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Old 18th January 2013, 10:20 PM   #1
kees52 is offline kees52  Netherlands
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Default linkwitz dipole with wsp26s.

Hi There


I have make a dipole with two visaton wsp26s speakers, I did not a ripole because the woofers has already 19 hz resonance and so it is better to do it like on the picture, it go deep low for such smal box, I was really suprised, this visatons are really good to experiment with.

the next will have 18 inch woofers, 35 hz fs in ripole, two stacked, how deep will this go, maybe 15 inch are also enough.

I do like it, very clean and fast.

But the slot and outputs I can,t find a lot about it how it has to be calculated, I have use 1 x sd for slot, and 3/4 for the outputs and it works deep low. I have use the sd from one speaker only I have not double it because of the two woofers used, what is 660 cm2 together, I hope this was the good path, please let me now if not.

She work the best in the middel of the room. blue line is front, red is back 120 cm distance of mike from box.

see pictures.

thanks.
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File Type: jpg DSCN0534.jpg (371.0 KB, 186 views)
File Type: jpg visaton-dipole-linkwitz.jpg (454.0 KB, 180 views)
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Old 19th January 2013, 03:14 AM   #2
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Quote:
Originally Posted by kees52 View Post
I hope this was the good path, please let me now if not.
It is all about SEX. With the right packaging, even POOP can be sexy.

Short and Wide is not sexy.

Linkwitz and JohnK have evolved to long-and-lean sexy 4-way dipole speakers.
---Two 10" or 12" stacked H-frame beat superior short-fat W-frame or 18"-H.
Design a complete speaker to solve listening room position and ear-height challenges.

Short and Wide is not sexy.

Woofers with open motor pole air vents usually have high levels of dipole distortion from wind noise. They were built for sealed boxes. Hold a naked woofer running at 30Hz and listen for rear vent noise to judge dipole suitability. A front-facing-cone H-frame hides rear vent noise and physical motor interference. Ears beat math.

When I study JohnK and Linkwitz 4-way dipoles it is easy to sketch a sexy great sounding dipole speaker as long as I use narrow+short H-frame bass.

------------

"But the slot and outputs I can,t find a lot about it how it has to be calculated"

linkwitzlab and MLK quaterwave websiteshave some info, mainly explaining cavity resonance and wing length. I've moved from W-frames to H-frames for width advantages. Short and Wide is not sexy. My W-frames had a modest "V-shape" center cavity to spread resonances and help the air pressure push to the open exit.

I cut a cardboard profile of my dipole speakers and put them in the listening room before construction. Short and Wide is not sexy.
Attached Images
File Type: jpg PooP.JPG (39.4 KB, 160 views)
File Type: jpg Dipole Style Poll.jpg (71.0 KB, 161 views)
File Type: jpg Height_Width_Ear.jpg (84.7 KB, 152 views)
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Old 19th January 2013, 12:08 PM   #3
kees52 is offline kees52  Netherlands
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Thanks for your info, so I see there is little math.

Oke, I had before H frames with this speakers, but these dipoles go deeper, but not louder, spl is the same, but dimensions are cut twice.

What woofers has little noise? I presume this only happens with high spl, I want to build stacked 18 or 15 inches, with four speakers eacht side, I think that give a nice and enough spl without to much noise.

PS I don,t like POOP, I watch my pussycat..
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Old 19th January 2013, 02:34 PM   #4
kees52 is offline kees52  Netherlands
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here I had a H frame with the two visatons, it did good.

second test of H frame dipole speaker. - YouTube

I had two per H frame.
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Old 19th January 2013, 03:04 PM   #5
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Without EQ for dipole roll off, entire performance is lost. Between not being flat, and Fletcher-Munson curves, your not hearing anything close to correct. Slot has virtually no bearing here, it is the dipole separation, determined by exterior dimensions.

In above posted plots smoothness in roll off also looks like measurement doesn't extend low enough, analysis window too short, and smoothing employed.

This is raw response of 37cm x 37cm x 53cm U frame with Dayton HF 12" measured at about 2m:

Click the image to open in full size.

It sounds like one note bass until equalized to flat:

Click the image to open in full size.

Get this to work before building giant stacked system.
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Old 19th January 2013, 03:28 PM   #6
kees52 is offline kees52  Netherlands
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What dou u use as meareings software, holmimpusle is not so good as arta.

My room is also not so super with its L form, I have use a line level shelf filter, I have to experiment with it or us a linkwitch shelf with a opamp. (afcourse only burr brown because I have a hybrid amp.

I feel the very low bass very good, I have not made a ripole because then the FS of the speaker drops to 10 hz, and I don,t now it that works, but I can test in the same enclosure. I do first make the schenatic and ppcb ready of the measurement system so I don,t use the mic input of pc anymore, not best..

Do you eualize with a electronic one, or do you use filters like me. I see that with red line is without shelf filter (line level) and blue with it there is not much effect except lower amp sensitivity, so I go for a more complicated filter with opamp.

thanks.
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File Type: jpg test2-redwithout-shelf.jpg (458.6 KB, 13 views)

Last edited by kees52; 19th January 2013 at 03:56 PM.
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Old 19th January 2013, 04:25 PM   #7
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REW produces excellent measurements, and has great GUI for analysis too.

Holm also produces excellent measurements.

If you feel very low bass is very good, then you will be blown away by how it really is suppose to sound with EQ.

Old engineering philosophy: Don't build what you can buy, unless you can do it cheaper, and better. Why build soundcard?
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Old 19th January 2013, 04:34 PM   #8
kees52 is offline kees52  Netherlands
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Hi I have measured the dipole with 1 meter distance (photo 1 ) and two meter distance (photo 2), after two meters there is one meter left to the wall, with two meters I get a lot of cancelings etc, the thirt photo is 0.5 meter and an extra coil for the low pass, so first I go make a proper lowpass, and a shelf filter.

yellow line is 20 hz start, photo 3.

thanks
Attached Images
File Type: jpg 1 meter distance.jpg (73.6 KB, 32 views)
File Type: jpg 2 meters distance.jpg (79.4 KB, 31 views)
File Type: jpg extra coil lowpass.jpg (76.8 KB, 24 views)
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Old 19th January 2013, 04:51 PM   #9
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Seems that space is tight indeed. Shelving filter will help immensely, looking forward to your results.
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Old 19th January 2013, 06:09 PM   #10
kees52 is offline kees52  Netherlands
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I have a schematic of the linkwitz mic amp, that is what I go build, not a soundcard.

I have seen that in china there are a lot of big drivers, maybe let make special ones for th open baffle.

The bas is stronger now I have change the low pass, I see and have learn that a eq is important in the pas band, hee I am a amp designer loudspeakers is new for me but very
nice to play with special the sub tones.

I have also a while ago tought of a Tapped Horn, wil go low and loud, but not now about it,s sound, ob is for me the best until now but lack of efficienty so not nature friendly

I did a measurement within the room, who is 7 meter long total, and with is 2.80 meter in the middle (smal wall) and backm is a deep open kichen, and front is 3.70, to kitchen is L form.
and room self is 7 x 3.70 minus small part in the midlde of room w.89 with, all meters.

The measurement with holm and in the 20 hz part, everYthing did shake a little, with low volume so it is promising, I don, try it with high volume, qts of speakers is 0.34 a little low and a ripole she are not suitable for (own 19 hz resonance). I first go make the low pass (120 hz) and then shelf it with more poles.

And now I go connect the shelf because if was not, let you now..

Oke did it quickly, one resistor adjusted see picture, only the low pass is still to high but I have not the big enough coils for filter, and need 24dB roll of.

looks promissing
Attached Images
File Type: jpg extra coil lowpass.jpg (76.8 KB, 23 views)
File Type: jpg with shelf filter on..jpg (162.8 KB, 21 views)

Last edited by kees52; 19th January 2013 at 06:37 PM.
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