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Calling Bgavin and other cab gurus!

Discussion in 'Amps and Cabs [BG]' started by Bigwan, Apr 23, 2004.


  1. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    Hi there guys,

    You've been very helpful to me in the past and I'm hoping that I can call on your expertise once again! I have an Ashdown 1x10 combo that's the center of my rig, along with 2 1x15 cabs loaded with eminence Kappa 15 LFs (I built them to Bgavin's design and am thrilled to bits with the results :D ). However, good as they are, I find myself missing my upper mids and highs.

    The 10" Celestion in my combo is completely wrecked and I've been considering what I could use to replace it. Since the combo isn't exactly standard (I've had the soldering iron out and it's now capable of somewhere in the region of 500 watts into 4 ohms) I'm not restricting my choices to 10" replacements. From Bgavin's reference spreadsheet I've pretty much narrowed it down to 3 drivers - Eminence Deltalite 2510, Eminence Kappa Pro 12 and Eminence Omega Pro 12 (I'm set on Eminence drivers as everything else is quite difficult to obtain in the UK. Even some of the Eminence line isn't available in the UK :spit: ). I've roughly calculated the volume of the cab in the combo at approximately 1.5 cubic feet.

    My plan is to replace the driver in the combo with one of these and install an Eminence APT200 tweeter, an L-pad and 3 way crossover in one of my 1x15 cabs. That way I can either run the combo on its own or couple it to my 2 1x15s and use the combo speaker as the midrange driver in the rig. I suppose my question is, since I would like to be able to use the combo on it's own too, what would be the best of the 3 drivers to use?

    Sorry this is a bit long winded! :bag:

    Cheers

    Ian
     
  2. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    Bump
     
  3. Ian,

    First, the Kappa 15LF is good to 1,500 Hz. For smooth results, you should cross over 1 octave lower, or 750 Hz. The closest 3-way crossover is the Eminence pxb3:3k5 at 500 and 3,500 Hz. The APT:200 has sufficient air column length to be fully loaded to 2,500 Hz, so you are pretty safe crossing over at 3,500 Hz. The shorter the horn, the higher up you go before you reach full loading.

    The Deltalite 2510 is the only neo driver from Eminence worth a sh!t. It is ideal in 1.39 cubic feet at 41 Hz. If we assume 0.1 cubic feet displacement for the 2510, this makes your existing cab perfect for an SBB4 alignment at 41 Hz. This is the ideal alignment for this driver. This gives you a port diameter of 2.9 inches and a length of 5.5 inches. Gray Schedule 80 PVC pipe is 2.90 inside dimension, and is the ideal minimum for no chuffing. Here in the US, this size is readily available at construction yards. It is commonly used for electrical conduit.

    The Deltalite 2510 runs out of gas at 3,500 Hz, where the tweeter comes in. There will be loudness issues between the drivers, as each is markedly different in sensitivity. An L-pad or attenuator is a must. The crossover mentioned above is a "not cabinet ready" type (internal) and has no attenuator pads.

    Now let's think it through as a multi-use cabinet:

    1) Full boat: 2x15 + Delta + Tweeter
    2) Solo: Delta (full range) + Tweeter

    I smell a difficulty now.

    2nd approach: Run the 15LF full range. Use a pxb2:3k5 2-way crossover inside the combo cabinet. The Deltalite sees full range, the tweeter is correctly crossed over. Downside: the 2510 will be taking the full brunt of the low end when driven along with the 2x15 cabs. Farting may be an issue.

    3rd approach: Run a 2-way pxb2:800 in the 15LF cabinet where everything below 800 Hz goes to the 15s, and the rest goes out of the cabinet. Run a pxb:3k5 high pass in the combo for the tweeter. When the combo cab is plugged in, it gets 800 Hz and higher from the 15LF, or gets full range when used by itself. The tweeter is crossed over either way, at 3,500 Hz. Downside: the 15LF will always run out of highs at 800 Hz, and will always require the combo to avoid sounding dead.

    If I read your note correctly, Door Number Three is the most workable. The combo can be used standalone, or as the 800 Hz+ component.

    Note: if you are paralleling 2x15 (4 ohms), this is going to confuse hell out of the passive crossover. I would wire 1x15 as full range, paralleled with the 2nd 1x15 which has the 800 Hz 2-way in place. This keeps the low crossover at its nominal 8 ohms, runs the first 1x15 as full range (no big deal). The amp is still seeing a combined 4 ohm load, albeit the 2nd portion is crossed over.
     
  4. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    Hi Bruce,

    So, first off, it would be the deltalite that you'd choose of the three options? Thats what I thought too...

    I had actually thought that door number 4 would work quite well:-

    1) Full boat: 1x15 + ((1x15 + Tweeter) + Delta)
    2) Solo: Delta (not ideal but this would be for home practise only - if it bothered me that much I could change and go with option 3)

    By installing a pxb3:3k5 and APT200 (with attenuator) in one of the 1x15 cabs and using the combo driver as the midrange for the three way crossover, this should keep the load at 8ohms (it might mean some quite messy wiring ie. Combo to both 1x15 cabs with midrange only signal returning from crossover in 1x15 to the combo cabinet). Then I can run the second 1x15 full range and bring the load to 4 ohms. Does this sound like it would work OK?

    Cheers again

    Ian
     
  5. I see... keeping the APT:200 in the same cab as the 1x15 and crossover. The midrange is a separate jack/cable and goes to the combo. I biamp with a 2nd cable that runs from the subs to the Highs cabinet. Two pair Speakon cable handles the separation of Low and High signals in a single cable.

    This provides the end result of the combo is Delta solo (no tweeter). The 1x15 with crossover + tweeter can only be used when the combo is plugged in. In exchange, there is no cutting on the combo speaker board to install the tweeter.

    Yeah it will work. The Deltalite runs out of gas at 3,500 Hz which is good enough for practice and small stuff. It is reputed to be pretty bright, so you might consider trying the Deltalite + 1x15 without a tweeter. There may be enough highs that you don't have to spend the extra money on the APT.
     
  6. Bigwan

    Bigwan

    Feb 22, 2002
    Ballymena (hey)
    I'll probably go without the tweeter in the meantime. If I found there wasn't enough high end then I could always go back to the 3 way crossover and install the tweeter in one of the 1x15s. The only loss would be I would have a 2-way crossover spare, which I could always get some sort of use from!

    Cheers

    Ian
     
  7. andertone

    andertone Supporting Member

    Mar 22, 2000
    Southwest USA
    Hi:

    I actually did buy a Deltalite 2510 to slap in my
    Ashdown ABM-C110-300 to try to get a little
    more bottom. Didn't modify the ports, and decided
    that the stock speaker had just as much bass in
    the unmodified cabinet. I might have squeezed a
    little bit better response, but decided it was turning
    into a project and I gig regularly

    I push the E string hard, and finally decided I need
    more than a single 10".

    Sold both the Ashdown (sigh, great amp) and the
    Deltalite and am looking for a Mesa Walkabout Scout.

    BTW, my 65 Blackface Fender Showman through a
    Bag End S15D loaded with a JBL D140F blows the
    Ashdown away, not even close.

    Phil Anderson
    Tucson, AZ