Mid-bass Horn calculations (BD-Design)

by Marco, Bern, Sunday, August 12, 2012, 21:36 (1982 days ago)

Hi to all, I (Marc) am new here and planning a horn-setup. Bert's tutorial is very useful. Some basic decisions remain before the individual components can be planned correctly.
Tapped Horn : BC 18PS100, TH with one fold. 30-130 Hz ( details later)
Mid-bass horn : BC 12NBX100 ( http://www.bcspeakers.com/product.php?id=366) with spherical wave horn calculated in hornresp, below are the data ( I couldn't upload the text-file, my fault ?). Back chamber should be 3.8 L, lower roll-off was better with 6-8 L. Throat chamber is set at 0.7 L. I will make the throat chamber with MDF, does the form matter ? How do you measure the air volume of the basket btw ? Total driver volume is 3 dl3. Avantgarde Acoustics ( kompendium_der_horntechnik.pdf) writes that the throat chamber is a 6 dB high pass filter, high or low ? Smaller throat chamber increases the upper range in hornresp. I will build a mold and make the horn in fiberglass.
ID=28.00
Ang=2.0 x Pi
Eg=2.83
Rg=4.00
Fta=89.26
S1=85.00
S2=11300.78
Sph=92.20
F12=120.00
S2=0.00
S3=0.00
L23=0.00
AT=6.54
S3=0.00
S4=0.00
L34=0.00
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=531.00
Bl=25.60
Cms=1.27E-04
Rms=2.49
Mmd=30.63
Le=1.40
Re=5.10
GCd=1
Vrc=7.00
Lrc=8.00
Fr=0.00
Tal=0.00
Vtc=500.00
Atc=400.00
Pmax=100
Xmax=10.0
Comment=12NBX100
MF and HF horns - later. I would wellcome any comments and critics. Thanks !

Avatar

Mid-bass Horn calculations

by Bert @, Monday, August 13, 2012, 14:51 (1982 days ago) @ Marco

Hi Marc,

...I couldn't upload the text-file, my fault ?.

Not your fault, only images can be uploaded.

I will make the throat chamber with MDF, does the form matter ?

It should be as small as possible with some wave guidance if possible. You do not want to create an extra acoustical roll-off because it will act as a sort of "spring" for all frequencies killing/reducing impuls behaviour. Better correct this within the crossover for better results in real life.

The "wave" guide is needed more or less depending on the frequencies played through that throat. The higher the frequency the more audible...

Avantgarde Acoustics ( kompendium_der_horntechnik.pdf) writes that the throat chamber is a 6 dB high pass filter, high or low ?

Low pass filter, of course. :fool:

Smaller throat chamber increases the upper range in hornresp.

And might help to extend the roll-off frequency to some point or to smoothen the response towards a certain crossover frequency so that you'll need less components.

Don't theorize too much, buy some measuring gear (and try to understand the data) to actually see what you're doing.

Cheers,

Bert

--
BD-Design - Only the Best!

Mid-bass Horn calculations

by Marco, Bern, Monday, August 13, 2012, 16:49 (1982 days ago) @ Bert

Thanks Bert. Hamlet is not my ideal for speakerbuilding. Am soldering a mic with panasonic WM61. br Marco

RSS Feed of thread