RT55 Crossover refresh

Tbone289Tbone289 Posts: 669
edited August 2014 in DIY, Mods & Tweaks
I refreshed the crossovers in my RTE55s last weekend, and took a bunch of pictures. I thought I'd post them here for posterity. It is worth mentioning that the 4 RT55 crossovers I own are identical in every way to the RT55i crossovers I've seen posted here, with the same cap and resistor values as the RT55i schematic. I believe that the crossover alterations mentioned here and in the schematic took place sometime during the production of the RT55, before Polk began producing the RT55i. Therefore, the only differences between the late-run RT55 and the RT55i are the tweeters and drivers.

Empty cabinet. "RTE" export versions are RT55 models with black oak veneer:

2014-08-24%2008.31.59.jpg

Original xover, "top", showing capacitors C2 mylar, C3 & C4 electrolytics, inductors L1 (air core) & L2 (laminate core):

2014-08-23%2017.00.28.jpg

Original xover, "bottom", showing wire-wound ceramic resistors R1 & R2, C1 poly:

2014-08-23%2017.00.46.jpg

Xover unpopulated, and showing new Mills resistors R1 & R2 relocated to the "top" of the board. This opens up the full bottom side of the board for fitment of the larger film capacitors:

2014-08-23%2017.01.21.jpg

16uf Solen on the LPF (C4):

2014-08-23%2018.08.54.jpg

2x1.5uf Clarity PX in parallel for C1, 9.0uf for C3 in the high-pass:

2014-08-23%2018.08.10.jpg

Fully re-assembled and ready to mount in the cabinet:

2014-08-23%2019.35.05.jpg







2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
Post edited by Tbone289 on

Comments

  • pitdogg2pitdogg2 Posts: 14,606
    Nice pictures....gulp whoops
  • Tbone289Tbone289 Posts: 669
    pitdogg2 wrote: »
    Nice pictures..

    Thanks...
    pitdogg2 wrote: »
    ..gulp whoops

    ? :|

    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • westmassguywestmassguy Posts: 6,445
    Very nice, and creative!
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
    Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
    Interconnect: Furez 10/2 with SpeakONs
    ICs: Custom Furez by Douglas Connections
    Den:
    Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
    Carver CT-3 Pre, Carver C-500

    dhsspeakerservice.com/
    Exclusive Distributor of Gimpod's Custom SDA Circuit Boards

    "And keep her under 70, would you, huh? Betty likes a slow ride"
  • pitdogg2pitdogg2 Posts: 14,606
    edited August 2014
    Tbone289 wrote: »
    pitdogg2 wrote: »
    Nice pictures..

    Thanks...
    pitdogg2 wrote: »
    ..gulp whoops

    ? :|


    They do not show up for me....Gulp whoops..... In case they do for everyone else...goofy face...... in case I'm the only one in that aspect....

    well we all know how well this is working for some of us.

    I can't even copy it and paste to show you what I see on my end.

    just my .02



    Bring back ZITFUL....good grief
  • Tbone289Tbone289 Posts: 669
    edited August 2014
    Ah, that makes sense now that you explain it. It's not working out too well for the most part, is it? I debated on whether it was worth posting at all, but decided I might as well since I took the time to take the pics. They are nice pics, BTW... :\ Geez, the smilies don't even match what you select....

    I can see the pics whether I'm logged in or out, so I'm not sure what the issue is.
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • Tbone289Tbone289 Posts: 669
    edited August 2014
    Very nice, and creative!

    Thanks. I try not to be restrained by the exact location of the original components when i do these. Many times you can relocate things and use different solder points and still keep the circuit intact. Figuring out how its all going to fit is fairly entertaining for me. (I don't get out much ;) )
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • westmassguywestmassguy Posts: 6,445
    Tbone289 wrote: »
    Very nice, and creative!

    Thanks. I try not to be restrained by the exact location of the original components when i do these. Many times you can relocate things and use different solder points and still keep the circuit intact. Figuring out how its all going to fit is fairly entertaining for me. (I don't get out much ;) )
    That's par for the course, especially with the newer Polk crossovers. I lot is crammed on a small circuit board

    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
    Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
    Interconnect: Furez 10/2 with SpeakONs
    ICs: Custom Furez by Douglas Connections
    Den:
    Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
    Carver CT-3 Pre, Carver C-500

    dhsspeakerservice.com/
    Exclusive Distributor of Gimpod's Custom SDA Circuit Boards

    "And keep her under 70, would you, huh? Betty likes a slow ride"
  • Tbone289Tbone289 Posts: 669
    edited August 2014
    That's par for the course, especially with the newer Polk crossovers. I lot is crammed on a small circuit board

    I've only worked on "RT" series so far, but I was actually very pleased when I saw the size of the board in these 55s. There's lots of room to work with compared to the smaller bookshelves like the RT3 and RT25i, or even the RT7. The RT55 has a more complex circuit though, with the 2nd-order LPF.

    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • schwarcwschwarcw Posts: 7,208
    The RTi55s are a great sounding speaker! I'd be interested to hear your impressions of any sonic improvements.

    Carl

  • Tbone289Tbone289 Posts: 669
    The new components haven't had much burn-in time, but noticeable immediately was an improvement in the midrange. A slight chesty, congested quality is now gone, with better transparency and a more focused image.
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • msgmsg Posts: 5,008
    edited December 2014
    Hey Tbone - how are these working out for you? Great photos and nice write-up, btw!
    I disabled signatures.
  • Tbone289Tbone289 Posts: 669
    edited December 2014
    Thanks! ;)

    The improvements I mentioned above still apply. I haven't noticed more improvement over time. I use the speakers for HT though, so I don't listen to them "critically". I'm satisfied with the project simply from the standpoint of increasing the quality and lifetime of the components. So any other sonic improvements are really just a bonus, IMO.
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • Tbone289Tbone289 Posts: 669
    Sorry for the necro--just restoring the pics.

    I refreshed the crossovers in my RTE55s last weekend, and took a bunch of pictures. I thought I'd post them here for posterity. It is worth mentioning that the 4 RT55 crossovers I own are identical in every way to the RT55i crossovers I've seen posted here, with the same cap and resistor values as the RT55i schematic. I believe that the crossover alterations mentioned here and in the schematic took place sometime during the production of the RT55, before Polk began producing the RT55i. Therefore, the only differences between the late-run RT55 and the RT55i are the tweeters and drivers.

    Empty cabinet. "RTE" export versions are RT55 models with black oak veneer:

    31824780187_25a0c17a6c_b.jpg

    Original xover, "top", showing capacitors C2 mylar, C3 & C4 electrolytics, inductors L1 (air core) & L2 (laminate core):

    31824780397_3200607ede_b.jpg

    Original xover, "bottom", showing wire-wound ceramic resistors R1 & R2, C1 poly:

    31824780347_39162e4211_b.jpg

    Xover unpopulated, and showing new Mills resistors R1 & R2 relocated to the "top" of the board. This opens up the full bottom side of the board for fitment of the larger film capacitors:

    32890784428_d04dcb14d6_b.jpg

    16uf Solen on the LPF (C4):

    46713467752_afca786625_b.jpg

    2x1.5uf Clarity PX in parallel for C1, 9.0uf for C3 in the high-pass:

    31824780317_7256e8b5ce_b.jpg

    Fully re-assembled and ready to mount in the cabinet:

    31824780177_844cdccfb7_b.jpg
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • pitdogg2pitdogg2 Posts: 14,606
    HEY I can see those LOL

    Very nice @Tbone289 one of these day that will be me doing my RTi55's
  • Tbone289Tbone289 Posts: 669
    LOL 4 years later you finally get the satisfaction!
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • Tony MTony M Posts: 8,352
    edited January 16
    I thought this was a new thread too until I saw 2014. :o But it's all good to those of us who have Rt55s and might want to upgrade those Crossovers too.
    Most people just listen to music and watch movies. I EXPERIENCE them.
  • Tbone289Tbone289 Posts: 669
    That's my hope. The post was useless without the pics, IMO.
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • Carbo3DCarbo3D Posts: 9
    Tbone289, after doing a 5-speaker shootout with various other Polk speakers I'm really noticing my RT55is have a midrange deficiency, as you described it as "a slight chesty, congested quality". Is this common with the RT55i model? I just picked these up last month and I'm still evaluating, but I don't know if they are known as midrange vampires. What's the word on the street?
  • Tbone289Tbone289 Posts: 669
    edited April 15
    No, I wouldn't say that it's common for the model. But I can think of a couple of things you might keep in mind that could be contributing to the issue:
    1. The RT55i is now over 20 years old. Electrolytic capacitors in the crossovers could be going out-of-spec by now.
    2. Placement. The RT55i, being a rear-ported bass reflex loudspeaker, can sound chesty in the midrange and bloated in the midbass region if it is located too close to the front wall.
    2.1: S/PDIF>Schiit Gungnir MB>Creek Evolution 100a>Ascend Acoustics Sierra-1, HSU STF-2
    5.1: HDMI Bitstream>Denon AVR-1910>polkaudio RTE55, CS350-LS, RT3, HSU STF-2, Visio M55-F0
  • Carbo3DCarbo3D Posts: 9
    Tbone289, now I know why the mids were lacking from my recently purchased pair of RT55i's: when opening up the crossovers to re-cap I discovered each speaker had the 2 ohm resistor burned out and one was missing from its circuit board! In the first photo the resistor is completely gone, while in the second it melted and reattached on its side against the 3ohm. Good grief! Luckily after replacing the resistors and recapping, the speakers now sound terrific. Granted they are "only" being used as my center channel, but believe me, voices are much more natural and defined. No more EQ needed to correct the earlier "congested" sound. Can one of you experts explain what causes a burn out like this? Is it simply overdriven by an amp? dg6g1jbv5uuk.jpg
    5x5awtjjyc8m.jpg
    3hjwa4lt7z55.jpg
  • F1nutF1nut Posts: 42,904
    Clipping will do that. You'll likely find the missing resistor in the Dacron or at the bottom of the cabinet.
    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

  • pitdogg2pitdogg2 Posts: 14,606
    This is the reason why we up the wattage when recapping. 5w3.5ohm would become a 10w or 12w 3.5 ohm resistor. Not much help if you're going to overdrive your receiver or amp into clipping on a continuous basis though.
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