Please review the site Rules, Terms of Service, and Privacy Policy at your convenience. Rules, TOS, Privacy
Get familiar with the reaction system: Introducing the Reaction System

Shockwave Build



( ( ( ( s h o c k w a v e ) ) ) )
____________________________________________

objectives
inexpensive 3-way with a coaxial driver and 7" woofer
meant for desktop nearfield listening
aiming for f10 of 35Hz
very close to sealed, overdamped impulse response
group delay x frequency under 400 rule being followed
mdf - silicone - tile constrained layer sides, top and bottom
linear phase crossover
____________________________________________

drivers
rockford fosgate r1675x2 6.75" coaxial driver




vifa/tymphany pl18wo-09-08 woofer


parts express #299-018 buyout passive radiator



____________________________________________

plan of attack
concept
design
c.a.d.
sawdust
glue
cut holes
finishing touches
measurements
crossover design
buttoning up
finished

____________________________________________

concept
so i've been helping out my parents build a house lately mainly because they're letting me live in it rent free while i'm in school. new room for grey means new battlestation since i'm a total computer gaming nerd. one thing i've never had is some really nice looking speakers on my desk and i need to remedy that.

i bought the vifa woofers from mr. scott quick a while back and needed to put them to purpose. i really love the aesthetic of coaxial drivers, having two in one really cleans up the baffle and allows for a more compact design, which is great because i over-engineer everything and like to try new concepts for each build.

a few months ago i stumbled upon this rockford fosgate driver while looking at car audio stuff. wow, they're only $40 on amazon prime and would you know it, i got a $25 gift card from the parents for xmas.

modeling the woofer hundreds of times and slowly working out a shape and various alignments. sealed is great quality bass, but i've done 3-4 builds now with sealed. ported is too "floppy" - if i may - and balancing the port volume and enclosure volume is tricky, not to mention i need a 2.5" port in a .5cf box which is silly huge, and in turn, ventures into peter north territory.

so i opened up parts express' website and looked for a passive radiator, size doesn't change, so it's more simple than a port. first one i picked, i get a similar response to sealed, but with more booty, and my anaconda don't, so that was the way to go. group delay, what's that? did a little research, and read about the 400 rule (frequency x delay in ms <= 400) and tweaked my box size a little to attain that quality. gotcha. unibox (sorry bagby, i just prefer unibox still) says the impulse response is nearly identical to the sealed, over-damped impulse response, which i used in my last build and i loved those speakers, didn't want to give them away, but they're being enjoyed by a real vinyl lover, my bff.

so the new things i'm trying out this build are: coaxial driver, passive radiator, constrained layer, (possibly) hardwood baffle, and distortion measurements. This will also be my second ever passive crossover.

finally the name, in case you were wondering is my favorite transformer, he's only got one eye (coax driver looks like an eye).






____________________________________________

design
with this being a desktop speaker, they need to be compact, but not too compact because i have a pair of 27" monitors that i use.

after tweaking the design a bit i experimented with a piece of birch, silicone and tile, to see if it compresses and after a couple weeks, it's still sitting pretty at 29mm thick. 19mm for the wood, 3mm of silicone and 7mm thick ceramic tile. so i fired up boxycad and 1.1412" thick top, bottom, and sides. the front and rear baffles are different monsters, they'll be 1.5" thick on the backside, and a total of 2.25" on the front with a normal 3/4" baffle and recessed drivers and a "facade" 1.5" thick with some fancy (to me) router work.

the mid/tweet coaxial driver will have it's own compartment, which i sized to make the woofer compartment the correct volume. which leaves a small amount of room for the crossover between the woofer and passive radiator, or in the tiny compartment in the back of the box.


____________________________________________

c.a.d.
i have been using eMachineShop forever now, so that's what i use to draw stuff up and do simple 3D like the baffle, etc. the massive 1.5" roundovers and 1.375" chamfers are only meant to be aesthetic, but will probably just introduce some wiggles into the frequency response due to their size, no doubt. here's what i've got so far:



this is as far as i have gotten, and i'm hoping to be able to cut some wood tomorrow, stay tuned for updates!
deadhorse - leviathan - harbinger - shockwave (wip)
kennyk
«1

Comments

  • sawdust
    i finally got some wood cut! everything is on the money except the tops, bottoms, and braces are only 1mm off! also did a mockup to see how fracking huge they're going to be and they're going to be fracking huge. finally I will definitely need to do the crossovers externally because there will be little to no room inside the cabs for crossovers. i will move on to the router work over the weekend possibly, we're still very busy with moving and getting settled into the new house.



    deadhorse - leviathan - harbinger - shockwave (wip)
  • edited September 2017
    sawdust & glue
    girlfriend's sister came to visit, so i ended up working on these all day long! first i had to go find my handheld router, and it had gotten wet, so it's all oxidized and rusted up, unfortunately, but still works like a charm. when i finally got the bit installed and tightened down, i rounded over the cutouts on the braces, when ended up looking like a kinda nice turd. I thought to myself, "never mind them, they'll be inside the box, nobody will see them." and proceeded to begin gluing up the first box...


    ... at which point i realized that the holes in the braces, which were supposed to create extra airspace for the woofer, were cut on the side of the brace instead of the rear ughhhhhhhhhh. so i had to create new braces, but had limited scraps, so i cut pieces big enough to replace the holes wrongly cut in my original braces. Well, the new braces turned out much nicer, and aren't quite turds. 


    so now i can start gluing up panels... no. i actually decided it would be easier to attach the ceramic tiles to the inside of the enclosure while it's open. so then i setup the tile saw and marked all the tile to be cut. this was probably the easiest thing i've ever cut in my life, especially having never used it before. 


    so now i finally started gluing up panels. my plan is to glue up the brace (which was the first one I glued up), top and bottom. then onto the side panel tiles, then top and bottom tiles, finally onto the front and rear baffles. I'll get started on those in the morning. 


    thanks for tuning in!


    silicone & tile

    i spent the entire day yesterday working on these again, feels great. anyway, i started with the silicone and tile, pretty messy endeavor. so what i did was lay down a bunch of silicone (the one speaker carcass used 3 whole bottles of silicone caulking!) and used some little pieces of 1/8" aluminum rod for spacers, dropped the tile in place and weighed it down with some bricks we had left over from the house. This took pretty much all day because i did two side pieces, left it to dry for 30 minutes, other side pieces, top, then bottom. 10 minutes of work, and 30-40 minutes of drying time. then i went back and filled in between all the tiles with silicone, so they will never touch one another and aren't touching the wood either.




    i got curious and decided to weigh them this morning and just the shell you see in the above picture weighs in at 21.6lbs!

    Also, forgot the knuckle wrap test

    D1PP1Nkennyk4thtryjoeybutts
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Cool!   That is a very fast decay.  And that should be even better when you get all the panels put together.  What kind of tile cutter are you using?  Is this a large wet saw or a smaller type unit?  I have been thinking of doing something like this on a future project.
  • 4thtry said:
    Cool!   That is a very fast decay.  And that should be even better when you get all the panels put together.  What kind of tile cutter are you using?  Is this a large wet saw or a smaller type unit?  I have been thinking of doing something like this on a future project.
    I believe it's THIS MODEL dad got it on sale at Home Depot we put like 10,000 subway tiles in this house (2 showers and the entire kitchen) 

    Yeah I did a little bit of reading up on constrained layers before I tested out this combo. Then I bought a small piece of 3/4" birch and siliconed a tile to it. Measured the thickness and compared "knocks" and decided it would work well enough to try. I'm headed to the "gittin' place" for some more silicone and other doo-dads to get started on attaching the tile to the second carcass today.
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Ok well, this project is on hold again until I replace the battery in my car.
    kennyk
    deadhorse - leviathan - harbinger - shockwave (wip)
  • You need to go see a witch doctor and get a "limpia"...
  • You need to go see a witch doctor and get a "limpia"...
    Or I'll go see Ace


    Silver1omojoeybutts
    deadhorse - leviathan - harbinger - shockwave (wip)
  • ok so I have a bit of a quandary. How should I proceed with the "Mid wall" that is, the wall that separates the Coax driver from the woofer chamber? Not sure if I should glue the "mid wall" to the brace and use silicone to isolate it from the tile, or use silicone to isolate all the way around.

    What do you think?
    No automatic alt text available
    deadhorse - leviathan - harbinger - shockwave (wip)
  • My suggestion would be to use silicone to isolate it all the way around.  And then silicone another piece of tile to the mid wall.  You could also experiment with difference size tiles glued to the mid wall, changing its resonant frequency for the best knuckle rap test.   
    greywarden
  • what I ended up doing was attaching the "mid wall" on all four sides with silicone. I used some 1/8" aluminum rods that I used to as spacers for the tiles (making the silicone layer 1/8" thick) and trimmed the mid wall a kerf-width at a time until it fit. then I put a bead of silicone between each of the aluminum rods. I let it dry/cure overnight and the following day I pulled the rods and started filling in silicone around the edges of the panel. I ended up putting three layers of silicone on either side of the wall, so it is definitely air-tight.
    ps - black silicone is $4/tube and clear is $6/tube...
    No automatic alt text available 
    4thtry
    deadhorse - leviathan - harbinger - shockwave (wip)
  • I was wondering how you would keep the panel "floating" in place as the silicone set up.  Nice solution! 
  • 4thtry said:
    I was wondering how you would keep the panel "floating" in place as the silicone set up.  Nice solution! 
    Thanks, yeah when I did the initial "prototype" of the constrained layer, I ruminated over that detail for a week or so, and when I was walking around lowes one day I saw the little 1/8" aluminum rods, like $2 for a pack of them, and decided that would work great, and it did.
    deadhorse - leviathan - harbinger - shockwave (wip)
  • This would be good at Indiy, except for the buyout PR. :/
    ............. could you hum a few bars.
  • kennyk said:
    This would be good at Indiy, except for the buyout PR. :/
    What do you mean? I'm going to try to make it to Iowa. Yeah the PR models pretty perfectly with the PL18s, I just hope the coax driver can can keep up. It'll be a challenge for sure.
    deadhorse - leviathan - harbinger - shockwave (wip)
  • edited September 2017
    Cool, I'm bringing a coax to iowa. Coax 3-way is the comp for indiy '18.
    ............. could you hum a few bars.
  • kennyk said:
    Cool, I'm bringing a coax to iowa. Coax 3-way is the comp for indiy '18.
    Ooooh ok, gotcha, I didn't know that. I'd use a much nicer coax if I were in a competition haha.
    deadhorse - leviathan - harbinger - shockwave (wip)
  • No automatic alt text available
    Got some more work done on the second cab yesterday before work, bought some more silicone, too, I'm about to get started on attaching more tile today, should have the cabs finished up this week!
    kennyk4thtryJasonP
    deadhorse - leviathan - harbinger - shockwave (wip)
  • No automatic alt text available
    Image may contain shoes
    No automatic alt text available
    When I did this in the first box, I was having phone problems and couldn't take any pictures. This is how I aligned and siliconed in the mid-wall, the wall that separates the coax and woofer enclosures. I measured and trimmed the mid wall to be 1/4" smaller than the opening and taped the 1/8" aluminum rods into the area where the wall goes, then I squirted some silicone into the areas around the sides of the panel. Pretty simple, and works. In an hour or so I'll go back and do the backside, then lay the enclosure down and do the vertical sections, I just don't want the silicone running (it probably won't but I don't like leaving things up to chance like that)
    4thtryJasonPkennyk
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Cool.  How does this floating mid wall affect your overall knuckle rap test?
  • 4thtry said:
    Cool.  How does this floating mid wall affect your overall knuckle rap test?
    AFAIK they both sound pretty solid, I'll make a video when I go to finish up this one. The midwall doesn't run across the center of the top panel, so both sides have a slightly different "knock" sound to them, which, AFAIK, that's a good thing in speaker building, not having similar resonant frequencies in an enclosure.
    4thtrykennyk
    deadhorse - leviathan - harbinger - shockwave (wip)
  • edited October 2017
    Testing an Instagram Embed Code @JasonP (bunch of html and the video dead in the middle of it, lol. I just used the link instead)


    deadhorse - leviathan - harbinger - shockwave (wip)
  • I'll also upload the Youtube version when it finishes uploading, it'll be about 30 minutes (<1mbps upload ftw!)

    deadhorse - leviathan - harbinger - shockwave (wip)
  • Here's the Youtube version, much better sound... I think...


    kennyk4thtry
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Nice to see someone trying a cheap coax in a 3way. I have always wanted to try a coax. Seems like a lot of people dismiss the cheaper ones just because of small wiggles in the tweeter response that may not even be audible.
      I have heard some pretty good sounding car speakers and that is in an environment that sucks for speakers.
    greywarden
  • Killa said:
    Nice to see someone trying a cheap coax in a 3way. I have always wanted to try a coax. Seems like a lot of people dismiss the cheaper ones just because of small wiggles in the tweeter response that may not even be audible.
      I have heard some pretty good sounding car speakers and that is in an environment that sucks for speakers.
    Thanks! Yeah I took a HUGE gamble on using a cheap car audio coax. I mainly chose it because I like the look of it - it looks more like a typical home audio coaxial driver than most other car audio drivers, and I think I mentioned in the OP that I got an Amazon gift card for Christmas and used it to pay for most of if not the entire cost of the speakers.

    I *SHOULD* be getting some router work done this week and then mounting the speakers in the box for measurements. It's been a loooooong time since I've done measurements and I'd like to do some THD measurements this time because I never had and that has quite a bit more to do with  sounding good than FR does, IMO. It would be badass if I could actually have these buttoned up enough to take to Iowa DIY (and if I'm able to go in the first place). 
    deadhorse - leviathan - harbinger - shockwave (wip)
  • My opinion on THD is that people seem to get hung up on it. While i'm sure it does affect the sound I have to wonder to what degree once it gets down to a certain level. I need to start measuring this too. Maybe when it gets cold outside I will break out the minidsp and eq multiple drivers to the same response and do some THD tests to see what I hear.

     Your tiled boxes remind me of these btw. Tiles really do deaden a box. http://techtalk.parts-express.com/forum/tech-talk-forum/52993-killa-continuum-build-thread

    greywarden
  • Killa said:
    My opinion on THD is that people seem to get hung up on it. While i'm sure it does affect the sound I have to wonder to what degree once it gets down to a certain level. I need to start measuring this too. Maybe when it gets cold outside I will break out the minidsp and eq multiple drivers to the same response and do some THD tests to see what I hear.

     Your tiled boxes remind me of these btw. Tiles really do deaden a box. http://techtalk.parts-express.com/forum/tech-talk-forum/52993-killa-continuum-build-thread

    I'm definitely not worried about it being too low, hahaha. I'm very worried about there being a of large spike, due to crossing the tweeter too low, or with a shallow slope. Now, I'm hoping that Rockford Fosgate assumed that people want to crank these speakers up as loud as they're HU or an amp will make them go, so they used drivers that could withstand that sort of abuse without too much distortion. That way I'll be able to cross them over *similarly* without too much off-axis dips. My last passive crossover took a couple days to get right, but the off-axis was great and they sound great anywhere in the room. 
    deadhorse - leviathan - harbinger - shockwave (wip)
  • If the woofer behaves well you can cross the tweeter fairly high since driver spacing won't be an issue.
    greywarden
  • Got some silicone work done today and ordered a couple sheets of 3/4" Sonic Barrier, won't be in until the 11th, so I'll probably have to ratchet strap the baffle on and do measurements that way.
    deadhorse - leviathan - harbinger - shockwave (wip)
  • Thanks for the knuckle rap testing videos and links.  Seems to work quite well.  Any thoughts on mortar verses silicone to attach the tiles? 
Sign In or Register to comment.