Eminence 15" Subwoofer and Midbass Information

Discussion in 'General Topics' started by Erich H, Feb 14, 2019.

  1. #76 RPWoodbine, Dec 4, 2019
    Last edited: Dec 4, 2019
    I'm considering purchasing the Impact M4-15i Baltic Birch 4.0cuft Midbass flat-pack from DIY Sound Group for the 4 Buyout 15" Subwoofer's I purchased. If I purchased my own 3" ports in longer lengths, would this lower the tune for the box? I would like them tuned to around 25 to 30hz. If this would lower the tune, and given the fact that there are 4 ports in each enclosure, how long would I have to make each port for a 25 to 30hz tune?

    My end result will be an HT-12 sitting atop of a Buyout 15" Subwoofer, to make a 3 way setup. I'll most likely use a pair of Crown XLS 1002 amps to power each speaker set up, one amp(bridged 700 wattsx1 channel) for the Buyout 15" Subwoofer and one amp(bridged 700x1 channel) for the HT-12. I'll use the crossover settings in the amps to blend them together. I'm thinking about 250hz and below for the Buyout 15"Subwoofer and 200hz and above for the HT-12. Thanks for any help.
     
  2. There will be some ported boxes coming soon that will work better than the Impact model if you want to tune lower. The ports that go with the Impact M4-15i are 10" long and I'm not sure where you would find longer ones that fit the same hole cutout.
     
    RPWoodbine likes this.
  3. Thanks Erich. I'll wait then and keep an eye out for the boxes your referring to.
     
  4. [QUOTE=" I'm thinking about 250hz and below for the Buyout 15"Subwoofer and 200hz and above for the HT-12. Thanks for any help.[/QUOTE]

    I don't know how that high a crossover (200hz and above for the HT-12) setting will react with the existing passive crossover in the HT-12. It just sounds problematic to me. Maybe Erich or MTG will chime in regarding that?

    So your plan calls for 4 of the Crown XLS 1002 amps, correct? Just wanted to be sure that is what you are planning.
     
  5. I'm new to the DIY audio world. I've purchased one 15" and a 1.5 cubic foot sealed box. I'm looking to install this in my vehicle. Can anyone recommend an amp that would be appropriate? I'm also looking for information on gauge sizing, et cetera, so if anyone can recommend a resource where I can educate myself further, that would be appreciated.
     
  6. #81 qguy, Dec 18, 2019
    Last edited: Dec 18, 2019
    In large ported enclosure, say 5 cubic ft, which SVS sub will this be comparable to ?
     
  7. I don't know how that high a crossover (200hz and above for the HT-12) setting will react with the existing passive crossover in the HT-12. It just sounds problematic to me. Maybe Erich or MTG will chime in regarding that?

    So your plan calls for 4 of the Crown XLS 1002 amps, correct? Just wanted to be sure that is what you are planning.[/QUOTE]


    Hey Marc...thanks for the reply/post. I don't think it will be an issue. I''m definitely not a sound engineer or speaker designer, but I wouldn't think it would cause an issue with the HT-12. I've heard good things about the Crown XLS line and like how they have adjustable active crossover functions built in. I was thinking of running them all in mono, one for the HT-12 and one for the Buyout 15 bass module. The only other option I was considering was buying an active crossover, such as the Behringer DCX2496 and running Behringer amps for the Buyout 15's and an A/B amp, like the Monolith, for the HT-12's. What were you thinking the issue would be by only feeding the HT-12's a signal void of frequency's below 200hz? Thanks for any input and knowledge you have to share.
     
  8. Has anyone modeled these in a dual opposed sealed sealed configuration like the initial post suggests, compared with single ported? Curious how they would stack up .

    I have a single SI HT18 v2 ported at 22hz. Any thoughts on integrating sealed and ported? If I were to go ported instead, Is it important to have similar tuning freq with my existing sub?
     
    taloyd likes this.
  9. How much stuffing do I need to use for a 4 cubic foot enclosure loaded with two subwoofers?

    Jeremy
     
  10. You can just heavily stuff the entire cabinet with polyfill.
     
  11. Are these sold out for good now? I've had them in the back of my mind to pair with my new Vortex-15s. If so, any ideas on what commercially available driver would be a good equivalent?
     
  12. Pretty sure they're all gone but I'll check over the weekend. They were in stock on the site for over a year! :D

    I don't know any 15" in that price range that would be as good as the buyouts. I might talk to the Vortex designer about adding some 15" woofers to them at some point.
     
  13. I stuffed the cabinet with about 100 ounces of stuffing. I ran the setup for about a week with stuffing and can’t believe the difference with the stuffing. I wish I had bought a couple more of these when they were in stock. This setup replaced Dayton 390HO in a 3.75 ported encounter tuned in the high 20’s. The two 15’s in a 4 cubic foot performs so much better.

    Thanks,
    Jeremy
     
  14. I ended up buying 4 of the buyout 15's. My plan from the beginning was to go dual opposed in a 3 or 4cuft flat pack with some mods. Right now my plan is to go with a 3cuft (2.7 net) cabinet using a NX3000D bridged. I am obviously not looking for really deep extension with this build. Based on my Winisd models I should be able to easily keep cone exscursion under control even with a small 2-3db boost in the 30-35 HZ area with out maxing the amps output.
    Everything is ready waiting on me to get off my butt and get started building! Lol if anything this covid mess has made me more lazy than I already was!
     
  15. Ok, so I'm finally starting to plan to cabinets for the pair of these I snagged earlier this year.

    In the ~4cuft ported alignment, what port configuration should I be looking at? I have them modeled in WinISD but I don't really understand the tradeoffs around port diameter. Would dual 3" ports work well?
     
  16. When sizing ports there are three things to keep in mind.

    Will it physically fit in the enclosure (this one is kind of obvious).

    Port airspeed at max drive level, this is the main consideration for port size.
    Lower airspeed is better and results in less output losses due to compression and turbulence along with lower overall port noise. The way you decrease airspeed is by using a larger port area, but remember a larger port area also means it must be longer to achieve the same tuning. In my mind if port airspeed can be <10m/s at max drive level that is excellent, if you can keep it <20m/s that is good and I try not to have anything that pushes it beyond 30m/s at which point it is already usually compressing a decent amount and making a bunch of noise.

    The third factor is the port resonance frequency. Generally you want to keep this at least an octave above the highest frequency the sub will be used. This is usually only an issue on large subwoofers with massive ports tuned very low.

    For these woofers unless you are driving them with only 100-200w each you will want to go with at least a pair of 4" ports.
     
  17. That is very helpful, thanks. Looks like I may need to investigate putting an elbow into the port tubes if I want to hit that 22Hz tuning.
     
  18. So I still have these sitting around, with the baltic birch for ~4cuft cabinets cut and ready to go. In getting ready to start the project, I've realized that I sized the cabinets to match my Vortex-15s and that this could make the subwoofer build a bit tricky. Specifically, they are 17 inches wide, which is juuuuust wide enough for a 15 inch driver to fit on the front baffle. The issue is that this width makes two 4" Precision Ports a very tough fit on the front baffle. I think they do fit, but just barely and I'm a little concerned about the structural integrity of the narrow bit of wood that will be between them. I will also need to put an elbow in the port tube and this will make bracing and the overall build a bit more complex.

    I suppose making the ports rear facing is an option for dealing with the lack of real estate on the front baffle. But I am also now thinking that a rear-facing passive radiator might be a good option, specifically the Dayton Audio RSS390-PR, which seems like it might be beefy enough. I'd really rather not modify the box dimensions, and I'm not concerned about the cost of the PRs since I already paid for the subs and wood long ago.

    Does 4cuft with a PR seem like a reasonable alignment for these subs? I have modeled it in WinISD and it looks like with zero mass added to the PR, this will net me an F3 of about 31Hz compared to about 26Hz with two 4" ports tuned to that frequency, which is the best I came up with. Just looking for a sanity check on these numbers since I'm fairly inexperienced with modeling and have never done anything with PRs. The yellow line is the PR alignment while the teal line is the ported alignment.

    It's unfortunate to give up a bit of low frequency extension, but I haven't totally decided whether these are going to end up in my home theater or a separate two channel system and am basically OK with them being more optimized for music. They will be paired with my Vortex-15s either way.

    upload_2021-8-30_9-36-46.png
     
  19. Generally passive radiators need more volume displacement than the active speaker - so they're frequently sized up, ie: a 12" active woofer is paired with a 15" passive radiator, or a pair of 12" PRs (then you get some inertial cancellation, which is always nice).

    One thing to consider, which is seldom done but actually has no drawbacks that aren't aesthetic - is having some of the port length outside the enclosure. The tube of the port doesn't really care where it is - so if you can route the port outside the enclosure, which requires minimal structural support, then you have a winner. Especially if you can use one port instead of two - though larger ports need more length for the same tuning. But perhaps a 6" port, routed outside the enclosure and in a u shape (going up, then U-ing and going back down so it's facing down and doesn't get dust) could get you where you want, without any passive radiator. Hsu subwoofers did this for some of their enclosures, using the name Turbo IIRC. It's not magic, it's just a bit ugly, but it absolutely works.
     
  20. Front firing sub, dual side firing passives :).
     
  21. Thanks. Side firing dual 12" PRs might work for me, I will look into it. I don't think the external port tube idea will work given the places where these subs may end up, although it's some good out of the box thinking (lol).
     

Share This Page