External LSiM703 crossover modification

I've learned so much from this forum and this is an attempt to contribute a little back, a few photos follow the lengthy write up.

I started planning this project over a year ago and I barely finished about a week ago (life happened). I’ve done internal crossover mods for four other speaker models, but after seeing VR3’s LSiM703 internal mod I decided it would be best to go external due to the capacitor and inductor component count. I decided to fabricate my own enclosure for cost and size flexibility. Fabricating and painting the enclosure took up nearly 90% of my build time since I haven’t worked on a wood project since middle school, this was my first time working with MDF, and I initially did not have all of the tools needed to complete the project the way I wanted it.​ Tools that I acquired to complete this project: router, drill press, bar clamps, 90 degree corner clamps, LCR meter, and 4wire low ohm meter.

Neotech OCC copper in Teflon insulation was used for all wiring. 18ga wire was used inside the crossover enclosures. 16ga wire was used inside the speakers and terminated with gold plated copper fastons/quick disconnects. 4 pole speakon connectors, with litz braided 16ga wire, were used to attach the crossovers to the speakers. Vampire gold plated copper binding posts were used.

Metalized polypropylene capacitors were used all around: Sonicaps in the highs and mids (exception of a larger value Erse cap that was placed in an LCR filter). In the woofer section a Dayton capacitor was used due to size. The woofer capacitor would have been from Erse, but they removed the cap from my order (without notifying me) since they were out of stock of the desired value, and would remain out of stock for a while.

Air core inductors from Erse and Jantzen were used in all positions. Some needed to be unwound to closely match stock values. Care was taken to keep the inductors at 90 degree angles or to keep them distant, in the case of the smallest inductors. Measurements were made with an LCR meter and a low ohm meter.

Run of the mill Mills non-inductive resistors were used all around. One of the resistor leads had a faulty weld and snapped off when it was slightly bent to be in line with the body, the deviation was only 10 degrees or so. The good folks at Sonicraft replaced it free of charge! They said they’ve only heard of it happening one other time.

Crossover components were mounted with zip ties and silicone to a 0.25 inch lacquer coated MDF board. Standoffs were made with cut pieces of half inch oak with brass threaded inserts, threaded with glue. The enclosure was made of 0.5 inch MDF, held together with butt joints and Titebond II. External edges were shaped using a 1/8th inch router bit. Rear panels for the crossover enclosures and speakers were made of 0.25 inch oak panels, A 1/4 inch round over bit was used on the four corners of the panels, the panels were then sprayed with lacquer. Recesses for the panels in the crossover enclosures were created with a 1/2 inch router bit. The lid was secured in a similar way as the crossover board, MDF pieces were glued to the top internal corners with threaded inserts for the lid fastening screws.

The original paint/finish for the enclosures was high gloss black lacquer. The edges were filled with Titebond II and sanded smooth, surfaces coated with multiple layers of Rustoleum filler primer, with sanding in between, resulted in a smooth surface with few imperfections. Rustoleum gloss lacquer in the spray can was then applied with unfavorable results. I was unable to attain a consistent smooth glossy finish throughout using the Rustoleum lacquer. I ended up sanding down to bare wood and just moving to a hammered finish (I become impatient). The hammered finish turned out pretty well. It required very little prep, just a coat of primer and two coats of paint. Surface imperfections and joint seams disappeared, it is to be determined if they will show through when the weather changes.

All screws, nuts, washers, and threaded inserts were non-magnetic (brass and stainless steel).

Since completion they have been burning in with my new amplifier and LSiM706c (it dwarfs the LSiC it replaced, it even dwarfs my LSiM703s). I have a little over 215 hours on the modded LSiM703s now, but I still haven’t done any critical listening yet, but I am definitely happy with what I have heard so far (even prior to the amplifier change). I would have to do a side by side with the stock crossovers for a true comparison.

With stock crossovers flash and no flash photos:
8ynyq5p8mbv0.jpg
jbj0vh3ne8oc.jpg

With the lids in place:
e6o9fg68cb8t.jpg

The rear speaker panels, sitting in the recesses for the original binding post plates, with my DIY speakon cables are in place:
mprutoco18t8.jpg

My cluttered suboptimal set up, excuse the mess. The LSiM706c's cloth bag is under the speaker, for the time being, until I place proper feet:
y5spvmqcceon.jpg

Without grills:
e3jo6hiqb0j0.jpg


Next project, new speaker stands sized for the LSiM703s.

Comments

  • drumminmandrumminman Posts: 3,372
    Nice work - moving the Xovers outboard seems like a nice touch given the size of the speakers and the number of components. I've used the hammered finish paint on a large drum hardware case- that stuff is forgiving and very tough.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
  • EndersShadowEndersShadow Posts: 16,903
    MAN that looks CLEAN! The size difference is by no means subtle lol.

    As a though, have you looked if the 706 is wallmountable? If not what plans do you have for feet? I ask because these puppies are fairly cheap and would help you out, though wallmounting would be the better option IMHO.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • Mikey081057Mikey081057 Posts: 6,639
    nice
    My New Year's resolution is 3840 × 2160

    HT:Polk LSiM 706 LSiM 705's VR3 LSiM 703's LSiM 702's| Marantz AV7704 | Sunfire TGA-7401 | Oppo UDP 203 | Sony PS4 Pro| Directv Genie HD DVR | Samsung 75" Q8 QLED | SVS PB13 Ultra | MIT EXP 2's (Fronts & Center)

    ManCave: Parasound Halo A21 | Parsound Halo A52+ | Marantz AV7002 AV PrePro | Usher Dancer Mini-x DMD's | Usher BE-616 Center | SVS Ultra Surrounds | SVS SB4000 Sub | SVS SB2000 Sub | Oppo UDP 203 | MIT Shotgun S3's | PSAudio Stellar GCD | Music Hall MMF 5.3se TT w/ Soundsmith Carmen | Mytek Brooklyn DAC+ | Lumin U1 Mini | HP Elite Slice PC | ROON'd for life | Samsung 50" SUHD TV | Sony PS4

    Patio | Polk Atrium 8's | Yamaha R-N303BL |

    Office |Cocktail Audio X14 | KEF LS50 | Peactree Nova 125SE |

    Bedroom | Focal 905's | Chromecast Audio |

    Garage | Polk Monitor 5B's

    Closet Yamaha M80 | 2 Polk MP3K subs| Yaqin MC100B with Shuguang Treasures KT 88's & CV181Z's | Tesla E83CC's | Marantz 2252B | Marantz 2385 | Bluesound Node |Polk SDA SRS 2.3 |
  • Mikey081057Mikey081057 Posts: 6,639
    very nice work
    My New Year's resolution is 3840 × 2160

    HT:Polk LSiM 706 LSiM 705's VR3 LSiM 703's LSiM 702's| Marantz AV7704 | Sunfire TGA-7401 | Oppo UDP 203 | Sony PS4 Pro| Directv Genie HD DVR | Samsung 75" Q8 QLED | SVS PB13 Ultra | MIT EXP 2's (Fronts & Center)

    ManCave: Parasound Halo A21 | Parsound Halo A52+ | Marantz AV7002 AV PrePro | Usher Dancer Mini-x DMD's | Usher BE-616 Center | SVS Ultra Surrounds | SVS SB4000 Sub | SVS SB2000 Sub | Oppo UDP 203 | MIT Shotgun S3's | PSAudio Stellar GCD | Music Hall MMF 5.3se TT w/ Soundsmith Carmen | Mytek Brooklyn DAC+ | Lumin U1 Mini | HP Elite Slice PC | ROON'd for life | Samsung 50" SUHD TV | Sony PS4

    Patio | Polk Atrium 8's | Yamaha R-N303BL |

    Office |Cocktail Audio X14 | KEF LS50 | Peactree Nova 125SE |

    Bedroom | Focal 905's | Chromecast Audio |

    Garage | Polk Monitor 5B's

    Closet Yamaha M80 | 2 Polk MP3K subs| Yaqin MC100B with Shuguang Treasures KT 88's & CV181Z's | Tesla E83CC's | Marantz 2252B | Marantz 2385 | Bluesound Node |Polk SDA SRS 2.3 |
  • gcegce Posts: 2,178
    Very cool...can't wait to hear your final thoughts after burn in.
    Anaheim Hills CA,
    HT 5.1: Anthem MRX 720 / BDP-Denon DBT1713UD / Polkaudio LSiM703 / W4S mAmp's / Polkaudio LSiM706c / Polkaudio LSiM702F/X's / SVS PC12-NSD / Panasonic TC P55VT30

    2 Channel: Rogue RP-5 / WireWorld Electra power cord / Marantz TT-15S1/ Ortofon - Quintet Black MC / Marantz NA8005 DAC / W4S mAmp's / Synology DS 216+ll-4TB / Polkaudio LSiM703
  • F1nutF1nut Posts: 42,966
    Beautiful crossover work, well done sir!

    If I may, to obtain a proper high gloss finish you have to finish the finish regardless if it's applied from a rattle can or pro spray gun. This involves wet sanding and polishing compounds. The other thing I'd like to mention, never use silicone. The out gases are corrosive as it cures.
    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

  • blehmboblehmbo Posts: 180
    edited December 2014
    Thanks for the feedback folks.

    As a though, have you looked if the 706 is wallmountable? If not what plans do you have for feet? I ask because these puppies are fairly cheap and would help you out, though wallmounting would be the better option IMHO.

    I was considering just sticking on some regular 3M rubber feet, but the product you listed is interesting. I will look more into it. Do you have experience with their foam isolation pads?

    As for wall mounting, I'm sure it can be done with the proper mount, but it lacks mounting holes in the power port backing like the LSiC.

    F1nut wrote: »
    If I may, to obtain a proper high gloss finish you have to finish the finish regardless if it's applied from a rattle can or pro spray gun. This involves wet sanding and polishing compounds. The other thing I'd like to mention, never use silicone. The out gases are corrosive as it cures.

    Thanks for the input. I assumed it should have looked somewhat glossy after four coats, certain areas were and others were dull. I may have been mistaken for assuming it would turn out as smooth as the Deft spray lacquer I used elsewhere, which is a nitrocellulose lacquer. I'll have to do more testing on scrap MDF.

    I was concerned about the corrosiveness of the silicone during curing. I did a test on a few of the inductors by applying a thin layer to the side that would mate with the board. I didn't see any discoloration through the clear silicone after 48 hours (cure time is listed as 24, but it still smelled like vinegar). I suppose it's possible that it still could have affected the wiring of the inductors. I wasn't too concerned about the resistors or caps since they have thicker insulation. The crossover boards sat outside of the enclosures for over a month before installation, for ventilation and due to the boxes not being finished. ;)
    Is it something I should still be concerned about? I would have went with hot glue, but I wasn't confident that it would be able to hold the heavy inductors over time.
  • F1nutF1nut Posts: 42,966
    edited December 2014
    I don't know that exact chemical nature of the Rustoleum lacquer, but since it says the valve can be cleaned with mineral spirts, it is not nitrocellulose lacquer. At the same time Deft isn't really nitrocellulose lacquer either as it contains additional chemicals. I hate the smell of that stuff. Whatever the Rustolem is I would say you'd need 10 coats minimum to build up the finish.

    As for the silicone, once it has finished gassing out any corrosion concern is gone.
    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

  • ken brydsonken brydson Posts: 7,558
    F1nut wrote: »

    Once it has finished gassing out any concern is gone.

    That's what my wife said...

    HT/Main- Panny 50" G10 Plasma, Pioneer SC-1222k AVR, Panny DMP-BD60 BDP, Polk LS90 mains, CS350LS center, LS/fx side surrounds, LS50 surround backs, SVS 25-31PC+ sub, Harmony One

    Office Rig- Marantz 2252B, Denon 2910, Kenwood KD2070 TT, Polk RTA 12B's/ RTA8t
  • Moose68BashMoose68Bash Posts: 3,599
    Nice project and well done!

    Congratulations!

    How do you like the sound?
    Family Room, PS Audio PW Transport, DirectStream DAC w/Bridge II; AQ Sky XLRs, McIntosh MC 220 Tube Pre; AQ Sky XLRs, CAT 600.2 Dualmono Amp, Morrow SP7 Speaker Cables, SDA SRS 1.2tls (RD0198s, Dreadnought, Black Hole 5, Acousta-Stuf, Dynamat Extreme, JBWeld. Vr3 Mods: "The Abbot" Monastery-Level Xovers, Custom Internal Wiring, Binding Post Plates, & SDA ICs).

    Exercise Room, Wadia 171 iPod Dock, PS Audio PerfectWave MkII DAC w/Bridge II, AQ Sky XLRs, Perreaux PMF3150 Amp, Dreadnought, Supra Rondo 4x2.5 Speaker Cables, SDA 1Cs (Vr3 Mods Xovers).

    Synology 713+ NAS on Gigabit LAN serving PW MkII DAC & DirectStream DAC.
  • DSkipDSkip Posts: 16,216
    F1nut wrote: »

    Once it has finished gassing out any concern is gone.

    That's what my wife said...

    That's assuming it ever finishes.
  • VR3VR3 Posts: 23,486
    Those turned out great!

    Good job!
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • blehmboblehmbo Posts: 180
    I'm not much for leaving detailed reviews, so I'll keep it short. After having about 350 hours or so on the crossovers and tweaking speaker placement, I finally had some time to sit down and really listen to them. All I will say is, in my far from perfect room, I'm very impressed by the improved detail and soundstage of the modded 703s.

    Maybe the next project will be room treatments rather than new speaker stands.
  • F1nutF1nut Posts: 42,966
    I'm thinking you should do the center channel next.
    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

  • Excellent. Thanks for sharing.
    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • DSkipDSkip Posts: 16,216
    VR3 wrote: »
    Those turned out great!

    Good job!

    Your sig makes me miss Mark.
  • hello, I know this is an thread , but do you have the values for capacitors and coils?
    Maybe the schematic ...Thank you
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