Picked up a mint pair of SDA CRS +'s...I'd like to bring them back to their former glory, or better.

91rtstealth · February 11

F1Nut's parts list. I have a few missing things noted below in bold:

SDA SRS 4.1TL parts list (for both boards)

Polk Audio tweeter
(2) RD0198-1

Sonicap capacitor 5% or better tolerance
(2) .1uF Gen II (replaces the 750pF Silver Mica) I thought I didn't need to worry about the 750pF Silva Mica? What is this for?
(2) 5.8uF
(2) 12uF
(2) 20uF
(2) 30uF
(2) 10uF (combine the 30 & 10 to equal the needed 40uF as the largest cap from Sonicap is 30uF)

Mills Wire-wound 5 watt resistor 5% tolerance
(2) 2.7ohm MRA-5

Cardas Quad Eutectic solder

A short piece of 20 gauge solid copper wire (to extend the lead on the 30uF cap) Where would I find solid copper wire like this? I only have stranded wire...I assume i'll need some for a jumper when I delete the poly switch?

Hot glue gun (to secure the caps to the board). I don't have one, but I can order one from Amazon easily...any specific glue I need or just any old hot glue will do?

xschop · February 12

Looks good. F1 can chime in about his bypass cap choice. I think he omitted it in the end.
Any hot melt glue will work.

pitdogg2 · February 12

These would be a much better choice for resistors. The resistor from Digikey is only 1/4 watt, you need 5 watt minimum. A 10 or 12 watt would be mucho mo'better, like these
https://www.madisoundspeakerstore.com/mundorf-10-watt/
https://partsconnexion.com/mills-resistor-collection/
Find your correct ohm value and go from there.

The other thing is IF you must double up caps to make value you want to stay as close to half value as possible OR the smaller cap becomes a bypass cap. The 30 and 10 value to make 40 would be a no go for me. 20 and 20 would be ideal.

91rtstealth · February 12

I shouldn't need to double up any caps if I get two of these, correct?

https://partsconnexion.com/claritycap-capacitor-40uf-250vdc-px-series/

and thanks for the correciton on the resistors..once I get a definitely OK on everything, i'll make a list and place an order once I get the green light from ya'll..I don't want to accidentally order the wrong stuff..

91rtstealth · February 12

ok so is that all of the parts i'm going to need?

xschop · February 12

Will he need the 1/4" female fastons for the -198 tweets?

91rtstealth · February 12

xschop wrote: »

Will he need the 1/4" female fastons for the -198 tweets?

I have all kinds of stuff like that around here from doing car audio stuff. I got those. I’m just not sure about the rest.

91rtstealth · February 14

alright..I just ordered all of the caps that I listed above...

I'm about to order the resistors but I want to make absolute sure I got this right...

two of these for the TL mod
https://soniccraft.com/product_info.php/27-ohm-vishay-mills-mra-p-5217

and then two of these to replace the Polyswitch?https://www.soniccraft.com/product_info.php/050-ohm-vishay-mills-mra-p-4610

91rtstealth · February 14

Also does anyone know where I can get four of these? They are good on the other crossover but these arrived broken off like this and I’m not sure how I’ll mount the crossovers otherwise. I’d like to try to keep it somewhat “stock-ish” mounting wise.

pitdogg2 · February 14

https://www.soniccraft.com/product_info.php/050-ohm-vishay-mills-mra-12-p-5332

https://www.hificollective.co.uk/catalog/resm1110-mra12-mills-resistor-p-1286.html
Try to stay with 10 or 12 watt resistors, mo-better insurance.

You can either go with different standoffs or remove them from the old XO inductor.
https://www.mcmaster.com/product/1895N18, maybe these

Also when replacing the resistors, give them air under the resistors. They can get rocket hot so lots of breathing room is better. Do not hot melt any resistors. I say this just because the same reason that there is a warning on hair dryers not to use in the shower. We've had others here that when replacing components slathered enough hot melt everywhere and they completely covered the resistors which caused problems quickly.

91rtstealth · February 14

Excellent. Thanks for the detailed help. I’ll look into ordering those resistors tomorrow or Monday.

I may give those standoffs a try and if they don’t work out I’ll try to salvage the old ones from the other crossovers.

And don’t you worry. I won’t be making any permanent decisions without first showing pics or videos on here. Haha.

In the mean time, I’m going to start dynamating the drivers next week. I’m assuming I should also do the passive radiators?

audioluvr · February 14

Yes and make sure you glue your magnets too. Also you may be able to secure the new caps with thin long zip ties

91rtstealth · February 15

How about these two resistors? I’m already ordering most of the stuff from Madisound anyways. I’d rather not order them from England. That will take forever and cost an annoying amount in shipping.

https://www.madisoundspeakerstore.com/mundorf-coppernickel-10-watt/mrec10-mundorf-coppernickel-wire-0.47-ohm/

https://www.madisoundspeakerstore.com/mundorf-coppernickel-10-watt/mrec10-mundorf-coppernickel-wire-2.7-ohm/

91rtstealth · February 23

alright guys...I got everything I need...let me know if I have the right idea here before I start soldering stuff..

https://dropbox.com/scl/fi/xswgjgefb3qiy380rzydu/SDA-CRS-Crossover-Rebuild.MOV?rlkey=1tfgke2mhke3jqx3gmgz5x37w&dl=0

Gardenstater · February 23

Here's how westmassguy (RIP) did his, with some interesting additional innovation https://forum.polkaudio.com/discussion/169838/sda-crs-crs-something-different/p1

91rtstealth · February 24

Got the crossovers done. I’m putting one of the speakers together to test it out

Does it matter which way these two wires go? There doesn’t seem to be any label or difference between the two terminals. I’d rather know for sure before I send any signal through this speaker.

Toolfan66 · February 25

It doesn’t matter..

91rtstealth · February 25

All done. And they sound great. I only got 10 or so minutes to listen to them before I left for my gig today. I’m gonna let them burn in the next few days and hopefully sometime next week I’ll actually be able to sit down and really listen to them.

Thanks again for the help.

workjng

91rtstealth · February 26

alright..I let them run with pink noise for roughly 14 hours so far and I listened to them a bunch today...I moved them all over the place..tried different speaker stands, etc.......

Notes:

Some Pros:
-Resolution is def improved. The imaging is clearer than it was before. I'm very pleased with that.
-Bass is not as pronounced...less boomy, but that's more than likely due to the dynamat...while there's less perceived bass, it's at least more articulate and pronounced
-Midrange is slightly improved...but still can't hang with the Mofi's...not even close..haha...but I didn't expect that. That's where the Mofi's shine, and comparing the two is apples to oranges, anyways.
-Vocals are more out front than they were before, and the center image is more impressive due to the increased resolution. I'm also very pleased with this result.

Some Cons:

-while the rdo 198 tweeters are def an improvement over the SL2000, I'm not exactly falling in love with them. In fact, at this time, I'm not the biggest fan. The imaging and clarity is great, but I don't like the tonality of them. They sound a bit clinical, and they are a little boosted in the 7-8k range, which is an area I typically hate. However, they are brand new and I'm thinking that over some more burn in time, the caps and tweeters will open up. Right now they just sound stiff and a little unrefined around 7-8k. Hopefully that will change over time. If not, i'll try the rdo194 and rework the crossover. Also, I haven't tried them out on my tube amp yet. Sometimes that helps.

-They still have that annoying ringing sound on certain instruments around 500hz, particularly Piano. Every SDA speaker I've ever owned does that. I usually just EQ it out if it really gets on my nerves during a long listening session. It's hard to explain, but it's a part of the SDA effect. If I pull the SDA cable, that issue goes away. To me it sounds like stored energy/ringing. It's not the end of the world, but it's worth noting. Small price to pay for an insanely huge sound stage.

I'm going to let them run overnight for a week or so and see what kind of changes I notice.

xschop · February 27

"If I pull the SDA cable, that issue goes away. To me it sounds like stored energy/ringing."

Intriguing, yet strangely familiar.
Assuming you Dynamatted ALL stamped steel baskets, the culprit could be worn suspensions on those 6511's causing coil rub around that frequency.

Find a pair of 6502's to substitute and see if it goes away.

xschop · February 27

Forgot to ask if you did the PR push test on both cabs as well?
If you re-use the factory thin gaskets, they can sometimes make noise in an area where the frame flange is slightly distorted. Seen this a couple times before.

91rtstealth · February 27

I don't think it's related to a driver issue. This is my 4th pair of Polk SDA's. I've had SDA1B, SDA1C, SDA2B, and now these. They all had that same characteristic. I think it's just a product of the SDA effect. It is what it is and I"m not terribly concerned with it. I just cut 500hz on all of them when it got annoying. No speaker is perfect. They all have pros and cons. I just hope these tweeters/caps come around after burn in, or that I simply get used to it. People tend to neglect brain burn in. It's a thing. haha.

I'm not familiar with the PR push test? It does sound familiar, though. I vaguely remember a test where you push one of the 6.5" drivers in and see if the cab holds the pressure difference by seeing what the other drivers do. Is that what you're referring to?

billbillw · February 27

91rtstealth wrote: »

I don't think it's related to a driver issue. This is my 4th pair of Polk SDA's. I've had SDA1B, SDA1C, SDA2B, and now these. They all had that same characteristic. I think it's just a product of the SDA effect. It is what it is and I"m not terribly concerned with it. I just cut 500hz on all of them when it got annoying. No speaker is perfect. They all have pros and cons. I just hope these tweeters/caps come around after burn in, or that I simply get used to it. People tend to neglect brain burn in. It's a thing. haha.

I'm not familiar with the PR push test? It does sound familiar, though. I vaguely remember a test where you push one of the 6.5" drivers in and see if the cab holds the pressure difference by seeing what the other drivers do. Is that what you're referring to?

I think I hear the same thing in my TL modded 2B as well. I really only notice it when I run a frequency sweep from a test disc. I'd call it more of a resonance than ringing.

xschop · February 27

billbillw wrote: »

91rtstealth wrote: »

I don't think it's related to a driver issue. This is my 4th pair of Polk SDA's. I've had SDA1B, SDA1C, SDA2B, and now these. They all had that same characteristic. I think it's just a product of the SDA effect. It is what it is and I"m not terribly concerned with it. I just cut 500hz on all of them when it got annoying. No speaker is perfect. They all have pros and cons. I just hope these tweeters/caps come around after burn in, or that I simply get used to it. People tend to neglect brain burn in. It's a thing. haha.

I'm not familiar with the PR push test? It does sound familiar, though. I vaguely remember a test where you push one of the 6.5" drivers in and see if the cab holds the pressure difference by seeing what the other drivers do. Is that what you're referring to?

I think I hear the same thing in my TL modded 2B as well. I really only notice it when I run a frequency sweep from a test disc. I'd call it more of a resonance than ringing.

Could also be the RDO plastic or even loose terminal tab mounts on the MWs.
IMO the old particle board construction lends to midbass resonance/muddying as well unless extra bracing is done.

xschop · February 27

91rtstealth wrote: »

I don't think it's related to a driver issue. This is my 4th pair of Polk SDA's. I've had SDA1B, SDA1C, SDA2B, and now these. They all had that same characteristic. I think it's just a product of the SDA effect. It is what it is and I"m not terribly concerned with it. I just cut 500hz on all of them when it got annoying. No speaker is perfect. They all have pros and cons. I just hope these tweeters/caps come around after burn in, or that I simply get used to it. People tend to neglect brain burn in. It's a thing. haha.

I'm not familiar with the PR push test? It does sound familiar, though. I vaguely remember a test where you push one of the 6.5" drivers in and see if the cab holds the pressure difference by seeing what the other drivers do. Is that what you're referring to?

Push the PR in and the MWs should slowly return back to rest.

Another thing to look for is that the thin spiders of 6510's and 6511's are prone to cracking and separation at the cone/coil junctions.

91rtstealth · February 27

nah it's not related to the tweeter..it's a lower mid frequency..and it did it on all of my SDA's before and after I switched to RDO's......I really just think it's an artifact of the SDA effect, which makes sense...when you mess around with phasing like that, you're bound to run into some interesting sonic anomalies...

if anyone wants to see what i'm referring to, here's a perfect (and extremely nerdy) example:

Diana Krall-The Look of Love

the main piano riff on the intro is: E flat, D, C, and back to D....and that particular D is the one just above middle C..so it's around 588hz. THAT note really cuts on Polk SDA's. Turn it up loud and you'll see what I mean. It might even hurt. haha. Granted, there are two factors here. The Piano is a little loud in the mix for my taste, AND in general, anything around 630hz is fairly unpleasant to most people's ears. In fact, Dave Natale, sound guy for the Rolling Stones always removes that from his live mixes, and so do I because it sounds like butt. haha. In all fairness, the mixing engineer should have dialed back the lower mids on that piano track, but who knows what they were mixing on. Every speaker, room, mixing console, mic, etc sound different.

Which leads me to one of my favorite topics with audiophiles, EQ. Tone controls and EQ are not the devil. haha. Every single record you've ever listened to uses EQ, and most of them use compression as well. Every audio engineer, including myself, uses EQ more than literally anything when mixing. It's absolutely necessary. I ended up getting rid of all of my Polk SDA's because that weird bump in the lower mids, but then as I learned more about audio engineering, I learned that literally every single speaker has imperfections...every room, every mix..etc....so, now I just cut 500-600hz on my Polk's if a certain track gets on my nerves. I will say though, the CRS's aren't nearly as annoying as my bigger SDA1's were around that range.

Also, every single human being hears things differently, so some of you might not even hear it and that's awesome for you. We're all different. Overall, I ended up getting another pair of SDA's (these CRS's) just because I think it's fascinating how they exaggerate the sound stage. It makes them super fun to listen to. It's not natural, but who cares. It's fun.

billbillw · February 27

Honestly, that particular Diana Krall album sounds off on just about every system I've heard it on. Try the Live from Paris album. Sounds much better.

91rtstealth · February 28

I spent a few hours listening to them last night. They def sound better on my tube ST 70 kit that I built. In fact, I’m shocked by how well that amp can drive those speakers.

Question:

I’m trying to further understand exactly what I did.

1. What exactly does that 5.8uf cap do for the tweeter? I’m assuming it high passes, but what frequency and what slope?

2. If I wanted to try the rdo194’s, all I would have to do is ditch that 5.8uf cap and leave the 2.7 resistor, correct?

pitdogg2 · February 28

The 5.8 creates contouring circuit for the 198. Forget about the 194, the 198 is a much better tweeter.

Read this if you have not.

https://forum.polkaudio.com/discussion/comment/2435714#Comment_2435714?utm_source=community-search&utm_medium=organic-search&utm_term=tale+of+5+tweeters

91rtstealth · February 28

got it..thanks..but "better" is a subjective concept..the only way to find out if you like something more or think it's better is to find out for yourself...everyone perceives sound, and life in general, differently....

Picked up a mint pair of SDA CRS +'s...I'd like to bring them back to their former glory, or better.

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