Modifications to the RTA 15TL

BSUfbfan

There is a single SL3000 on Ebay right now... snag it and then let us know where you live so one of us can help you install it and i'd updrade the caps at the same time

bcwsrt

mrwirez wrote: »

Hello Polkies! Long time lurker. I'm looking for someone that rebuilds the RTA-15TLs. I don't know the first thing about it. I bought the speakers new in 1991 and they sat for the last 5 years as we've been busy. I recently brought them up and they sounded ok. Then I blew an SL3000 Tweeter. So it's time for an upgrade. I contacted the fellow that used to do them on from here and eBay, but no longer does that work. Any ideas? Thanks.

I think you are going to get a lot of recommendations to swap the SL3000s out for the latest generation RD0198-1s as your first upgrade. I did this a few months ago now. I honestly didn't notice a very significant difference (maybe a little less sizzle on the very top end), but I also upgraded my amp around the same time, so it is hard to know for sure. I only say all that to offer up one of my SL3000s if you want to stay with those to get back up and running as you consider mods. You can have either the original February 1992 dated one I have, or the August 1996 warranty replacement. Just cover shipping cost for me via PP F&F. The two do look different. The earlier one has a "blacker" dome, whereas the replacement is more silver in color. I'll post photos if you're interested in going that route.

As far as all the other possible mods, I'll let the experts here chime in. Oddly, I was just getting ready to start a thread on what is going on with the refresh of my own RTA-15TLs which I also purchased new, when I saw your post. Mine's going to be a pretty minimalist approach compared to what you see in this thread and others here, but the recommendation to let everyone know at least your general location is a good one. I ran into the same thing with the fellow you are talking about, but ended up getting help from a member about 30 miles away from me. The folks on here have a ton of experience and knowledge and are more than willing to help.

Fermenter

New to this forum, I hope some are still here to comment.
Long time Polk fan I just acquired a pair of RTA 15T.
I do plan on using the crossover mod from here as wall as upgrading the tweeter to the 0198.
Inspection and cleaning complete, drivers all with 1990 dates and stamped 15T in black over red SDA/ CRS?
But not the tweeters, they are also stamped over but the date is a few years older and they are SL2000's.
Assuming they had been replaces as used.
Cabinets were in great shape in walnut , I taped them off and am applying tung oil.
One grill cover had been wet at one time and is swollen at the bottom...need a couple od mounting posts also.

Very excited to get started !

pitdogg2

The SL2000 tweeters AFAIK were never used in the RTA15tl (there was never a RTA15T). They would have came with the SL3000 tweeters.

Welcome to the forum!

Fermenter

Thank you Pitdogg2, I assumed as much with the research I had done about the tweeters. They are definitely coming out. But i do have the RTA15T serial number stickers on the back of the cabinets, not the RTA15TL. This topic has been exhausted for sure other places on the internet. Its only in the labeling.
The only differences I have found in the research is the shape of the crossover board had changes with time and internal bracing.
It appears the pair I have do have all the internal bracing.

pitdogg2

Originally the T stood for tower. The RTA11T had the sl2000 tweeters and a pedestal under the cabinet. I believe the RTA 15t release was held up at the time so they could release both the RTA11tl and RTA15tl with the new sl3000 trilaminate tweeters. The TL designation was for the trilaminate tweeters.
Your XO should match the RTA15tl schematic. Trust me those little boards take some ingenuity and taller stand offs for the newer larger poly caps, but as you see it can be done.

skrol

pitdogg2 wrote: »

The SL2000 tweeters AFAIK were never used in the RTA15tl (there was never a RTA15T). They would have came with the SL3000 tweeters.

Welcome to the forum!

True. The RTA15TL only came from Polk with the SL3000. Some early 15's were labled RTA15T but they had the SL3000.

boston1450

skrol wrote: »

pitdogg2 wrote: »

The SL2000 tweeters AFAIK were never used in the RTA15tl (there was never a RTA15T). They would have came with the SL3000 tweeters.

Welcome to the forum!

True. The RTA15TL only came from Polk with the SL3000. Some early 15's were labled RTA15T but they had the SL3000.

Even my boxes are labeled RTA15t. They are tl. Upgraded the tweeters is a bonus & worth every penny

boston1450

Fermenter wrote: »

New to this forum, I hope some are still here to comment.
Long time Polk fan I just acquired a pair of RTA 15T.
I do plan on using the crossover mod from here as wall as upgrading the tweeter to the 0198.
Inspection and cleaning complete, drivers all with 1990 dates and stamped 15T in black over red SDA/ CRS?
But not the tweeters, they are also stamped over but the date is a few years older and they are SL2000's.
Assuming they had been replaces as used.
Cabinets were in great shape in walnut , I taped them off and am applying tung oil.
One grill cover had been wet at one time and is swollen at the bottom...need a couple od mounting posts also.

Very excited to get started !

@Fermenter

Fermenter

Boston; I saw that on the drawings too, along with a hand written note that later models didnt get the poly switch.
Ordered the RD0198-1 pair last night, deciding on capacitor and resister brands.

F1nut

RESISTOR

Fermenter

Finally got some time to work on this project. Cleaning oiling is done. Got to the bottom of an issue with my 2220B and started listening to these.
Very happy with the condition of the bass drivers, clean all the way down to the known tubby Polk bottom end. Fortunately my room allows me to space them some from the back wall.
Listened with the wrong tweeters first to get a baseline. Swapped in the RD0's. I pretty much noted the same as the OP here as they were even more edgy in the upper mid range.
So then I sat and mulled over replacing the inductors feeding the woofers.
Had some issue with the caps being sold out so spent some time on that too.
In the end I decided to replace the woofer inductors and got all the crossover parts ordered.
Popped in Cosmic Messenger to listen to the first track only.....ended up listening to 4.
The bass on that one really meshed well on these speakers..
Wondering about these old caps, the poly switches and my hearing....I feel there is little above 8 or 10k coming out of these..
Now that old Marantz with 20 WPC drove these things to "Call the Police" levels with ease.

I will post up some more thoughts after I get a listen with the updated crossover.

Cheers!

pitdogg2

The old Polks really thrived on high current amps so do not sell yourself short.

skrol

Fermenter, are you sure yours have the poly switches? Some of the early release ones had them but they were elinated in later versions and the 1.5 ohm resistor was increased to 2 ohm.

Fermenter

Pitdogg2, 2 systems going but I am fairly sure everything is ending up in the living room.
RTA s are hooked to the 2220B run full range for the time being. I dont want to blow the tweeters overdriving the 2220.
I have a 100WPC (66??) Harman Kardon integrated main amp for the high pass that must go to repair again.
Low pass duty is a Marantz 240.
I would like to run the 240 full range with the RTA.s for a while but at the moment would have to carefully run straight from the variable output of the CD player....I dont have an extra pre amp.
I may pick one up soon.
Are you suggesting I am missing out without more power on tap?
Cheers!

Fermenter

Stan, yes this is a pair of earlier models: poly switches, round crossover boards, 1.5 resistor and RTA 15T (not TL) labels on the back, however they are new enough, and look so, to have all the internal bracing as far as I have been able to tell.
Considering tweeter fusing after the crossover and wondering if any affect on sound quality.

pitdogg2

Considering tweeter fusing after the crossover and wondering if any affect on sound quality.

I'm normally against that, but the way you're running them with different amps or intergrated amps on each pair of binding post probably a good idea. A good Parasound, Sunfire, Aragon or other high current amp would be a better choice. I'm not sure what you're trying to do or accomplish by what you are doing.

Fermenter

Pitdogg2, Trying to accomplish?
I wanted a larger speaker than my Polk 4.6's for my living room and the 2220B.
I wanted to move much or all of my basement system to the living room.
Get two units serviced.

Looking at all kinds of older speakers for sale I ran into the RTA's and didn't want to pass them up.

I am just running the small Marantz till I can get the HK fixed.

I dont think I will be using the active crossover and subs with the RTA15's.

If the HK and RTA15TL dont sound well together I will look into your amp suggestions.
As well I have been told older, larger Yamaha receivers sound well too.

The HK at 100WPC and the Marantz 240 at possibly 120WPC should have plenty of current, we will see what the sound is like.