VBS-315 - A 15" 3-way DIY Speaker Design with Vintage Inspiration.

Discussion in 'DIY Speakers and Subwoofers' started by Matt Grant, May 16, 2019.

  1. #1 Matt Grant, May 16, 2019
    Last edited: May 23, 2019 at 2:09 AM
    Oh yeah and you can build a pair for less then $200!

    Expanding the value buster series beyond just the VBSS subwoofer this design started on a whim when I looked at how inexpensive could I make a decent DIY speaker design using a 15" woofer. Once I started adding up the costs based on this concept and noticed it came in lower then I had expected I knew I had to buy the parts and actually build these speakers.


    Forming the foundation of this design will be the GRS 15PF-8 Woofer. It's the least expensive 15" woofer that parts express sells but is what makes this build of a 15" 3-way possible for under $200 a pair. At first glance the specs don't look great, severely underpowered motor means a very high Qts and also means a massive peak in the bass response. I'm hoping to tame that with heavy fill but am not planning to eliminate it entirely as I want to try and find the sweet spot where that rise will help to give some nice kick to the bottom end without sounding boomy. I'm shooting for internal volume around 3cuft and actually planning on going ported, though I suspect it could be built sealed as well. The port does not actually add additional output at the low end due to the woofers motor strength being so low but my intention is to use it for the wide bandwidth reduction in xmax it should provide. I am expecting to get usable in room extension into the 40's with this design and with the rise in output in the bass these should provide a satisfying bass response for most music without requiring subwoofers.

    For the mids the GRS 5SBM1-8 5" sealed back midrange looks to be an excellent value and should be able to cross low enough to prevent beaming from the 15" woofer and at the top end cross provide a smooth directivity handoff to the waveguide loaded Dayton tweeter. I also wanted to go with a sealed back midrange for ease of installation with no need to build a separate midrange chamber.

    Dayton ND25FW-4 will be the tweeter, I've actually had a number of these for a while now and had plans to use them in a number of designs but never got around to building any of them so this will be my first time putting them to use. I wanted to go with a low cost tweeter that will be able to play a spirited levels without straining too much and I feel the loading from the waveguide on these should help keep distortion that occurs towards the crossover under control while also giving better directivity control and handoff to the midrange then a regular dome would.

    Enclosure is looking like it will be around 29.5"-30" high x 18" wide x 15" deep. The design/baffle layout will end up looking a lot like the JBL L100 classic except with a 15" woofer. I didn't set out to copy the L100's and only realized my plan for driver and port was pretty much the same after I had drawn it up.


    More info to be added soon.
     
    louisdamani and LuisV like this.
  2. Hey Matt, any hints on the driver parts for this?
     
  3. #5 Matt Grant, May 23, 2019 at 1:33 AM
    Last edited: May 23, 2019 at 2:17 AM
    Everything is still in flux, I've not actually started the build yet just purchased drivers and taken some preliminary measurements. I'm planning on updating the first few posts as the build progresses.

    Currently planning on using the GRS 15PF-8 for the woofer, GRS 5SBM1-8 for the midrange and Dayton ND25FW-4 as the tweeter. I was originally planning on using horn loaded Goldwood soft dome tweeters because they were less expensive but upon testing I found them to be garbage. The horn section on those has screws that go through it to clamp the diaphragm down but both the diaphragm mounting ring and the horn are warped so it doesn't clamp down evenly and the plastic ends up buzzing instead of just the soft dome diaphragm moving cleanly by itself.
     
  4. Thanks for the info! Looking forward to the speaker / design!
     

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