Crossover upgrade on the SDA IA

dcmeigs

I just ripped the stereo and sound array boards out of my buddies SDA IAs for the crossover upgrade. They used to be mine and I still love them so I'm going to do the deed. My SDA 2s are next if there is a significant improvement. It was nspindels post that got me off my arse.

http://www.polkaudio.com/forums/showthread.php?t=62106&highlight=crossover+upgrade

I do have a few questions. I have read quite a few of the posts on crossover upgrades, several dozen anyway, and I'm starting to get the gist but I haven't found a thread specifically for the SDA IA yet. If anyone can link me to a specific IA thread, that would be greatly appreciated.

So, now with the silly questions:
1) The schematics posted by DarqueKnight show a 3.5 ohm resistor with a rev.A note. These on my boards are 4 ohm. I will assume that a change to 3.5 ohms was the revision and use 3.5 unless someone can offer a reason to stay with the 4 ohm.
2) It seems that the cap values change with tweater upgrades. I suppose I will upgrade to the 198s if they are still the recommended favorite. The schematics for my boards show 12 uf caps on the tweeters. If I do go with the 198s, what caps should I order?
3) My boards dont seem to have polyswitches. Instead they have a pair of fuses. I think these need to go away. Any reason why I should not be done with these? (200w Hafler amp and reasonable -wife limited- listening levels).
4) I have a total of three of the 750 silver mica caps (that are often refered to as the bypass caps, I think). Do all three of these go away with the polyproplyene caps?
5) My stereo array board has a 0.5 uf ??? cap in parallel with the 4 (3.5)ohm resistor. The drawing says mylar but it looks electrolytic to me. Anyway, is polyproplyene the way to go with this cap and am I correct about the value? The drawing is a little hard for me to make out.
6) The 6501 driver caps are 27 uf. I'm going out on a limb here and assuming they dont change with a tweeter change. Correct, or did I break an arm?
7) I see the holes refered to as alpabetically labled. I'd love to see a drawing of the SDA IA board with these labels. Can anyone offer a link?

Finally, most of the posts I read concerning the tweeter upgrades are several years old. Are the 198 tweeter upgrades a cut-and-dry issue or should I give that some more consideration? I'm not saying cost is no object, but hey, it's not my money. I just want these babies to rock.

Thanks in advance.

Dave

danger boy

I could be wrong. but I don't think the SDA 1A's qualify for the RDO-198 tweeter upgrade. don't quote me.. but pretty sure it has to be the SDA 2B for that.

F1Nut will chime in and he'll for for sure though.

Face

It appears your crossover as the same as SDA1's.
http://www.polkaudio.com/forums/attachment.php?attachmentid=31008&d=1201824729

dcmeigs

Face wrote: »

It appears your crossover as the same as SDA1's.
http://www.polkaudio.com/forums/attachment.php?attachmentid=31008&d=1201824729

I don't think it is because it does not have the 130 uf cap. These are both the round planform with the array board on back of the post molding and the stereo board mounted to a large coil held in place several inches above the array board by a single allen head screw through the cabinet.

I noticed that the sda 2 drawing had a notation that the 3.5 ohm is a revision from the 4 ohm value. This must have been across the board at some point in time.

ben62670

Seeing that you have 2 fuses, and the 4ohm tweeters I will have to agree that you have the SDA1's on your hands.
1 Stay with the 4ohms. Even the RDO-194 runs a little too hot for my taste.
2 The 12uf caps should be retained unless someone has a simple upgrade solution to the 198's.
3 keep the fuses
4 yes kill the 750pf caps
5 I would go electrolytic
6 correct
7 sorry no help here on that one

Yes I would get rid of the SL2000's

Can you possibly post a pic with the grills off?
How many tweeters per cabinet?
Thanks
Ben

F1nut

1. Go with the 3.5 ohm.
2. You can not use the RD0198-1, you must use the RD0194-1.
3. Get rid of the fuses.
4. Get rid of the 750pF's. You won't need them anymore.
5. Yes, it's 0.5uF and yes, a poly will work well there.
6. Correct, no change.
7. Can't help you there.

The new tweeters are a vast improvement, period.

If you could, please document your upgrade and post the results with nice color pics.

Have fun.

ben62670

F1nut wrote: »

1. Go with the 3.5 ohm.
3. Get rid of the fuses.


Have fun.

1 If it is the single tweeter I agree.
3 Why, and how do you suggest getting rid of the fuses? Performance? Bypass internally, or just a large fuse would do?

Thanks
Ben

dcmeigs

F1nut wrote: »

2. You can not use the RD0198-1, you must use the RD0194-1.

The new tweeters are a vast improvement, period.

OK, I go with the 194's. Do I stick with the original cap values? I guess what I'm asking is if the 194s have the same impedance as the original SL2000s?

AND, when I do my SDA2s, with single tweeters, is that the application for the 198s?

I'll post a pic here soon, but for now, they have 2 tweeters mounted side by side and horizontally above a square matrix of 4 mw5601 drivers and a single pasive radiator.

The serial no. tag above the posts says "R SDA IA 1146"

Thanks for the help. I'll take lots of photos.

F1nut

He's got 1A's, so they have two tweeters. I'm basing my suggestion on the fact that Polk thought the 3.5 was a better choice and that the RDO194-1 is even more laid back. However, I'll gladly defer that one to you as I've never upgraded a pair of 1A's.

They aren't needed, he's not blasting the volume levels. It would depend on how they have at all wired up. I'm guessing one could jump the connections on the board like the later crossovers.

F1nut

Yes, stick with the same values.

You can use the RDO198-1 with your 2A's. You have to remove one of the 2.7 ohm resistors. There are two, you want to remove the one in series with the 0.4mH inductor.

dcmeigs

ben62670 wrote: »

1 If it is the single tweeter I agree.
3 Why, and how do you suggest getting rid of the fuses? Performance? Bypass internally, or just a large fuse would do?

Thanks
Ben

OK Ben, good question re the fuses. Here is my take for what it's worth. We all pretty much agree that large gauge speaker wire is an improvement so it seems a poor idea to put a fuse with a hair width element in its place. Yes I could use a 20 amp fuse but then it serves no purpose so why not keep it simple and remove them altogether?

And, it's not a single tweeter speaker. These SDA IAs have a pair of tweeters and 4 drivers.

dcmeigs

OK then, I will call Soniccraft tomorow and get some pricing from Jeff on the caps and resistors. I'll compare that with pricing on Solens from Parts Express. Some avocate using Solens on the low pass (driver) caps and the high end Sonicaps on the high pass (tweeter) section. What do you think of that strategy?

ben62670

I have modded the 2's with the dual tweeters, and used the RDO-194's. Still a bit too hot for my taste. The SDA's have gone through five generations, and the first is the only one that used the dimensional tweeter. What I did with mine was disable the dimensional tweeter, and drop the series resistor to 3ohms. 2.7 is stock for single tweeter arrangements. I know that this mod gets flames going, but there is a reason that Polk dropped the dimensional tweeter. It made things too wild, and killed the accurate sound stage SDA was built for. A simple test to see if you like this mod is to remove the dimensional tweeters fuse. You will experience a cut in the high end, but will get an idea what the sound stage is like with a single tweeter being used. When I first got my 2's I fired them up, and was amazed at how wild they sounded. This didn't last very long. I got tired of the lack of accuracy in the sound stage.

F1nut

I agree with your assessment of the dual tweeters, Ben.

www.soniccraft.com

All prices are listed. You definitely don't want to use Solens for the high end.

ben62670

dcmeigs wrote: »

OK then, I will call Soniccraft tomorow and get some pricing from Jeff on the caps and resistors. I'll compare that with pricing on Solens from Parts Express. Some avocate using Solens on the low pass (driver) caps and the high end Sonicaps on the high pass (tweeter) section. What do you think of that strategy?

I have used the Solen's based on many recommendations, and there are better caps in that price range. The PE Dayton's are much better than Solen's especially on the highs.
I did a review.
http://www.polkaudio.com/forums/showthread.php?t=61727
As far as Sonicaps VS Solen's I have not used the Sonicaps. I do know that I thought Solen's were a great cap for the money till I did a comparo between them, and the Dayton's. They got smeared. I have not tested the Jantzen's lower priced caps, but after hearing the difference between the Solen's, and the Dayton's I can say with faith that I would recommend the Dayton's as a low cost alliterative to Sonicaps. The beloved LSI line uses cheap generic caps, and so did the original SDA's.

dcmeigs

That's very interesting to me. I can't exactly fire them up again because I have them apart, but the reason I handed these speakers off to my friend in favor of the SDA2 is that the 2s seemed to have a better sound stage than the 1As in my listening room. What I'm saying is that I have had a similar comparative experience and your comments resonate. I'll give it some more thought. I suppose if I were to do it this way, I would just buy one tweeter per enclosure and fill the second hole with a disconnected SL2000.

ben62670

F1nut wrote: »

All prices are listed. You definitely don't want to use Solens for the high end.

I concur:p
I hold my head in shame knowing how many Solen's I have used on the top end:o

ben62670

dcmeigs wrote: »

That's very interesting to me. I can't exactly fire them up again because I have them apart, but the reason I handed these speakers off to my friend in favor of the SDA2 is that the 2s seemed to have a better sound stage than the 1As in my listening room. What I'm saying is that I have had a similar comparative experience and your comments resonate. I'll give it some more thought. I suppose if I were to do it this way, I would just buy one tweeter per enclosure and fill the second hole with a disconnected SL2000.

Yes kinda. The only fair way to do this would be to replace the 4ohm resistor in series with the tweeter with a 2.7, or 3 ohm. Also you will save $100 in tweeter, and some money in caps, and resistors in the top end.

dcmeigs

Yes Ben, I did get the cap and resistor angle. I don't find my SDA2s offensively bright with their 2.7 ohm resistor but, if I understand you correctly, I think you are suggesting that the replacement tweeter is brighter - or hotter as you suggested, hense the need to turn it down a bit with more resistance. Have I got that right?

And, I finally figured out the soniccraft web site and got the pricing. I'll look at the Daytons too. Have either of you used Clarity?

I formed the opinion reading past threads that Soniccraft is the prefered choice for caps, setting cost aside. Is that a fair statement or is there some debate on the subject?

ben62670

If you liked the 2's with the 2.7 I would say with the single tweeter mod to stick with it. The RDO-194 isn't brighter than what it is replacing. I have not used clarity caps So I have no grounds to give an assessment of them. Yes Sonicap is the preferred choice For SDA's. One day I will compare them to the Dayton's, but I am totally satisfied with the Dayton's. That being said I was happy with the Solen's on the highs. I don't think anyone has done a fair comparo between the Sonicaps, and Dayton's. For the price of modifying a single tweeter you are looking at only 2 12uf caps. I would recommend sticking with Sonicaps on those, and the Dayton's on the rest. On the Low frequencies the signal doesn't actually pass through any of the caps, and carry on to the drivers. I am not saying that there is no benefit using good caps here, but the benefit is not as great as in the high sections.

dcmeigs

ben62670 wrote: »

On the Low frequencies the signal doesn't actually pass through any of the caps, and carry on to the drivers. I am not saying that there is no benefit using good caps here, but the benefit is not as great as in the high sections.

I see your point and it is a good one. The lower two bass drivers are driven without crossover, as you say, and the third stereo driver is in parallel with a 27 uf cap. I suppose this is because the third driver is the counterpoint to the array driver in the other cabinet and Polk wanted to exclude the highs from the SDA effect. It seems odd that they would then use a tweeter in the SDA. Or maybe I miss the point.

Also, i'm thinking about using one of the fuse holders in series with the 2.7 ohm tweeter resistor so I can easly add another 0.3 ohms of resistance to the circuit externally (by soldering the resistor to a fuse). This will facilitate the comparison.

candyliquor35m

Do you or your friend have any complaints about the sl2000 tweeters? They are awesome tweeters and I haven't found anything even close to how they sound.

TroyD

Shut up, Carl. This was/is a good discussion without your banality.

Jstas

candyliquor35m wrote: »

Do you or your friend have any complaints about the sl2000 tweeters? They are awesome tweeters and I haven't found anything even close to how they sound.

Your "mod" is crap, the SL2000WC doesn't exit and you have mercury in your brain. Go away fairytale man.

dcmeigs

ben62670 wrote: »

Can you possibly post a pic with the grills off?
How many tweeters per cabinet?
Thanks
Ben

The cabinets are across town but these are the same configuration.

http://cgi.ebay.com/Pr-Floor-Studio-Pro-Audio-Polk-Audio-SDA-Speakers_W0QQitemZ350038689937QQihZ022QQcategoryZ14993QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

dcmeigs

candyliquor35m wrote: »

Do you or your friend have any complaints about the sl2000 tweeters? They are awesome tweeters and I haven't found anything even close to how they sound.

Mine sound fine. His sound like crap. Could be a crossover problem too. I have read your posts supporting the SL2000s and the others who favor the silk. Since we need to replace the tweeters on his anyway, it will give us a chance to compare the two. Thanks for weighing in, I keep you posted.

Joe08867

Those are original SDA1's. They have the SL2000. I don't think you can upgrade to the RDO198 with that setup. I think you would be better served going with the RDO194. It is a big improvement over the SL2000 either way. Right Carl??? sorry couldn't resist.

dcmeigs

Jstas wrote: »

You're just jealous 'cause the voices don't talk to you!

I'm am a little jealous. Can you send them my way?

F1nut

Let's not get into the CL and his tweeter crap again. PLEASE!

dcmeigs

Joe08867 wrote: »

Those are original SDA1's. They have the SL2000. I don't think you can upgrade to the RDO198 with that setup. I think you would be better served going with the RDO194. It is a big improvement over the SL2000 either way. Right Carl??? sorry couldn't resist.

Joe, I think you are correct about that. I'm about to call polk and get them on order. I'm also going to order the tweeters for my SDA 2B/CRS+ while I'm at it. They are the ones that get the 198s, correct?

Also, on the subject of the SDA 2B/CRS+, I will order a 12 uf sonicap for the tweeter and I will need another cap as well for the high pass, but I must be suffering from a head injury from the beer last night and I can't quite make sense of it. Is it the 5.8 uf for the C5 position on the board? Can you explain why; I suppose it is a different impedance.

Joe08867

Yes the CRS+ can get the upgrade. But I think you need to do the TL upgrade. I am not sure on that.

As far as the 5.8 uf I don't have the schematic in front of me so I don't know.