RTA11TL Upgrade Project

F1nut

I'd say you reached a limitation of the power rather than that of the speaker. It takes a lot of power/current to handle deep bass.

skrol

Dang! My stock Volvo car stereo handles it with ease.

skrol

I finally got all my parts for the crossover upgrade and some 1" Sonic Barrier foam for damping. Depending on when the kids go to bed, I may start on thing tonight.:)

Stan

skrol

Nothing is ever easy. Everything was going great. I got the new caps and resistor installed on one of the crossovers. It is a true work of art if I have to say so my self. The only problem... How do I get the damn thing back through the hole? The caps are just too big.

I figure I'll remove the crossover board from the cup, try to slide it through and reassemble from inside the cabinet. It is late, I'll try tomorrow.

Any other ideas?

John30_30

That might be a toughie, as the cup is also soldered to the board, right? I'm not the EE guy here, but one workaround occurs-
Maybe you can solder a couple 2"-4" insulated wire extensions from the points on the board to the + & - points on the cup to give some flex. I'd hate to recommend inserting an extra loop otherwise.

Face

Can you stand them up on their sides?

skrol

Success!:D I was able to unscrew the circuit board from the cup and leaving the wires connected, I was able to slide it through. It was a little tough getting the circuit board reattached to the cup but not too bad.

Since I had all the drivers and PRs out, I also took advantage of the Mighty Tight advice. I had been skeptical about the leak test, pushing on a cone and watching how long to takes to equalize pressure. This stuff makes a difference. Before, it took about 1.5 sec to equalize and now it is about 3 sec. I did also caulk all the cabinet seams which may also factor into the improvement.

I have made all the upgrades to just one of the speakers so that I can compare. The other is stock with the exception of the RDO98 tweeter. The sound difference is amazing. The upgraded speaker is so much more open and detailed. It even shows it dimensionality when played solo. The bass is clean and tight. This has been will worth the money, time and effort.

Now it is time to start on the other speaker.

Stan

skrol

Sorry I meant "Moretite" not Mighty Tight.

ben62670

I mortited 32 driver last night;) 16 more to go...

skrol

I have just about completed my tinkering with the RTA11TLs. The advice that I have gotten here has been great.

What I did:

· Replaced the SL3000 tweeters with the RDO198-1 – These really smoothed out the highs

· Swapped out the electrolytic capacitors for Metallized polypropylene film capacitors MKP (Clarity Cap PX for the tweeter and Jantzen Cross Cap for the MWs)

· Swapped the resistors for non-inductive wire wound (Mundorf MR10). – The crossover upgrades further smoothed out the highs and really opened the sound stage

· Applied some acoustic damping foam to the cabinet interior behind the MWs.- There was not enough Dacron to be applied the way that Polk customer service (Ken Swauger) said it should be. Thanks again Ken

· Applied damping material (Peel-and-Seal) to the baskets of the MWs, PRs and cabinet interior – The cabinet now makes a nice solid “thud” when tapped on the side. Lows and mid-lows are more detailed (string bass and drums)

· Sealed the cabinet seams with RTV and sealed the drivers with Moretight – The speakers are sealed better as shown when gently pressing the PRs in and comparing how long it takes for the pressure to equalize (MWs retract) with and without the Moretight (>3sec vs <2 sec without Moretite). Dang, it more difficult to remove them after Moretite is applied!

In the end I can hardly believe that these are the same speakers. I always liked the sound of the RTA11TL’s but they always seemed slightly harsh in the highs and kind of “in your face”, for lack of a better way to describe. I also never realized how colored the sound had been. The sound now is much more natural yet very detailed and open with an almost 3-dimensional quality. I find my myself carried away by the music like never before. The true test is that I think that my wife has notices too. She usually doesn't pay attention to such things as sound quality but she has suddenly taken a renewed interest in listening to music during the day.

This has been a fun project for me that produced great sonic benefits and I couldn’t me more pleased with the results. The total cost of the upgrades was under $85 / speaker. :rolleyes:Now I need a new project.


Thanks again for all your advice.
Stan


The photo of the upgraded XO is before the elephant snot was applied. I did stake the components down to reduce vibrations.

MillerLiteScott

Nice job, enjoy.

Scott

george daniel

Very nice work indeed,, LOL,, when I read the part about "staked down",,I thought that you were speaking about our resident vampire.;):)

skrol

I know this is digging up an old post (of my own) but I wanted to post a change to my XO upgrade so that others can benefit from my learning.

We can't always find the exact capacitor values in the brand of cap that we are looking for. We end up choosing between living with something close or combining capacitors to get the exact value. I had chosen the later.

Apparently, there are right ways and wrong ways to go about this. My OX calls for a 16uF capacitor in series with the tweeter. In the Clarity Cap Px, I was able to find a 15uF. I had placed a 1uF Clarity Cap in parallel to make the 16uF. This seemed like a good idea. After all, the original had a 12uF electrolytic in parallel with a 4.4uF mylar to make the 16uF.

Later I heard recommendations that it is not a good practice to parallel different values and that you should parallel capacitors that are half the desired value (ie. 8uF ||8uF = 16uF). Electrically, I was figuring "what's the difference"? I played with comparing the configurations in PSpice and it made no difference in amplitude or phase. I also looked at the difference that the 15uF would make vs the 16uF. There is a slight shift in the crossover point.

Yesterday I decided to remove the 1uF caps to see if it would make a difference. It does! I did one first and you could immediately tell something was odd. The one with the 1uF seemed restrained in the upper mid frequencies. I am guessing that it is phase related as the effect would change as I moved side to side between the speakers.

I removed the 1uF from the other speaker and they were balanced and more open and natural sounding than with the 1uF in both. Ever since the original upgrade the sound was much improved but there was something about male vocals seemed slightly off. The speakers also seemed rather listener height dependent (good if I am sitting, less good when standing). both issues are improved with the 1uF caps removed.

I am at a loss as to why 15uF + 1uF is sonically different from 15uF or 16uF or 8uF + 8uF etc. It seems that it must be phase related. Perhaps the PSpice capacitor models that I am using are just too generic to show.

A wise man once told me (as he finished his Pabst), :A day you don't learn anything is a day wasted."
Stan

Face

I'm not sure of the technical reason either, but in the HF or MP circuits, a single cap has always sounded better to me. The two things that stand out the most are better coherence and imaging.

Face

Here's a 16uf for you.

http://madisound.com/store/product_info.php?manufacturers_id=170&products_id=8380

F1nut

A smaller cap charges and discharges faster than a larger cap. In essence, the 1uF is acting as a bypass cap.

skrol

You may be right about the charge/discharge speed. I'll have to ponder it more.

That is a pricey cap. If I get the itch, I may get some Sonicaps. They said that they could do custom values.

Disc Jockey

F1nut wrote: »

A smaller cap charges and discharges faster than a larger cap. In essence, the 1uF is acting as a bypass cap.

This is it right here. No further pondering required. If you have to use two caps, it's best to get them as close to equal values as possible.

agfrost

skrol wrote: »

You may be right about the charge/discharge speed. I'll have to ponder it more.

That is a pricey cap. If I get the itch, I may get some Sonicaps. They said that they could do custom values.

Methinks Face was just busting your balls a little with that recommendation. I've got the Sonicaps for the 12 and 16 uF spots in my 11TLs and have been quite happy.

Jay

skrol

This is potentially some good discussion and not specific to the RTA11TL, so I am going to take this to the DIY, Mods & Tweaks.
Stan

Face

Well, half kidding. I've used them a few times and they do sound amazing, but they're on the pricey side for his application.

skrol

I am truly amazed by what good capacitors can do. This is stuff they don't teach in text books. It would be cool to have a batch of different brands and models to do side-by-side comparisons and figure out why they sound the way they do. I wish I still worked in NASA's parts analysis branch. I used to have the tools at my disposal to do some really cool studies (SEM, EDAX, and automated test equipment).

For my application (and budget) the Clarity Cap PX or maybe the Sonicap will do nicely.

On that subject, would there be benefit to switching the caps to Sonicap? I could use the Clarity Cap 12uF in my Monitor 5As that I want to upgrade.

Stan

Face

From plain old Claritycaps to Sonic Caps, same quality, different flavor.

skrol

Thanks. That is good to know. I might still do it next time they run a special.

Gary VT

@ Skrol and Ben62670: I'm gonna go for it. I've decided to change out the tweeters from the SL3000's to the RDO198's if still available from Polk. I'll also be changing the capacitors and resistors and inspecting the solder points. Your posts in particular are well written and understandable to me.

My reason is that I've noticed some discoloration to the trilam dome on the right channel SL3000 whereas the left is bright and shiny. I can also detect some SQ change to the highs on the right side. Kind of muddled...
Per your suggestion Skrol, I've looked into the Clarity caps and Mundorf resistors. not too expensive but I too am concerned about the rating. 33micro farads vs 34 and 15 vs 16 etc. Thanks Ben for discussing this.
I would also like to consider the internal wiring as an upgrade. Do you have any preference?

As for the room treatment I'm moving the area rug to the front of the speakers to eliminate the floor deflection of the PR's on the hardwood bamboo. I'll let you know how that works. I'm also looking into a higher grade sub that digs deeper than my Hsu VT-1 does.

Another change I've made, I removed the Cambridge Soundworks Bi-pole/Di-poles from the rear surround channel and installed my former fronts. I get more volume and greater frequency response from the rear channel now.

I am however tossed about leaving the RTA's on the A/V system. My boss(wife) is trying to get me to place the RTA11TL's in the parlor and move the model six's to the living room A/V. She likes the sound(range) from the RTA11's when connected to the 2.1 system I've set up for music only with the Yamaha CRX 330. My only concern is that the receiver has only 20W p/c and the Polks may suffer signal distortion from such low power at higher volume. They would be married to a Polk PSW12 in a carpeted, 20' high vaulted cathedral ceiling room. **I made the mistake of testing them there when she was home... But, given they were purchased pre- A/V boom, they may not be complete in an A/V system since I did purchase them for music listening in '91. (I made my decision to buy them listening to both BTO's Blue Collar, and, Tina Turner's Private Dancer)

I'm no electronics type, but you folks have written clear and understandable posts. Thanks!

Outfitter03

Gary VT welcome to Club Polk. A lot of information and questions in the above post.

If you are planning to use these for two channel audio, you will be able to hear a difference in the caps. If you are still looking to get something very good, but not outrageous for caps there is another choice to the Sonicaps. That is Clarity ESA in the 250vdc rating. You will have to be willing to wait for these to deliver, but these caps should top the Sonicaps in performance and at almost the same cost. You would use two 8.2uf caps in parallel for the 16uf position.

http://www.partsconnexion.com/capacitor_film_claritycap_esa.html

For internal wiring the real upgrade comes if the original wiring is damaged or oxidizing. If it is in good shape you probably won't notice much of a difference. Recommended brands are Neotech available from Sonicraft or DH Labs from their site or Ebay. There are a lot of other choices out there. If you are looking to do a wiring change, the binding posts would be as, if not more important. Go with a quality copper post. The Vampire posts are a drop in connector.

http://www.soniccraft.com/products/connections/bindingpost/vampire_bphexcb.htm

A bit less expensive would be these but will require drilling the holes a little bigger.

http://www.soniccraft.com/products/connections/bindingpost/cardas_ccbp.htm

You definitely want something better to power these with in your two channel system.

F1nut

Per your suggestion Skrol, I've looked into the Clarity caps and Mundorf resistors. not too expensive but I too am concerned about the rating. 33micro farads vs 34 and 15 vs 16 etc. Thanks Ben for discussing this.

IMO, saying it is ok to use a 15 when a 16 is called for is simply bad advice these days when it is possible to have high grade caps within 1% tolerance. If you can't find the exact value, use 2 caps in parallel of as equal value as possible.

BTW, measuring the stock caps out of my 2.3TL's shows a 10% tolerance, not 20%.

skrol

I am presently running a single 15uF in each speaker now until I come up with a decent 16uF. I had a 15uF and a 1uF in parallel to make the 16uF and it did not sound right. I still haven't found out why this does not work but it doesn't. PSpice circuit analysis indicates that it shouldn't matter but it does. I probably should have gone with two 8uF in parallel instead.

You can order custom Sonicap in 16uF. This is likely the route that I will take. Just waiting for some extra cash and a Sonicraft sale.

Regarding the internal wiring, the engineer who voiced the RTA11TL cautioned me about changing the Equivalent Series Resistance (ESR) of the wiring and the inductors. The crossover was designed taking that ESR into account. Therefore, stick with the same gauge and lengths if you must.

Enjoy
Stan

Face

skrol wrote: »

I am presently running a single 15uF in each speaker now until I come up with a decent 16uF.

http://www.madisoundspeakerstore.com/mr-cap-630vdc/claritycap-16-mfd-mr-range-polypropylene-caps/

skrol

Face wrote: »

http://www.madisoundspeakerstore.com/mr-cap-630vdc/claritycap-16-mfd-mr-range-polypropylene-caps/

...that are within my budget. Thanks for the link though.