RTA 11TL - recapping/mod

mrbadmf

Hi,
I'm new to this.
So I looked into some of your comments/moddings for the RTA 11TL. Bought them in the early 90's. Blew out my SL3000's at a party a few years later due to an electric surge of some kind. Replaced them with new ones. Until this day I still use them as my main pair of speakers. They're connected to a Pioneer SC-LX85. I had them also connected to Onkyo P-3030 and M-5030. While having better imaging and clarity, the Onkyo now resides in the bedroom, powering a DIY-speakerset (work in progress, with spare parts of different quality - (Original) Peerless tweeters, Monacor woofers, Philips woofers - matched pairs for all). I'm still amazed by the RTA 11TL's clear and natural good sound, although I hear some of the little flaws like described in these forums (A little harshness in some frequencies). So maybe it's a good thing to mod the x-over. After reading I checked on Mundorf site. What I found was this:
Mundorf MCap EVO 12uF 450VDC
Mundorf MCap EVO 15uF 450VDC
Mundorf MCap EVO 33uF 450VDC
Mundorf MRES20-1.50 1.5 ohm.
The used caps in the original x-over are like 12/16/34 uF. Is it necessary to have the correct values? Does this have consequences electronically? Or in the way the x-over works/behaves/filters?
Found GEN I Sonicap in correct values at Sonic Craft. But with a max load of 200VDC.
I'm not into electronics, so any good advice is appreciated... Like how I should calculate caps and resistors on which values of a speaker...

It's a pity there's no archive or link to the vintage speakers on the POLK Audio site anymore. It would be helpful to have schematics and manuals available.

Kind regards,
Luc

Gear:
INKEL MD2200
PIONEER SC-LX85-K
ONKYO INTEGRA P-3030
ONKYO INTEGRA M-5030
TECHNICS SU-V900
PIONEER BD-30-K
PIONEER BD-10-K
PIONEER BDP-440-K
TECHNICS RS-BX646
TECHNICS SJ-MD100
TEAC X-1000R
PIONEER RT-707
AKAI AP-206C
TECHNICS SL-BD20
NUMARK TTX1
POLK AUDIO RTA-11TL
PIONEER S-DJ08
some other stuff...

F1nut

You don't need those high voltage Mundorf caps, the originals are rated at 50V, so anything equal or above is fine. I think you'd prefer the more musical sound of the Sonicap caps verses the tipped up treble of the Mundorf caps.

Some will tell you the 15 and 33 will be fine considering the original +/- 10% tolerances. I say hogwash, you want as exact to spec as possible.

While you're ordering, get the Mills resistors too.

mrbadmf

Thanx F1nut.

Still, it's hard to decide without having heard the difference
Maybe trial and error?
Maybe depending on the style of music to be played. And the type of source. They tend to ease up more to vinyl then cd, where they have more that tendency to harsh in guitar. While playing Tangerine Dream, there's a difference at about 12K depending on the source material, but still there's that little distortion.

The vintage Peerless I use in them DIY speakers have a clear presence, imaging and clarity, and also have a little more treble than the SL3000's. But it can be influenced by the other speakers and x-over I use Specs: https://www.parts-express.com/pedocs/specs/279-179-peerless-buyouts-specifications-46421.pdf.

But as you stated, specs for the x-over are better to be followed in my honest opinion. That is why I asked, to get confirmation. Yet the originals don't seem to have a fatigue. But maybe it's because of the aging of my hearing. (And some Tinitus since childhood - an always present high pitched disturbance between 12K and 18K).

I see there's level precision matching possible at Sonic Craft.

Btw, did you swap your SL3000's for the newer ones?

I am having a hard time trying to find the specs of the SL3000 and the newer RD0198-1.

Surely grateful for your reply.

Kind regards!
Luc

mrbadmf

Btw, the voice coils of the SL3000's are still looking silver, like new. Most of them shown are having a black voice coil. Any comments on that?

pitdogg2

Those 450v caps will be HUGE. It will be hard to place them on the board. The sonicaps are very well regarded here. They will still be larger but way smaller than 450v caps.
I used all sonicaps and mills resistors in my sda's no regrets.

mrbadmf

Thanx pitdogg2!

Been surfing for awile... Seems to me they are the best deal, those Sonicaps.
Just now I was searching for the right Mills resistors... Is it this one? 1.5 Ohm Mills 5 watt MRA-5

F1nut

mrbadmf wrote: »

Btw, the voice coils of the SL3000's are still looking silver, like new. Most of them shown are having a black voice coil. Any comments on that?

The SL3000's came in a silver tone, gold tone and black/silver tone. This was due to the manufacturing process.

mrbadmf

Never seen the gold nor the black here in Belgium But the originals which blew out, changed from silver to black. So I guessed black was bad So now I stand corrected!
Thanx!

F1nut

mrbadmf wrote: »

Thanx F1nut.

Still, it's hard to decide without having heard the difference
Maybe trial and error?
Maybe depending on the style of music to be played. And the type of source. They tend to ease up more to vinyl then cd, where they have more that tendency to harsh in guitar. While playing Tangerine Dream, there's a difference at about 12K depending on the source material, but still there's that little distortion.

The vintage Peerless I use in them DIY speakers have a clear presence, imaging and clarity, and also have a little more treble than the SL3000's. But it can be influenced by the other speakers and x-over I use Specs: https://www.parts-express.com/pedocs/specs/279-179-peerless-buyouts-specifications-46421.pdf.

But as you stated, specs for the x-over are better to be followed in my honest opinion. That is why I asked, to get confirmation. Yet the originals don't seem to have a fatigue. But maybe it's because of the aging of my hearing. (And some Tinitus since childhood - an always present high pitched disturbance between 12K and 18K).

I see there's level precision matching possible at Sonic Craft.

Btw, did you swap your SL3000's for the newer ones?

I am having a hard time trying to find the specs of the SL3000 and the newer RD0198-1.

Surely grateful for your reply.

Kind regards!
Luc

You won't find any specs for either tweeter. They simply are not available.

A little story.....I was given the opportunity to try two RD0198's a long time ago, putting both in the prime position. I called the next day to order a full set. 'Nuff said.

mrbadmf

Sooooo, that's an option!

F1nut

mrbadmf wrote: »

Sooooo, that's an option!

More like mandatory.

mrbadmf

skrol

I did my RTA11TL XO's with Clarity Cap PX for the highs, and Jensen for the lows. I believe I went with Mills for the resistors and swapped the SL-3000 for the RDO198. I also did the Dynamat treatment on the MW and PR baskets, added Sonic Barrier to the upper section above the PRs, and sealed all cabinet seams. Here is the link to my RTA11TL upgrade project: http://forum.polkaudio.com/discussion/73017/rta11tl-upgrade-project/p1

I was amazed at the difference in sound stage. They sound effortless to drive.

mrbadmf

Allright. Great tips.

About the cabinets. I build my DIY with 22mm (about 0.87 inch) MDF panels, doubled them inside at the side panels, so they stiffened up nicely. A lot less resonance there. A lot more weight too, so less vibrations to the floor.
(At high volume, the RTA's tend to dance around on their spikes ).
It might be lessening the inside volume, but I would like to try if it dampens the little woolly sound a bit. Wanna try it this summer if using the right cutouts with the Polk hardware would be an upgrade. I will get to that in time.

But just wondering, has someone tried an adhesive bitumen (or asphalt) coating inside? I know there are high end speaker builders who use it for deadening resonance...

deronb1

Dynamat. Also, if the boards on the 11TLs are the same size as the 8Ts, you wont have a lot of room to work with. I replaced the mylar caps with about same sized Bennic caps. That alone made a big difference, but the biggest difference you will hear will be in the tweeter upgrade.

pitdogg2

mrbadmf wrote: »

Allright. Great tips.
But just wondering, has someone tried an adhesive bitumen (or asphalt) coating inside? I know there are high end speaker builders who use it for deadening resonance...

You might look into blackhole5. A strip on the back panel behind the woofers works well. I wouldn't line the cabinet with it it'll suck the life and music out of the speaker. A little goes a long way. This is used with the dacron not in place of.

mrbadmf

Again, great tips!
Thank you people

F1nut

Just to be clear, do not line your speakers with Dynamat Xtreme as it's the wrong product. However, do use it to damp the driver/PR baskets.

mrbadmf

Okay. I understand. Using it on the baskets will prevent the resonance a bit more. I could try that. But it's not a priority for the moment I'd rather do the caps and resistor as you suggested.
And later on the upgrade of the speakers. (Should I contact Polk if I want to buy them? - This is not America! ).

As for the cabinets I guess they used fibreboard instead of mdf because of the latter's tendency to vibrate/resound more, the first somewhat more absorbent. Been reading some stuff and reviews. Somewhere along the line there was an extended test (should have kept the page) that revealed some resonance slightly above 200Hz coming from the cabinet. Maybe some dampening material in the lower end of the speaker can prevent this phenomenon? Maybe the cabinets should have weighted more, to keep them from dancing around. So shipping costs would likely been the reason to keep the weight down.
Anyway, I got a little Sony sub hooked up to have a somewhat more punchy presence on the bass. I like the EQ on the amp flat But the bass still sounds like coming from te Polks, so I think I adjusted it well...

Again F1nut, thanx for your insights!

Btw, for not being the best speakers, there is strangely enough not many parts to find out here. I guess most of the owners still use their vintage gear