V-baffle for midrange drivers |
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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Posted: 14 November 2018 at 6:33am |
Couldn't find any discussion about this kind of design, where speaker baffle is angled so that drivers are somewhat facing to each other (tilt may range from 10..30 degrees or so).
Any directivity or efficiency advantages / disadvantages? In this case, there would be 2 x 10" or 12" drivers (frequency coverage 100-700Hz, paired with JBL 2445 + 2380A horns ). |
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Jo bg
Young Croc Joined: 08 March 2017 Status: Offline Points: 552 |
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Hi
search tony Wilkes projects, he had some with v baffle and there was some discussion about it's merits. the cavity should start loading the driver only over something like 500hz (depends on the depth and size of the cavity, 10-30° angle will make little depth i think), so there should be little difference crossing at 700, maybe a little raising response that could be overcomed shifting the lowpass lower. DISCLAIMER, distant memories of old threads, could be wrong, but if you think about it as a horn/waveguide the small depth and mouth perimeter seems to confirm it will be effective only above those frequencies |
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dlyxover
Old Croc Joined: 14 June 2007 Location: Liverpool Status: Offline Points: 1502 |
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As Jo bg said around 700-800Hz it will roll off also gets rather beamy.
I use a v baffle cab, 2x12" and BMS 1.4" coax. I went for 90 degrees, did some test with various angles and acoustic lenses infront of the 12's to try and raise the roll off but effort vs effect did not really balance. Very happy with the cabs performance over all.
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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I recall the late Windmill tilter did a 8x8" in two columns of 4x8", on a V.
Measured a dip in response at 800Hz, which may have corresponded with a top to bottom standing wave, as much as a horn issue. At low frequencies a V baffle will do squat. In the mids, when the wavelength starts to get of the order of magnitude of dimensions of the baffle/cab, then you will start to get affects. Almost becomes a very short tapped horn, if you squint hard. On one of the many HR tutorials on HI-Fi sites, there is a diagram of a V baffle, with labels on which dimensions are S1-S4, Vtc, etc, to make converting design to HR easy. Try this one: Linky Build it, measure it, then throw your DSP at it - it is what everyone else is doing! |
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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moyano
Young Croc Joined: 12 May 2008 Location: Bedfordshire Status: Offline Points: 1219 |
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Hi Matt,
Do you happen to have a link to the 8x8 project ? I can’t seem to find it
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MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7816 |
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Only benefit of doing a V baffle is to make the baffle area smaller.
The cavity is too small to have any significant horn loading effect and it will be at very small bandwidth that you would have to eq out anyway. If you add a hf horn in front of it it will then create reflections and cancelations on some frequency. The goal here is to play with the distance between the drivers and the angle to get the dips and peaks as much out of the intended band as possible. Reflections can be somewhat dealt with by using some sort of foam at the back of the hf horn.
Edited by MarjanM - 24 March 2019 at 3:16pm |
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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I couldn't find it either, when I wrote the previous comment! However, I do recall he had a V baffle, each half of the V baffle had 4 x 8" drivers in a column, making a 4 high by 2 wide "array" of drivers. He noted a marked dip in response at around 800-850Hz, which corresponded to the height of the V, or maybe the column of air height inside the cab (Windmill Tilter's usual array of braces on the inside) The link in my above post, is to how to stick a driver in a horn, but not in the throat, at some point in the wall of the baffle/horn wall. It mentions that sound waves enter the horn at some point along the side wall, but go both ways, towards throat and out of mouth. Obviously those that go towards the throat, bounce out of throat, back towards mouth. At some point, there will be a cancellation between bounced throat wave and mouth directed wave. This point will be at some frequency which is a function of the distance of the driver from the throat, further from throat, the lower this cancellation effect. Even though a shallow baffle is barely a horn, this effect will occur, but its effect will be mitigated by the shallowness of the "V" and the width of the driver (drivers are not point sources, the mouth end edge of cone is 8" nearer mouth, than the throat edge side of cone!). Deeper V will lead to a more pronounced effect. As I said though; build, measure and then throw your DSP at it! Only way to be sure, and it also solves many issues... I have found this thread, which mentions the same box, but with anomalies at 2K ish. https://forum.speakerplans.com/new-small-rig-for-live-use_topic55514_page1.html There was another thread where he noted the 800ish dip, but I am buggered if I can find it!
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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