Modifications to the RTA 15TL

2456789

Comments

  • decatodecato Posts: 150
    edited April 2008
    You have an early release of the RTA 15TL. You can tell by
    1) The large, circular circuit board used in the crossover.
    2) The use of a 1.5 ohm rather 2.0 ohm resistor in the high-pass filter.
    3) The convex rather than flat dustcaps on the drivers.
    4) The lack of side braces in the cabinet.
  • BSUfbfanBSUfbfan Posts: 199
    edited April 2008
    decato wrote: »
    You have an early release of the RTA 15TL. You can tell by
    1) The large, circular circuit board used in the crossover.
    2) The use of a 1.5 ohm rather 2.0 ohm resistor in the high-pass filter.
    3) The convex rather than flat dustcaps on the drivers.
    4) The lack of side braces in the cabinet.

    Gotcha! kinda confusing though... even the owners manual says 15T. Maybe originally they were going to designate anything with the trilaminate just with a "T".

    My drivers are the same as yours though... MW6503's & passive's with the flat dustcaps.

    You're right, it did have the 1.5 ohm resistor, and I swapped it out for a 2.7 as per the schematic and it seems spot-on.
    SDA SRS 2.3
  • F1nutF1nut Posts: 39,620
    edited April 2008
    even the owners manual says 15T

    Interesting! That's the first I've heard of that one.
    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."


  • FaceFace Posts: 14,714
    edited April 2008
    F1nut wrote: »
    Interesting! That's the first I've heard of that one.

    I found a pair locally some time last year, the owner was asking $650 firm. I believe he claimed the box had RTA-15T written on it. I should contact him again and see if he came down on his price and to confirm no L.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • heiney9heiney9 Posts: 23,694
    edited April 2008
    In the end the important thing is these have always used the sl3000 tweeter which is the better tweeter compared to the sl2000. The "T" and "TL" designation is a minor issue and a typical Polk "mystery".

    Thanks Decato, I'll be adding you precise info about the 15's to my internal database. :)

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • decatodecato Posts: 150
    edited April 2008
    The earliest advertisement I can find for the RTA series is from the October 1987 edition of Audio Magazine. The title reads The Genius of Matthew Polk Towers Over the Competition. Therefore, I believe the t in RTA 8t and 11t (and the very first release of the 15 we are discussing in this thread) stood for tower. I guess this is how they differentiated the original Monitor 11 from the new tower design with the same number. Interestingly, this ad shows what we know as the RTA 8t as the RTA 11t! I have attached a PDF of this ad.

    The second generation of RTAs were labeled TL, after the new SL3000 trilaminate tweeter.

    -Brian
  • BSUfbfanBSUfbfan Posts: 199
    edited April 2008
    Here is the RTA-15T addendum that was inserted into the owners manual for the RTA-11T & RTA-8T. It states that the 15T has the Polk SL-3000 trilaminate. hmmmm.

    Picture010.jpg
    SDA SRS 2.3
  • BSUfbfanBSUfbfan Posts: 199
    edited April 2008
    Well, after @90 hours of break in I sat infront of the 15's today and ran through a bunch of my favorite CD's.... Very impressive. The overall frequency response from top to bottom is much smoother now! Also with the raised crossover point on the tweeter, the speakers take a lot more volume before distortion, in fact, with my 200wpc Aragon I reached half volume and the Polks played extremely loud without a pop or a crackle.

    My CRS+ definitely have a wider, more defined soundstage, but I think the 15's have a fuller sound in the midrange/midbass......nothing like having 8 drivers :p. Overall this crossover upgrade is a no-brainer for the cost (<$200 for tweeters, caps, coils, resistors), and I feel is a must for the 15TL owner that is planning on an upgrade to the RDO tweeters.
    SDA SRS 2.3
  • decatodecato Posts: 150
    edited April 2008
    That's great! I am glad to hear that you are pleased with the modifications.
  • acerjacacerjac Posts: 28
    edited November 2008
    Decato,

    I am thinking about modding my 15's with the same layout as you came up with. I am new to this and am wondering what you think of just replacing the cap's and resistors? I would leave the stock inductors alone.

    Thanks for your opinion.
  • decatodecato Posts: 150
    edited November 2008
    acerjac wrote: »
    I am new to this and am wondering what you think of just replacing the cap's and resistors? I would leave the stock inductors alone.

    If you wish to perform the modification, at the very least you will need to change the inductor in the high-pass section of the crossover. BSUfbfan did this and was pleased with the results. Be sure to use the mod from 03-29-2008.
  • acerjacacerjac Posts: 28
    edited December 2008
    I replaced all the caps and resistors on my crossovers on my 15's and oh my what a difference. I used a combination of solens and clarity caps. A quick question though, I used a 2.5 ohm resistor instead of the stock 1.5 ohm. They sound great but I am just wondering if it is something to consider. Thanks

    Mark
  • FaceFace Posts: 14,714
    edited December 2008
    acerjac wrote: »
    I replaced all the caps and resistors on my crossovers on my 15's and oh my what a difference. I used a combination of solens and clarity caps. A quick question though, I used a 2.5 ohm resistor instead of the stock 1.5 ohm. They sound great but I am just wondering if it is something to consider. Thanks

    Mark
    The 1.5ohm resistor and 12uf cap are part of a contour circuit, which is used to flatten the response curve. It may not make a night and day difference, but I would replace it with the correct resistor when you have a chance.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • decatodecato Posts: 150
    edited December 2008
    acerjac wrote: »
    A quick question though, I used a 2.5 ohm resistor instead of the stock 1.5 ohm. They sound great but I am just wondering if it is something to consider.

    The 2.5 ohm resistor will reduce the tweeter's output at the lower end of its operating range. I have attached images of the crossover's transfer function with a 1.5 ohm and 2.5 ohm resistor in the circuit.
  • acerjacacerjac Posts: 28
    edited December 2008
    You guys are great
  • acerjacacerjac Posts: 28
    edited December 2008
    Where do you get this information? Are you doing these curves yourself?
  • decatodecato Posts: 150
    edited December 2008
    acerjac wrote: »
    Where do you get this information? Are you doing these curves yourself?

    I use LspCAD to generate these graphs.
  • acerjacacerjac Posts: 28
    edited February 2009
    I replaced the 2.5 resistor with the 1.5 and a clarity cap sa in place of the solen. The sound is smoother on top. The clarity cap does a great job in the high pass filter.
  • phandnotphandnot Posts: 18
    edited May 2009
    How would this x-over upgrade work with the SL-3000 left alone? Would this even be a good idea? Just curious.
    Also, I have the RTA-15TL model, but the boxes they came in new have RTA-15t on the side.

    RTA-15t.jpg

    Weird.
    Downstairs Theater System
    Polk Audio RTA-15TL fronts
    Polk Audio M5jr+ rears
    Polk Audio CS350(LS) center
    Homemade Sony sub/Kenwood Amp (being replaced w/2 Paradigm)
    Toshiba HD-D3 HD/DVD
    JVC RX-6000v (being replaced w/Integra DTR-9.9)

    ...and HD/DVR, vcr, cassette, cd, and various game systems.
  • acerjacacerjac Posts: 28
    edited May 2009
    By that you mean you would leave the high pass circuit alone correct? If you are going through the trouble of rebuilding the x-overs why not do the whole thing? It would only make the sl- 3000 tweeters sound better. My speakers have the upgraded tweeters and they sound great with the x-over rebuild. As for the T vs TL issue, it is discussed above. I think my boxes say TL on them.

    Mark
  • phandnotphandnot Posts: 18
    edited May 2009
    What I meant was, will the x-over upgrade/rebuild work without upgrading the tweets, and left my SL-3000s in there. Or does the upgrade just work better with the RDOs. I do like the sound of a good silk dome...

    As far as the T - TL thing goes, I know there is no difference, I was just including a picture of the "T" boxes to show that they do exist! Mine say T on the box, but the speakers themselves show the correct TL.

    Any info on the tweets will help!

    Thanks.
    Downstairs Theater System
    Polk Audio RTA-15TL fronts
    Polk Audio M5jr+ rears
    Polk Audio CS350(LS) center
    Homemade Sony sub/Kenwood Amp (being replaced w/2 Paradigm)
    Toshiba HD-D3 HD/DVD
    JVC RX-6000v (being replaced w/Integra DTR-9.9)

    ...and HD/DVR, vcr, cassette, cd, and various game systems.
  • ben62670ben62670 Posts: 16,077
    edited May 2009
    The upgrade would work for either tweeter.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
  • F1nutF1nut Posts: 39,620
    edited May 2009
    Weird.

    Not really. Polk used up whatever excess materials they had around, be it boxes, labels, cabinets, etc.
    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."


  • skrolskrol Posts: 2,618
    edited May 2009
    Here is an interesting tidbit of information regarding the RTA15T that came from the designer when I asked him about the RTA15T vs TL. They were likely renamed as the RTA8T and RTA11T were upgraded to TL and it may detract from RTA15T sales. It is interesting what goes into choosing a name. From the designer:

    "...I guess marketing changed the name later to TL. ... Original RTA8 and RTA11 had different tweeter ... new tweeter SL3000 came up just before I started design on RTA15T. So RTA15T started with tri-laminate tweeter ... but 8 & 11 went from T to TL when they were upgraded. Your assumption is correct RTA15T and RTA15TL are the same.

    RTA15 was originally being scheduled and introduced as RTA14, I worked on it as RTA14 ... we had some literature printed ... when one day national sales manager came and said stop, stop, can't call it RTA14 ... he learned from Asian distributor that number "four" means on Chinese "death" and that we wouldn't sell any speaker ... (after RTA11 we didn't want to call it 12 because of Monitor 12, didn't want to call it 13 because of western superstition, couldn't call it 14 because of Chinese superstition and the next number was 15)"
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Monster HTS3600-MKII, Grado SR-225i

    HT:
    Denon AVR-888, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW10, Marantz UD5005, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, TSi100; Pioneer: CT-6R, PL-530; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, Polk: RM7, Parasound C/PT-600, HCA-800ii
  • LPNLPN Posts: 42
    edited May 2009
    Superstitions play into model numbers? ... interesting. I guess the 9-11 designation would never come to be.

    Cheers, Barrie.
  • skrolskrol Posts: 2,618
    edited May 2009
    The superstition has even played a role in the design of buildings and factories. Many buildings skip the 13th floor. I saw a program where some Chinese factories have 5 smoke stacks instead of 4 even if the fifth is a dummy.

    I guess the Germans are not superstitious. They still make Porsche 911's.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Monster HTS3600-MKII, Grado SR-225i

    HT:
    Denon AVR-888, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW10, Marantz UD5005, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, TSi100; Pioneer: CT-6R, PL-530; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, Polk: RM7, Parasound C/PT-600, HCA-800ii
  • decatodecato Posts: 150
    edited May 2009
    phandnot wrote: »
    How would this x-over upgrade work with the SL-3000 left alone? Would this even be a good idea? Just curious.

    No, I have tried the SL3000 with the modified crossover, and it does not sound as good as the RD0198-1.
  • acerjacacerjac Posts: 28
    edited July 2009
    Hey does anyone know where I could get the inside cabinet dimensions for the srs 3.1's? I would like to build a pair.

    Mark
  • rhubarb9999rhubarb9999 Posts: 2
    edited February 2010
    I have a pair of 15TLs that I like a lot. I have found the top end to be a little 'in your face' and the bass a little muddy. I fix some of that with EQ, but I am interested in trying the mods in this thread.

    I have all the parts from a set of Monitor 10a's. The tweaks mention using the PRs from the Monitor 10 and 10b .. is the 10a different?

    Also, I have the Peerless tweeters out of the 10a's. Would these be a suitable upgrade to the 3000 tweeters that are currently in the 15TLs?

    Thanks
  • dorokusaidorokusai Posts: 25,231
    edited February 2010
    Just buy the replacement silk dome tweeter and no, you cannot use the Peerless tweeter.
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!