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BGavin or Joris, cab design.....

Discussion in 'Amps and Cabs [BG]' started by TJBass, Jan 26, 2003.


  1. I've got an Avatar 410, what I intend to do is remove one of the drivers and build a cab for 1x10. The reason is because I will be deploying to the middle east soon and size is crucial, volume is not. Anways, on the winISD program it shows a default plot for the driver, box volume at .647 cu ft being tuned at 80.32 hz. Question is this, by moving the box vol up to .8 cu ft is it possible to get better low end response without making it muddy or should I stick to the default measurements displayed? No matter where I move the box tuning or the box vol the cutoff stays between 80 and 90 hz. Is this the best this driver can do, will this cab sound decent? I will run my amp thru a PA so vol is not a major factor, however I would like to use this when a PA is not available at moderate levels with around 350 watts. Any assistance is greatly appreciated....

    Jay
     
  2. Welcome to Delta 10 drivers. You are stuck, because they perform as they are designed. My advice is do not butcher your Avatar, but purchase another driver.

    Download my spread sheet from my signature.

    Sort by driver size, and ascending SBB4 cabinet volume. From the 10" group choose a driver that suits your needs. Look for a Fb tuning frequency close to your lowest note. 41 Hz for a 4-string.

    The SBB4 vented drivers are better quality than the BB4 types.

    Look into the DeltaLite 10" driver from Eminence. Weight is much reduced, and it performs better than the Delta 10 in the low range.

    Consider using a sealed box. Smaller size, least amount of mud. Also, tuning a very small vented box is a real chore. Look at the B2 and D2 sealed box columns. The B2 has the flattest response, and the D2 has the best transients (lowest mud), but it comes in a bigger box.

    Car subwoofers fit the catagory of very small sealed boxes with good low frequency response. They are notorious for sucking up huge amounts of power, and will require another driver or tweeter for the highs.
     
  3. Unfortunately I am stuck with this driver as I don't have the cash for another. I don't intend to butcher the cab, just remove one driver and add to the cab I am building. When I return I will re-install the driver back in the original 4x10 cab.

    Will moving the box volume to .8 cu ft make that big of a difference on the low end response? Is there any suggestions on what I can do to make this specific driver sound decent in a stand alone cab?

    Thanks for the rapid response....I'm hoping this will get me by till I return...

    Jay
     
  4. If you are satisifed with the way the Avatar 4x10 sounds, put one of those drivers into 1/4 the internal volume. Adjust the internal volume for the 0.12 cubic feet displaced by the driver itself.

    1) Measure the internal volume of the 4x10.
    2) Subtract 4 * 0.12, or 0.48 cubic feet
    3) Divide this volume by 4

    This is the net volume occupied by a single driver.

    The Avatar uses the extended bass shelf alignment, which is larger than the optimum. You can see the shelf effect in WinISD The EBS alignment has more mud at the tuning frequency.

    The Fs of the Delta 10 is 66 Hz. Avatar tunes their cabs at 65 Hz, and I'm guessing at about 1.25 cubic feet per driver, to get the EBS alignment.

    Myself, I don't like the mud, so I'd go 0.52 cubic feet net volume, which is the SBB4 alignment that gives the tightest bass. The larger you go above 0.52 cubic feet, the more you approach the EBS alignment.
     
  5. Can you adjust the box tuning by added polyfill in the event the box is muddy?
     
  6. No.

    A layer of stuffing is desirable because it controls internal reflections inside the cabinet. Filling the cabinet with stuffing makes the cabinet perform as if it were larger than it actually is.

    Mud comes from high group delay numbers. It is part of the design parameters for the driver at hand. Some drivers have extremely low (good) group delays (JBL E155) and others are high (Kilomax Pro 18). It somewhat follows the Qts value: high Qts = more mud. A low Qts driver is nearly always a sign of better quality, and higher price. The JBL drivers are always very low Qts.

    The Delta 10 is not a muddy driver. In SBB4, it has a maximum 8 msec delay, which puts it easily into the realm of a sealed box. 20 msec and longer is what folks hear as mud.


    Link to Delta 10 Gain Plots



    Link to Delta 10 Group Delay Plots
     
  7. So should I go sealed or vented? I originally intended for it to have two 2 13/16 ports to ensure they had plenty of clearance behind them from the back wall, but if I can go sealed and get better tone thats what I'd like to do. Altrhough your spreadsheet on the delta 10 recommended it in a vented enclosure.

    So the recommendation would be to utilize a minimum amount of polyfill on the sides only?

    Thanks for taking the time to explain this to me...

    Jay
     
  8. The Delta 10 is not designed for sealed boxes. It has a very high EBP of 188, where > 100 is considered for vented boxes.

    I have modified the links to the Delta plots in the previous message. The plots show the Flat, EBS, and SBB4 response curves, and the group delays.

    The EBS alignment has the best bass extension, which is why Avatar is using it. EBS also suffers the highest group delay numbers. Even then, 13 msec isn't a terrible number, which is why the Avatar doesn't have a reputation for being muddy.

    The Delta 10 just doesn't have much bottom end, no matter which way you squeeze it. As for tuning, you must do this with a signal generator and volt meter. Port calculations will get you into the ball park, but I've never found them particularly accurate.

    For the record, I prefer SBB4 alignments for minimal mud. The 2nd reason for SBB4 is they are typically tuned lower and offer more protection to the driver at low frequencies. The Delta 10 is tuned terribly high no matter what alignment is used, so don't over drive it.
     
  9. Based on the .52 vo, on your speadsheet, the port is listed at 2.40, is this the port diameter? If so do I use this on the winISD program to get a ballpark length for the port prior to tuning with a sig generator?
     
  10. WinISD will get you a ballpark port diameter automatically. You can adjust the diameter and see the length change automatically.

    This is a ballpark figure only. Actual port length must be done by measurement.

    There are caveats with port diameter. The ideal is 0.045 MACH for minimum port noise. Note this is at the port tuning frequency only. Air velocity in the port diminishes radically as the frequency moves away from the tuning frequency.

    If you have a port tuned at 29 Hz, and your lowest note is 31 Hz, you can make the port diameter smaller. If the box is tuned at 23 Hz and you play down to 41 Hz only, the port diameter can be much smaller. Robert Bullock's DOS BOX modeling program will plot this for you. It runs marginally in an NT/2000/XP DOS window, but fine in Win9x.

    You can adjust the port diameter in DOS BOX, and plot the port velocity. Bullock's program is quirky to use, especially under the NT kernel, but it does things WinISD will not.
     
  11. The link for the box modeler on your site is not working, did you know this? LOL So based on this speaker, what would you do? Box volume, port diam, port length, yada yada yada?

    Thanks for all the help...

    Jay
     
  12. I'd use this speaker for a PA driver.

    Thanks for the tip on the web site. The main reference file link is working, but I have pulled all the other stuff, and need to update the site links.

    [ edit ]

    The Bullock link is working now.
     
  13. Gus Autine

    Gus Autine

    Aug 25, 2000
    New York, NY
    I don't know what either of you just said, but it sure sounded smart!