DIY bass compression drivers

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#81
Candidate Thuras Surrogates

jzagaja said:
Before we go into details let me simulate "Thuras" driver.

1) Outer diameter 20"
2) VC diameter 8"
3) Optimum coil mass for 8" is 32g
4) Membrane thickness is ca. 0.1mm
5) Membrane mass is then 8.3g (plus suspension)
6) Assumed Bl is 30Tm, Re=6R.
7) Total Mmd is then 40.3g
8) Resulting Fs=53Hz and Qt=0.12 for Cms=1.6E-04 m/N
9) Optimal throat S1=210cm2 for Rg->0.

Largest domestic horn S2=18000 cm2, length 400-500cm, Hypex 0.6.
Click to expand...

Sans Carcass

Model PD2150/PD2151
Nom.Dia.: 21”
Dvc: 6”
Fs: 22/27 Hz
Sd: 1630/1688 cm^2
Xmax: 12.0/10.5 mm
Qts: 0.19/0.18
BL: 34.28/37.13 Tm
Vas: 628.0/474.8 L
Mms: 305/281 g

Precision Devices International Limited
Precision Devices International Limited

Regards,

WHG
 

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#83
No progress so far and price of neo magnets has increased 3-4 times. Once we try spun aluminum diaphragms and apply diamond coatings on standard mid-high compression drivers we could move into bass compression drivers. Onkens and bass horns with classic woofers are good enough. We tried OB-Horn but results were less exciting however space saving.
 
#85
jzagaja said:
No progress so far and price of neo magnets has increased 3-4 times. Once we try spun aluminum diaphragms and apply diamond coatings on standard mid-high compression drivers we could move into bass compression drivers. Onkens and bass horns with classic woofers are good enough. We tried OB-Horn but results were less exciting however space saving.
Click to expand...

….anything??
 
#88
angeloitacare said:
Basshorn have despite the fact of reproducing low frequencies, which are more omnidirectional, clearly perceivable directionality, which is even more perceived in small rooms. I see no advantage to use them domestically anymore. Much better use a bass array.
Click to expand...

Hello,

Perception of directivity Under 150Hz is something very hypothetical IMHO may be a bit more around 250Hz... but I surely cannot accept such opinion as " a bass horn has a perceivable directivity"...

Best regards from Paris,

Jean-Michel Le Cléac'h
 
#89
Jmmlc said:
Hello,

Perception of directivity Under 150Hz is something very hypothetical IMHO may be a bit more around 250Hz... but I surely cannot accept such opinion as " a bass horn has a perceivable directivity"...

Best regards from Paris,

Jean-Michel Le Cléac'h
Click to expand...

Jean-Michel

of course it depends as well how big the bass horn is. If you have a basshorn that has the mouth size as big and high as the entire room wall, then distribution will be even. But most common bass horns we see around have a rather small mouth exit, so the radiation angle is rather limited, and the energy of the sound waves directional in a way that can be clearly perceived. That was a reason, why i did add two 15" woofers above my basshorn, having now even vertical distribution of bass in my room.
 
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#90
angeloitacare said:
Jean-Michel

of course it depends as well how big the bass horn is. If you have a basshorn that has the mouth size as big and high as the entire room wall, then distribution will be even. But most common bass horns we see around have a rather small mouth exit, so the radiation angle is rather limited, and the energy of the sound waves directional in a way that can be clearly perceived. That was a reason, why i did add two 15" woofers above my basshorn, having now even vertical distribution of bass in my room.
Click to expand...

Hello Angeloitacare,

I cannot call bass horn any VOT or Altec 211, JBL4550 and such

The lowest reproduced frequencies by them being is emitted by the bass-reflex part like in that example

http://www.artec-france.com/photos/salle-ecoute-2007.jpg

and even that one (in the middle) , I don't call this bass horn!

http://www.melaudia.net/zfoto/bretagne1205/P1040088-800x450.jpg

Only the upperbass range and midbass range being emitted through the small and too short horn part.

This is what I call a bass horn (and even this is a Le Cléac'h basshorn )

http://nsm01.casimages.com/img/2009/05/17//090517055721545253677910.jpg

http://www.melaudia.net/zfoto/bretagne1205/IMG_9967-800x533.jpg

And with such true bass horns the directivity is very low...

Best regards,

Jean-Michel Le Cléac'h
 
#92
Jmmlc said:
Hello,

Perception of directivity Under 150Hz is something very hypothetical IMHO may be a bit more around 250Hz...
Click to expand...

I have long had doubts about this as well, but I have searched in vain for any scientific studies that quantify how well humans can locate sound sources at various frequencies, in azimuth vs. elevation, etc.

Can anyone link me to one?
 
#93
I will be interested in this also (under 150Hz directivity). It opens up flexibility in bass horn arrangements, potentially allowing them to enter the rear of the room to counter time alignment issues and reduce horn height and issues associated with mid bass horns in front of bass or sub bass horns.
 
#94
Absolutely. It seems to be audiophile "common knowledge" that midbass frequencies are localizable. But if this is in fact not true, then stereo bass is a useless design goal, and summing to mono below 150 or 200Hz opens up all kinds of design flexibility for high-performance sub/satellite systems with much smaller L/R speakers.

Edit:

Midbass localization is off-topic for this thread, so if a mod would care to split these last three posts off into a new thread, that would be fine with me.
 
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#97
Maybe someone should start out with a simple PPSL before going to extremes. My set is very likeable.

Depending on ones needs they should consider using 8-10" woofers to use a smaller manifold for more midbass bandwidth.

Mine uses 15" woofers and goes to crap 2 octaves below where I'd like. But I do get full output below 24hz. A design that did well 70-400hz 96-100db might be reasonable and much easier that the designs in this thread.
 
#98

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  • 3-way horn-loaded midhigh cabinet with Celestion CDX1-1446, TF1225, TF0818MR by James.jpg
    3-way horn-loaded midhigh cabinet with Celestion CDX1-1446, TF1225, TF0818MR by James.jpg
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