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Thread: Full HF with 2-way 2245, 2445?

  1. #1
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    Full HF with 2-way 2245, 2445?

    I like things that are simple - like 2-way systems that have large woofers and compression drivers.

    Anyway, would it be advisable to build a pair of two-way systems comprised of 2245H - 18" woofers and 2445(h) 2" large format compression drivers crossed at 500?

    I suppose my concern is that the woofer would not play well up to the 500 cross.

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    Administrator Robh3606's Avatar
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    Two ways are always a compromise because it is difficult to find drivers that do well at both ends of the extremes and in the woofers case also do a good job high enough into the midrange. I also wouldn't run a compression driver that low but that's just me. I would go with something like a smaller 2 way with a 12" woofer a compression driver. Maybe a 1" driver which normally do better up top and use a sub to bring in the lowest 1 1/2 octaves.

    Rob
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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by robertbartsch View Post
    I like things that are simple -
    ...and that is a very good mantra especially in audio.

    Quote Originally Posted by robertbartsch View Post
    -like 2-way systems that have large woofers and compression drivers.

    Anyway, would it be advisable to build a pair of two-way systems comprised of 2245H - 18" woofers and 2445(h) 2" large format compression drivers crossed at 500?
    Now this sounds like a very, very bad idea to me... that is unless you like this type of sound but with a rolled off top end.
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    [quote=Mr. Widget;230900]...and that is a very good mantra especially in audio.

    What? Isn't an active 4 way system simple?

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    Senior Member Hoerninger's Avatar
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    ... 4 way system ...
    Isn't it common JBL terminology to talk of an augmented two-way?
    ____________
    Peter

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    Quote Originally Posted by Hoerninger View Post
    Isn't it common JBL terminology to talk of an augmented two-way?
    ____________
    Peter
    yup, but probably not with a 2245.

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    Quote Originally Posted by robertbartsch View Post
    I like things that are simple - like 2-way systems that have large woofers and compression drivers.

    Anyway, would it be advisable to build a pair of two-way systems comprised of 2245H - 18" woofers and 2445(h) 2" large format compression drivers crossed at 500?

    I suppose my concern is that the woofer would not play well up to the 500 cross.
    It depends on the horn/waveguide for the 2445 to what freqency the woofer has to operate.

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by mini View Post
    It depends on the horn/waveguide for the 2445 to what frequency the woofer has to operate.
    You know, when measuring a driver's impedance you can clearly hear even an 18" woofer reproducing 10KHz... that doesn't mean you want to use one that high in an actual music reproduction system. The 2245 works very well to 150Hz or so, and pretty well to 300Hz, but at 500Hz not so much.

    For you to get very good results from the 2445 at 500Hz you need a very large horn... the 2360 comes to mind.


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    So, what mid-range driver would you put between the 2245 and the 2445?

    I built a couple of systems using 12 inch 2206 drivers and they are outstanding.

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    Administrator Robh3606's Avatar
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    I built a couple of systems using 12 inch 2206 drivers and they are outstanding.
    So what's stopping you now??

    Rob
    "I could be arguing in my spare time"

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    Augmented 2 way is now a 3-way?

    OK, so if a two unit system comprised of an 18" 2245 and a 2445 will not work since the woofer will not play well to 500 and the compression driver will roll off above 10K, what are my options?

    What about a 3-way system with these:

    Low = 2245
    Mid = 2206
    High = 2425 ?

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    Quote Originally Posted by robertbartsch View Post
    OK, so if a two unit system comprised of an 18" 2245 and a 2445 will not work since the woofer will not play well to 500 and the compression driver will roll off above 10K, what are my options?

    What about a 3-way system with these:

    Low = 2245
    Mid = 2206
    High = 2425 ?
    Hi,

    surely the 18" will operate up to ~500Hz. The 18" is only 20% larger. If a 15" can do well up to ~1kHz the 18" will in linear proportion do well to 800Hz. The other way round the 18" will do as good at 500Hz as a 15" does at 600Hz. From the papers the 2245 compares to the 2226 just like that. Would people tell that the 2226 is a definite no go at 600Hz?

    The other point is the 2445 at 500Hz. You would need a full size horn like 2360. Every JBL biradial horn acclaims it's provenience at 10kHz. Whether or not some level above that is provided depends on equalizing. I've got the 2352s with 2447. The ribbed diaphragm is changed to that of a 2445, plain surface. No nasty spikes as with the original one, so equalization could help it up to ~16kHz. Judged by subjective listening impressions it's absolutely o/k. And of course much better than 30kHz something hi fi tweeties.

    ps: as JBL wrote in an older paper, HF extention does by the most depend on the horn, not on the driver! Anyway, 2/3-way, the horn, if any does make the sound.

    good luck

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    Dis Member mikebake's Avatar
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    Quote Originally Posted by mini View Post
    Hi,

    surely the 18" will operate up to ~500Hz. The 18" is only 20% larger. If a 15" can do well up to ~1kHz the 18" will in linear proportion do well to 800Hz. The other way round the 18" will do as good at 500Hz as a 15" does at 600Hz. From the papers the 2245 compares to the 2226 just like that. Would people tell that the 2226 is a definite no go at 600Hz?
    Apparently you haven't listened to a 2245H at 500hz.
    Can produce output at 500hz is not the same thing as sounds good at 500hz.

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    Quote Originally Posted by mini View Post
    Hi,

    surely the 18" will operate up to ~500Hz. The 18" is only 20% larger. good luck
    You need to look at the area of the cone, and it's 44% larger.

  15. #15
    Administrator Robh3606's Avatar
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    Low = 2245
    Mid = 2206
    High = 2425 ?
    That will work. What about horns?? That's a key issue that you would need to work out.

    Hi,

    surely the 18" will operate up to ~500Hz. The 18" is only 20% larger. If a 15" can do well up to ~1kHz the 18" will in linear proportion do well to 800Hz.
    You need to actually listen to some of these drivers. A 2235 sounds fine in a 4430 but when used with a 10" midrange like the 2122,2123 the combinations sounds even better only using the 2235 up to about 300Hz or so.

    Every JBL biradial horn acclaims it's provenience at 10kHz. Whether or not some level above that is provided depends on equalizing.
    All of the JBL horns have a difraction slot that determines the directivity in the last octave. The larger the gap the less control so with 1" drivers you generally get better results above 10K or so. It's not just the EQ it's the physical dimension of the gap as well.

    Rob
    "I could be arguing in my spare time"

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