters per speaker. Roughly how much will 4 RD0-194 Silk Dome tweeters cost? Does Polk provide installation instructions? Is it as simple as unscrewing and removing old tweeters? Do I need to solder contacts, or are they modular plugs like internal computer connections? I've built a few computers. Would it be a different tweeter w/blade-blade ICs if I replaced the x-overs? ". . . RD0-194's if you didn't want to do the crossovers." That wasn't clear.

My opinion--STOP thinking about the RD0-194.

You will be upgrading the crossovers anyway. This is a simple, D-I-Y procedure if you can solder and un-solder. It's a simple capacitor swap along with a simple resistor swap. Pull out degraded electrolytic caps, install new film caps of equal or very-nearly-equal value. The new film caps are physically larger so you may have to be clever about how/where you mount them. The film caps don't degrade over time like electrolytics, so they're not only better for sound quality, but they're more durable and tighter-spec, too. SAME with the resistors. Remove original resistors, install new resistors of the same value in their place.

There are four exceptions, and they're all on the HF board:
1. You'll take out a 4.4uF cap in each high-frequency crossover board. Install a 5.8uF in place of the 4.4uf. THEN you install the RD0-198 tweeter using the original wiring connector on one blade, and a smaller-than-original wiring connector on the other blade. Easy. The 198s (or the 194s) are ~$50 each from Polk, comes out a little higher due to sales tax or handling or some such charge. I think I paid $110 for two. You'll probably want four.

2. The main resistor on the HF board is a 3.5 ohm; you'll replace this with a 1.5--2.5 ohm resistor to increase the volume of the treble in relation to the volume of the midrange/bass.

3. There's a tiny, tiny bypass cap--I forget the value, but it's picofarads, and silver mica. Remove it, don't replace it. Not needed with the improved-quality caps going back in.

4. The "Safetyguard" "Polyswitch" can be removed and not replaced. Some will advocate installing a low-value resistor (~ 1/2 ohm) in it's place. You do not need to do this since you're can add that half-ohm to the resistor described in #2 above. Simply install a jumper wire across the Safetyguard traces on the circuit board.

There is a VERY LONG thread about this. The first few pages are something of a mess. It gets good later on, and has EVERYTHING you need to know about the blade/blade SRS-2 and the very similar 1B.
http://www.polkaudio.com/forums/showthread.php?74946-SDA-SRS-2-Crossover-Parts-list

In my case, I used less-expensive capacitors that those commonly recommended on this site; and I'm astounded at the difference (improvement!) it made in my 1Bs. ANY ANY ANY tight-spec film caps are going to be a big improvement over the wide-tolerance electrolytics that came with the speakers new, and those electrolytics are guaranteed to be degraded by now. So, sure, if you can afford the "better" film caps...have at it. Just do not be afraid to use the Daytons or the ERSE "budget" caps, they are MUCH better than what's in there now.

The Mills resistors are almost universally recommended. I used another brand, and they are physically larger than the Mills, that makes them difficult to attach to the circuit boards. Buy the Mills resistors. They'll fit the board better.

Original wide-tolerance 34uF caps replaced by tight-tolerance 33uF caps. Original wide-tolerance 130uF + 55uF caps (185uF combined) replaced by pair of tight-tolerance 91uF caps (182uF combined)


Low-frequency crossover circuit board (Modified) (SDA 1B, SDA SRS-2 identical)


I'm sorry, I was too dumb to take photos of the HF board.

Schurkey

As usual, I ran out of edit time.

I wanted to clarify that the original 3.5 ohm resistor, plus the approximately 0.2--0.5 ohm poly switch can be replaced by a single ~2 ohm resistor. The speaker is treble-shy, this brings the treble volume up.

The silver mica cap is a 750pF.

rncala

Thanks Schurkey -- That's a lot of information to digest, but I'll read through it a few times and get some info on those resistors & caps. I'll probably ask for help since this is my first time working on a speaker with soldered contacts. Wouldn't want to mess up my speakers in the learning process.

Sounds like this will work quite nicely once it's done

Rob

drumminman

rncala wrote: »

Thanks Schurkey -- That's a lot of information to digest, but I'll read through it a few times and get some info on those resistors & caps. I'll probably ask for help since this is my first time working on a speaker with soldered contacts. Wouldn't want to mess up my speakers in the learning process.

Sounds like this will work quite nicely once it's done

Rob

Lots of help and experience here, and a dedicated group of SDAer's. Don't be shy about asking questions, and like someone in a post above said, if you can solder you can do this!