LDS 1-12s: Houston, We Have A Problem!

Discussion in 'Amps and Cabs [BG]' started by ::::BASSIST::::, Sep 4, 2010.


  1. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Well, it happens at rehearsal volumes (a volume you'd need to be heard over the drums). My RH450 was set flat so no bass boost at all.

    Decreasing the low-end or volume would not be an acceptable solution for me. :(
     
  2. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    Dang, if I knew that I would have went with that port design. Don made a point of giving me the option.
     
  3. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Torin, trying my suggestion may at least help you figure out where to go next?

    The last time I had that problem in one of my DIY cabs I was able to tune the port lower than my lowest note (I only play 4-bangers), which was an acceptable compromise in my case.

    Best of luck. I'm sure it'll get sorted.
     
  4. will33

    will33

    May 22, 2006
    austin,tx

    Nothing wrong with port tubes, I think you just need a little bigger ones. I like them way better for DIY, simple easy to work with, easy to change sizes/length until you get what you want. Just make sure you have enough area. Building the port as part of the cab is great if you've got all your homework done and done right. If any adjustments are needed it means cutting or adding wood in a cramped little corner where the saws and hands don't fit easily.
     
  5. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I appreciate the assistance PW, but alas its sort of beyond me as I don't know how to tune a port lower.

    I think the best bet is to hear what Don has to say.

    I play 4 string only as well. However, to be honest, I'm not willing to make compromises with these cabs. I was really hoping these cabs would be "it" for me. I occasionally do play at very loud volumes and my tone is quite bass-heavy (very little highs, upper mids but lots of upper bass & low-mids). I really want these cabs to deliver. Anything less is unacceptable. I'm pretty picky when it comes to this stuff!
     
  6. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Yep. I'm not suggesting you do any mods on brand new cabs, regardless of the difficulty/ease factor. But are you positive this isn't just a simple air leak, say through an unused and unsealed 1/4" or Speakon jack? Either one of those can sound amazingly bad...

    You, picky? :cool: Why do you think I gave up on all commercial cabs years ago, except for my very non-demanding jazz gigs?
     
  7. will33

    will33

    May 22, 2006
    austin,tx
     
  8. rpsands

    rpsands

    Jul 6, 2007
    I would wager the epi is tuned a bunch lower which will lower the frequency where air speed is max.
     
  9. will33

    will33

    May 22, 2006
    austin,tx


    Good point.
     
  10. BassmanPaul

    BassmanPaul Inactive

    The LDS box is lined. I had a case somewhat similar to yours. Turned out to be piece of the batting had come loose and was vibrating in the air stream from the port. Easy to check and and, if so, an easy fix.

    Paul
     
  11. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I did check out the batting when I took the driver out and it looked okay. I did not give it a super close inspection though. Its happening with both boxes so....
     
  12. rpsands

    rpsands

    Jul 6, 2007
    I will guarantee that with two three in ports and a 50ISH Hz tuning those boxes Will chuff before running out of excursion.
     
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The shape of the port has little to do with the noise level, which is primarily the result of the friction of air against the port wall. The smaller the port the higher the air velocity, and the higher the friction and noise. The location doesn't make much difference either. I recently measured some prototypes using both corner located triangular ports and baffle mounted circular ports and they were exactly the same with the same port area. Long/thin shelf style ports can affect things, but only when the length to width ratio is severe, as in a port the full width of the cab.
    There is a reason to make the ports as small as possible, as doing so keeps the overall box size down. In some cases you can get away with it, in some cases you can't. Part of the prototyping process is finding out how small you can go before 'compact' becomes 'too small'.
     
  14. SlingBass4

    SlingBass4

    Feb 28, 2009
    Kansas City
    In this situation the length of the port must be factored in, as well as the inside dimensions, and insulation type too - therefore the term "tuned port".
     
  15. will33

    will33

    May 22, 2006
    austin,tx

    I have about pulled my own hair out before messing with shelf ports trying to get them right. I think the interaction of the walls had a lot to do with it but even so adding and removing shelf from way too high to way too low and everywhere in between never ended up being right. I know it can be done, people do it all the time but in my case, I ended up patching it all up and sticking a couple pipes in, problem solved.

    I think rspands probably got it right in the case of the OP's Epi. It likely is tuned lower. If it was tuned the same, in theory it should have the same problem as his LDS. The LDS ports are likely fine with a speaker up to about the level of a deltalite or so. I think something with the performance of an HO just needs more "room to breath".

    According to his description, there's enough baffle room to go to a little bit bigger pipe, or heck, maybe just lower the tuning some using the same size port tube, putting the chuff down to or just below the low E. He did like how it sounded in the Epi. cab after all.
     
  16. rpsands

    rpsands

    Jul 6, 2007
    The downside is with the QTS so low on a 3012HO a lower tuning sacrifices a lot of important response. Not ideal. I'd rather have more port area and a lower tuning. You really want this driver tuned at 50hz, 48hz at the lowest, by my models. I liked mine with ~52hz pretty well, but 20 square inches was the MINIMUM port area I'd go with there.

    The solution here is simple: Need to enlarge those ports and re-tune them. It sucks that either the OP or Don is going to be eating it financially to make it happen.

    IMHO, if I were Don, I'd eat it, because he blatantly went against the basic Eminence standard design for this box (two 4" ports for a med vented cabinet). Probably just an oversight.

    On the flipside, this issue specifically with the 3012HO has been discussed extensively by me here on TB, and the OP should have known enough to say "I want at least 20 square inches of port area" if he'd done a little homework.

    I can't remember who I talked to but I know someone asked me this question specifically via PM at some point and I said as much -- "If you use the 3012HO, be sure to get at least 20 square inches of port area, 28+ for the 3015."
     
  17. will33

    will33

    May 22, 2006
    austin,tx
    Oversight probably, used to doing a little different take on the same thing for awhile but yeah, the homework's been done here. Coming at it from a builders, make a run of a bunch of whatever you're already set up for point of view I could see upgrading a driver in a configuration that's already laid out, tuning adjustments are easy for purposes of tone or whatever but it's apparent they didn't plug a bass in it and see what it could do.

    I think the increase of the level of performance in the kappalite series in addition to them being affordable is one of those signposts that's going to make everybody have to re-think things in order to take full advantage of them instead of considering it a little better take on the same thing. It's stepping up to another level instead of making the same/similair thing a little better. Wouldn't hurt to add an extra brace or two either.
     
  18. bobcruz

    bobcruz

    Mar 10, 2004
    CA
    Would flares at both ends of the 3-inch ports be enough to mitigate the noise or is that something that takes experimentation to determine?
     
  19. ::::BASSIST::::

    ::::BASSIST:::: Progress Not Perfection.

    Sep 2, 2004
    Vancouver, BC Canada
    I guess I am partly to blame for not telling Don to make the ports 4". However, I am a novice when it comes to this stuff & Don is the expert. I paid him the money to provide the expertise. I'm just a bass player!

    and T'was not I who PM'd you. :)
     
  20. lomo

    lomo passionate hack Supporting Member

    Apr 15, 2006
    Montreal
    As a satisfied LDS customer (15/6) who knows zero about the physics of porting a cab, I don't agree that the OP bears ANY responsibility for specifying port details. Don is a custom cab builder who has made many boxes before-IMHO it is up to him to alert the customer if something they ask for is amiss, and make sure a cab design is sound (pun viciously intended) before starting a build. My cab is the best I've ever had and I recommend LDS highly, but I feel that if the issue is insufficient porting, the onus is on Don to fix it at no additional cost to the OP.
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Sep 18, 2021

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