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The Super Bees - Garage two way build

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  • KEtheredge87
    started a topic The Super Bees - Garage two way build

    The Super Bees - Garage two way build

    Hi Guys,

    This build is my first original speaker design, and is intended for me to really learn and apply some crossover knowledge. I've got a head start since the boxes were pre-assembled door prizes with blank baffles from InDIYana 2017. I decided to use the HiVi L6-4R woofer and Dayton ND25FW-4 waveguide soft dome tweeter after doing some crossover simulations in PCD and seeing that I could achieve what I think will be good results from relatively modest XO parts in 2nd order LR filters. This project has also been a convenient way to start learning Autodesk Fusion 360 CAD software, which I'm finding is more full featured than google's sketchup.

    I've been working on these here and there, and wasn't totally sure when to start this thread, so I figured now is as good a time as any. I'll try to post meaningful pictures over the next few entries to catch everyone up. At a high level, here's where we're at:

    1) Naming them the Super Bees after the Dodge muscle car of the 70's. I like the name, and the super bee logo... and these are garage speakers, so naming them after cars only made sense!
    1a) This leaves me open to re-use an Ultimax-15 driver for a garage sub, name it the Rumble Bee, and then have the whole project called the Scat Pack!

    2) Bassbox predicts Fb=51.9 Hz / F3 = 56.5 Hz with a 4.75" long x 1.728" ID round port with internal and external flares.

    3) DATS measurement shows Fb is actually 45 Hz, so I'm clearly off in BassBox somewhere.

    4) Woofer LP target is 2nd order LR @ 2200 Hz, Tweeter HP target is 2nd order LR @ 2500 Hz

    My next steps are to take frequency response measurements of the woofer and tweeter in the cabinet with my Omnimic and follow Jeff Bagby's approach to combining nearfield and farfield responses to get quasi-anechoic frequency responses for crossover design. I currently have a 10 conductor - 18AWG wire divided up between the woofer and tweeter (3 wires + and - for woofer, 2 wires + and - for tweeter) so I can hook up only the drivers I want at any given moment.

    OK, enough of my jabbering for a while. Here's some pictures of where we are, and a rendering of what I hope it looks like when I'm done!

    Click image for larger version

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  • KEtheredge87
    replied
    Originally posted by BOBinGA View Post
    That 6 db rise in response from 300 to 600 hz looks like classic baffle step.* When you put these against the wall in your garage, that should flatten out and it looks like your Super Bees will be one of the flattest response "garage speakers" around.* Good job. *

    I'm not sure the 1 db difference between the two is anything more than driver variances.* I don't know that I would change anything to compensate.* But to see if it is a XO component, swap the XOs between the speakers and if the difference moves to the other speaker then it is indeed a component and not a driver variation.

    -Bob
    Hi Bob, Thanks for your comments That 300-600 Hz area has been one of the areas that I was a bit confused about during the early stages of this XO design (circa post #41). My first attempts tried to model a nominally flat response by attenuating everything above 300/400 Hz down to match, but this caused a sizeable inductor bump isssue below 300 Hz as well. I thought the XO electric phase and impedance response could have been better too, so I came up with the version I have now. I figured I would spend less effort fighting that 300-600 Hz area and aim for good response above there. My ability to accurately measure this region for XO work is also suspect. The most recent OmniMic FR plots show a lot of room interactions since I was measuring at 30" on-axis with the tweeter. I wasn't interested in doing blended nearfield / farfield for each cabinet. That's a lot of microphone movement! At the very least I thought it sounded good, so whether or not the OmniMic showed it being well behaved from a technical standpoint is almost secondary. We'll see how it sounds outside of my basement soon enough!

    I like your ideas regarding swapping the XO to determine if the issue is driver based vs. XO based. That's an easy thing to do! Thanks for suggesting it!

    Leave a comment:


  • BOBinGA
    replied
    That 6 db rise in response from 300 to 600 hz looks like classic baffle step.* When you put these against the wall in your garage, that should flatten out and it looks like your Super Bees will be one of the flattest response "garage speakers" around.* Good job. *

    I'm not sure the 1 db difference between the two is anything more than driver variances.* I don't know that I would change anything to compensate.* But to see if it is a XO component, swap the XOs between the speakers and if the difference moves to the other speaker then it is indeed a component and not a driver variation.

    -Bob

    Leave a comment:


  • dynamo
    replied
    Seems plausible that the esr of the npe could affect the knee of the roll off enough to make that 1db difference. I would venture to guess that in high end matched pair designs, at least commercially, they likely keep all components and drivers used in a tight tolerance range to the original design vs tweaking each speakers crossover to match a specified response. No idea though, just speculation.

    Leave a comment:


  • KEtheredge87
    replied
    Originally posted by dynamo View Post
    Looking good. I had to do a very similar notch in my breezy monitors (new version of the dynavox 6.5 poly in a br1 cab) to tame an odd hump that showed up when trying to cross high enough to keep the xt25 happy. It looked to me from the drivers factory response that it would be a super simple woofer circuit but once in cab it got a little funny. To avoid the notch and not have the hump I would have had to cross too low for the xt25.
    Thanks Dynamo! I was hoping to make this XO as simple as possible and avoid any notch filters if possible. The external XO boards were easy to put together, but I suspect compacting all these parts into a smaller 5" x 7" (or maybe even a 3" x 5" board ) will be a challenge!

    If I have time between today and tomorrow, I might try swapping out one of those 2x15uF parallel NPE caps for a different pair to see if that is what is causing my FR difference around 2K. When I decided the XO was done, I was listening to it as the blue line version (lower 2K and no funny spike at ~14K). OmniMic says this is a 1 dB difference at the 2K range. I suspect that would be audible (and thus undesirable!).

    I wonder how common it is to customize the XO design for each cabinet in a pair of speakers? My thought process currently stops at "make a custom XO" rather than tailoring it to each set of drivers.

    Leave a comment:


  • dynamo
    replied
    Looking good. I had to do a very similar notch in my breezy monitors (new version of the dynavox 6.5 poly in a br1 cab) to tame an odd hump that showed up when trying to cross high enough to keep the xt25 happy. It looked to me from the drivers factory response that it would be a super simple woofer circuit but once in cab it got a little funny. To avoid the notch and not have the hump I would have had to cross too low for the xt25.

    Leave a comment:


  • KEtheredge87
    replied
    3rd time is the charm Sent from my Pixel 2 XL using Tapatalk

    Leave a comment:


  • KEtheredge87
    replied
    Hopefully the photos attached this time! (XO diagram and FRD plot in next post)
    Sent from my Pixel 2 XL using Tapatalk

    Leave a comment:


  • KEtheredge87
    replied
    Hey Everyone,

    Here's an update on the SuperBees ahead of InDIYana! I decided to overhaul my XO design from the last time I posted about it since I couldn't quite put my finger on what sounded "off" to me from January. This time I didn't try to pad everything down to match the levels I measured at 100--200 Hz. I thought this choice should cause the low end to be quieter than the rest of the frequency range (at least in theory). However when I tested it and listened to some music I didn't find the lows to be lacking. This XO design is still preliminary (although closer to done than not, I think), and it will be used at the InDIYana show later this week.

    Also of note... I think I am dealing with component tolerances between each cabinet. The parts and XO setup are identical, yet one cabinet is showing a 1dB boost through the 2 kHz range, as well as an odd boost at the high end near 15K. I was not expecting that kind of variance, but I could easily see some part to part variation in the NPE caps I used causing the 2 kHz shenanigan. I did buy some 30uF polypropylene caps to test as well... but they are pretty darn big to fit inside this cabinet! For what it's worth, I couldn't hear a difference (or a detraction per se) in my XO testing for using the NPEs in the woofer section of this design.

    When you see these on Friday/Saturday, please feel free to offer me your thoughts! These and the SevenSixTwo Coaxials will be the first XO designs I've put together, and while I think they sound good... I'd like some unbiased feedback as well.

    See you guys this Friday!

    I'll try uploading photos via tapatalk... the forum isn't allowing me right now. Says photos are corrupted

    Leave a comment:


  • xmax
    replied
    Originally posted by KEtheredge87 View Post
    Sweet action, Sir! Do you recall your finishing methods for it? I don't think I plan to go for the literally polished look on these, but I'm not opposed to some elbow grease to ensure a decently smooth finish. Provided of course that I can keep being patient while things dry.

    The cabinets have been drying indoors for 2 days now, which is supposedly OK for top-coating according to the rustoleum can instructions. If I trust the can instructions, it sounds like I would be OK to mask off and add a gloss black racing stripe down the middle at this point.

    I have a hot rod shop paint them, I don't know the details other than they are paint wizards.

    Leave a comment:


  • Kevin K.
    replied
    Patience is a good thing, wish I had more of it. Looks like you've still got plenty of work to do on the coax cabinets anyway. Good luck!

    Leave a comment:


  • KEtheredge87
    replied
    Originally posted by Kevin K. View Post
    Keith, unless you're going to bake the enamel finish, it would be best to take John's advice about waiting a while before wet-sanding. Enamels dry in two stages, first is the evaporation of the solvents and second is the polymerization of the oils in the paint. Solvent evaporation doesn't take long depending on how many coats were applied, but polymerization can take weeks or longer. Baking the paint will accelerate the polymerization process but it's a bit tricky, too hot or the wrong kind of heat (radiant) can mess it all up, especially if there are still some solvents trapped in the coats. I've had pretty good luck using an oil-filled heater placed inside a gaylord box (I'm assuming you know what that is). Place the cabinets in the box with the heater overnight and then give them another full day outside of the box before attempting to wet-sand. I would also suggest some scrap samples painted and cured the same way so you can test the wet-sanding on the scraps before trying it on the cabinets. You'll know if it's still not ready because the paint will roll off instead of sand off. Here's a link to a heater similar to the one I have if you're interested and as always, Good Luck. https://www.lowes.com/pd/PELONIS-150...tat/1000179783
    Hey Kevin, missed this earlier. Seems I am not getting my notifications when folks post anymore... I'll have to get that sorted out.

    Yep, I know what a gaylord box is. Took a few years at work before I heard the term though! Setting up a bake oven for them is a great idea. I haven't done anything to the cabinets yet except (in the words of our friend johnnyrichards "Put your beak on it!" My beak tells me I still smell paint, so it isn't cured up yet.

    It's apparent to me that I won't have these cabinets finished to the level I expected before getting them to InDIYana. As much as it pains me to do, I will exercise patience and not paint anything more on them until After InDIYana. This way I can focus on making an external XO mock-up or two, and give Drjay something to hear and give me some feedback on at the show! I should be able to rig that up without worrying about the paint.

    Once I get back, I can work on these a bit more and get them fully dressed for a field trip to MWAF in July!

    Leave a comment:


  • Drjay
    replied
    Even if they are not perfect, this is a really neat project. I am really looking forward to seeing them and hearing them at Indy.

    Leave a comment:


  • KEtheredge87
    replied
    Originally posted by xmax View Post
    Nice work! Here's my yellow speaker for 3rd Man Records.
    Sweet action, Sir! Do you recall your finishing methods for it? I don't think I plan to go for the literally polished look on these, but I'm not opposed to some elbow grease to ensure a decently smooth finish. Provided of course that I can keep being patient while things dry.

    The cabinets have been drying indoors for 2 days now, which is supposedly OK for top-coating according to the rustoleum can instructions. If I trust the can instructions, it sounds like I would be OK to mask off and add a gloss black racing stripe down the middle at this point.

    Leave a comment:


  • xmax
    replied
    Nice work! Here's my yellow speaker for 3rd Man Records.

    Leave a comment:

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