4.1TL Modification for 1989 version SDA CRS+

DarqueKnight
DarqueKnight Posts: 6,760
edited August 2010 in Vintage Speakers
I had been mildly intrigued by the idea of modding my 1989 version CRS+'s according to the 4.1TL specification since I first discovered it while compiling information for the first edition of the SDA Compendium (way back in the winter of 2002). Similar to the interconnect cable mod, it wasn't something that had a high priority in my audio life.

This simple modification, which only entailed adding a 5.6uF capacitor in parallel with the 2.7 ohm resistor in the tweeter circuit and replacing the RDO194-1 silk dome tweeters (SL2000 replacements) with the RD0198-1 silk dome tweeters (SL3000 replacements), has evolved these 17 year old speakers to a higher level of performance. I was only expecting some modest improvements in high frequency response. What was achieved was a night and day improvement in the overall sound of the speakers. But, before I talk about that, I would like to say a few words about the CRS+'s prior modifications.

This pair of 1989 model CRS+'s, which is one of three pairs I own, was purchased used in 2002. They are currently used in my home office audio/video system. They came with nice light oak veneer cabinets. However, I subjectively thought the cabinets would look better with teak veneer, so I had the cabinets re-veneered at a local cabinet shop. In addition to the new cabinet veneer, I also made the following changes:

1. The stock electrolytic capacitors and cermet resistors in the crossover circuits were replaced with AudioCap polypropylene film capacitors and Mills MRA-12 wire wound resistors.

2. The polyswitches were left on the circuit boards, but were shorted out.

3. The stock SL2000 metal dome tweeters were replaced with RD0194-1silk dome tweeters.

4. The rather thick, rather heavy, coarse textured grille cloth was replaced with a lighter, thinner, silkier textured black knit fabric.

5. The stock binding posts were replaced with Cardas CCGR-S gold plated copper posts.

6. The stock 18 gauge SDA interconnect cable was replaced with a custom SDA interconnect made from Monster Z2 Reference speaker cable (12 gauge conductors).

All modifications except the binding post upgrades and new cabinet veneer provided improvements in sound quality.

Modification Procedure

The SDA driver (MW6511) of each speaker was removed to gain access to the crossover circuit board. The driver wires and binding post wires are attached to the crossover circuit board with wiring harnesses and easily disconnect. The tweeters and associated wiring harness were removed.

While holding the crossover circuit board with one hand, the circuit board's retaining bolt at the rear of the cabinet was removed with a 5/32" hex wrench.

Parts-Vendors-Prices:

RD0198-1 tweeters: Polk Audio, $48.00 each.
Sonicap 5.6uF* 200 VDC polypropylene film capacitors: Soniccraft, $12.40 each.
Sonicap 0.001uF 600 VDC polypropylene film capacitors: Soniccraft, $4.00 each.
Buchanan aluminum wide spade clip connectors (part #70072): Home Depot, $0.99 for a pack of six.

*The modification specification calls for a 5.8uF electrolytic capacitor, but 5.6uf falls within the 10% tolerance range of the specified part.

I was initially going to replace the 750pF silver mica bypass capacitor with the 0.001uF polypropylene capacitor, but I decided to just remove the 750uf capacitor altogether. Upon reconsideration, I didn't think that a high quality bypass capacitor was required when using a high quality film capacitor. I removed the polyswitches, since they were shorted out and were not active in the circuit anyway. Finally, I ran a jumper wire from the postive terminal of the input wiring harness to the lead of the 12uF capacitor. This bypassed a wire jumper and the circuit traces for the polyswitch.

Replacing the RD0194-1 with the RD0198-1 required a little improvisation. The RD0194-1 has two narrow metal tabs that are attached to the wiring with narrow spade clips. The RD0198-1 has a narrow tab and a wide tab. No problem with attaching the stock narrow spade clip. I cut off the white wire (negative terminal) narrow spade clip and replaced it with a wider one. I had originally just tinned both the wide tab and the flat back of the other narrow spade clip, then soldered them together. This was quick and easy, and saved me a trip to Home Depot, but I though that I might appreciate quick disconnect capability in the future.

The Sound

These are my initial listening observations as I just performed the modification yesterday:

1. The bass is cleaner, more defined, and has more impact. Change the tweeters and the bass improves significantly. Interesting isn't it? The RD0198-1 tweeters are evidently a much better match for the existing CRS+ drivers.

2. The speakers sound larger and faster. Vocals have more presence and sound more natural.

3. The overall clarity of the speakers is significantly improved.

4. The soundstage is projected a couple of feet farther in front of the speakers.

5. The treble is smoother, more defined, and more detailed without a hint of edginess or grain.

6. The impedance was raised a little bit as evidenced by my having to increase the volume a little bit (from -44 to -42) to achieve the same pre-mod average sound level of 80 dB. The DC resistance of the speakers measured the same as before the mod: 3.9 ohms.

Prior crossover mods have demonstrated optimum sound quality after two to three weeks of listening (60 to 100 hours). I will submit supplementary observations in a few weeks.

Associated Equipment

The improvements provided by the CRS+ TL mod were vividly evident, even with equipment of moderate resolving power:

Sony TA-E9000ES preamp/home theater processor,
Sony DVP-S9000ES CD/DVD/SACD player,
Adcom GFA-5500 power amp,
Monster Z3 Reference speaker cables,
Audio Research coxial digital cable,
Monster Z200i interconnect (SACD out).

Picture Captions

1. CRS+ with silky black grille cloth.
2. Front-top-side view of teak veneer cabinet.
3. Closeup of teak veneer.
4. Cardas binding posts.
5. Custom 12 AWG SDA interconnect cable.
6. Modification parts.
7. Modified crossover.
8. Sideways view of CRS+'s in home office system.
Proud and loyal citizen of the Digital Domain and Solid State Country!
Post edited by DarqueKnight on
«13

Comments

  • ESavinon
    ESavinon Posts: 3,066
    edited November 2006
    As usual, this is just another excellent post coming from raife.
    Bravo! I'm waiting on the opportunity to purchase a pair of crs + to perform these modifications.
    SRT For Life; SDA Forever!

    The SRT SEISMIC System:
    Four main satellite speakers, six powered subs, two dedicated for LFE channel, two center speakers for over/under screen placement and three Control Centers. Amaze your friends, terrorize your neighbors, seize the audio bragging rights for your state. Go ahead, buy it; you only go around once.
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited November 2006
    I'll sell you my newly modded CRS+'s for $5,995.14. This price includes a Club Polk discount of 20%.:)
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • ESavinon
    ESavinon Posts: 3,066
    edited November 2006
    I'll sell you my newly modded CRS+'s for $5,995.14. This price includes a Club Polk discount of 20%.:)

    Is that $5,995.14 in mexican pesos? ;)
    I'll add .85 for shipping to ny.
    Do we have a deal? :D .
    SRT For Life; SDA Forever!

    The SRT SEISMIC System:
    Four main satellite speakers, six powered subs, two dedicated for LFE channel, two center speakers for over/under screen placement and three Control Centers. Amaze your friends, terrorize your neighbors, seize the audio bragging rights for your state. Go ahead, buy it; you only go around once.
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited November 2006
    I'm sorry. I stated the initial price in US dollars. I meant to specify Euros.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • F1nut
    F1nut Posts: 49,711
    edited November 2006
    Excellent!!!
    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

  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited November 2006
    Jesse,

    Did you experience an improvement in bass response when you did your 4.1TL mod?
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • amulford
    amulford Posts: 5,020
    edited November 2006
    Excellent play by play. I've bookmarked this for reference. I'm curious as to how you know the 1989 manufacture?
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited November 2006
    If you look at the picture of the crossover in my first post, you will notice a little white sticker near the front edge of the circuit board. That sticker has a date of "2/6/89". The 6-1/2" drivers also have 1989 date stamps on the rear. The 1989 CRS+ is the only version that used the combination of a MW6510 stereo driver and a MW6511 SDA driver.

    This mod might work with the 1987 version CRS+, since the only difference between the 1987 version and the 1989 version is that the 1987 version used a MW6503 stereo driver and the 1989 version used a MW6510 stereo driver. If someone wanted to try this mod with the 1987 CRS+, I would recommend asking Polks engineering department if it is feasible.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • F1nut
    F1nut Posts: 49,711
    edited November 2006
    Jesse,

    Did you experience an improvement in bass response when you did your 4.1TL mod?

    Yes, quite a bit actually.
    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

  • Zap Rowsdower
    Zap Rowsdower Posts: 2
    edited December 2006
    I just completed this modification last night on a stock pair of '89 CRS+ I recently inherited from my father.

    The difference is amazing, just like F1nut & DarqueKnight noted.

    I encourage anyone who is thinking about performing this upgrade to do so. And don't be discouraged if you've never done any soldering before - Last night was my first time!

    *Many* thanks to F1nut & DarqueKnight for their informative posts!!
  • BobMcG
    BobMcG Posts: 1,585
    edited December 2006
    Dang they're beautiful! Nice work.
  • Dennis Gardner
    Dennis Gardner Posts: 4,860
    edited December 2006
    Would a version of this simple upgrade be available for my SDA1Cs since they have the same 6510 & 6511 drivers used? I haven't been into the crossovers on my speakers yet, but would consider doing it instead of the common RD0194-1 tweeter change.
    HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable

    2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable
  • nadams
    nadams Posts: 5,877
    edited December 2006
    DK- Those speakers are beautiful! Now you have me interested in trying to get my SDA's refinished... how much did the refinishing cost you?
    Ludicrous gibs!
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited December 2006
    Would a version of this simple upgrade be available for my SDA1Cs since they have the same 6510 & 6511 drivers used?

    Polk's engineering department would have to answer this.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited December 2006
    nadams wrote:
    ... how much did the refinishing cost you?

    Cabinet refinishing: $175.
    Crossover capacitors and resistors: $208.
    Three pairs of Cardas CCGR-S binding posts: $96.
    RD0198-1 tweeters: $96.
    Custom SDA interconnect cable: $107.
    Grille cloth: $5.

    Total modifications/upgrades: $687.
    Increase in aural satisfaction: Priceless.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited December 2006
    Based on the remarkable results from modding the CRS+'s in my home office, I gave my other two pairs of CRS+'s the treatment. A pity I didn't do this sooner...such good sound.:D
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • Deadof_knight
    Deadof_knight Posts: 980
    edited December 2006
    The wood work in the ole homestead is nice ..........




    Big fan of wood everywhere !!!

    ps. was the house built for the speakers or vise versa ?
    :cool: " He who dies with the most equipment wins Right ? "

    Denon 3300 Adcom 535 BBe w/sub out 1 pr 4.6s 2 pr of 4 jrs Recent additions Samsung Lns-4095D LCD, Samsung hd-960 DVD, Monster HT-5000 Power center
    ,HPSA-1000 18" sealed DiY home sub.:D
    Black Laquer 1.2tl's w/ upgraded x-overs and Tweets BI-Amped with 2 Carver tfm-35's Knukonceptz 10ga cables
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited December 2006
    A little bit of both.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • dcoil
    dcoil Posts: 153
    edited December 2006
    DarqueKnight, I should be getting a pair of SRS's (original, in every way). I've read about your 2nd edtion compendium and I'd like to get a copy. Can't pm yet (almost there), so I'm posting to this thread. I know you moded your 1.2 TL's, and I was wondering how my upcoming project would compare - both to work to be done, and how you think the finished product will compare?
    SDA SRS modded: X’ovrd, de-polyed, inductorized, interconnectorized, re-posted, dynamited, RDO’d, spiked, gasketed, ringed (Larry's), and grill cloth blinged! Done this on my own? Not a chance. Thanks to Raife and all who forged easy to follow upgrades. At least a 100% improvement in sound and my personal listening pleasure! :cheesygrin:Pass XP-10 preamp, Parasound A21 amp, Pioneer Elite DV-58AV (Ric Shultz modded), Audioquest Sky IC's, No longer need my Sunfire sub after mods...
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited December 2006
    See this thread: Improvements to the SDA SRS

    I have sent you a PM.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited February 2007
    I prefer not work on other people's speakers, but I will be happy to answer any questions you have. There are a couple of forum members who have expressed interest in doing such work (Madmax is one).
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • Refefer
    Refefer Posts: 1,280
    edited February 2007
    Whoever re-vinyled your speakers did a knock up job. How much does something like that cost anyways? I'm interested in doing that to a couple of my speakers.
    Lovin that music year after year.

    Main 2 Channel System

    Polk SDA-1B,
    Promitheus Audio TVC SE,
    Rotel RB-980BX,
    OPPO DV-970HD,
    Lite Audio DAC AH,
    IXOS XHA305 Interconnects


    Computer Rig

    Polk SDA CRS+,
    Creek Audio 5350 SE,
    Morrow Audio MA1 Interconnect,
    HRT Music Streamer II
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited February 2007
    See post #16 for costs. BTW, the speakers were redone in real wood veneer, not vinyl.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • Refefer
    Refefer Posts: 1,280
    edited February 2007
    See post #16 for costs. BTW, the speakers wereredone in real wood veneer, not vinyl.

    Explains why it looks so good. I gotta do some priceshopping, that's impressive.
    Lovin that music year after year.

    Main 2 Channel System

    Polk SDA-1B,
    Promitheus Audio TVC SE,
    Rotel RB-980BX,
    OPPO DV-970HD,
    Lite Audio DAC AH,
    IXOS XHA305 Interconnects


    Computer Rig

    Polk SDA CRS+,
    Creek Audio 5350 SE,
    Morrow Audio MA1 Interconnect,
    HRT Music Streamer II
  • hoosier21
    hoosier21 Posts: 4,408
    edited February 2007
    this mod would work with a pair of 2B, right? They share the same crossover.
    Dodd - Battery Preamp
    Monarchy Audio SE100 Delux - mono power amps
    Sony DVP-NS999ES - SACD player
    ADS 1230 - Polk SDA 2B
    DIY Stereo Subwoofer towers w/(4) 12 drivers each
    Crown K1 - Subwoofer amp
    Outlaw ICBM - crossover
    Beringher BFD - sub eq

    Where is the remote? Where is the $%#$% remote!

    "I've always been mad, I know I've been mad, like the most of us have...very hard to explain why you're mad, even if you're not mad..."
  • DarqueKnight
    DarqueKnight Posts: 6,760
    edited February 2007
    I don't know if this mod is applicable to the SDA 2B. Two things to consider:

    1. This mod was only specified for the 1989 version CRS+. While it is true that the 1989 versions of the SDA CRS+ and SDA 2B used the same crossover, they also used different stereo drivers. I would check with Polk's engineering department to see if this mod is applicable to the 1989 version 2B.

    2. If the mod is applicable to the 2B, you would need to make sure you have the 1989 version rather than the 1987 version, which used a different crossover.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
  • Stew
    Stew Posts: 645
    edited February 2007
    Hi all! Life's been hectic and haven't been here in a while. Looked around the other day and this thread caught my eye. It sounds like one of the big improvements from this mod is bringing the vocals forward. I've never noticed recessed vocals on my 2B's (1989 version). Is this only an issue with the CRS+ or have other 2B owners noticed recessed vocals? What are the differences between the RD0194-1 and the RD0198-1, other than the impedance difference, that would contribute to the difference in sound?
    SDA 2B-TL (Sonicap/Solen/Mills, Erse Super Q, Rings, Spikes, No-Rez)
    1000VA Dreadnought
    Dared SL-2000a (Siemens & Halske TM 12AT7WA's, Brimar 5Z4G)
    Jolida JD-100a (Sylvania BP TM Gold Brand 5751's), NAD C275BEE, Blue Jeans

    RTiA3, Onkyo TX-SR605
  • F1nut
    F1nut Posts: 49,711
    edited February 2007
    While Raife is correct that the '87 and '89 versions use a different stereo driver, the basic crossover remains the same and since this mod is strictly for the high frequency circuit, I can see no reason it can't be done to any of the pin/blade CRS+'s or 2B's regardless of year.

    Stew, not sure where you got that the vocals are brought forward, it's the entire soundstage that is. Having said that, I did notice a vast improvement in the vocals with the use of the RD0198-1 vs the RD0194-1, but to use the RD0198-1 you must change the crossover as Raife describes.
    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

  • Stew
    Stew Posts: 645
    edited February 2007
    An earlier post on "SDA SRS 4.1TL Upgrade" mentioned something about recessed vocals but maybe I misunderstood. I'm not sure if I want to bring the soundstage forward but the additional clarity and bass response sounds tempting. The crossover mod associated with this sounds easy but I'd have to buy $100 of tweeters to replace the $100 of tweeters I just bought. At least there's only two!!
    SDA 2B-TL (Sonicap/Solen/Mills, Erse Super Q, Rings, Spikes, No-Rez)
    1000VA Dreadnought
    Dared SL-2000a (Siemens & Halske TM 12AT7WA's, Brimar 5Z4G)
    Jolida JD-100a (Sylvania BP TM Gold Brand 5751's), NAD C275BEE, Blue Jeans

    RTiA3, Onkyo TX-SR605
  • F1nut
    F1nut Posts: 49,711
    edited February 2007
    Ah yes, I remember now. I did notice that when I changed from the SL2000 to the RD0194-1 that the vocals became somewhat recessed. When I completed the 4.1TL mod using the RD0198-1, I noticed that the vocals returned to the proper depth. Perhaps a better choice of wording, instead of more forward would be a deeper soundstage, which I feel is a good thing.
    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