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Thread: Are Iwata horns that good?

  1. #16
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    I bought a pair of the Polish IWATA 300 fiberglass horns. That's a JBL 2035 driver below it in a stock JBL Cinema cabinet. I am really, really pleased with how nice these sound! In my case I am using JBL 2446H compression drivers loaded with aftermarket 'cheapy' aluminum diaphragms crossed at 24dB per octave at 550Hz. I am toying with the idea of buying a pair of Truextent beryllium diaphragms.





    I used an AP20 as active crossover and Dirac Live to optimize the room. below are the before and after room plots. As you can see a super tweeter could be easily justified, but even without the end result is very pleasant to listen to.




    ____________
    Best Regards,
    Carl Huff

  2. #17
    Senior Member louped garouv's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    of my goals on this production of a prototype is to make the horns lighter than the bulkier ones we usually see posted.
    have you seen some of the Fostex designs?
    I have a pair of H425s (in need of repair) that seem much lighter than the 350Hz edgarhorns I am using...

    here's a post with brochure posting of the Fostex line...
    http://www.audioheritage.org/vbullet...l=1#post225774

  3. #18
    Administrator Mr. Widget's Avatar
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    I have a couple of questions... does anyone know the sonic differences between the flat sided wood and the swept back sided fiberglass Iwata 300 horns? I assume the fiberglass horns have this shape because it is supposed to reduce diffraction and edge termination issues, but in real terms what does it do?

    Carl, how dense is your horn? Free floating like that, and with that type of geometry, free floating is about the only way you can use them, but free floating, I have to think they must ring a some level.

    Lee, thanks for posting the AVS link... very interesting. I wasn't aware of these fiberglass horns. They look well made and seem to be a nice low to moderately priced source for horns.

    From my experience playing with fairly dense and inert horns, there are measurable and audible differences between lower mass free floating horns and massive horns that are baffle mounted.


    Widget

  4. #19
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    Quote Originally Posted by Mr. Widget View Post
    I have a couple of questions... does anyone know the sonic differences between the flat sided wood and the swept back sided fiberglass Iwata 300 horns? I assume the fiberglass horns have this shape because it is supposed to reduce diffraction and edge termination issues, but in real terms what does it do?
    This is an elliptical horn. It does not sound like any horn that I have heard before. It's presentation is wide and coverage is even. You can walk about the room and not hear the boundaries from left to right that I had expected to hear.

    http://diysoundgroup.com/IwataWG.htm

    Quote Originally Posted by Mr. Widget View Post
    Carl, how dense is your horn? Free floating like that, and with that type of geometry, free floating is about the only way you can use them, but free floating, I have to think they must ring a some level ...

    From my experience playing with fairly dense and inert horns, there are measurable and audible differences between lower mass free floating horns and massive horns that are baffle mounted.
    The fiberglass is surprisingly dense. When you rap on the body of the horn with your knuckles you hear more of a thud than a ring. The character of that 'thud' does change slightly as you move from throat to mouth. But you are right, the horn might well benefit from having an acoustic dampening material applied to it. They are without a doubt more resonant that the same contour carved by CNC from a block of wood. I would be very interested in comparing them to one another.

    My IWATA 300s are from the first group buy. They have since made some improvements. Newer horns have a metal mounting ring similar to that of the old Gauss fiberglass horns. Mine have an MDF ring. The metal ring is said to be stronger and affords more support to the horn body.
    ______________
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    Carl Huff

  5. #20
    Senior Member Lee in Montreal's Avatar
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    Here's a response graph I found off Phil Mundi's website. It is for a very simliar Iwata horn as the ones I am building, but with a mouth that seems to have a bit less horizontal opening. Nonetheless, it seems to me as it is a 400Hz horn if not a useable 300Hz (can a diaphragm safely widthstand such low frequencies in a home environement - aka low sound levels?). I am a bit surprised though at the upper cut-off. 9kHz? Could that be that Mundi is using non-stock 2441 diaphragms?

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  6. #21
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    Nonetheless, it seems to me as it is a 400Hz horn if not a useable 300Hz (can a diaphragm safely widthstand such low frequencies in a home environement - aka low sound levels?).
    I'd expect the diaphragm to age more rapidly when asked to operate at such a low frequency even if you keep the levels quite moderate... more over, if you are concerned about sound quality, using a horn too low gives you that classic "horn" sound. I have found that if you use a 300Hz horn to 600Hz you will have a much more natural sounding horn that doesn't "honk" at you.

    Quote Originally Posted by Lee in Montreal View Post
    I am a bit surprised though at the upper cut-off. 9kHz? Could that be that Mundi is using non-stock 2441 diaphragms?
    Possibly, but I wouldn't count on it.

    Small changes in the horn can have large changes in the performance... two horns that "look" the same may not be the same or sound the same. That said, many DIYers use vintage or used drivers and the performance of these drivers can differ widely from their specifications.


    Widget

  7. #22
    Senior Member Lee in Montreal's Avatar
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    The distance from the diaphragm to the mouth is 0.692m or 1/4 wave of 125Hz

    The mouth is 0.158m tall by 0.935m with a total perimeter of 2.186m. Shouldn't it "allow" a 158Hz cut off? Therefore, I suspect that this horn could well work down to 400Hz "cleanly" if the driver allows it. These are only suspicions and only testing will tell.

    I found this, where the manufacturer claims it "can reproduce frequencies from 250Hz".
    http://www.jgaudio-systems.com/lesni..._iwata_en.html

  8. #23
    Senior Member 1audiohack's Avatar
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    Sadly what's nearly always missing from these graphs is the phase response. With that information, literally the other half of the picture, one can better determine if the driver simply can't produce the required / desired energy or it there is something else at play.

    A properly functioning 2441 on a 2311 horn would tempt even me to run without a tweeter, put that same driver on a big Yuichi or the Iwata pictured or a 2360 and there's little hope in my mind the driver can deliver the energy needed to satisfy my requirements for HF. Even the 2397's frequency response curve sinks like a safe about 9.5 kHz.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  9. #24
    Senior Member Lee in Montreal's Avatar
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    Yup. These are only physical measurements that don't take in account the specific shape of the horn, which is where reflections and nulls are eliminated, and will impact the audible bandwidth, not just the calculated one.

  10. #25
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    3D Iwata Model for CNC

    Where to find 3D model for making wooden Iwata horn on CNC machine? Can somebody help please? I need it to go as low as 250Hz or maybe 300Hz and not to be wider of 85cm in size.

  11. #26
    Senior Member Lee in Montreal's Avatar
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    Quote Originally Posted by cody_zox View Post
    Where to find 3D model for making wooden Iwata horn on CNC machine? Can somebody help please? I need it to go as low as 250Hz or maybe 300Hz and not to be wider of 85cm in size.
    There are plenty of 2D drawings on the internet. You can have the 3D model done from those 2D drawings.

  12. #27
    Senior Member JoMoCo's Avatar
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    Iwata 300

    Now that Carl has lived with his IWATA fiberglass units for awhile maybe we could talk him into sharing .. some measurements perhaps ..

  13. #28
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    Quote Originally Posted by JoMoCo View Post
    Now that Carl has lived with his IWATA fiberglass units for awhile maybe we could talk him into sharing .. some measurements perhaps ..
    The PIC server that I had used in my previous post has since gone offline. Here is my latest use of the IWATA 300s.

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    These are restored Altec 828 cabinets loaded with a new GPA 416-8C driver. And below is the amplitude response that comes out of them. This particular PIC is of the right channel. However the left is very similar.

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    The 'Before' PIC is what what was measured using Dirac Live software tools running on my PC laptop. The red overlay was the target curve that I created. The 'After' PIC is what Dirac Live running in a Datasat RS20i was able to provide. I confirmed the After curve using RTA software measured at my favorite listening position. I really, really like the IWATAs! I use them every day.
    ________________
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    Carl Huff

  14. #29
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    Project Update ...

    Just a quick update on my aging ALTEC 828 cabinets and IWATA 300 horns.

    Thanks to our very own Widget I have recently acquired a pair of Truextent beryllium diaphragms for my JBL 2446H compression drivers. Within the last week I have mated them with my IWATA 300s and have spent the last few days tweaking the install. I am absolutely enamored with them! I am an aging (grumpy??) bugger that had grown cynical watching the published claims for new products and had been slow to buy them, but am now very glad that I did.

    Truextent beryllium diaphragms and IWATA 300 horns are at the heart of my reference listening system.
    _____________
    Best Regards,
    Carl Huff

  15. #30
    Member A Vanderkruk's Avatar
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    I have made several of the modified iwata 270 hz 400hz 600hz and 800hz all test very well and have the best home use sound stage coverage I have heard as well, I have to agree with the coments. My approach was to mould the top and bottom profile's and I made them with a sand epoxy composite, this is hard like granite and offers no stored energy is very relective and increase sensitivity and clean clean sounding.The side profile is wood veneer backed with composite, much more build time than fiberglass but worth it.Name:  DSC03768.jpg
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