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Old 14th October 2012, 11:31 AM   #261
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It sounds just fine to me. I have tried other solutions for mid-bass without any particular success. It did have an array of eight 10" covering some ~100 to ~300 Hz. Actually, the big 21" H-frames were better to my ears.

Others do run woofers and especially midranges way above the dipole peak, and we are talking several octaves.... I would not do that because the off-axis response gets weird, but from the dipole peak and down the dipole figure-8 pattern is there, but not above.
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Old 14th October 2012, 11:46 AM   #262
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Thanks for the precision
Things are not so simple in OB, specially above the dipole peak...
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Old 14th October 2012, 12:02 PM   #263
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Things are not simple with OB at all! That's why its to fun to do I guess...

A lot of EQ is required to make it work properly, that's for sure. To build a dipole with drivers operating only below the dipole peak is very difficult, and it results in 4- or 5-way system.
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Old 14th October 2012, 01:07 PM   #264
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Quote:
Originally Posted by StigErik View Post
Dipole peak described in details. In this example at 680 Hz.

Electro-acoustic models
Thanks StigEric but the math is way too complicated for me to follow, so I will need to find a dummies guide to H frames.

Studiotech pointed me in the direction of a PDF, hopefully it is a little easier to follow.
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Old 14th October 2012, 03:04 PM   #265
Rudolf is offline Rudolf  Germany
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Quote:
Originally Posted by jerome69 View Post
Yes 100Hz is an experimental approximative number when you use 2x10" in the H Frame It is just a point of reference for discussion.
Jerome,
I use 2x10" drivers in a H frame up to 400 Hz - without complaints. And that is almost one octave below the dipole peak. I would be thankfull if you could give the slightest hint, what kind of physics forbids going beyond 100 Hz.

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Old 14th October 2012, 04:06 PM   #266
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Rudolf : Stored energy... I made this project :
Ultimate OB Gallery
And I heard something wrong in the mid, and I notice a lot of stored energy (see attachments).
Easy for me to conceive, a mass of air cannot do mid, but good for bass.

I'm not alone to think this, See also the build discussions the S20z project of Gainphile on HT guide
Gainphile: S20-Z Compact Open Baffle using Zaph Kit
Why Linkwitz doesn't go up to 120Hz and now 90Hz with his Orion 4 ?

As I said some people can support the sound like MJK, you ? but for my ears the sound is not right. It can have exceptions but I have not heard it.
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File Type: jpg rawmeasurement.jpg (93.7 KB, 199 views)
File Type: jpg bdhframe.jpg (52.0 KB, 199 views)
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Old 14th October 2012, 05:00 PM   #267
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Originally Posted by Silent Screamer View Post
I asked Tc Sounds for a frequency response but to date they haven't responded to my request. What does the dipole peak look like?
You're still not doing any measurements?! Speculation is ok fwiw, but hard data is necessary when building a speaker whether it's a dipole or anything else.
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Old 14th October 2012, 05:03 PM   #268
Rudolf is offline Rudolf  Germany
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OK, Jerome

your "Ultimate OB" H frame is 40 cm wide and 40 cm deep. Mine is 30 cm wide and 20 cm deep. So any "trouble area" should be moved to higher frequencies, right?

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Old 14th October 2012, 05:07 PM   #269
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40x40 should place the dipole peak around 300 Hz.

My own H-baffles are 60x60 cm, and the peak is at approx 200 Hz.
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Old 14th October 2012, 05:24 PM   #270
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Yes Erik you are right, see the response curve

Ok Rudolf, yes you push higher "the trouble area" (~500-600Hz ?) but 400Hz is still high ?
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