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Acoustic image contra extension speakers

Discussion in 'Amps, Mics & Pickups [DB]' started by paulgraybass, Feb 29, 2004.

  1. paulgraybass


    Feb 9, 2004
    I have just got hold of an acoustic image contra in England. I am impressed by its sound at lower volume levels but disappointed by its volume level and headroom, it doesn't seem to want to go very loud before starting to sound a bit strained.

    It obviously needs an extension to help it out and Ive tried experimenting with anything that came to hand. Any existing bass cabs I had around were disappointing in that they lost the natural sound of the contra. However the thing that sounded surprisingly good were some PA speakers I had. These were a pair of 8 ohm EV S200s. I tried one as an extension and it sounded good. I then wondered about getting a 4 ohm load to give maximum power. I then realised that if I connected the second EV to the output socket of the first it was parallelling them up and creating a nice 4 ohm load for the contra ( I checked the impedance with a multimeter to make sure). This really seemed to allow me to run the contra hard and gave a significant volume increase.

    I was wondering:

    1/ If I am likely to cause problems for the speakers in terms of cone extension etc. given that they are not designed for bass (but they are rated at 300 watts continuous each and I'm using 2 connected together into the extension socket of the contra).

    2/ If my assumptions about power into each speaker was correct. I was reckoning that on full whack the contra would be pushing 150 watts into its own internal speaker and 150 watts into my PA speakers, which presumably means 75 watts each.

    3/ If I do overdo it in terms of power or cone extension, will I be able to hear it in terms of degraded sound quality before causing damage?
  2. contrabajisimo

    contrabajisimo Supporting Member

    Feb 9, 2004
    Irvine, CA
    Founder and Director, SoCal Jazz Academy LLC
    What about AI's own extension cabs? I'm expecting Contra soon and was wondering how do you mean that it can't be too loud? What was the setting that you played which was too big for the combo? I'm thinking when playing big venues I might as well use the house PA through the DI out? But I got it specifically for small venues anyway. Later.
  3. paulgraybass


    Feb 9, 2004
    I think the problem is that most of the power is fired into the floor which sounds great close up, but doesnt project well. Also you seem to need a lot of watts to get a given volume level. Plugging anything else with a front facing speaker in to the contra as an extension produces a massive increase in perceived volume (and swamps the contras internal speaker). The contra on its own can keep up with a drummer with brushes, but headroom for me is a bit marginal for a drummer with sticks. The DI out is great though for venues with a house PA.

    I will probably get an EA cab when I can afford it, But I was wondering if anybody else had experimented with PA speakers and also hoping someone who knows their stuff would answer my original query about cone extension and power etc.
  4. Chris Fitzgerald

    Chris Fitzgerald Student of Life Staff Member Administrator

    Oct 19, 2000
    Louisville, KY
    PA speakers are really just full-range speakers, so it shouldn't be a problem as long as you don't overpower them with unprocessed bass frequencies. I use a small 1x8 PA speaker with my Clarus for small "almost don't need an amp" gigs, and I love it.
  5. dnburgess


    Jul 20, 2003
    Sydney, Australia
    Proprietor: Bass People, Green Square Music
    The impedence of the built in speaker of the AI combos (and the EX extension speaker) is 4 ohms. The extension speaker output is in parallel with the built in speaker connection - so when using an 8 ohm extension speaker the amplifier will be driving a 2.66 ohm load and producing approx 250W.

    The amp is designed to drive two 4 ohm speakers in parallel - a 2 ohm load.
  6. dnburgess


    Jul 20, 2003
    Sydney, Australia
    Proprietor: Bass People, Green Square Music
    i.e. you should have no problems with the slightly higher load.
  7. paulgraybass


    Feb 9, 2004
    Originally posted by Chris Fitzgerald
    One thing I've tried when the sound is not "natural" enough is to point the speaker at a reflective surface like a wall, or even at the floor. I don't own a Contra, but I do own a Clarus, and when the sound comes out as too "aggressive", I'll sometimes try to tone it down a bit by using reflection. Sometimes works and sometimes doesn't - depends on the room.

    Thats interesting. The point about the contra seems to be the way that the sound projects with omnidirectional bass and directional highs is a bit like the way a double bass projects, which is probably why it works so well close up. When using 2 paralell Pa speakers as a 4 ohm extension, and also pointing them in different directions and using a bit of reflection did seem to produce a loud and natural sound. Probably have to be a bit careful about phasing problems?
  8. Anyone tried the contra with the extension? I'm curious to know how much more volume it produces.
    I play with a combo that gets a little loud even in small venues.
    I'm not sure if I should get the AI extension or a front firing woofer.
  9. Adrian Cho

    Adrian Cho Supporting Member

    Sep 17, 2001
    Ottawa, Canada
    I know this is not exactly what you asked and probably not what you want to hear. I owned a Series I AI rig for two and a half years and then had a Series II on trial for about a month. Although I liked it when I first started using it - i.e. the reproduction was pretty natural, I have since decided that the downfiring woofer is just such a dumb idea. Sure it makes the unit more compact but apart from that it's just a stupid idea. Projection is definitely an issue and the results are inconsistent depending on what floor surface you are using. The biggest issue I found is that the lows are too muddy - there's no clarity there. Sure it goes down to 20 Hz but what use is it if you can't hear it? Yes you can probably hear those notes through an AI cab on your own but how about in a band and with lots of people in a room?

    If you like the functionality of the AI head then I suggest you think about getting a Clarus and teaming it with a different cabinet. You may find you don't even need an extension at all. I used the Schertler Pub last night with a guitar, sax and bass trio with just the AMT mic in a huge room with 400 people and it could be heard clearly in all registers.
  10. I have an Acoustic Image Contra and have found that the "boominess" is easily dealt with by tilting the cabinet back slightly using a small block under the front. AI provide a small triangular-shaped metal stand which does just that - it works very well. I also have a GK-150 and a couple of other cabs (EA and Raezers Edge) and I've found that as a general rule the key to removing any "muddiness" is to get the cabinet off the floor by either tilting it or putting it on a stand or a chair (the EA has a fold-out handle on the lower side which can be used for tilting it). On one occasion I didn't have a stand or a chair, so I layed the GK-150 flat on its back - that also worked.

    BTW (paulgraybass) are you using it for double-bass or EBG? The AI cabs are of 4 Ohms impedance each, and the Contra would put around 300W into 2 cabs in parallel (total impedance of 2 Ohms). Also, the sound you hear at the position you are playing can be different to the sound the audience is hearing. You might want to have someone play your bass while you take a listen from elsewhere in the room.

    Hope this helps -
    - Wil
  11. paulgraybass


    Feb 9, 2004
    I am mainly a double player. On the little bit of electric playing I am doing I am still using my old amp.

    On the subject of tilting the contra back, the series 2 has a little lifter like a double bass spike that screws into a socket in the bottom. The only thing about it is that the socket already feels a little flimsy and wobbles a bit after a month! I can't see it standing the test of time. I am interested in experimenting with other angles of tilt and also maybe experimenting with a stand that lifts the whole combo up off the floor a little.

    On the subject of AI extensions, I considered one but have been advised by several people including the owner of a contra and contra extension to go down the front firing route.
  12. dnburgess


    Jul 20, 2003
    Sydney, Australia
    Proprietor: Bass People, Green Square Music
    Re the flimsy socket: There is an improved socket retrofit which your dealer should be able to instal.

    Re front firing extensions: You might want to look at the Acme Low B-1 - it is small, light and "clean".
  13. Laurence U.

    Laurence U.

    Oct 25, 2003
    Paul, whereabouts did you buy your amp, and for how much? I have searched england for one and only found the most outrageous prices!!!
  14. paulgraybass


    Feb 9, 2004

    I've now purchased an 'extension' for my contra. I ended up buying a euphonic wizzy powered monitor. 200 watts and runs from the DI socket of the contra. The level is set by the input level of the contra.

    I chose this for a number of reasons. Firstly the input level controls the wizzy level, and the master volume controls the contra. If you just use the wizzy passive extension speaker, it is so much louder than the contra you might as well not bother with the contras own internal speaker. Also the sound is different. THe contra becomes more middly as you turn it up and it runs out of headroom. The wizzy is very bass heavy on its own. The combination of the two is very nice.

    Having compared my EV PA speakers with the wizzy, Im still impressed with them. so now I have a rig that is VERY flexible in terms of volume. My options are for a very quiet gig, use the contra. For a gig with a jazz drummer use the contra and EV PA speaker as an extension. Louder still add the Wizzy powered monitor. This would be more than loud enough for any double bass situation I have ever played in, loud big band or funky jazz with heavy handed drummer.

    The ev pa speakers can be chained together to give a 4 ohm extension load which alllows me to run the conra at 300 watts, which gives me a 500 watt rig if I use the wizzy too. This allows me to disperse my sound around the stage and overcome feedback problems, and have several light boxes to carry instead of one back breaking one if I had bought a single really powerful combo.

    The only other thing I might have considered with hindsight was buying an IAmp 200 combo instead of the contra, but I would still have to carry a moderately heavy amp to any quiet gigs I am doing. I am still impressed by the simple but very double bass friendly features and EQ of the contra.

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