35-100hz ported/hybrid horn |
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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Posted: 25 March 2020 at 4:55pm |
Hey all,
Here's a little idea I've been toying with, I'm trying to make a ported/hybrid horn for use between 35-100hz. I'm open to suggestions any of you may have. The criteria I've set myself are as follows:
There are reason I want a single cab solution between 35-100hz is because I want to use this cab bellow my 3 way mid top I'm currently working on(link here). The idea is to have a 4 way solution allowing to run one 8 core nl8 cable to each stack. As a side note the reason for a simple construction is to allow me to either manufacture multiples of these cabs easily myself or release them as a free plan. So far the cab is modelled using an rcf lf18n401 although it also works well with a faital pro 18 1600xl. 2pi Xmax - Currently quite concerning given that it is 10mm over xmax. Although I do understand this is calculated as a sine wave and not a true representation. I would however like to get thoughts on the cone becoming unloaded. |
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Meat
Old Croc Joined: 05 June 2009 Location: Manc Status: Offline Points: 1514 |
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Did you already see the Startec HR118 ported horn? That uses the same RCF driver that you are considering. Comments The RCF looks like a good choice, it's used in several similar designs. Your mouth seems quite small, you might get more gain by opening it up. Rear chamber seems pretty massive! |
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Don't test the champignon sound
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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Yep, I have played around with the hr118 a fair bit, but I never quite managed to make it work for the response I wanted out of it. I played with opening up the mouth but it seems to create a peak around 60hz and cause the response to drop off sharply above 80hz. Maybe worth playing with again though. Rear chamber is definitely huge! Which to me seems pretty logical considering the low tuning of 32hz. Cheers for the comments, food for thought :) |
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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I should add, I'm happy for the horn to be less efficient in order to keep the bass extension and overall system balanced. I don't want it to be only good for... psytrance
I think the end aim is for the cab to be a compromise between 6th order bandpass enclosure and a short BPH. Edited by luthier - 25 March 2020 at 10:23pm |
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VECTORDJ
Young Croc Joined: 11 June 2006 Location: United States Status: Offline Points: 513 |
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A+
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VECTORDJ
Young Croc Joined: 11 June 2006 Location: United States Status: Offline Points: 513 |
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Hi, What is the horn response for 4 units? 8 units???? VECTORDJ
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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Cheers VECTORDJ, here you go:
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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With a bit of playing around here's the results with a larger mouth, also I seem to have gotten rid of the dip at 80hz.
What I've noticed with the modifications:
My worry with the larger mouth and faster flare rate is that I will loose too much space in the ported chamber and won't be able to get the sensitivity I want at my 32hz tuning. Here's .5pi (or 4 cabs) 2pi |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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My approach that has worked for me when prototyping is to make a box that is as easy as possible to adjust re tuning, for example, build oversize ported cab, use tubes to tune, easy to cut different lengths etc, bricks to reduce internal volume. Make your different flares so as can be bolted to ported box. Doesn't need to be pretty, 'sticks like shit' type gap filling adhesive is great for speeding things up :)
With regards to tuning the reflex part, look at the frequency response without the horn, if you have a big peak then it will ring like a bell, all to often, ported horns are tuned flat, to do this the reflex part is very peaky. Bottom line is that the bit near cut off is reflex only and sets the min sensitivity. By building an adjustable prototype, you will soon get a feel for what works and what doesn't. Corner loading can help with it equating to a larger number of boxes. |
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luthier
Registered User Joined: 21 July 2013 Location: UK - London Status: Offline Points: 271 |
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Thanks once again @fatfreddiescat, some really useful techniques and insights. As for the 'sticks like shit' glue I've got a tonne of EVER BUILD 5 MIN LUMBERJACK WOOD ADHESIVE which does exactly that! Reflex part is definitely very peaky, thanks for the warning. |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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The loudspeaker is the limitation. It is easily shown in the TS Parameters. Because you are using Horn Response which uses parameters that do not show the weakness of a driver when constructing a reflex box, Horn Response does not tell you why you have such a peaky response. The ideal enclosure size for the driver in question is 7 cubic feet. When you take into consideration other drivers that are smaller in diameter that offers similar TS Parameters as the driver in question, it becomes obvious the driver's diameter is the limiting factor why it cannot take advantage of a large enclosure. The driver will offer a good response for horn loading and
an adequate response for a reflex box. That is the price you pay when aiming
for the best of both worlds using one driver than can execute both tasks. All in all, the driver is at it's limit (37 Hertz) on how low it can go while maintaining a flat response. Because you are tuning the driver lower than it's limitation, you will attain a sharp peak followed by a sharp decline. The overall frequency response is pretty much standard of a double-tuned band pass box.
Best Regards,
Edited by Elliot Thompson - 26 March 2020 at 3:29pm |
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Elliot Thompson
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VECTORDJ
Young Croc Joined: 11 June 2006 Location: United States Status: Offline Points: 513 |
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Now WE have some Bass!!!!!!
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