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12" BPH design.

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LeruSound View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2018 at 2:57pm
This is some result i obtained from last measurement. Quite a bit of processing has been needed, but nothig CRUCIAL :D (Global polarity should have been reversed, but this is just a screenshot i got by the hurry)




Edited by LeruSound - 06 August 2018 at 2:59pm
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MarjanM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2018 at 4:39pm
That is quite a complex built for a box that dies at 150hz.
Marjan Milosevic
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LeruSound View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2018 at 10:36pm
Indeed, that graph has a filter at 140 Hz, but the cab is supposedly to go down to 100Hz.. by the way, I had another measurement today and I have to admit it's not a total winning idea. I would expect it better.. I will try to switch on a bigger compression driver, 1,4 or more probabily 2", cuz it's the sufferinf band when you push it. But 15 + 8 is not bad at all, just I found difficulties in matching the 8 and the 1". Even if i get the cut lower, the 1" doesn't have enough.. will see..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 07 August 2018 at 9:12am
Because it peaks at 150 Hz quit strongly, you should be able to make it go down to at least 125 Hz in an enclosure of similar size. Also, up to what frequency does it sound good?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 07 August 2018 at 1:26pm
I measured, it does go down around 100 /120 Hz. Would say the 1" driver is the source of harshness. Everything up to 1 kHz comes out strong and spread well.  I don't know. Everytime i'm on a hurry doing measurements, cans stay listening for long.. But i would say the tweeter have something strange when plays loud. It is DE550 filtered at 1,5kHz with 24db/oct filter.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote FrederikMA Quote  Post ReplyReply Direct Link To This Post Posted: 08 August 2018 at 10:08am
DE550 is a very high quality driver with large voice coil. So with such a high crossover even on a small horn it shouldn't be the cause of distortion.
From the looks of that 8-horn, the rough throat and mouth will cause som very objectionable diffraction/reflections/HOMs.
These kinds of linear distortion are perceptively non-linear and happen in the CD's lower passband, so its quite in line with your subjective observation.

Deffinately loosen up that 8-horn to let it breath a bit. The problems is not really within the effective range of the phaseplug. An 8" driving a straight horn without any compression chamber will go higher than 1,5Khz and also have improved LF response. Once you have the lower mid in order, you can play around with a phaseplug to extend the upper mid response.

I don't mean to talk ill of your attempts, just dont spend money and time fixing the CD-horn non-issue.

Best regards Fred

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 09 August 2018 at 2:02pm
Thanks Fred. I always appreciate your precious advices. I had played around with phase plug for a while. I would love to try fill the front chamber even more or try a different phase plug design at least.
You've seen what i've done in previous pictures. I would avoid to model the plug inside the horn, as still throat is very tight (around 40sqcm), i would so try to model something that fills up the front chamber (very small, just the volume of the paper cone) while it splits the phaths and keeps some kind of horn expansion. Any suggestion on that? 



This is how it looks now. The plug stays 0,5 to 1 cm from the cone.



Edited by LeruSound - 09 August 2018 at 2:06pm
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