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Thread: Looking For More Punch From My 2245, 4345 Clone

  1. #31
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    Now we’re getting somewhere.... It would be interesting to get Audiohack’s opinion on this as well. He has been known to turn the system up loud occasionally.Widget
    .

    I am working on it. I spent a couple of weekends knocking something up to see what all the fuss is about.
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    If we knew what the hell we were doing, we wouldn't call it research would we.

  2. #32
    Senior Member Ian Mackenzie's Avatar
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    When you’ve built up a dual 2226 based system like Robert had and then compared both systems in a 10.5 x 21 ft room let us know....Lol

  3. #33
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    When you’ve built up a dual 2226 based system like Robert had and then compared both systems in a 10.5 x 21 ft room let us know....Lol
    Haha I currently only have 12 dual 2226 boxes and used to have more so that ground is well trodden here.

    This is my second 2245-2123 system and I pretty much know how this ends. Will they sound nice? You bet they will. They will play deep down low and full effortlessly, at low and moderate volume. They will have a lack of visceral impact that a cranked up proper dual 15 box will have and there is little that can be done about it. That is not the primary design goal for these here.

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

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  5. #35
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    From a sheer spl point of view, two 15"s should outdo a single 18". So maybe it´s not fair to compare those setups?
    Changing the 2245 to a 2241 or 2242 wouldn´t change the shortage in cone area of those 18" woofers...

    But the way those woofers sound is a different chapter.
    I believe we should differentiate between spl and the way they sound.
    Using two 2235 would give you more headroom compared to a single 2245. But they will still sound "softer" than the SR woofers...


    As Ian and widget pointed out, when using the 2123 instead of a 2122 or 2202 you have to use a different crossover. Those 2123 have less bottom end and JBL used to cross them over higher.
    2123 was used above 340hz, as 2122 or 2202 where used above 290hz.

  6. #36
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    Quote Originally Posted by Mr. Widget View Post
    Now we’re getting somewhere.

    Years ago I built a pair of 4355 clones. They really didn’t do it for me… they certainly kicked ass, but I prefer speakers with a more refined capability… that also can kick ass.

    I don’t think the 2245 is letting you down, but I don’t think that the 10 inch mid bass driver is ever going to give you a bad ass rock concert in your house if that’s where you’re going. it will certainly get loud, but there’s something about it that doesn’t quite have the slam of a PA system driven hard. The 2202 will give you that. It would be interesting to get Audiohack’s opinion on this as well. He has been known to turn the system up loud occasionally.


    Widget
    A very interesting comparison.
    I own those 2123 myself, but no 2202 around...
    My impression of the 2123 is they have a lot of slam, punch etc.... But they have no low end at all, they are pure midrange woofers.
    The 2202 on the other hand looks more like a midbass woofer.
    So I guess the 2202 simply puts out more spl down low than the 2123... They have more efficiency below 350hz than the 2123. JBL crossed over the 2202 lower than the 2123...
    Maybe that fact yields to the impression of more punch?

    It would be interesting if the 2202 would still sound more punchy when crossed over above 350hz like the 2123

  7. #37
    Senior Member Ian Mackenzie's Avatar
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    Its really quite simple.

    The 2226 is a front of house sound reinforcement driver 97 dB, 30-2500 range, Fs 40 hertz, aluminium voice coil, mms 90 grams, 1.6 inch P - P excursion before damage. Used in pairs it’s 100 dB and 1200 watts into 4 ohms. It’s lethal but it’s not going to give you low bass.

    On the spl of dual 2226 drivers it going to more dynamic than a single 2245.

    The 2245H used in two pairs per size to match the sensitivity with dual 2226 per side would be a more appropriate comparison. In any direct comparison you are going to hear differences.

  8. #38
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    So I changed the crossovers to 24db LR and tried a different amp and they have a lot more punch. The amp is a Crest 7001 and has about 550w, the Ramsa had 350w. My next step is to raise them off the floor a bit.

  9. #39
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    Quote Originally Posted by toddalin View Post
    If you want a good track to assess "slam," listen to a high quality recording of the drum track at the opening of Billie Jean by MJ. With a bit of volume it should kick you in the chest and about knock you out of your chair. Don't expect it on the YouTube video over you computer.

    https://youtu.be/Zi_XLOBDo_Y
    I bought this CD off eBay last week, but I don't have it yet. I remember a friend saying this song has good bass. I never thought I would ever buy a MJ CD, I never was a fan of that type of music.

  10. #40
    Senior Member Ian Mackenzie's Avatar
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    Ditto

  11. #41
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    Unless I missed it somewhere in your post are you high pass filtering the woofers?
    Find you boxes tuned frequency, the tone sweep method mentioned works perfect.
    Set a high pass frequency at of just slightly below the tuned frequency.

    There is no sense in wasting power amplifying on what the system can't reproduce and at the
    same time causing unnecessary woofer excursion that can take away from the "punch"

    What are you using for a crossover?

  12. #42
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    Quote Originally Posted by Mike Caldwell View Post
    Unless I missed it somewhere in your post are you high pass filtering the woofers?
    Find you boxes tuned frequency, the tone sweep method mentioned works perfect.
    Set a high pass frequency at of just slightly below the tuned frequency.

    There is no sense in wasting power amplifying on what the system can't reproduce and at the
    same time causing unnecessary woofer excursion that can take away from the "punch"

    What are you using for a crossover?
    I'm using an Xilica XP4080 crossover, the high pass is at 40 Hz and 6 db per octave.

  13. #43
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    Quote Originally Posted by robertg View Post
    I'm using an Xilica XP4080 crossover, the high pass is at 40 Hz and 6 db per octave.
    You got a real DSP!!

    Have you tried a little steeper high pass cutoff, if your not all ready use a BW "butterworth" filter for the high pass, there flat out to the cutoff frequency.

    Have you played with under lapping the crossover frequencies, look at the phase response as you open up the crossover overlap.

  14. #44
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    Quote Originally Posted by Mike Caldwell View Post
    You got a real DSP!!

    Have you tried a little steeper high pass cutoff, if your not all ready use a BW "butterworth" filter for the high pass, there flat out to the cutoff frequency.

    Have you played with under lapping the crossover frequencies, look at the phase response as you open up the crossover overlap.
    So underlapping crossover frequencies would mean kind of leaving a hole between frequencies? Instead of using 300 hz use 290 and 310?

  15. #45
    Senior Member Ian Mackenzie's Avatar
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    Here are some guidelines for matching the crossover characteristics to jbl systems using your drivers in a 4 way monitor.

    These characteristics are set for the driver locations on the baffle and the amplitude and phase characteristics of the drivers. The guidelines refer to the voltage drives not the amplitude response.

    Use the Crossover Butter-worth filter characteristics
    Woofer low pass
    2nd Order Butter-worth 260 hertz


    Mid 2123
    Low pass 2nd order Butterworth 360 hertz
    High pass 3rd order Butterworth 1,100 hertz
    Wire the mid electrically out of phase.

    What l suggest you do is install those values in the woofer and mid crossover and listen while adjusting the amplitude levels for a smooth tonal balance. See how that goes.

    Edit : The above text book crossover parameters are an approximation of the customised voltage drives.

    If you decide to use other filter characteristics your on your own.

    You can try the 4th order LR characteristics @ 290 hertz and 1,100 hertz but it will take some experimentation to get the system optimised. As Mike said you may need to shift the crossover points around. Then listen and measure. Its quite tedious.

    Edit
    One point l will make is that most off the shelf active crossover networks use text book crossover characteristics whether they be Butter-worth, LR, Bessel or something else. These text book crossover characteristics rely on text book drivers to work properly. No driver is text book and they should be viewed as pass band transducers with varying amplitude and phase response.

    This means the user needs to work with the transducer to come up with a crossover characteristic that is as close as possible to optimal. That means modifying the filter slope, Q factor and crossover points with a number of iterations while measuring, simulating, testing and listening. To be effective this requires a degree of skill, test equipment and a detailed understanding of network theory and design. This level of optimisation can be quite time consuming as you tinker with the various parameters. But people have fun doing this activity and it can be quite a journey as you try different approaches.

    If you are of the persuasion that near enough is good enough that’s your call. But the system won’t deliver the potential it’s capable off or the subjective experience.

    I find squeezing the most out of a system particularly rewarding in bring you ever closer to the music which is what its all about.

    Once the crossover parameters have been set measure the system with REW using Greg Timbers method in 5 or 6 locations near your listening position. Use the PEQ to reduce the main room modes down by 1/2 the magnitude of the peak below 150 hertz. If you try removing the entire peak it might do more harm than good. Moderation is the key. There might be room resonance around 290 hertz. Use a PEQ dip filter with Q of 1.5 and - 1.5 dB.

    The 2245 couples to the floor quite effectively so you need to compensate for that you want realistic bass from this system in your scenario with the enclosure close to walls and the corners of your room.

    The idea is to apply a solution to specific issues that you can actually hear and measure.

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