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midrange driver recommendations?

Discussion in 'Amps and Cabs [BG]' started by MuzikMan, Jul 17, 2004.

  1. I'm thinking about adding a 6" midrange driver to my 1x12 cab. It has good lows but lacking in the mids. I want to keep the 12 full range. I believe I want something in the 500 - 5k hz range but I'm flexible with that (more or less a guess). The 12" driver is a 4 ohm Eminence Delta 12lf. This cab will be getting 450 watts pumped into it.

    Does anyone have any favorite brands for a 6" midrange for $100 or less?
    Branting likes this.
  2. Petebass


    Dec 22, 2002
    QLD Australia
    Look into an Eminence Alpha 6.

    There's a good discussion about this topic HERE.
  3. Petebass


    Dec 22, 2002
    QLD Australia
    Don't forget you'll need a crossover for it. You mentioned 500Hz. Look at an Eminence pxb2:500 (cabinet ready).

    Or make your own with a 28uF Capacitor and a 1.8Mh Inductor.
  4. The Alpha 6 is an excellent match for the 12LF.

    Both run a calculated SPL of 94.x, so they are very closely matched in sensitivity. The 12LF is flat up to 2,000 Hz, and the Alpha is flat down to 150 Hz.

    Keeping this in mind, use an Eminence PXB2:800 crossover that mounts inside the cabinet. (No tweeter volume control). It is very cost effective, and since the drivers are equally SPL matched, the control is not required.

    The 800 Hz crossover point keeps the fundamentals out of the Alpha, preventing it from getting damaged. Each driver should have at least 1 full octave of flat response on both sides of the crossover point for best results. This pair of drivers has this at the 800 Hz crossover point.

    Put the Alpha 6 into a sealed chamber to avoid interaction with the woofer. A B2 sized chamber is 0.28 cubic feet, but you can get away with much smaller than this, due to the driver producing no bass notes. Use a chamber just large enough to enclose the driver, then stuff it with some fiber fill to absorb high frequency waves inside the chamber.

    This is an ideal match for your existing 12LF driver.
  5. Are you suggesting that I run the crossover on the Delta 12lf as well? If so how do I deal with the 4 ohm impedance of the Delta 12lf, and do you think I will get the desired boost in mids while cutting them out of the 12?
  6. Petebass


    Dec 22, 2002
    QLD Australia
    It depends what you want it to sound like. Personally I'd go against the textboks and only bother crossing the Aplha 6. This means there's an overlap between the 2 drivers from 800Hz to 2k, so the cab will have a very strong midrange prescence. If you like that in a bass cab (as I do), then go for it. But remember that if you do it this way, the cab becomes virtually useless for recorded music reproduction.
  7. This is exactly what I had in mind. Thank you for the responses. I am going to give the alpha6 a try and begin with a first order crossover point of 800hz.
  8. Petebass


    Dec 22, 2002
    QLD Australia
    First order (6dB per octave)? I'd use second order (12dB per octave) or better. Were you planning to buy one or are you going to make one up your self?
  9. I would probably make a first order or buy a second order. Do you think the first order would damage the driver?
  10. Petebass


    Dec 22, 2002
    QLD Australia
    There's a couple of issues here.

    Lets not forget that the Alpha 6 is a cheap driver. Cheap drivers have one thing in common, crappy bottom end and poor excursion limits. Poor excursion can cause blown drivers but before you get there, the thing might distort every time you dig in a bit. The trick here is to use this driver in a matter which wipes out those 2 negative points.

    A First order filter may or may not work. It might allow a little too much of the lower frequencies to get through to the driver. As a general rule, whenever you decide to use a first order instead of a second order, you should cross it over at a higher frequency, say 1.6K to account for the shallower rolloff. But in doing so you might rob the cab of some of that midrange punch.

    A Second order filter isn't much harder to make that a First order, especially at mid and high frequencies. Bass frequencies can get difficult because the components get pretty large. But for 800Hz, it should be a breeze.

    All you need is a 15uF capacitor and a 2mH inductor. Both a re readily available and inexpensive. Then wire it up as per the attached diagram.
  11. The point about the 12LF being 4 ohms is well made.

    Knowing this, a high pass filter is more appropriate because a crossover will be skewed at the crossover region due to the impedance mismatch of the 12LF. The Eminence crossover is expecting 8 ohms.

    If you are going to roll your own, 800 Hz is too low for a 12dB/octave slope. Push it up to at least 1,600 Hz because the roll off is too gradual to keep the fundamentals out of the 6" driver.

    The 12LF is flat to 2,000 Hz so you have room to work. The point of adding the 6" is for the missing highs above 2,000 Hz.
  12. Petebass


    Dec 22, 2002
    QLD Australia
    But in this case he wants the speakers to overlap in the mids. That's the whole point of this exercise. Muzicman, jump in and correct me if I'm wrong.
  13. Yes I want to experiment with overlapping midrange frequencies. Not only am I trying to get the sound I want without EQ I am also interested in getting some real hands on experience. I will more than likely be trying a series of different cutoff points and slopes while recording the results. It's a matter of curiosity.
  14. Eminence also has a closed back 6" mid driver called the LA-CBMR. What say Ye?
  15. The closed back speaker is pretty trashy.

    If you are looking for experience, then I suggest you rent, buy, or borrow an active crossover. Then you can use it to dial in the crossover frequency that suits your ears.

    Note that 12dB slopes are pretty gradual... no sudden cutoff. The Alpha crossing over at 1600 Hz is only down -3dB at that frequency, and rises at 12dB/octave to its flat point.

    The 12LF beings to roll off above 2,000 Hz, but certainly does not drop dead above that frequency. Crossing over at 1,600 Hz will give you plenty of band overlap, but still keep the 6" out of harms way.

    I can tell you from experience that the lower crossover points don't work. I was doing the same thing with a 4" driver, and it was getting the snot pounded out of it by crossing over too low. I use an active crossover, so I just turned it up higher until it stopped farting.
  16. Petebass and Bgavin, you guys are real assetts to TB. I agree that I could and should build a second order high pass filter. I also like the idea of experimenting with the sweep of an active crossover. I am beginning to understand that I need to work "with" the given drivers and not try to make them do whatever I want them to. I will take all points and suggestions into account and most importantly listen to the effects of the different frequency boosts. I am going to enjoy doing this. Thanks again.
  17. Petebass


    Dec 22, 2002
    QLD Australia
    If you're gonna grab an active crossover for a while, don't forget you'll you'll need a second amp of some sort.

    And you are OBLIGED to let us know how this experiment goes OK :)
  18. OK no problem :D
  19. As long as you don't cross it over too low, I'm sure you will be very pleased with this driver combination.

    They are well matched to each other in output.