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Cab Tuning for drop C

Discussion in 'Amps and Cabs [BG]' started by FlashLBL, Jul 11, 2019.


  1. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Hey guys, New member here.
    I have a Celestion Pulse 15 and 2 Pulse 10's which I plan on installing into the respective Harley Benton cabs. I've been reading about cab tuning the last few days and have gotten a bit confused with it all. Basically I want to know what the best tuning is for Drop C (this is what I primarily play in)and how to find out what the cabinets are tuned to from the factory? any help is much appreciated, Thanks:)
     
  2. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Song Surgeon slow downer. https://tinyurl.com/y5dcuqjg
    Welcome to TalkBass! Thanks for joining up.:thumbsup:

    Cab tuning happens between the speakers and the cab. A cab is built to the specs of a speaker to optimize it's frequency range. Whether or not a specific speaker will work in a specific cab not built for it, it's usually a crap shoot.

    It's not directly related to the tuning of your bass though you can find cabs that go lower and handle more power if that's what you need.

    And, a HPF can protect your cabs no matter what tuning you use. See my TB Wiki on the topic for more info.

    More tech people will be along shortly to get into more details and to help you out.
     
    Last edited: Jul 12, 2019
    oZZma, rockinb and FlashLBL like this.
  3. Wasnex

    Wasnex

    Dec 25, 2011
    The electric bass does not put out a strong fundamental, and most of what you hear is the first overtone. If the bass is tuned down to open C, the fundamental is 33hz and the first overtone is 66hz, so you will probably be fine with a speaker that is flat to 66hz or a bit lower. Here's a relevant thread: Bass frequency/waterfall plots: what they mean to rigs

    It would be natural to think a lower frequency response is better, but usually you trade low frequency extension for efficiency. So if you want a reasonable size rig, it can either play low or loud, but typically not both.

    Here's a basic description of how a ported cab works:
    The driver produces a strong response down to a certain frequency, and then the response begins to roll off. The frequency the rolloff occurs at is related to the driver's Thiele & Small (T/S) parameters and the volume of the box. The port is tuned to a lower frequency; so that as the driver's response drops off, the port starts producing sound. As the port becomes more resonant it starts controlling the movement of the driver. The driver's excursion is at its minimum at the port tuning frequency. Below the port tuning frequency the response of the cab will drop off very quickly and the port stops exerting control over the driver. If your amp has output significantly below the port tuning frequency, you should consider an HPF to help protect the driver from over excursion. I believe a common practice is to set the HPF at the point where the cabs response is down by 6dB, but this varies by how the cab is tuned.

    Parts Express includes cab design documents with most of the Eminence woofers they offer. I'll include the cab design document for the 3012LF. Take a look at the vented designs. The first one starts on page 7. A few terms you need to know: Fb is the port tuning frequency, F3 is the point where the cab is down 3dB, and Xmax (in this case 9.1mm) is how far the cone can travel linearly. Specifically look at the amplitude response graphs and the cone displacement graphs and compare to Xmax an Fb of each design.

    Hope this helps you gain a basic understanding.
     

    Attached Files:

    oZZma, JRA, rockinb and 3 others like this.
  4. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Song Surgeon slow downer. https://tinyurl.com/y5dcuqjg
    Can you post more info/specs on the Harley Benton cabs? And the speakers.
     
    FlashLBL likes this.
  5. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Sure no problem! The Pulse 15 is 400w 8ohm with a range of 40-3500Hz, fs of 35.7Hz, Qes of 0.474 and Xmax of 4.75mm. The Pulse 10 is 200w at 8ohm with a range of 45-3500, fs of 68Hz, Qes of 0.53 and Xmax of 4mm. both are ferrite magnets. The 2x10 cab- SPL: 98 db, Frequency range: 45 - 17 kHz (has a tweeter), 15 mm plywood housing, Dimensions (W x H x D): 586 x 486 x 465 mm, wired to 8ohm
    and the 1x15- SPL: 98 dB, Frequency range: 45 - 17 kHz, 15 mm plywood housing, Dimensions (W x H x D): 586 x 500 x 458 mm

    sorry if that's not what you meant
     
  6. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Oh also I'm not sure if this helps but i use a Hartke TX600 head (600w at 4ohm, 400 at 8)
     
  7. Need port dimensions.
     
    FlashLBL likes this.
  8. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    You can't do what you think you can do with the things you have. It goes wrong at having a 15 and two 10s and thinking you can make them work together well, and doesn't get better from there.
     
    seamonkey likes this.
  9. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    could you explain why having a 1x15 and a 2x10 won't work? I've used this combination for nearly 6 years and know of others who have for much longer. My reason for the speaker transplant is purely for the extra power requirements I now have, I really like the pulse series speakers and finally can't afford to commission the 2 custom built cabinets as I'm in university and they aren't factory fitted in any cabinet as far as I'm aware or could make the investment into right now.
     
  10. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Thanks I'll measure up in the morning
     
  11. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Because you can't make everything optimal for two different things, so you just get a compromise. Either figure which does what you want, and double up on that, and if neither does what you want, get something that does do what you want.
     
    Systolic likes this.
  12. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    It isn't 2 different things though, the combination of the 1x15 and 2x10 does do what I want. The sake of this post was purely just to find out how I can be sure the current port sizes I have are big enough or not too big to cause over excursion and damage to the new drivers. Which thanks to the previous responses I've had I'm closer to knowing, it has nothing to do with figuring out what works together as I already know that this combination does. I appreciate your input on the subject none the less.
     
  13. Some things have to be learned the hard way. It looks like OP is past point of no return. It might sound more than passable if done right but could equally wind up rather lackluster.
     
    FlashLBL likes this.
  14. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    2 8 ohm tens in one cabinet can either be wired in parallel for a 4 ohm load, or series for a 16 ohm load. You can’t wire them for an 8 ohm load.
     
    thetragichero likes this.
  15. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Would that mean the current drivers in the cab must be 16ohm each as its an 8ohm cabinet which is wired in parallel?
     
  16. I missed that in the update! Yep, non starter.
     
  17. Most likely. Otherwise twin 4 ohm in series.
     
    FlashLBL likes this.
  18. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Okay thanks, I just tested them with the multi meter and they are 4ohm so I believe I've been mistaken in saying the speakers are wired in parallel when in actual fact it's the speakon input&output that is :')
     
    ctmullins likes this.
  19. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    If its the diameters that do what you want, then the porting doesn't matter. But what actually happens is the right port size for the 10s and the right port size for the 15 are different.
     
  20. FlashLBL

    FlashLBL

    Jul 11, 2019
    Cardiff, UK
    Sorry I probably should have been clearer in saying that they are separate cabinets.
     

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