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Slot port Tang Band w8-740p subwoofer advice/suggestions

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  • Slot port Tang Band w8-740p subwoofer advice/suggestions

    I've searched and read just about everything I can find from a google search regarding this subwoofer and DIY builds with it. I built a sealed subwoofer with it a year ago and used the yung 200watt amp from PE. It was in a small room. I liked it, but I know that isn't the best/loudest/optimum setup to get the most out of this sub. The amp stopped working after a lightning storm last summer so I just forgot about it for a while.

    Ok so a month ago I received a gift card from my job and decided to buy the Dayton 250 watt plate amp. I have been obsessively researching a slotted port design for this sub. I am trying to decide whether I want to tune to 25, 30, or 35 hz. So far I've used winisd and online calculators to design a box tuned for 25hz and 35hz. I figured it was time to ask for advice, comments, and/or suggestions from people that know much more than me. I live in a studio-ish apt and this will be in my kitchen/living room combo. The room is rectangle about ~15X12. I have a custom ported sub with a 6.5 tang and 70 watt amp and it's ok for music, but I want more. Maybe I will double up with the new one OR move the 6.5 to my bedroom and let the new 8 inch tang perform alone in my living room. I have no room constraints as far as size, and I can thump it loud very often. It's a dream come true bachelor pad, ha.

    Ok so I want this sub to perform for music and movies. 80% music. That is what initially led me to only considering a 35hz tune. It is nice that it's a bit smaller, but then I started thinking about no size constraints and using it for movies too. Hence considering 25hz or 30hz. The dayton amp has a high pass crossover at 20hz and I've considered that in winisd (cuts down on excursion and port velocity). So I'll attach the transfer function graph, the port velocity graph, and cone excursion graph. I will design the port roughly 1 inch high, and between 9 and 10.5 inches wide (for the 35 and 25hz tune respectively). The port will use the walls and bottom, then fold about 3 times before opening to the main cabin. I've found examples of success with this design online on various forums with this amp in fact. Given everything I've said and the graphs, what do you all think? I want to enjoy the occasional action movie scenes, but am most interested in music, hip hop, reggae, EDM, some of the lowest music, I guess. Oh the volume for the 35hz tune is .577 ft^3 and for the 25hz tune is 1.11 ft^3. I can make either design work, but as you can see the box nearly doubles in size for the 25hz. Is a 30hz design a decent compromise? Can this 8 inch driver even do 25hz well? I just can't assess this given my state of knowledge. If you request more information let me know. Thanks for reading.
    Transfer function (purple 25hz, green 35hz) Max port velocity for 250watts (RMS for amp) purple 25hz, green 35hz. Cone excursion purple 25hz, green 35hz

  • #2
    Here's the (a) problem - Mr. Zarbo had one of those woofers and (IINM) his measurements weren't very close to TB's AT ALL.
    TB's Qts, Fs, Vas:
    tb: 0.30, 28, 0.81cf
    tz: 0.32, 35, 0.30 <-THIS could change everything

    Unless you can DATS your actual driver, I'd go w/something more like 0.25cf tuned to 40Hz. This is on the small side (but still usable) for one set of parms, yet still usable (but on the large side) with the other set. Wouldn't expect much lower than 40 out of it w/out room gain.

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    • #3
      I am surprised to hear this. Many people have built DIY subs with this driver through the years and I haven't read any accounts of the TS parameters being so "off". Thanks for pointing this out to me. Is it well known among the knowledgeable DIY crowd that TB's TS parameters are off by so much? Pardon my ignorance, but why do you say that 40hz is as low as i should shoot for? Do you think the driver just can't go much lower? Is that the size that will give the flattest response for that tuning frequency? Lets just say that hypothetically the TS parameters that TB states are correct...... and I want to try for 35 OR 25 hz, what do you think of my box designs as far as what you see in the graphs and/or my idea for the slot port with those dimensions? In addition to advice and/or suggestions on what I'm trying to do, I'm also trying to gain some knowledge here, and you seem quite knowledgeable. Thanks for your response, I appreciate it.

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      • #4
        Using TB's parms - 0.30 Qts, 0.81cf Vas; 0.70cf looks good tuned to 33Hz w/a 1"x10.5" slot that's 3 feet long. F3 = 30Hz.
        OTOH, if the Vas is 0.30cf, then that same box still (technically) has an F3 of 30, but w/over 3dB of "ripple" (run your own sim).
        It might SOUND like its F3 was more like 50-60Hz. If you low pass THAT sub @ 50, it ends up w/a very narrow spike right at Fb (33) which would sound pretty much like "one-note-bass".

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        • #5
          Suggest you read this thread.

          Project #2: The 'Tenacious Bass 6' and 'Tenacious Bass 8' Subwoofers - Techtalk Speaker Building, Audio, Video Discussion Forum

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