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Multi-Way Conventional loudspeakers with crossovers

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Old 4th January 2019, 07:44 PM   #301
augerpro is offline augerpro  United States
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I can design you mic holder to print tonight. I'll need the barrel diameter and specs of the threads at the end of the boom. You really want the tip of the mic to just be a little point out in space with no reflections nearby. Here is mine, the mic slides into it and there is a slot on the bottom for the cable to exit:

Click the image to open in full size.
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Old 4th January 2019, 07:51 PM   #302
Pida is offline Pida  Czech Republic
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Ergo, thanks for Bliesma and WG measurement, it shows that it really has a potential. I definitely recommend to try roundovers at least R20, I have experiences with WGs of similar sizes in baffles of normal sizes, and WG responses were similar. Larger roundover always helped. I use R30. WG outter diameter is 170mm, depth 30mm.
Check the result here: SatoriWG7 :: Pkaudio
It is still not perfect, as WG profile was not machined pricely a the small diffraction at ~6kHz is probably from the midwoofer frame running into WG, next itteration will be better.
Earlier prototype with correct WG prototype was better in that regard. The baffle was just chamfered 15mm 45deg, which was not perfect in other regards (broad dip at 3-4kHz) - this made me to try R30 roundovers.
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Old 11th January 2019, 02:09 PM   #303
Rokytheman is offline Rokytheman  Denmark
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Very cool to see and follow how this thread has evolved!

Amazing! :-)

Quote:
Originally Posted by Gaga View Post
You can put off the faceplate of the SB26ADC and mount the dome directly to a WG.
I already have the SB26ADC. When screwing of the 4 screws on the faceplate -
The dome and the faceplate are like one unit. How do I seperate the dome and the faceplate from each other?
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Old 11th January 2019, 03:50 PM   #304
Mayuri is offline Mayuri  Finland
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They should be separate, but mine came off as single as well. Just gently pry them apart.
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Old 11th January 2019, 04:24 PM   #305
augerpro is offline augerpro  United States
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Yeah just use a butter knife and keep prying around the edge until they pop apart
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Old 11th January 2019, 04:51 PM   #306
Gaga is offline Gaga  Europe
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Open source Waveguides for CNC & 3D printing!
Hi,

taking off the faceplate should look like this:


You have to take care about the wires on the faceplate when coupling to a horn/waveguide-throat...
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Old 11th January 2019, 05:42 PM   #307
Mayuri is offline Mayuri  Finland
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I have modified the 6" waveguide made originally by augerpro to fit ScanSpeak R2604 (also fits all other models with same faceplate, for example D2604). There is a round mounting plate that is easy to route for, diameter is 142mm, mounting depth is 6,4mm. The mounting holes are standard M4, diameter of holes is 130mm. You can use normal machine bolts to attach tweeter to waveguide with the backplate.

Dropbox - SSR2604wg.zip

Measurements coming soon when I can figure what's wrong with my measurement microphone. It shows a rapid drop-off starting from 8k, even from speakers I know can easily go past 20k...
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File Type: jpg 6inchSS2.jpg (62.1 KB, 48 views)

Last edited by Mayuri; 11th January 2019 at 06:00 PM.
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Old 11th January 2019, 10:01 PM   #308
DSP_Geek is offline DSP_Geek  Canada
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Quote:
Originally Posted by ergo View Post
In addition two THD measurements

Mic to baffle distance for THD: 315mm

I tried to keep plots comparable to the hificompass.com test

*****

All in all, not a bad result for a first attempt to find a profile for this huge dome tweeter. I will try to print a phase shield out of interest too. There is a small dimple at 7.6k that could maybe be improved a bit, but not sure yet if it is that or might it be also the baffle edges as I'm using a realistic baffle not a huge IEC type baffle here.
Congratulations! You've made a fearsome tweeter terrifying.

Just for grins & giggles, have you tried a series resistor of about 8 to 12 ohms or so? Hawksford and others claim drivers show lower distortion with current drive, and a fat resistor might emulate current drive well enough to show decent results. You'd want to update the drive voltage and capacitor value, of course. The comparison won't be exactly apples-to-apples since the tweeter impedance variation would increase gain at the extrema, but setting the driver voltage to the same values in the middle of the range, say around 5 kHz, should be sufficient.

http://mariobon.com/Articoli_storici...ith_iDrive.pdf

Distortion examples | Current-Drive - The Natural Way of Loudspeaker Operation

Last edited by DSP_Geek; 11th January 2019 at 10:06 PM.
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Old 12th January 2019, 10:42 AM   #309
Rokytheman is offline Rokytheman  Denmark
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Thanks for the advice and the pictures! I will try that

Does the same account for the SB26STAC - The normal dome with alu frontplate.
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Old 12th January 2019, 11:03 AM   #310
Rokytheman is offline Rokytheman  Denmark
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augerpro: Do you have stl file for the 8" waveguide without phase-shield?

Im all new in regards to 3D printing. I found the following web-based-shop that can print in all kinds of materials.

ABS is cheapest, but nut sure if the quality is high enough.

And do you think this version is in its final stage?
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