RTA15 Modifications

geoff727

jimiles wrote: »

Thanks man! Glad you like Let me know if you are working on any projects, or recently completed any. I'd love to see what your up to!

The last completed project I did was the SDA-1C's (in two different threads on the forum). These are they, and I sure do enjoy them.

http://www.polkaudio.com/forums/showthread.php?t=63110&highlight=geoff727

http://www.polkaudio.com/forums/showthread.php?t=71828

Hopefully, I'll be posting the Monitor 5's in a couple weeks with crossover upgrades and a piano gloss finish.

Once again, nice job. I enjoy seeing people do more than just throwing nice caps and resistors at a design. It is a great learning experience for me as well, seeing what people like yourself do.

Cheers,
Geoff

jimiles

geoff727 wrote: »

The last completed project I did was the SDA-1C's (in two different threads on the forum). These are they, and I sure do enjoy them.

I love the new endcaps you made. They look awesome. :cool: The dowels were a great idea, too. I regret having hot beefed up the front baffle of my cabinets before I painted everything inside with SoundCoat.

Keep up the great work!

geoff727

jimiles wrote: »

I regret having hot beefed up the front baffle of my cabinets before I painted everything inside with SoundCoat.

There you go....the perfect excuse to buy another pair of speakers! :rolleyes:

jimiles

geoff727 wrote: »

There you go....the perfect excuse to buy another pair of speakers! :rolleyes:

Don't tempt me, because I'd like to do up a pair of Monitor 5jrs to use for surrounds. That said, Mrs. Jake is going to have a seizure (gross understatement) if I don't finish the SR124 based passive subwoofer that I started last year. Its been sitting directly in the path to the washing machine for nearly 9 months.

http://picasaweb.google.com/jimiles/Subwoofer

geoff727

Jake,

I keep looking at your project and getting more curious about a few things. Mind if I fire off some questions?

I'm interested in the blue Cascade damping compound you used inside the enclosures. I'm curious to know how you discovered that stuff, where it can be bought, what it feels like when it dries (i.e., rock solid, rubbery, like taffy, etc.). Is it something you have used in other speaker projects, or is this a "trial run"?

The foam you used, I see it doesn't have as many 'constrained layers' as BlackHole (which would be quite expensive with that much area coverage). What make of foam is that? Is it difficult to cut in a perfect straight line? I'm interested to know how you arrived at the decision to use that particular foam as opposed to the many others that are available.

On the crossovers, it looks like you used paralleded combos of 10uf's and 2uf's to make the 12uf values. Are those gold-foil-wrapped caps Jantzen's too? For the foil inductors, I'm curious to know what gauges you chose, and your technique for terminating the ends of the foil.

How long have you been into this hobby? For me, about one year now. I think I'm going to save this thread in my favorites list; threads like this one are the ones that I really enjoy. And, by the way, don't worry about the washing machine. I gave up my dining room table set for Polk's and Infinities.

Cheers,
Geoff

jimiles

I appreciate the questions. There are lots of little things I glossed over in my write-up that someone attempting to modify their speakers would want to know.

The goop (technical term) I used to paint the inside of the enclosures is called Cascade VB-1X Damping Compound. I got it at PartsExpress.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=268-256

It goes on like very thick paint. Looks blue-gray going on, and dries dark gray. It feels a little more rubbery than typical latex paint when dry. One gallon was more than enough to do both of my RTA15s. It quieted panel resonance considerably at higher frequencies. Messy, but recommended

I also got the foam from PartsExpress. Blackhole is likely a technically superior product, but the 13 acres of surface area inside these cabinets suggested a more frugal approach!

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-535

Unfortunately, the price of this stuff appears to have exploded since I bought mine last year. It smoothed out the midrange nicely. At the current price, I might not wallpaper every square inch of the enclosure like I did.

After applying the Cascade and the Sonic Barrier, the midbass was as flat as a pancake and the midrange was also much smoother. It's one of those improvements where you initially think, "Oh crap, I just ruined my speakers" but once your ears adjust to the flatter sound, you realize how much more accurate they are...and how colored what you were listening to before was.

As I said earlier, what I REALLY should have focused more attention on is reinforcing the front baffle.

I'll make another post about the caps and such...stay tuned.

ben62670

I used a rubberized latex driveway sealer on mine. It worked very very good, and it is real cheap. Later I discovered if you mix some sand into it it helps deaden even more.
http://www.polkaudio.com/forums/showthread.php?t=53273&page=4
Post 119

jimiles

Hi Again Geoff,

There are three types of capacitors in the crossover. The red 10uF caps are Jantzen Z-Superior, the 2.2uF are Obbligato (dry film copper-cased version) and the black oil cans are 10uF Obbligato film in oil.

I read the Tony Gee cap shootout to get an idea what I wanted. I am now a firm believer in mixing capacitors. The Jantzen's are on the bright side of neutral, and the Obbligato's are on the warm side. Mix them together, and you are left with just "really nice sounding capacitor."

Overall, I really like the Obbligato caps; the copper casing is not foil; it's massively thick. That capacitor weighs a ton. They have recently changed their production a little, so I can't say that the new ones are as good as the old ones I have. The film/oil caps are not the absolute last word on resolution, but are seriously smooth. Oh, and did I mention dirt cheap :cool:

Guys still running non RDO tweeters might try running the Obbligato caps to take the edge off. These are not radically more expensive than the Sonicaps that everyone here is enjoying so much.

I'd love to see some guys/gals experimenting with ClaritySA, Obbligato, and Jantzen. I understand that we all recommend the Sonicaps because there is just zero chance that a new Polk modder will install Sonicaps and be disappointed. If I were looking for a "next level" I might use a ClarityMR to bypass a Jantzen Z-Silver. That project will unfortunately remain on hold pending a check of my lottery numbers! So many cappies, so little time

Guys running and liking Sonicaps/Mills who want to try a drug-dealer expensive component would be well advised to give the Duelund silver-graphite resistors a try. They sound every bit like a $20 resistor. I used Mills before and loved them, but the Duelunds are out of this world :cool:

jimiles

ben62670 wrote: »

I used a rubberized latex driveway sealer on mine. It worked very very good, and it is real cheap. Later I discovered if you mix some sand into it it helps deaden even more.
http://www.polkaudio.com/forums/showthread.php?t=53273&page=4
Post 119

The sand is a fantastic idea!!!

ben62670

jimiles wrote: »

The sand is a fantastic idea!!!

Too bad I found that trick out after I did my monsters:(
The rubberized latex driveway sealer is about $25 a five;)

Face

The thinner Parts Express foam works well also.

ben62670

I know I went from a high pitched ring to a thud when a piece was treated with the sealer. Like liquid dynamat;) Try it on a scrap piece of wood for HaHa's

Face

jimiles wrote: »

If I were looking for a "next level" I might use a ClarityMR to bypass a Jantzen Z-Silver. That project will unfortunately remain on hold pending a check of my lottery numbers! So many cappies, so little time

I went from Sonic Caps to Claritycap MR's in a pair of my Tannoys. The MR's are more dynamic, extended, musical, and even have a lower floor. I would only recommend using them in tweeter shunt caps though, unless you have money to burn.

As for Duelund resistors, I'm still waiting to receive mine, the values I need have been on backorder.

ben62670

I have a whole bunch of caps, and resistors here to do a pair of 3.1's, and 1.2's. I am doing it a little different this time. You'll see in the pics;)

geoff727

jimiles wrote: »

I read the Tony Gee cap shootout to get an idea what I wanted. I am now a firm believer in mixing capacitors.

On an upcoming Infinity project, I am going to use a Black Gate AC topped with a Mundorf Silver/Oil, a combo recommended by the very-heplful-very-talkative-we-all-know-who-he-is man at Soniccraft.

jimiles wrote: »

I'd love to see some guys/gals experimenting with ClaritySA, Obbligato, and Jantzen.

Well, within the next couple of weeks I'll be finishing up a pair of Monitor 5's re-capped with ClarityCap PX's. These were done to a careful budget for a friend of mine, so the SL2000 tweeters will still be in there. I will certainly post some impressions.

jimiles wrote: »

Guys running and liking Sonicaps/Mills who want to try a drug-dealer expensive component would be well advised to give the Duelund silver-graphite resistors a try. They sound every bit like a $20 resistor. I used Mills before and loved them, but the Duelunds are out of this world :cool:

I've been curious about those. I'm glad to know of someone who has used them with great success. Now I might have to try them.


Your and Ben's recommendations of these damping compounds is giving me food for thought for the next project (the Infinity's). Thanks for all the links to these products!
Geoff

ben62670

Keep us posted, and take pics. I forgot where I bought the sealer. It was Lowe's, or HD. Just make sure it is rubberized latex. The asphalt based materials have solvent in them that can separate you cones from their surrounds. Give the stuff one, or two days to dry completely! I did two coats, and on the second coat I installed the poly batting to the wet sealer. This helps hold it in place;)
Ben

geoff727

ben62670 wrote: »

Keep us posted, and take pics. I forgot where I bought the sealer. It was Lowe's, or HD. Just make sure it is rubberized latex. The asphalt based materials have solvent in them that can separate you cones from their surrounds. Give the stuff one, or two days to dry completely! I did two coats, and on the second coat I installed the poly batting to the wet sealer. This helps hold it in place;)
Ben

Good info, Ben. Thanks!

jimiles

geoff727 wrote: »

Well, within the next couple of weeks I'll be finishing up a pair of Monitor 5's re-capped with ClarityCap PX's. These were done to a careful budget for a friend of mine, so the SL2000 tweeters will still be in there. I will certainly post some impressions.

Geoff

The PX are at a very tasty price point, so I look forward to hearing your impressions. :cool:

Soverign

Howdy, this is an old thread, but thought I would ask you about the resistor idea across the woofer terminals for an passive radiator in rta 15 tl? Thanks for the real good write up you did on your 15's! I have an pair also, in black, I use for front surrounds with RTI 70's in the rear.....I am curious about the passive idea, as I may have to change mine out, and Polk does not make the passive radiators for these anymore......Thanks for any help

jimiles

You want a relatively low value resistor, as you are trying to mimic the output impedance of an amplifier. I'd start with something like 2 ohms and work around from there. Having never tried this myself, I can't say how much of a difference you'll notice. I assume that if it's good enough for Sonus Faber, it's probably good enough for us.

Let us know how the experiment works out. As the world's supply of Polk passive radiators dwindles, the need for a go-to replacement/upgrade is rapidly approaching.

I also have always harbored a fantasy of using some PVC to make four dedicated enclosures for the 6 1/2 drivers and converting the tens to active drivers. I've done so much work to inside of my cabinets that there's no going back to try something that radical. If I ever find a sketchy pair in a pawn show, I might give that idea a try, though!