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Cabinet tuning help

Discussion in 'Amps and Cabs [BG]' started by randyg, Oct 29, 2013.


  1. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    Ok , so I've been working on my diy 2-15 cabinet on and off for a while now and I have a question. The internal dimensions are 35"x23.5"x12" for a net volume of about 5.3 cuft. It has 4 3.75" diameter flared ports that came 7.63" long and it has 2 3015's in it. My calculations came up with a tuning freq of 46.5hz. I did a rice test and the grains never stopped bouncing , but bounced a lot less in the 42hz range. I shortened the ports one at a time by 1/2" each and the rice movement slowed closer to the 47 to 48 hz range. I have tried the cab lined with thin quilt batting as well as 2" thick white fiberglass insulation. I have also tried it with one port blocked and one tube removed , which should greatly lower and raise the tuning freq. Here is the question , it sounds great in the mid and high ranges , but the low notes , especially the open E string , do not sound full and strong. I have to really crank the bass on my SVT-CL or it sounds hollow and mid rangey. Describing tone is difficult , but it does not have much low end. It also sounds the same when I was playing around with the port tuning. Nothing I did changed the tone much at all. Any advice on what tuning frequency to shoot for? It is built from 3/4" 13 ply baltic birch , glued and screwed. Maybe I just don't get along with the tone of the 3015's. My favorite cabinet is an Ampeg 610hlf which some people find too bassy. Thanks for any help.
     
  2. Double check that the drivers are wired 'in phase'.

    If they are in phase, you can increase the prominence of the bass by tuning higher, say around 55Hz. Seems counter-intuitive because you will get less deep bass, but that will make the bass more prominent overall.

    If that doesn't work consider trying a different driver (like the Faital Pro 15PR400).
     
  3. My bets would be drivers out of phase, sounds like the classic one driver moving out while the other moves in cancellation.
     
  4. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    I've checked the phase issue and it's ok. I had these speakers in a Peavey 2-15 shallow cabinet and to me they did not have that full , round big bottom sound the stock speakers had in that cab , but I figured it was that speaker/cab mismatch problem. I'll try tuning the cabinet higher and maybe close the ports and try it sealed , but I'm not getting what I was expecting from it. Maybe I've been hearing that bottom heavy 610hlf too long.
     
  5. Are these 3015, 3015LF, or 3015HO?

    [ edit ]

    If 3015 type, with Vb=2.65*2, and Fob=45 Hz, you are looking at F3 around 65Hz.
    This is a mid-range strong response. Down -9dB at 41 Hz.
     
  6. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    The speakers are the 3015. I got the port tubes from Parts Express , part number 260-480 and put four of them down one side. It's built to look like a Greenboy Dually and has about the same dimensions , but I have no idea what port tubes are in the Dually.
     
  7. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    Any tips on how to get better low frequency response from this cabinet?
     
  8. The key here may be your expectations. The 3015's in a 'Dually' cab will NOT have 'that full, round big bottom sound the stock speakers had in that cab', at least not without some serious EQ. Note that if your cab's internal volume is less than the dually its bass will not be as full. It will indeed be bass shy as bgavin pointed out. As I said earlier, you can regain some bass fullness by tuning higher.

    If you followed the instructions that came with the port kit you should be fine with respect to tuning frequency.
     
  9. rberry7777

    rberry7777

    Feb 5, 2010
    Go on parts express. Search precision ports. Pick a 3" diameter flared port. For example then Click on the port calculator. Add in the simple info on the left hand column and it will give you the lengths for both straight and flared ports

    Just did it with my 2-12 emenence neo cab. Unbelievable! Totally fantabulous.
     
  10. rberry7777

    rberry7777

    Feb 5, 2010
    Make sure your cab is wired in phase
     
  11. will33

    will33

    May 22, 2006
    austin,tx
    Make it bigger? :D


    Your size is pretty compact for a 215. That combined with those drivers being fairly strong in the mids may sound bass shy overall. Can try raising the tuning some.

    Box panel resonances working against your output goals could be another contributor depending on your bracing scheme. Thick walls with little to no bracing is not as stiff as a bit thinner ply with more/better bracing.

    Are the drivers brand new? Takes a bit for break-in/suspension loosening up. Could try letting a LF test tone ( 30-40hz, pretty low power but enough to get the cones moving ) run through it overnight, and listen again after.
     
  12. will33

    will33

    May 22, 2006
    austin,tx
    Also try cutting some of what you don't want on the eq (mids/uppermids?) rather than adding what you do want (bass). Up the volume a notch to compensate.
     
  13. How did you check for phase? I just finished a 215 cab and on the first test drive, it had no bass and generally sounded horrible. I didn't even consider the possibility that I had wired the drivers out of phase. I had been very deliberate and methodical in the wiring and, frankly, I didn't think I could have made such a silly mistake. But I did. Didn't realize it until I did the battery test.
     
  14. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    I really thank everyone for the help. It was with help from this site I was able to get this cab built. It really sounds good , a beast in the mids and highs , and the low end is good too with some EQ boost. My expectations may be a good point as I had never heard a modern 2-15 with 3015's in it. I have also not used it in a band mix yet , only solo and it may shine in a rock band with Les Pauls and Marshalls. I'm going to trim the port tubes to a little over 50hz , Duratex it and rock the crap out of it.
     
  15. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    I did the battery test again a little while ago to make sure. It's ok. The speakers are still pretty new and I know the low end gets better as they break in. My Avatar 4-10 did that. I have the baffle braced to the back between the speakers and thought about bracing side to side , but with the 3/4" 13 ply , it seems pretty stiff. I may add a brace or two just to be sure.
     
  16. This exlpains it.
     
  17. randyg

    randyg

    Jul 10, 2010
    Creedmoor N.C.
    If I understand correctly , the Fob is the tuning freq of the cabinet , right? I'm a little unclear on what to do to get the low freq up. I've read the spec sheets for the speakers and tried to figure it all out but most of it is still over my head. That's why I tried to copy some proven designs. I'm close , but not quite there yet.
     
  18. will33

    will33

    May 22, 2006
    austin,tx
    The size, tuning, new drivers, and only hearing it solo tells me I wouldn't alter it to much until it's briken in a little and you've had a chance to hear it with the band.

    It's a whole lot easier to chop port tubes shorter than it is to stretch them. :smug:
     
  19. will33

    will33

    May 22, 2006
    austin,tx
    FWIW, if you have an android phone, there is an app called True Tone that'll do sine, square, triangle and sawtooth waves from 1 to 21000 hertz.

    Pretty handy for checking tuning, just rig up a 1/8" to 1/4" or speakon to run from phone to cab.
     
  20. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    What sort of room are you listening for this low end in?

    People got kind of used to being conned about lows by high cabinet tunings for a midbass bump.
     

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