My new 4.1TL's are complete!

[nspindel]

I?m really excited about these "new" speakers! Feel free to skip to the next post where I start talking about the upgrades, and pass on my little soliloquy here.

My SDA journey began in 1989. I remember it so clearly. I had a dj business as a teenager, but I became less and less active with it as I progressed through college. I had some decent pro-gear, but was using it as my stereo as my dj activity went by the wayside. By my junior year, I was thinking it was silly to have decent value tied up in that kind of pro gear, when it could be sold to fund some good hi-fi equipment. I found a buyer fairly quickly for the dj gear, and headed to a stereo shop that was right around the corner from my apartment. This was a great store, with a proper listening room, where they would take the time to set up the speakers that you wanted to hear properly, with a listening room that had good damping, and it wasn?t just a wall of 50 speakers. It was empty of other speakers, other than the ones that they were demoing for you by properly placing them in front of you.

That was the first time I had ever heard of Polk Audio. The salesman got a feel for my budget (I was buying a receiver, cd player, and speakers) and then introduced me to the SDA 2B's. I still remember the cd that he put on, which completely blew my mind - Caverna Magica by Andreas Vollenweider. If you have SDA's and don't have Caverna Magica, you need to get it. Talk about a cd that shows off what SDA is all about!.

Long story short, I was sold on Polk. However, I just couldn't squeeze the budget far enough to get those 2B's, as much as I wanted them. I was set on a Harman Kardon receiver and cd player, and there wasn't enough left over to afford the SDA's. However, the stereo shop had an amazing deal going. Buy a pair of speakers, and you could upgrade them within a year and get back 100% of your purchase price towards speakers that were at least twice the cost of the ones you were returning. They didn't offer the same deal with the receiver or the cd player, only with speakers, so it only made sense to make the speakers fit the budget and upgrade later.

So I left the store with my first pair of Polks - Monitor 5's. And I loved them! But I still had SDA on my mind. I couldn?t wait to do the upgrade. Along came senior year, though, and I had moved back on campus and my room in my apartment was quite small, I just didn?t know how to fit those big SDA's in the room. Not to mention, I still didn't have the money for the upgrade.

Well, along came my 21st birthday. I opened my mailbox and what do I find in there on my birthday! My very first... credit card! BINGO!!!! I drove straight to the shop to put myself in hock for the first time!

But I explained to the salesman who I'd been dealing with there that the 2B's were going to be a tight fit in my dorm room. He said he had just the answer for me, and he showed me the SDA-CRS+. He told me that they were basically the exact same speaker as the 2B, except in a smaller cabinet, but that I shouldn?t be put off by their small size. Bass is omnidirectional, as he explained (first time I'd ever heard that word!), and these just have the passive subwoofer on the back instead of the front. Wow! I knew I could definitely make these work in my dorm room. Happy birthday to me! So it began, I brought home my first pair of SDA's on that day in 1989.

And they served me well! I'm actually glad that I ended up with the smaller CRS+'s over the 2B's, because in the years that followed I was pretty transient. From college, to an apartment in NYC, to grad school, to another apartment, to a condo, and then to my house. Moving CRS+'s around is a lot easier than moving 2B's, so it was the right move at the right time for me.

I had those CRS+'s for 16 years. But in 2005, not coincidentally the time I found my way to this forum, I found a pair of 2B's on eBay for $200. They were in great shape, but the seller figured correctly that it would be a fortune to ship them, so he?d need to sell them fairly cheap in order for the total cost to be appealing. But these were only about 40 miles away from me, so I could pick them up myself. So 16 years later, I had the 2B's that I originally wanted, and I sold the CRS+'s to a friend at work.

A few years later, having been reading the Polk forums and learning all about the upgrades that could be done to the SDA's, I decided to get my solder-geek on. So I got busy on those 2B's! I did the TL upgrade, put 198?s in, and upgraded the caps and resistors. I was simply amazed at how much better they sounded! I could have easily stopped right there, but...

I was perusing CraigsList, and happened on to a pair of 1C?s not far away, listed for $250. I couldn?t resist! So up the chain I went, a bit more. I passed the modded 2B?s along to Mike (BigDawg), and started modding the 1C's. And I used those for several years after that.

But my wife and I have been hatching a plan lately to sell our house when our son goes off to college in two years, and drastically downsize. In the back of my mind, I knew the 1C's wouldn't fit with the downsized lifestyle, and I'd have to go smaller again. And then what do you know? Good ole Sal (Lasareath) posts a pair of CRS+'s and stands for sale, and he only lives about an hour away! So I grabbed them off of him, which was great because I got to meet him and get a demo of his incredible 1.2TL's that he did such an amazing job restoring.

It's a good thing I bought those CRS+'s too, because they came to the rescue of my 1C's. I fried one of the 1C's pretty badly with a dc spike, the photo of smoke coming out is the highlight of a pretty funny thread. The drivers from the CRS+'s went into the 1C that I smoked, and saved the day.

I replaced those drivers with new-stock Polk replacements fairly quickly, but the CRS+'s sat as a pile of parts (Sal had started doing some upgrades, but didn?t want to finish them). But I finally got motivated to start moving these recently, and just put the finishing touches on them (well, almost? more to follow) and got the stands cleaned up and set them up in my 2-channel system. I sold the 1C's over the weekend to another friend at work, and have now gone full circle. I'm back to the speakers I bought myself for my 21st birthday in 1989. The ironic part is... today is my birthday! 23 years to the day after getting my first pair of SDA CRS+'s, here are my newly restored CRS+'s, but from here on, of course, referred to as 4.1TL's:

[nspindel]

Well… If you read my first post, thanks! If not, no big deal, here is where I start talking about the restoration work.

First of all, let me just give credit where credit is due. There is absolutely zero that I have done here that should be considered creative. This was 0% innovation and 100% imitation. This forum is an incredible place. We have such knowledgeable members who take the time to figure all this stuff out, and share it here for people like me to benefit from. The speakers I’m about to show you simply would not exist if it weren’t for DarqueKnight, F1Nut, Toolfan66, Gimpod. Raife, Jesse, Larry, and Tony are the guys who deserve the credit here. All I did was follow instructions. Everything you need to know to do the same thing is right here in this forum thanks to these guys, so I just want to say thanks!

I never had these speakers in stock form. Sal had started to upgrade them, but decided not to finish. He sold them to me with the crossovers already dissected, and being rebuilt with gimpod’s boards, with Sonicaps and Mills. He had already purchased RD-0198’s for them as well as Larry’s rings. So he basically sold me a 4.1TL upgrade kit.

Knowing that these should end up being my speakers for life, I wanted to go all out. Here is what I have done, in no particular order – 1) TL upgrade, 2) RD-0198 tweeters, 3) Sonicap capacitors, 4) Dueland resistors, 5) Jantzen on-board inductors, 6) Gimpod’s crossover boards, 7) Solen 16mH inductor, 8) Dynamat, 9) Armacell, 10) Larry’s rings, 11) Sonic Barrier on the cabinet sides, 12) Cardas binding posts, 13) Replace the pin/blade connector with a Cardas binding post, 14) Re-finish the cabinets in maple veneer.

[nspindel]

Not necessarily going in order, but here we go! Cabinets first:

There?s a lesson to be learned from this photo. There is a difference between wood veneer and vinyl laminate! My CRS+'s were veneer. I wasn't aware they made these speakers with veneer, I thought they were all vinyl laminate. You cannot remove veneer with a heat gun! You need to sand it off. After a lot of unsuccessful efforts at trying to remove the veneer with a heat gun and putty knife, I did some damage to the pressboard. My repair to follow:



And then Jesse set me straight and I started sanding:



And more thanks to Jesse for suggesting to use Bondo to fix the dings I caused with the putty knife:





And then after the maple was applied, including the trim piece:



Finally, the finished product, after applying a 5-coat tung oil finish:

[nspindel]

Next, the crossovers. You can't beat using Tony's boards for the crossovers. The original stock components are so much smaller than the film capacitors we all use for these upgrades, and the stock boards are a very tight fit for the bigger electronics. Tony's boards are laid out soooo much better, I can't imagine trying to re-do a crossover again using the original boards. Here are a few pics of the finished crossovers, including the TL upgrade (the 5.8uF cap on the left). Sonicaps, Dueland resistors, and Jantzen inductors. The only stock materials on these crossovers are the black leads that go to/from the 16mH inductor:





How to mount the crossovers? In the stock speaker, the original boards mount on top of the 16mH inductor. I've replaced both the inductor and the board, so need to come up with a way to mount them. Well, one way to do it is to just copy Larry! All the credit goes to him here. Note that in the view below, I'm working on the speaker upside down. The crossovers are mounted via industrial Velcro from the top of the speaker, and are hanging down when the speaker is right side up:

[nspindel]

On those interior pics, you can see Larry's rings and tweeter brackets mounted inside the cabinet. Here are some more pics of the rings including the installation:



The ring for the binding post cup:



The passive radiator ring:







Quick pic of the Sonic Barrier (1" thick) on the side wall. This is repeated on all four side walls:

[nspindel]

The Solen 16mH. Such great research by DarqueNight on these inductors. I poached his method for mounting the inductor as well:









Here is the one thing I still need to finish. Right now I'm using the stock bolt to attach the inductor. I need to source a vinyl bolt, because a magnetic bolt inside the inductor is a no-no. So I'll be swapping that out in the near future. This is the only bit of this project that I still need to finish:

[nspindel]

Now for the binding posts and cup. Another Larry idea, using a delrin backer behind the stock cup. This provides a much stronger mount for the Cardas posts:





Hot glue keeps it airtight:





The Cardas posts, including the SDA connector:

[nspindel]

A few Dynamat and Armacell pics. These are actually from when I used the original CRS drivers to rescue my burned out 1C. not from this project:

[nspindel]

One final pic, everything all laid out for the final assembly:




I'll have more to say about these speakers as they burn in, but even after a few hours they already sound fantastic! Thanks for reading...

[parnold]

Great story and pics! I'm contemplating doing a recap on my 2b's and this just make me want to do it.

[Rick88]

Indeed, great story!! And fantastic work on the speakers, I am sure they sound great!!!

Attachment 75875

[Lasareath]

WOW!!!


Very Nice! Congrats they look great!

[oldmodman]

They really look great.

And probably sound even better than they look.

[PolkieMan]

Excellent write up and pictures!

[chumlie]

Nice job and a great looking setup ya have there.

[Toolfan66]

I wouldn't use a vinyl/nylon bolt, that inductor is to heavy IMO. Use an aluminum bolt if your that worried about it. I have used a nylon/aluminum/stainless/steel bolts and I can't hear one doing more or less then the other, I just left the stainless on in it..

Also when I installed the lexan plate for my crossovers I added a little hot glue to all four sides for a little more security to keep the boards nice and tight. Also if you need to take the boards out a nut driver fits in nicely to do so.

Also don't be afraid to play with the sonic barrier and take a little out, You just might find that they even sound better with less. If you do this I suggest you start by leaving two 8 X 8 squares on just the left and right sides leave the top and bottom free of it. I believe you will find the bass to be more realistic and true, yet keeping the highs clean..

This is something I learned along the way with my 1C's and 1.2tl's

Now with that said, DAMN!!!!! Those are a beautiful set of CRS+'s. Nice Work!!!

[drumminman]

Outstanding documentation, ns! I admire the finished product too.

FYI, several types of stainless steel are non magnetic, such as 316. Bigger hardware stores or marine supply stores will stock these. I wouldn't trust a bolt made of anything but aluminum, brass or ss to secure those big inductors.

[drselect]

Nice work. Enjoy.

[helipilotdoug]

Bravo!! Very nice work! I'm sure you will enjoy. Thanks for posting the detailed description, and photos.

[Conradicles]

Good job!

[Scottinwa]

This thread is nothing short of an all-out storm of ideas and craftsmanship. I know there is no way Polk could have offered the speakers at a reasonable price had all these touches been incorporated (if possible) back in the day. What you have done is elevated the product to an elegant high end product. I can't even imagine the vast difference in sound before and after. WELL DONE!

[DarqueKnight]

Excellent! Thanks for the writeup. These mod threads are aways a joy to read.

[Mike Reeter]

Excellent indeed! You have promted me to get started on removing the vinyl from my 4.1TL's and start the veneer process! Great job, n'joy!

[littlewoodboats]

Beautiful work.

[nspindel]

Thanks everyone! Nice to hear that this is inspiring others to get busy with your own speakers, that's the point!

Point definitely taken about the vinyl bolts, stainless should be much easier since I can just grab them at the hardware store. They had some vinyl bolts at the hardware stores in town, but too short, so I'm glad to hear stainless will work just fine.

@Larry - think you may have misunderstood how I did the Sonic Barrier. I only applied it to the side walls, I did not use any on the top/bottom/front/back.

@Gimpod - Forgot to thank you for suggesting the alternative placements of those Duelands on your boards. Your idea was perfect, they fit great.

[nspindel]

WOW!!!


Very Nice! Congrats they look great!

Thanks Sal! You sold them to the right guy!!

[EndersShadow]

So Neil.......... you wanna find me a pair and upgrade em for me.... since your now a pro at it and all

[nspindel]

Trust me, do it yourself. You'll feel a whole lot better about them if you've got sweat equity in them!

[EndersShadow]

Trust me, do it yourself. You'll feel a whole lot better about them if you've got sweat equity in them!

Oh I know. When I get the CRS+'s eventually I will be doing all this, though I plan to outsource some of the work. Although I love the craftmanship on yours, I like the finish gimpod suggested and if I end up doing a pair may just "borrow" it from him. Although I would do piano gloss black on the entire cabinet including the rear and then see about having the Polk SDA logo re-created as a vinyl decal added on before the paint is clear coated.... That or done by a pinstriper as I think that would look super classy.

[nspindel]

Piano black gloss sounds extremely cool. I would love that, too. But the Mrs. wanted light wood, she thinks they look perfect like this. Which means.... they look perfect like this! WAF is key on a project like this