Small midrange boost with conical "guide" suggestions?

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[FONT=Arial, sans-serif]Hi, [/FONT]

[FONT=Arial, sans-serif]I have a pair of these very cute Sica 4 inch paper cone midrange drivers. I am looking for a way to push out a few dB's more, with a small conical guide/ horn/ extension/ tube thing. Intended use is the 400 – 2.500 Hz range. Here are the midrange spec's: [/FONT]
[FONT=Arial, sans-serif]http://www.teamaudio.fr/media/catalog/product/datasheet/sica/Z001800C.pdf [/FONT]

[FONT=Arial, sans-serif]This would be the idea, easy to route with a 45 degree bit:
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This is what Aj Horn thinks will happen, note the dramtic dB scale. [/FONT]
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Would it be this simple? Or am i overlooking something? Will this simple conical extension effect the directionality of the driver? (hopefully not). Any input to improve this idea would be welcome![/FONT]
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I don't think it will load the driver, there's no horn throath. The idea would be a bit like these:
IMG_2548.jpg

Klein_Hummel_O-410_Monitor.jpg
 
I think we understand what you're looking for, but you still cannot get horn loading down to 400hz without a large enough horn to "contain" 400hz The bottom threshold wherein you will get horn loading is more or less equal to the dimension of the mouth compared with the size of the wavelength (in a conical).
 
Thanks!

You are right, as can be seen in the Aj-horn printscreen :) , 8.8 cm to 16 cm round in 3.6 cm length gives a boost at 1 kHz. So probably 1/2 wavelength needed to get some boost.

Anybody experience with taming the dip in the frequency (see the Aj-horn plot)? The dip moves lower with a larger mouth... I am not that annoyed with the dip, see plot below. Would need the 36mm offset anyway, so why not make the most of it. It's no problem to cross the woofer a bit higher up in freq. if all this does not work out.

2nqwnkz.jpg


Anybody experience with a middome or small midrange and shallow waveguide?
 
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I know that a 3.5in Vifa TC9FD in a 15in long tractrix with a 2in throat loaded down to 400Hz and went from 85dB to 108dB sensitivity. Crazy loud sensitivity. The model in AkAbak was pretty accurate with predicted bass extension and sensitivity. If AJ Horn is predicting this, it's probably right. I built it with foam core to test out and it works well. So good that I made a synergy out of it. Look in this thread for more info.
http://www.diyaudio.com/forums/full-range/261427-presenting-trynergy-full-range-tractrix-synergy.html
 
Thanks, i have seen these wonderfull creations :) nice work! I have a 2 inch stereolab fc 250 / 45 cm horn and a Vifa TC9FD at hand...

But that's not the idea, the idea is to make a 3 way like the pic below. See it as an "experiment in papercone" Fane 12-200 Onken, Sica LP 104.25 mid, Visaton FRS 5 X tweeter. 94 - 95 dB, first order passive x-over. Speakerbuilding like it's it 1977 :). Just to satisfy my curiosity.

So i needed to fill up some offset "space" between the woofer and the mid anyway. A small conical on the mid and tweeter hopefully gets me a bit more sensitivity and less problems with the sharp edges of the steps.
An externally hosted image should be here but it was not working when we last tested it.
 
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Thanks, i have seen these wonderfull creations :) nice work! I have a 2 inch stereolab fc 250 / 45 cm horn and a Vifa TC9FD at hand...

But that's not the idea, the idea is to make a 3 way like the pic below. See it as an "experiment in papercone" Fane 12-200 Onken, Sica LP 104.25 mid, Visaton FRS 5 X tweeter. 94 - 95 dB, first order passive x-over. Speakerbuilding like it's it 1977 :). Just to satisfy my curiosity.

So i needed to fill up some offset "space" between the woofer and the mid anyway. A small conical on the mid and tweeter hopefully gets me a bit more sensitivity and less problems with the sharp edges of the steps.
An externally hosted image should be here but it was not working when we last tested it.

Ok, I see what you mean. Get me the dimensions of the horn you are intending to make and I will see what AkAbak says for the gain and bandwidth. What is your desired freq range?
 
Oh wow, Super!

Intended freq, range is > 400 Hz - 3.0 kHz < for the Sica. A small 2 dB saddle between 1.5 and 3 kHz is no problem the Sica has a broad peak there. The Sica plot above is in Watt/ meter, @ 2.83 V things look a wee bit better. 2 dB extra would be nice so i can meet the Fane 12-200 and the FRS 5 X ( in a 18mm 45 degrees conical) in effiency. A small starting radius going over to conical would be something i could manage with a router.

The Fane can cross over higher, so can the Sica midrange. But i want to keep the dispersion even and wide as possible. Hence the not so seventies low x-over point to the FRS 5 X. For the Sica 5 or even 600 Hz would be ok, but since this will be a "first order time and phase align experiment", there is a limit to the Fane's range and what the intended LC nothch on 2.2 kHz can do.

Very curious if this could work.

-edit- Forgot the horn dimensions in all the excitetment! Max 180 mm round, depth max 54 mm. Preferable 160 mm round and 36mm deep.
 
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Ok, 160mm wide x 36mm deep. Baffle width is 450mm. Can this be a rectangular horn or do you have to have a round horn? Why only 36mm deep - that is not much depth to work with. I suggest at least 150mm deep, is that possible? If baffle is 450mm wide why not make horn go all the way to say 400mm wide x 160mm tall x 200mm deep for 90deg pattern?
 
Hi XRK,

The idea is to make it with a router, round works easiest with a router, at least for me.

The other idea is to make a phase linear speaker with first order crossovers. So i need to offset the drivers just a little so they all go +> on the same moment. For design purposes it's easiest to use the voice coil offsets as a starter. The offset between the Sica midrange and the Visaton is roughly 54 mm. 18 mm of these are gone for the conical the FRS 5 X uses. Imagine the Technics a page ago with the midrange "block" protruding the speaker 120 mm, i want the speaker to be big, not big and ugly ;) Big Onken threeway with a very thick stepped frontbaffle is the idea.

It's a design challenge i have set myself, what's possible chasing high efficiency using simple paper cone's. Without using elaborate hornloading. I have a 250 fc horn to use the Sica in. Simulates wonderfull. Even have drivers to meet and match the Sica at 500 Hz and above 4.000 Hz in horns and eff. And i sure will try this sometime, but today's speaker is a vintage wide baffle ode to the Technics SB 7000 :)

An externally hosted image should be here but it was not working when we last tested it.
 
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