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Closed cab using speakers from Acoustic Image Ten2

Discussion in 'Amps and Cabs [BG]' started by Mouldy, Jan 1, 2017.


  1. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    I play double bass, using a ten2 combo but I'm not so happy with the sound of the ten2 cab. It is fine for lower volume jazz gigs but when I have to turn up for some of the more kicking R&B tunes it is a bit lost. I'm thinking about building a closed 2x10 cab with these same drivers. I've used modelling software with the specs from Eminence and although the ten2 is a closed cab of about 22-25 litres the software is recommending a cab of about 80 litres. I will still be using the ten2 combo's amp.


    My question: BassBox pro has a setting for high output which reduces the size dramatically. How much will this sacrifice a good bass sound? Has anyone tried doing anything similar and does anyone have any recommendations? Attached are the specs from Eminence for the ten2 drivers.

    Re 5.38 ohms fs 23.7Hz
    Le 1.21 mH Mms 39 gms
    QM 6.73 Mmd 35.3 gms
    QE 0.39 Cms 1.151 mm/N
    QT 0.37 Rms 0.866 N*sec/m
    Xmax 5.55 mm Vas 194.4 litres
    Pmax 150 watts SD 344.9 cm 2
    Bl 9.00 Tm VD 191.4 cm 3
    Coil Dia 2.00 inches EBP 61.3
    Gap Height 0.313 inches Magnet wt. 44 oz
    Efficiency 0.65% Winding Width 0.75 inches
    SPL 90.2

    Thanks.
     
    DukeLeJeune likes this.
  2. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    At my non-commercial web site, I have a brief article on building what I call "small box" systems, which attempts to explain the rationale for building boxes that are much smaller than the typical recommended optimum. I don't know if this applies to your drivers, but it might be good bed-time reading.

    Here's what my modeling program gets for 2 of those drivers in an 80 liter sealed box, driven by 300 Watts. With the disclaimer that this is not professionally engineered software, the graphs tell me that the system will be pretty seriously excursion-limited. If you change the port tuning from 0 (for sealed box) to 40 Hz, you can see the effect of porting on those drivers. It may be that they are designed to be most happy in a ported box. I'm not the speaker expert around here (Duke, where y' hiding?) but my guess is that the drivers need a fairly massive cone in order to deliver good low end in the small box, which means they won't ever get super loud.

    http://personalpages.tds.net/~fdeck...Bport=8&nPorts=1&endCorrect=0.732&PinExc=300&
     
    DukeLeJeune likes this.
  3. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    Thanks fdeck. I don't know if it is relevant but the Acoustic Image amp is 650w into 4 ohms. cheers.
     
  4. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    First of all, THANK YOU for going WAY ABOVE AND BEYOND and digging up the actual T/S specs for the woofers in question!

    Now you aren't going to get any improvement in midband efficiency by increasing the box size, but imo you can get some improvement south of 90 Hz or so. For instance, if you increase the internal volume to about 40 liters net (maybe 44 liters including the woofers' displacement), and maybe decrease the stuffing density a bit, you can probably go from a having a "low-E cab" to having a "low-B cab".

    Unfortunately it sounds to me like you need a broadband improvement in efficiency, and increasing the box size won't do that.

    My computer program says the T/S parameters indicate an efficiency of just over 90 dB for that woofer, or just over 93 dB for a pair of them, so your guess is right on the money. But then you already knew that, didn't you?
     
    DaveKirkpatrick likes this.
  5. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    Thanks Duke. I am a novice at this and although I have read heaps and have learned heaps, the eyes have glazed over a bit and I realize I still know very little. My plan was to try and build the smallest sensible cab while still getting a decent in your face sound (unlike the ten2 cab that has one forward firing and one downward firing). In your opinion do you think it would sound crap if I built a 50 to 60 litre cab? As much as I appreciate the stats you mention I'm not really able to interpret them very well. This is for double bass only and only go down to E. I apologize for not catching on too quick.

    I should also add that I usually use the HP filter that is on the AI amp and roll off below about 60Hz.
     
    Last edited: Jan 2, 2017
  6. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    I wouldn't use those drivers. The 23.7 Fs is way too low, like a full octave. That low Fs is killing sensitivity and midrange response. I can't imagine why AI used them. If I was going to build a small 2x10 sealed cab I'd use the Eminence SC-10/16.
     
    Roxbororob likes this.
  7. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    Thanks Rick. The only thing is I want to get a 4 ohm cab.

    When someone else asked a similar question regarding a 2x10 closed cab for double bass on basschat, Bill Fitzmaurice said this... 'For these reasons I'd use the Eminence B102 in a 30 liter (net) box. It's whizzer cone gives it useable off-axis response to 4kHz. I'd do them as 1x10s, stacking vertically as many as you need. You could do a vertical 2x10 in 60L net, but IMO it's easier to carry two small cabs than one large one. If you want flat response to 50Hz you could put a B102 into a 60L ported box tuned at 45Hz, but IME double bass doesn't need to go that low."

    Rick, what is your view on this please?
     
  8. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Long ago, I investigated another speaker, the GK MB150 series, which is a 12" driver in an extremely small box. I think the design principle is to get the system resonance (cone plus box) as low as possible in a small box, by choosing a floppy suspension and massive cone. The box is the suspension. Given when this speaker was designed, it represents an intelligent engineering solution to a difficult design problem of getting gig worthy bass out of a tiny box. I think there's some pretty deep engineering insight in Bob Gallien's designs.

    The AI may work along similar lines.

    Today, things are different, partly because of the greater Xmax of neo drivers, and more amp power available in a small package.
     
  9. BassmanPaul

    BassmanPaul Inactive

    Why? An 8Ω box makes more sense and would allow you to double up on your cabinets. That said my cabinets are 4Ω BUT all my amplifiers are safe into 2Ω loads.

    I don’t play upright but I would not even try to play a gig with just one of my Acme 2x10s. I always use a pair stacked vertically.
     
  10. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    Sorry about all the geekspeak in my earlier post! I'll try to tone it down.

    I hadn't realized you would be using the cab for double bass only. In my opinion you do not need 50 or 60 litres. That much internal volume will give you a bigger bottom end, but you may get fart-out along with it.

    If you move both of the woofers around to the front panel, the mids and highs will be louder out in front of the cab, but in turn you'll have less mids and highs behind and to the sides of the cab (because you'll no longer have the downfiring woofer's mids and highs bouncing in those directions as well as bouncing out front). So the cab won't be putting out more energy, but it will be concentrating that energy more in the direction of the audience, at least in the mids and highs (the directionality of the lows won't change - they go pretty much everywhere anyway).

    My guess is that Acoustic Image chose that particular configuration because it more closely mimics the behavior of an actual acoustic instrument, which doesn't "beam" the top end like speakers normally do. Imo it's a valid and intelligent solution.

    If you don't want to use different drivers, then my suggestion would be, don't go over 40 liters, and play around with the amount of damping material a bit. Too little damping material and you could have a "boxy" sound, but too much can suck the life out of the sound. Trial and error is the usually the best approach to getting the damping material quantity right.

    If you are open to using different speakers let me know and I'll scratch my head a bit.
     
    Mouldy likes this.
  11. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    I wouldn't argue with Yoda. :rolleyes:
    I didn't think of the B102, because it doesn't have the xmax for high output in the lows, but double bass doesn't need that, so it should work well. In 25L the B102 gives up about 2dB of sensitivity compared to the AI driver below 100 hz, but it's much more sensitive above 100 hz, and works well in the mids, without the peaky mids that most regular bass drivers have.
    Acoustic Suspension. That's not an invention by G-K, it's the invention of Ed Villchur/Acoustic Research in the early 1950s. Acoustic Suspension owned the hi-fi market in the 60s, with a better than 90% market share. The problem with it was low efficiency. T/S designed ported cabs had higher efficiency, and they sent the acoustic suspension the way of the dinosaurs by 1980.
     
  12. I have one of those B102s in an undersized ported box. I use it for small gigs with my upright and an MB200 - and I love it. It's nowhere near a flat response (doesn't have deep lows), but it works great!
    For louder gigs I use one or two Ampeg 210AV cabs, a PF350 or PF-50T and an FDeck LPF(on the upright)
    Those cabs and the HPF roll off the lower frequencies. When I'm playing bass guitar, I usually add a little bass with the EQ.
     
    Mouldy likes this.
  13. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    My amp goes to 2ohms also. One 4 ohm cab would be fine for most gigs for me. 8ohm cabs would mean at least two cabs for reasonable output from my amp.
     
  14. BassmanPaul

    BassmanPaul Inactive

    The increase in available power between your amp into an 8Ω load and into a 4Ω load will not really be significant. It’s the doubling up on cabinets where the magic lies.
     
  15. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    I have a GKMB150 which I have used since 1994. I was gobsmacked at the bass response when I first powered up. I thought I was buying a practice/teaching amp but for years I've used this combo and a cab I built off EV plans for the EVM12L (Their TL806 cab) and it sounds pretty good with the GK combo. This cab is too bulky and heavy for me nowadays (41lbs).

    It is interesting that the GK combo and the AI Ten2 cab are each closed, small and zero damping cabinets. I did wonder about the engineering behind this gear.

    When I look at the suggestions that Bill Fitzmaurice says to build a closed 2x10 cab with eminence drivers I notice that the software seems to dictate something different from his ideas, but of course I am thoroughly respectful of his knowledge and experience and wouldn't question any of it, it just makes using the software a bit tricky.

    Since most are saying to not bother building a cab with the speakers from the ten2 I will now consider your 12" speaker plans for a lighter single 12 cab. Thanks for that info.
     
    Last edited: Jan 4, 2017
  16. Mouldy

    Mouldy

    Feb 27, 2010
    Western Australia
    I get what you're saying. I love the doubling up of cabs for electric bass but it can present some issues for feedback with double bass. I've used a single 12 ext cab with my GK combo for years and of course the extra cab makes it pick up significantly. I also have issues with lumping tons of gear around though. Nearly all of my gigs would only be medium volume so I'd like to only have 1x210 or perhaps 2x112 The AI head puts out 350w into 8 ohms, 650w into 4ohms and I think about 850 into 2 ohms. I like the idea of the extra headroom in the amp.
     
  17. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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