Modifications to the RTA 15TL
Comments
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I did the passive radiator modification today, as described on page one of this thread. Basically, this involves removing the SW104 passive radiator with the most weight on it (called "low resonance" by Polk), swapping the SW100 front "high resonance" one to the back, and using an SW105 passive in the front.
Here are some pictures of the passive radiators. The SW105 has a small mass in the center, the SW100 has a larger mass, and the SW104 has two of these masses stacked on top of each other. There is no real difference otherwise in their construction when viewed from the rear.
Here is one of them next to my Dayton/Advent Frankenspeakers.
Regarding my comment above about people complaining over what caps or resistors I used. It wasn't intended to upset or offend anyone. I too have done a lot of crossover work in my time, I've been into this hobby since I was probably around 10 or 11. Other kids used to read comic books, I used to read HiFi magazines. The fact is, pretty much any cap would be an improvement over 30+ year old electrolytics that have dried up. Everyone has their favourite flavour of caps, each to their own. It would be a dull old World if we all liked the same. The other fact is, I'm pushing 50 now, so I probably couldn't hear the difference between Mills and Dayton resistors. The mind is a very strange and peculiar thing, if it's telling us that one cap, inductor, or resistor sounds better than another one, we can't argue with that.
We're all cool, right? Like Sir Richard Starkey AKA Ringo Starr would say : "Peace and love, peace and love".
Lee.
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Who? Fluffy?
He's been off his food a little bit lately. He tries to drink milk, but it goes right through him. -
At least you don't have to worry about shedding.
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Hi, I debated posting this here v. posting it as a new topic. I opted for here but if you guys think it should be a new topic feel free to let me know and I can move it.
Question. Specifically regarding this Decato Mod (but could be a general discussion as well), what result would you get from using 16 awg copper foil inductors over the 16 awg wire-wound air core inductors? Also, what would be the result of using either a 1.70 mH and/or a 1.80mH inductors (readily available stock sizes) over the seemingly oddball 1.75 mH inductors?
Same questions relating to the 19 awg 0.22 mH inductors...
As I said these particular questions are specific to the Decato Mod but I am very interested in this as a general discussion on the topic as well. I would just like to better understand the effects of these changes in any instance (changes in awg, mH, wire v. foil construction, etc.).
Thanks for your perspectives and experience. -
I just moved this to a new topic "Crossover Questions (Inductors)" in Vintage Speakers hoping to get more views and comments. Things seem to happen pretty quickly on this forum so the fact that no one has chimed in after 14 hours or so I thought it best to move it. In hindsight I should have just started there anyway. Please go there to comment...
Link:
http://forum.polkaudio.com/discussion/182247/crossover-questions-inductors#latest
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Hi, All
I bought my RTA 15TLs back when they first came out and about fifteen years later, looked into whatever it might take to maintain and improve them. That's when I found this forum, which gave me a lot of great advice. I'm here now after all this time to thank everyone, especially decato, F1Nut, and VR3.
Getting the silk dome tweeters was a no-brainer, and I figured that I'd have new crossovers built for me using decato's mod, but didn't follow through back then. When I moved from NYC to Tucson ten years ago, I revisted this thread, and got in touch with VR3 to do the mod. That was nine years ago, and I think it was his first RTA 15 mod. He did a great job and here's his thread on it:
https://forum.polkaudio.com/discussion/122245/rta15tl-mod-thread)
I sent him the crossovers with the internal wiring, we discussed the design and agreed on the parts (including new wire and binding posts). He put them together really well, point-to-point, and they fit perfectly. I put the cabinets on new brass points, a bit taller in front. Put some banana plugs on my old 12-gauge wires, and I was set. They sounded great immediately, and burned in very nicely.
I started out as a classical musician, became a music critic and record reviewer back in the days of LPs, did a lot of recording back in the days of 1/2" tape, moved on to make a decent living at last (programming, technology, banking, finance) so I could afford nice things like the Polks, and finally "retired" as the COO of an art museum. I've done recording all along the way (classical and jazz) and am fairly demanding when it comes to sound.
With the modified crossovers, the RTA 15s are rich and detailed, nice and even bottom to top, nothing missing, strained, booming, or shrill. Very natural and revealing without sounding clinical, they suit my ears and the music I listen to exceptionally well. I figured it was time to come back here just to say how pleased I am with the great sound I continue to get out of these speakers, with all of your help. Thank you!
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This is probably a stupid question.... But do the speakers remain at 8 ohms after the crossover mods? I'm assuming the answer is yes.
I just performed the modification on one speaker, and it is now reading 4 ohms across the input terminals. -
If just switching caps and resistors yes it should stay at 6-8 ohms whatever the factory value was. If you switched inductors then yes it can go down.
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I replaced the L1 inductor in the HP circuit from the 0.4 to the 0.22 as indicated in the provided schematic. I was still expecting the same overall impedence though. I don't see any shorts or opens. All solder joints appear clean and intact. Not sure what to do next here...maybe just hook it up to an amp with good internal protection and give it a listen?
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This is probably a stupid question.... But do the speakers remain at 8 ohms after the crossover mods? I'm assuming the answer is yes.
I just performed the modification on one speaker, and it is now reading 4 ohms across the input terminals.
You are measuring resistance not impedance. You cannot obtain the nominal impedance with a DVM.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Good point F1nut.
I'm going to finish the other crossover and measure that one. Assuming they're both consistent, I'll hook them up and see if they sound full range. I have a old Denon AVR 2500 that has good over current protection and I also don't care about it. That will be a quick and easy way to find out if I wired something incorrectly. Wish me luck 🤞😃 -
Another hint: if the speaker isn't producing sound, during the measurement, you're not measuring impedance.
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Its sounds great! I hooked up both modified and original and listened to them for about an hour. The stock configuration had WAY more midrange and harshness. The modified speaker sounded natural and balanced. I can't wait to finish the other one and position them semi-permanently.
False alarm. All is well 🙂 -
I'm glad to hear that these mods are still bringing joy to listeners!
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They sound incredible on vinyl tooRandy-Maine
2ch-RTA15tl crossover upgrade
by David WMG
Yamaha cr1000 cr2040
HT-Yamaha Parasound Acurus
MIT BJC Cs1000p Polk Rotation -
Okay... Another question. I have been enjoying these reborn speakers for the past few weeks as my primary 2-channel system and I realized that I did not reverse the polarity on the 198 tweeters. Can anyone explain to me the purpose of that phase inversion? I can't imagine these sounding better than they currently do... What am I missing?
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Can anyone explain to me the purpose of that phase inversion? I can't imagine these sounding better than they currently do... What am I missing?
A second-order crossover will put the four woofers' and single tweeter's signals out of phase with one another, causing a dip in the frequency response centered on the crossover frequency. By inverting the polarity of the tweeter, the response of the woofers and tweeter will be summative. You should take the time to fix your crossover. You'll notice better driver integration and a more cohesive midrange. Let me know how it works out. -
Here's a picture of what changing the polarity of the tweeter can do:
KEF 207s / Coda Continuum / SST Thoebe II / Oppo BDP-105D / Technics SP-15 w/SAEC WE-308SX & Ortofon AS-309 arms / Ikeda 9C2 & Dynavector XX2 Mk II carts -
Wow, okay. That freq response improvement is more that I would have ever guessed. I'll crimp new connectors on today and flip them. Thanks guys. I'll post my thoughts afterwards. I've been listening to them at least an hour per day for a month, so any significant change should be noticable.
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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.
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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 timeSDA SRS 2.3
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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.Brian
One-owner Polk Audio RTA 15TL speakers refreshed w/ Sonicap, Vishay/Mills and Cardas components by "pitdogg2," "xschop" billet tweeter plates and BH5 | Stereo REL Acoustics T/5x subwoofers w/ Bassline Blue cables | Rogue Audio Cronus Magnum III integrated tube amp | Technics SL-1210G turntable w/ Ortofon 2M Black LVB 250 MM cart | Sony CDP-508ESD CD player (as a transport) | LampizatOr Baltic 4 tube DAC | Nordost & DH Labs cables/interconnects | APC H15 Power Conditioner | GIK Acoustics room treatments | Degritter RCM -
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 !Main 2 Channel System:
Yamaha CDX660, Harman Kardon 6650R
Paradigm X-30 Active Crossover
Marantz 240, Audax HM210GO with Klipch Horn Tweeter (Home Built)- Main Speakers,Peerless 831727, 10 inch pair loaded into Transmission line cabs -Subs
Extras:
Polk RTA15TL,Marantz 2220B,Polk 4.6 -
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! -
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.Main 2 Channel System:
Yamaha CDX660, Harman Kardon 6650R
Paradigm X-30 Active Crossover
Marantz 240, Audax HM210GO with Klipch Horn Tweeter (Home Built)- Main Speakers,Peerless 831727, 10 inch pair loaded into Transmission line cabs -Subs
Extras:
Polk RTA15TL,Marantz 2220B,Polk 4.6 -
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. -
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.Stan
Main 2ch:
Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.
HT:
Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60
Other stuff:
Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601 -
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 pennyRandy-Maine
2ch-RTA15tl crossover upgrade
by David WMG
Yamaha cr1000 cr2040
HT-Yamaha Parasound Acurus
MIT BJC Cs1000p Polk Rotation -
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
Randy-Maine
2ch-RTA15tl crossover upgrade
by David WMG
Yamaha cr1000 cr2040
HT-Yamaha Parasound Acurus
MIT BJC Cs1000p Polk Rotation -
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.Main 2 Channel System:
Yamaha CDX660, Harman Kardon 6650R
Paradigm X-30 Active Crossover
Marantz 240, Audax HM210GO with Klipch Horn Tweeter (Home Built)- Main Speakers,Peerless 831727, 10 inch pair loaded into Transmission line cabs -Subs
Extras:
Polk RTA15TL,Marantz 2220B,Polk 4.6
