Polk Audio SDA CRS+ Mods...

VR3

why would you leave c4 blank? Just curious and i will reroute the cable

F1nut

why would you leave c4 blank?

Because you no longer need to make that connection, C3 completes the circuit.

gimpod

C4 is a 750pF Silver Mica By-pass Cap for C3. If you put a jumper there (C4) you are by-passing C3 effectively taking C3 out of the circuit.

VR3

gotcha... Im learning! Will fix this.

VR3

Awesome!

Changed - appreciate the help!

VR3

The more I think about this - the more I do not see the danger will robinson warning -

The bypass capacitor is such a small value.. and the 12uf is still in line. I do not see this "removing" it from the circuit.

It would be no different than me popping the top of my Tylers and strapping a bare wire connection over the cap to each connection point. I dont think it would change anything respectively as the capacitor is still there and still connected...

Maybe I am over thinking this but I do not see how this would be a serious issue - if an issue at all. Maybe not necessary but not something "danger danger"

I have pondered this since I read the initial warning...

Outfitter03

The wire or shorting strip will electrically take the capacitor out of the signal path. The capacitor performs two functions in this circuit. Blocks DC to the tweeter as the first capacitor is bypassed with a resistor and blocks frequencies lower than the crossover point.

A wire connected in parallel will pass all DC and will pass all AC signal on to the tweeter. Technically the capacitor is still in the circuit, but with the jumper in place it is unable to perform it's required function.

VR3

Hmmm

Interesting! I learn something new everyday!

I wish this was the Matrix and I could just plug in.

Outfitter03

I just wish you weren't on the other side of the country so I could come and listen to your setup! Best wishes to Buddy. Sorry he isn't feeling well.

VR3

Thanks brother!

If you are ever in NC you are more than welcome to take a demo!!

I love showing off the Tylers too!

Whats cool is right now I have my entire audio journey in my den kind of - Polks, Def Tech, Tyler all together in one spot...

VR3

Both are done - wire moved, jumper removed

Just gotta replace the post... and wa la!

evhudsons

nspindel wrote: »

Glad you're still so enthralled with your CRS+'s, evhudsons. Sounds like you bought yours right around the same time I bought mine. My CRS+'s were a birthday present to myself, on October 3, 1989. I had them up until around 2004, when I purchased a pair of SDA-2B's close to home and sold the CRS+'s. A several years later I upgraded again from 2B's to 1C's, which is what I'm using right now. I also know that I'll be downsizing homes in a few years, so I've gone full circle and purchased another pair of CRS+'s that will eventually replace the 1C's in a few years.

You'll find that you are in good company here. There are many of us who have been using SDA's for over 20 years, like yourself. There are others on here who have found their way to SDA's more recently, after discovering their reputation on this forum.

Either way, you'll be quite surprised when you start reading about all the tweaks and mods people have discovered and applied to these speakers. Just about every modification is well documented in these threads, with photographs and step by step instructions.

The easiest modification, by far, is swapping the old SL-2000 tweeter for a new RDO-194. As you've already seen, replacing the tweeter with the newer silk-domes is such a great change because it eliminates the annoying frequency spike that the older plastic-domed tweeters suffered from.

There are a lot more adjustments to make, all of which I plan on doing to my new CRS+'s. Let me itemize these for you, so you can research each of these changes on the forum:

1) New wood veneer - As you've already seen, you can use a heat gun to remove the stock vinyl and replace with wood veneer of your choice. There are numerous threads where people have done this work with great success.

2) Crossover rebuild - The stock crossovers are now over 20 years old, generally past the recommended lifespan of the electronic components used in the circuitry. Newer, higher quality components can be used to replace the original electronics, which will greatly improve depth, detail, soundstage, and overall tonality of the speakers. The four main aspects of rebuilding the crossover are replacing the capacitors, removing the bypass capacitors, replacing the resistors, and removing the polyswitch.

3) Crossover board replacement - One of our members, gimpod, has designed replacement circuit boards for the stock crossovers. So instead of simply replacing certain electronics on the original board, you would use a completely new board, replace the electronics as described in 2), but also move any remaining electronics from the old board to Tony's and mount the board in the cabinet. You'll find that a lot of the newer components are considerably larger than the original electronics, and mounting them on the stock circuit boards can be difficult. Tony's new boards are designed from scratch to handle the larger modern components, and are quite nice to work with.

4) Inductor replacement - One of the more debated topics on the forums is whether or not to replace the large coils that your CRS+ crossovers are mounted on. There is a statement from Matthew Polk confirming that the original coils have a relatively high DC resistance that was used to compensate for current limitations in the amps that were common when these speakers were designed. Modern amplifiers shouldn't have the same current limitations, and using a lower DCR inductor in place of the stock one has been found to increase bass depth and slam. I have personally done this mod and am quite happy with it.

4) The "TL" mod. The addition of a 5.8uf capacitor in the crossover circuit would allow you to use the RD0198 tweeter instead of the RD0194 tweeter. Most around here agree that the 198 is a better tweeter, and if your crossover is condusive to the upgrade (yours is) then it is worthwhile.

5) Dynamat - Commonly used for sound dampening in automotive applications, you can use Dynamat (Dynamat Extreme is recommended) to eliminate resonance in the driver and passive radiator baskets, which has been found to provide better bass focus and all around sonic improvements.

6) Rings - Larry (TOOLFORLIFEFAN) has access to some amazing machinery and has created metal rings that you can mount from the inside of the cabinets, and allow you to attach the drivers and the passive radiator much more securely than you can simply by using the stock method of wood screws into to the cabinet. The more secure fit of the rings has been found to tighten up bass and improve sound stage.

7) New seals - The drivers, tweeters, and passive radiator have a thin layer of foam that sits between them and the cabinet, intended to compress into an airtight seal. Many have replaced these with various products, the best of which (or even the overall necessity to do the mod in the first place) is still a somewhat debated topic. Two items already being used and debated are Armaflex and Mortite. I intend to test both of these myself.

8) JB Weld - as you've already discovered, the magnets can shift, ruining the driver. People are using JBWeld on the drivers to ensure that this doesn't happen.

9) Speaker binding post replacement - Pretty self explanatory, often considered jewelry for your speakers, but many of us like it. Not suggesting you'll get huge sonic benefits from this mod, though.

10) A custom SDA cable - The pin/blade connector can be replaced with a single speaker binding post, and then you can use the speaker wire of your choice to replace the stock pin/blade SDA cable. You'll get a much improved SDA signal between the speakers, which will greatly improve soundstage and imaging. A very worthwhile mod.

11) New grill cloth - also self explanatory, and sounds like something you're already intending to do.

Welcome to the forums, always great seeing more people like yourself on here - long-time dedicated Polk/SDA enthusiasts who are just now discovering that the speakers you already love are capable of much, much more than you thought, even after owning them for over 20 years.

Stick around, do some research, gather the courage to do these mods, and take your listening to a whole new level!

Thank you all again for all the info. I recovered the the grill cloth, and picked up an extra Polk pin that had been missing for some time. My old one was faded, so I used a gold paint pen to refurbish them, and used a fine sharpie to blacken the faded black. It looks realllllly good now, and I think it has better acoustics as I had held both the old and the new grill cloth up, and the new one I could see clearly through, the original not as clear. I picked up an old Marantz 2230 receiver for $100 two nights ago because my new receiver doesn't have a phone input, and I figured the Marantz was much better than an adapter. It sounds fantastic.

I plan on doing the crossover next, but one question, should I go ahead and put in the necessary crossover upgrades (5.8uf capacitor) to accommodate the rdo198 tweeter but still keep the rdo194 for now? I'm on a budgeting thing, and am happy with the rdo194's for now. I don't want to have to do two crossover jobs if possible. I will certainly hope to get the bigger boards to do the crossover upgrades.

I mentioned before I have a separate sub-woofer, but I do get decent music bass from my Polks as they are. I only drive the subs for when I watch a movie. I know that most people have center channels, but do I really need one if I have the sda crs+? I like to hear voices clearly, but it seems to me having voices from the center would ruin the sda effect I love, especially when simply playing music which is more of a priority for me anyway. Any thoughts or expertise on this?

Thanks for all the links, and especially the veneer job examples. I'm thinking of going with KOA wood, I always liked the look.

nspindel

No. If you do the TL mod you need to replace the tweeters. Work your post coumt up and then sell the 194's in the flea market threads. You'll get most of your money back.

As for the home theater questions, I'll leave that for people who are using their sda's in surround setups. Mine are strictly in a 2-channel system with no sub. Old school...

nwohlford

The above crossovers arrived today and look great. I took a long lunch break to go home and install them in my CRS+s. I only had a chance to listen to two songs before returning to work but they sound great. I think that I will have to work at home some this week to give them a better workout.

What do most people do with the batting in the CRS+? Mine were in different places in each speakers. Given the set up of the speaker, it ends up being right near the PR no matter where you place it.

nspindel

nwohlford wrote: »

The above crossovers arrived today and look great. I took a long lunch break to go home and install them in my CRS+s. I only had a chance to listen to two songs before returning to work but they sound great. I think that I will have to work at home some this week to give them a better workout.

What do most people do with the batting in the CRS+? Mine were in different places in each speakers. Given the set up of the speaker, it ends up being right near the PR no matter where you place it.

Congrats on the xo upgrades. As for the batting, good question. I'm looking forward to the answer!

nwohlford

Finally got a chance to really listen to the modified crossovers. They sound great. I still have to do the RDO194 update. I left the batting out for now. (Actually, I just forgot to put it back in one speakers and was in a rush to get everything back.) I will have to listen a little more to decide if I like it without the batting.

VR3

Sorry I did not see this sooner!

Thats awesome!!!

Glad you are enjoying them!!!

F1nut

nwohlford wrote: »

What do most people do with the batting in the CRS+? Mine were in different places in each speakers. Given the set up of the speaker, it ends up being right near the PR no matter where you place it.

Yep, just stuff it back in there.

Finally got a chance to really listen to the modified crossovers. They sound great. I still have to do the RDO194 update. I left the batting out for now.

If I understand you correctly, you did the TL upgrade, but are still using the RD0194-1
tweeters, yes? If so, they cannot sound great. Put the batting back in.

nwohlford

The TL upgrade was not done. I still have the SL2000 tweeters in. I did occasionally hear some odd high frequency resonances but figured that was just the SL2000 tweeters.
I figured that I would put the batting back in. They actually did not sound bad without it, but I was listening to music without much bass.

nspindel

Realize that by doing it in the order you've chosen, you're doubling the amount of break-in time? Your newly modded crossovers take several hundred hours to settle in, and then your 5.8uF cap and RDO-198's will need to break in separately. It adds additional expense, but my advise is tweeters and crossovers at the same time, and then break everything in. Speakers and power amps are the two most painful items to break in, because you actually need the system producing sound to do it. You'll read lots of stories on here of speakers covered with lots of blankets, all sorts of trickery to try and keep the sound muffled, and an angry wife or two, because of people needing to break speakers in. I'd get that all over with together if I were you.

Edit: I shouldn't say it adds additional expense. You'll spend the money eventually anyway. But I would spend the ~$100 for the tweeter, plus the cost of the 5.8uF caps right now, and save yourself a lot of headache.

nwohlford

I guess I like having the option to still be able to update them later. It will keep me from getting bored of them and feeling like I need to buy a different set of speakers later.

evhudsons

I've been busy lately, and haven't had time to post. I want to say though that your advice on doing the tl mod with the 198 tweeters is the way I'm going to go, but probably in the next few weeks. I don't have a crossover mod yet, but did do the drop in 194 tweeter upgrade and noticed something over the last few weeks. I thought I was just imagining things, but the speakers are exponentially sounding better. It's beyond belief right now. I see from your posts that the tweeter has burn in time too? When I do my cross over mod/upgrade/198, I'll be looking to turn over the 194's, but by the time I get around to it they should be really broken in.

I am on a budget too right now, but next month will finish the upgrades. For now, I replaced the cover material, and put a layer of polyurethane clear on the speakers, and they look great. I was otherwise going to have to do a re-veener, but they are fine for a while now. I took 16 gauge speaker wire, and used one for each post doubling the amount of wire, I think giving the most copper on my budget. I did this for the sda interconnect too, and it really makes a difference. I haven't soldered the connection yet, but intend to later. Each speaker has three wires going to it, but I hid them through the stands.

I took my separate bandpass subwoofer, and built wood all around it, stained and varnished to match my wood floors and ceilings. It was an ugly cat scratched carpet eye sore, but now looks like tommy bahama. My wife asked me to post on here her advice: if you make your speakers match the house, your wife will be happy. I don't have to have the sub to get bass as the CRS does produce some, but when I do use it, the system sounds like the power of tower, but the beautiful clarity and size of my crs.

I can't believe my ears though, the tweeter upgrade is huge. I'm probably at the top of the burn in I suppose, I can't imagine it getting much better, but I hear things all around the speakers to the left, right, and behind the speakers. I got rid of the center channel speaker, it was definitely ruining the sda effect, and not needed with the polks. So that answers my earlier question about the center speaker. Now I have full acoustics. I do have surrounds for movies, and my amp can be changed to select stereo to use only my front polks for music. It's a pioneer, and I use an app on the iphone to control the volume and other aspects.

I noticed my dog sitting on couch listening intently to the center of the room. For some reason he really loves Diana Krall. I just happened to have it on. It's funny to see him stop, get on the couch and just sit there happy and content when I put her on. Dogs are funny.

evhudsons

nspindel wrote: »

Realize that by doing it in the order you've chosen, you're doubling the amount of break-in time? Your newly modded crossovers take several hundred hours to settle in, and then your 5.8uF cap and RDO-198's will need to break in separately. It adds additional expense, but my advise is tweeters and crossovers at the same time, and then break everything in. Speakers and power amps are the two most painful items to break in, because you actually need the system producing sound to do it. You'll read lots of stories on here of speakers covered with lots of blankets, all sorts of trickery to try and keep the sound muffled, and an angry wife or two, because of people needing to break speakers in. I'd get that all over with together if I were you.

Edit: I shouldn't say it adds additional expense. You'll spend the money eventually anyway. But I would spend the ~$100 for the tweeter, plus the cost of the 5.8uF caps right now, and save yourself a lot of headache.

I decided to go with your advice. With the rdo194's, I noticed the difference immediately with never ending improvement with playing. Will I experience the same thing you think with the crossover mod and rdo198's regarding immediate and then progressing improvement with burn in?

nspindel

Actually, no. In fact, just the opposite. There is no change to my system that I have done that was more needing of break in time than the crossover mod. You may, in fact, hate it out of the gate, and come back here and start telling us all that we don't know what we're talking about, and that your speakers sound like crap. At which point, we will reply by telling you to be patient As you let the break in continue, the sound changes dramatically. As the caps break in, with Sonicaps at least, the sound improves, then regresses, then improves again, then regresses again, until it finally stabilizes at about the 200 hour mark, and should reach peak performance at 300 hours. Yes, that's 200-300 hours of your system needing to be fully on and producing sound at a decent volume level before it is broken in.

Seriously, I am not kidding - when you finish your crossover mods and the system is back online, you should power things up, start things playing, and then leave the room! Don't even listen to it for the first 48 hours, or you'll probably hate what you hear and start getting worried. The only value in listening any earlier than that is to appreciate what comes later on in the break in. Yes, I know you won't follow that advice....

What I suggest is to take a few of your favorite tracks with the best dynamics that you have, and play them repeatedly with your speakers in their current state, and commit those tracks to memory as best you can. Then do the mods, and keep listening to those tracks over and over throughout the break in, and note how things are changing.

FYI, I also suggest replacing the large inductor. I have used Erse iron-core inductors with great success, but for my next project I will be using Solen air cores. I know it's hard to believe, but even a simple coil of wire requires break-in as well, so I suggest doing it alongside the other mods.

Of course, given the fact that you're pulling the speakers apart to get at the crossovers, you may want to think about also doing the dynamat, rings, and armacell mods, as these also require disassembling the speakers.

Others on here will give you opposite advice - do individual mods in isolation, so that you can appreciate what each mod is doing, rather than a big-bang, all at once approach. That's your call, it all depends on how much time you have on your hands, and how much appetite you have for the break in times. Speakers aren't like breaking in a preamp, you can have the amp off and still have your preamp breaking in...

dorokusai

I've been a proponent of inductor replacement for years so it's not odd to me at all. They do require an enormous amount of break-in so for those seeking a quick benefit to your investment, you have to be in for the long haul.

evhudsons

I'm really glad you prepared me. I read how people put linens over their speakers during the day. I won't have to do that, I can leave it on for the dog to think we are home. What does the inductor change out do?

I've had these things for many years, I think I have the patience to have them sing again, but thanks for the warning on the crossovers as the tweeter drop in was so dramatic at first and continuing.

nspindel

The inductors make a big difference in bass slam. Anyone have a link to Matthew Polk's write up endorsing the inductors upgrade? I'm on cell phone right now, not ideal for searching...

Long story short they used an inductors with a high dc resistance in original model to compensate for amps of the day that couldn't put out enough current. Modern amps can put out much more juice, so a lower DCR inductor like the Solen will definitely help out in the low end. DarqueNight has a great thread abou doin inductors in the CRS+'s, definitely worth the read. Note that he starts with Northcreeks but then switches to Solens.

evhudsons

The owner of this thread is doing the xrossover mods now. Is the inductor mod something a little easier I could do? I agree with you that I might as well use the burn in time to burn it all at once.

evhudsons

I'll look up the link, and thanks for the supremely fast reply!

nspindel

Trickiest part about the inductors is figuring out how to mount them, especially in the little CRS+'s. Definitely read Darquenight's thread.