The Alchemy of the Alchemy (Fusion-8 build)

Discussion in 'DIY Speakers and Subwoofers' started by Radorod, Mar 22, 2014.

  1. *** Please let me know if the pictures aren't appearing for you. Thanks. ***

    The Alchemy of the Alchemy

    Here's my story in the hopes of helping or inspiring others who have yet to take the plunge. Rather than documenting it here as I went, I've waited until the end to post everything at once.

    About a week ago I completed a pair of Fusion-8 Alchemy speakers for a home theater currently under construction. They'll be paired with a Fusion-8 MTM center, a pair of Fusion-4 Quad-4s as surrounds, and a single Fusion-4 Quad-4 in rear surround duty. The whole team will be crossed over to a Bill Fitzmaurice design THTLP subwoofer. The theater is a modest 15' x 10', but with the directivity of the horns, close-mounting to the side walls should be possible with proper toe-in and room acoustic treatments. Combined with an acoustically transparent screen a wide 50 degree visual FOV will still be possible, which is what I want. I'm putting a lot of design work into everything from screen material selection and masking, bass traps, acoustic panels, subwoofer integration and a dozen other things, and am looking forward to the result. Selecting the Fusions as the speakers are a big part of all this.

    Some photos of this first finished pair:






    They're not quite as red as the 1000W light used to take the photos make it look. Under typical living room TV viewing lighting they actually look quite dark.

    As far as how they sound - I'll save that for another post. This one's all about how I built them. Hilarously, now that they're done I kind of don't want to hide them behind a screen. Maybe I'll keep them in the living room and order another pair to DuraTex for the HT :)

    Even though I knew they'd be hidden, I took this as an opportunity to practice my wood finishing skills. Or rather I should say 'acquire' new skills, since I've never attempted this level of finish quality before. It was fun and I learned a ton. To summarize, translucent wood dye was sprayed on in 2 coats, followed by 2 toner coats, and then 4 coats of clear urethane. The results were stunning. The birch grain is holographic-like with patterns and color that change with viewing angle. Unfortunately, this quality isn't conveyed in the photos above.

    General Finish brand wood dye (50:50 mix of their Empire Red and Light Brown) was sprayed on in two coats to achieve the underlying color tone. Dye accents wood grain and yields a deeper color saturation which is superior, I think, to regular stain. Never having used it before, I'm now a big fan. However, I think I messed up the measurements a little somehow because the result was redder than expected from my sample boards. So, I followed up with a couple coats of toner to tame the reds and make things darker overall. The first toner coat was a 1:16 dillution of straight Light Brown dye to Endurovar urethane. This gave the color balance I wanted, but it wasn't quite darker enough. So, I followed this with a 1:10 dillution of pure black in urethane. This achieved exactly what I wanted. The nice thing about using toner is it evens things out, deepens the colour and lets you tweak your colour however you want as long as you like until you're happy. How ready for the top coat I sprayed four shots of straight Endurovar urethane clear. Everything was sprayed with a cheapo $20 HVLP gun and I couldn't be happier with the results.

    If that sounds complicated and difficult to anybody who's not done it before, I want to assure you it's not. It's a straight spray on, no-wipe, technique which can be completed in a weekend (plus a couple week nights). Everything's water-based, and even a newbie like me achieved really beautiful results. Recommended. Also, highly recommend the General Finish products. Light years better than the common minwax type stuff and no more expensive.

    The bezel was primed then sprayed with Tremclad brand 'Textured' finish. This gives a surface texture somewhat similar to the plastic found on a nice piece of electronics gear, and I think it works well with the sheen of the waveguide and the satin finish of the rest of the cabinet. I plan to use this on all the other speakers too and won't be attaching a grill to any of them.

    One big problem I had was gluing the painted bezel to the finished cabinet. Even though I used large wood blocks between the clamps and bezels, they still left marks in the paint. I'm not sure if this is because the paint hadn't cured long enough or what. So, I had to sand the marks down, mask off the entire cabinet body, reprime and repaint the bezel. Royal pain. So, for the next speaker I instead put clean cardboard on an assembly table, glued on the bezel, set the speaker bezel-side down onto the cardboard and then clamped the rear of the speaker down onto the table. Surprise! After removing the clamps the corrugated cardboard had also left very visible stripe marks embedded slightly into the textured paint finish. More sanding, priming and repainting. So, still experimenting with this part and will keep you posted...

    Cabinet Construction

    • 5/8" Baltic birch plywood throughout
    • glued rabbets for all joints (3/16" deep). No nails, screws or brads.
    • window brace between mid and horn (6 5/8" from top)
    • regular yellow wood glue used
    • caulked all interior seams, including bezel and port tube flange for air-tightness
    Here's the cut-list I used, as well as another one for anyone who wants to use 1/2" baltic birch. Exterior depth dimension has been increased slightly to ensure the proper 0.67 cubic foot interior volume for both. Finished exterior dimensions are 3/32" smaller than shown (WxH) due to bb plywood being slightly less than the nominal thickness.

    Cut List for 5/8" stock:


    Cut List for 1/2" stock:


    3D cut-away view for 1/2" plywood:


    3D Cut Away view for 5/8" stock:

    Panels ready to glue:



    Bracing Detail:



    Cutting tips:

    • on table saws, set the fence only once for each rip/cross-cut dimension to ensure perfect size-matched panels
    • same thing when rabbeting with your dado blade: do all perimeter rabbets at once with the fence position fixed
    • 5/8" bb plywood is actually about 3/64" less than 5/8", so the above cut lists require about 1mm worth of flush sanding on each side afterwards.
    • these cut lists give side panel grain direction parallel to the rear, and the top grain flows into the sides.
    Cabinet Dampening

    • regular 3.5" pink fiberglass insulation used throughout, torn to half thickness (i.e. 1.75")
    • both sides and top damped. Iinsulation held in place by simply wedge fitting (cutting each size slightly larger than available space)
    • the panel space behind the mid range driver was damped using the full 3.5" thickness instead of 1.75"
    • no dampening on panel area behind horn or the bottom
    • ensure neither port tube nor window bracing air passages are blocked, and pull away any dampening too close to the mid range driver
    Dampening in lower chamber:


    Dampening upper chamber:


    another shot...


    Waveguide Dampening

    Not being one to do anything half-way, I decided, hey, let's make that horn sound as good as absolutely possible. When knocking on the outside of the horn as-is it sounds fairly neutral, but rings out a bit like rapping a block of 1x4 wood. Getting the idea from other horn enthusists I added about a 1/4" layer of plumber's putty mastic material all behind the waveguide. From the throat right up to where it meets up with the bezel. This used exactly one tub's worth (400g) per speaker. Total cost $5/pair.





    Did it make any difference to the sound? Can't tell ya. I only listened to a single speaker for about 30 mins before adding it. What I can say, though is, now when you rap it with the knuckles it sounds completely different. A very dead-sounding thud - almost like you're knocking on a rock. That's can't hurt the sound as far as I'm concerned.

    Wiring Detail

    • basic 14 gauge stranded copper wire purchased from Home Depot (Southwire brand), ie. nothin' special. If I was to do it over again I'd use smaller 16 ga (even 18?). My philosophy is that quality solder joints using less solder (which is easier to achieve with smaller wire) is more important in crossover-to-speaker hookups than heavy wires. Over such short distances gauge is not very relevant. Also, smaller wire has less inductance which should help high frequency response somewhat (in theory).
    • plane-jane Kester 60-40 solder was used primarily. Nicer Johnson IA-423 tin-silver-copper lead-free solder was used at the binding posts and speaker tabs just cause I had it on hand. Doubt it makes any audible difference.
    • I used the standard 2" 3-way binding post cups Erich carries on his web store. So easy to install (using a 2" hole saw for doors). These are pretty nice quality and good value. But one needs very tiny fingers to get in there to tighten the posts onto spade external speaker wire connectors. Glad I prefer banana connectors! So, the 3" cups would be better if one uses spade connectors.

    • point-to-point soldered connections throughout. No extra wires, terminal blocks, or connectors used
    • components mounted with hot glue to an approx 4.5" x 6" (?) pice of 1/4" MDF.
    • Zip ties added to inductors only, since they're relatively heavy.
    • zip ties used everywhere hookup wire leaves the board, as strain relief devices.
    • mounted with a couple short screws directly behind the horn to the rear cabinet panel.
    Crossover mounted and wired:

    Can I post pictures of my completed cross-over, or is this forbidden due to copyright? Not sure. Hope Erich/somebody can let me know...

    well, that's it for now. All comments, criticism and suggestions for improvement are kindly encouraged because I've got a lot of speakers yet to build...! :)
  2. Re: Fusion-8 Alchemy completed build details

    I don't know if I'm the only one, but I can't see any of your photos. They all load as broken links.
  3. Re: Fusion-8 Alchemy completed build details

    Sorry, Ironcamel. I'm not sure why they're not working for you.

    Are the pics working for anybody? Are they not working for anybody else? Would really like feedback. Thanks
  4. Re: Fusion-8 Alchemy completed build details

    Pics are working fine for me. I take it you're logged in Iron Camel? But Radorod, how were you able to get around the 128K size limitation? That was a royal pain when I posted my pics of the Fusion-12 Tempest build :mad: .

    Nice build by the way, the only thing I would have changed is avoid the glossy finishes on the bezel and waveguide. I've had problems with reflections from shiny speakers behind my acoustically transparent screen, can get pin points of light reflecting off the shiny speaker surfaces. That was with NHT Classic Fours 's and the Three center, which were piano black, but you might be fine as yours seem more of a satin than gloss.
  5. Re: Fusion-8 Alchemy completed build details

    Thanks hardeng. I'll provide feedback about light reflection once I get them installed.

    The way I posted the pictures was with a trick I learned to use Google Drive as the host. That's why I'm looking for feedback its working for everybody.

    Steps I used (this might seem complicated, but once you've done it a couple times its easy):
    • on Google Drive, create a folder and upload all your pictures there
    • Share the folder as 'Public on the Web' (in Google Drive, right-click your new folder, click Share... --> Share, for 'Who has access' click Change, then set it to Public on the Web.
    • right-click the uploaded picture file you want to post and click Share... --> Share
    • copy the Link to share field and then paste the text somewhere temporarily (like notepad). You don't need to change anything, so just click Done to exit.
    • The link will look something like this:
    • (the part I've highlighted will be different for you. That's the unique fileID for your picture.)
    • in notepad throw everything out except your fileID. That's the only part you care about.
    • now, in your forum post click the Insert Image icon icon
    • finally, for Insert image location, simply use this as your hyperlink: replacing the red underlined part with the unique fileID of your particular picture, of course.
    Maybe there's easier ways, but this ain't too bad. Since I use Google Drive for all my cloud-based storage this trick let's me use it for forum pic hosting too. This is the first time I've tried it, though, so appreciate feedback whether it's working for everybody! Ironcamel, really curious why it's not working for you. I can't get it not to work, even if I'm not logged in to anything.
  6. Re: Fusion-8 Alchemy completed build details

    I'm using Chrome as my browser. I disabled all extensions and the usual troubleshooting measures, so more than likely it has to do with my using google's tracking opt-out.
  7. Re: Fusion-8 Alchemy completed build details

    Thanks Radoron, that's a neat workaround. However I'm viewing this thread from work now, using the latest Firefox, same as I have at home and unfortunately I can't see the pictures. So looks like the proxy server at my work is blocking the links.
  8. Re: Fusion-8 Alchemy completed build details

    would like to post a different Fusion 8 Alchemy build, but pic files are too big. A little over 1Meg each. What is best way, Google drive seems awkward. Thanks for any advice.
  9. Re: Fusion-8 Alchemy completed build details

    Awesome build. Thanks for sharing.

    *karma dust floating your way* attaboy ;)
  10. Re: Fusion-8 Alchemy completed build details

    For what it's worth, here's my listening impressions after a few weeks. They've only been hooked up for two channel music, and a couple movies so far, so will update this as I have more experience with them.

    My stereo gear is an Audio Note integrated tube amp and a highly upgraded Music Hall CD player. Nothing outrageously crazy, but pretty decent. And with this I've been blown away by what my Fusion-8s will do. Sheffield Lab demo tracks and 24-bit recordings really show them off. It seems the better the source material and gear, the better they sound. Quality differences in recordings and mastering are readily apparent, which is absolutely one of the marks of a revealing speaker. Crappy, compressed pop music sounds...well crappy like it's 'supposed' to, but somehow not nearly as crappy as through my usual speakers. Overall, they're very pleasant and easy to listen to, at any volume. A nice difference for me is, even cranked, they're not fatiguing, which is new to me with the speakers I had before (Energy 22 Pros). Not sure why that is.

    If interested, you can read more on their product page, where I posted a review.

    One thing I will say, though, and something I'm still struggling with a lot, is I find vocals 'plasticy' sounding with movie dialog. What have others found? However, I'm really reserving final verdict until I have more experience (not that my personal opinion should matter much to anyone anyway). This, I feel, is the hardest test for any speaker, because human ears are used to hearing people's voices, so know what they're supposed to sound like. Some metal-cone speakers I owned before were like this (only much, much worse) and I just hated them for that. So, take my initial criticism in that light. I've tried through the tube amp, my regular Denon HT receiver, CD source, PC optical-out source, movie dialog or music lyrics. The result is always this slight tinge of...plastic sound I'm not super fond of. Makes me wonder, if I've got too much damping inside, or not enough, or the wrong kind, or they're not broken in yet, or what... With the couple movies I watched, I compared two-channel stereo mode to center channel only mode and disappointingly I always preferred center channel only mode (through a very 'average' Paradigm LCR-350).

    BUT... I'm still workin' on it.

    Wish the highs weren't quite as rolled off - metallic instruments aren't quite as metal-sounding as I'm used to through the 22's famous tweeter. It's not distractingly bad, though, they still sparkle for sure. For most everything else, though. Wow! Don't want to lose these to my home theater because for music in the living room they're really making me smile and I'll miss them.

    Would love to hear others' experiences as well.

    I really don't put much stock in frequency response plots, but here's mine attached for those curious. Both L/R speakers perform within 0.1-0.5 dB across the board. This is in a non-acoustically treated room away from walls at regular listening height, with a lab calibrated mic on the tweeter's axis @ 1m. All the bigger peaks/valleys are probably just room effects, so ignore.

    Attached Files:

  11. Can I ask where you found the cross over design ?

    I just got my kit today from Eric but I can't seem to find any info on how to wire the parts up.
  12. Did you get the schematic that's included with the bag of crossover parts? Or, is it physical layout that you're wondering about?

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