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Small midrange boost with conical "guide" suggestions?
Small midrange boost with conical "guide" suggestions?
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Old 30th November 2014, 06:35 PM   #1
Phenoholic Anonymus is offline Phenoholic Anonymus
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Default Small midrange boost with conical "guide" suggestions?

Hi,

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:
http://www.teamaudio.fr/media/catalo...a/Z001800C.pdf

This would be the idea, easy to route with a 45 degree bit:

Small midrange boost with conical "guide" suggestions?


This is what Aj Horn thinks will happen, note the dramtic dB scale.


Small midrange boost with conical "guide" suggestions?


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!
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Old 30th November 2014, 06:37 PM   #2
winslow is offline winslow  United States
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It's not going to be small to load to 450 hertz.
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Old 30th November 2014, 06:55 PM   #3
Phenoholic Anonymus is offline Phenoholic Anonymus
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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:
Click the image to open in full size.
Click the image to open in full size.
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Old 30th November 2014, 09:37 PM   #4
alexwgoody is offline alexwgoody  United States
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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).
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Old 30th November 2014, 10:52 PM   #5
Phenoholic Anonymus is offline Phenoholic Anonymus
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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.

Small midrange boost with conical "guide" suggestions?


Anybody experience with a middome or small midrange and shallow waveguide?

Last edited by Phenoholic Anonymus; 30th November 2014 at 10:56 PM.
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Old 30th November 2014, 11:03 PM   #6
xrk971 is offline xrk971  United States
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Small midrange boost with conical "guide" suggestions?
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-...x-synergy.html
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Old 30th November 2014, 11:30 PM   #7
Phenoholic Anonymus is offline Phenoholic Anonymus
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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.
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Last edited by Phenoholic Anonymus; 30th November 2014 at 11:41 PM.
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Old 30th November 2014, 11:58 PM   #8
xrk971 is offline xrk971  United States
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Small midrange boost with conical "guide" suggestions?
Quote:
Originally Posted by Phenoholic Anonymus View Post
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.
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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?
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Old 1st December 2014, 12:44 AM   #9
Phenoholic Anonymus is offline Phenoholic Anonymus
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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.

Last edited by Phenoholic Anonymus; 1st December 2014 at 01:05 AM.
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Old 1st December 2014, 02:11 AM   #10
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Getting there bit by bit The radius of the horn is limited by the asymetrical placement of the Sica on the baffle.

Small midrange boost with conical &quot;guide&quot; suggestions?
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