Yes a compound horn it is. I am considering the possibility to fit a 300-500Hz mid-range horn with a BLH to extend it down to 150 or so. Also not sure if a 150Hz electrical cutoff is ok on a driver which on one side radiates into a 300Hz horn.
Concernes are for coloration, resonances etc. in the mid-range horn.
@Kolbrek would comment on that.
@BP1Fanatic, ICU WYATA (I Cant Understand What You Are Talking About)
TMAIYM (Too Many Acronyms In Your Messages)
And TMOT Pics AW...LOL
Did you read the Martin J. King's paper on the BLH/RLH turning into a TL???
BLH/RLH, TL, and BR
are ALL single chambered enclosures with a port. How is that difficult to understand?
BR with a positive flare port gets you big and loud = BLH/RLH.
BR with a negative flare port gets you small and low = TL.
BR with a long straight flare port (might have more volume than the Coupling Chamber) can be a BR or TL. What I don't know is at what port length does a BR become a TL.
It's just a semantic definition, based on simplified models.
Imagine blowing over a bottle (classic helmholtz resonator - BR). If shrinking the bottle to a simple one-end-closed tube (pan flute or organ pipe - classic quarter wave resonator, TL) - when is it not a "bottle" anymore?
Using hornresp it's easy to simulate "BR" or "TL" and getting very similar or identical results. The only difference (as far as i know) is that BR includes a q-factor while TL are simulated lossless. Workaround with dampening material in the resonator is possible, however.
I'm old I use them all. millimeters for anything from 0 - 300mm, or inches from probably 2 - 12", meters for anything big, never yards. Sometimes it will depend if I am talking to an American or not. We all know how the struggle with the metric system and have to make it simple for them. I can also converse in up to 64th's of an inch or even thou sometimes. I am hoping that one day Americans discover 1 x 10 = 10, 10 x 10 = 100 and 10 x 10 x 10 = 1,000 and then they will know everything they ever need to know about the metric system. You start with 0 and you go up in 10, 100, 1000, or you go down in 10, 100, 1000. Nothing too complicated.
yes sir! ! This is the million dollar question that’s constantly asked in the FB groups re: qw, etc.
this and how the air motion is different inside a long tapered tube verse a long chamber into a long port
i try and observe this with styrofoam beads and plexiglass or clear pvc pipes but just make a mess before any legit observations
Last edited:
The port tube in a bass reflex loudspeaker system needs to be short enough so that the air in it moves as a whole without appreciable compression. That is, it needs to behave as an acoustic mass. To act as an acoustic mass the length of the tube needs to be "small" compared to 1/16 of the Helmholtz resonance frequency wavelength.
There is no magic length where the system suddenly changes from BR to TL.
Yet subwoofers are advertised and sold in inches.
Less ink with 12" compared to 30.48cm or 304.80mm.
Better yet, 1'.
The following was mentioned here - https://www.diyaudio.com/community/threads/ath-to-bempp.410275/post-7630873
However I wonder about hornresp being the ideal example. hornresp may have had it's beginnings as a 1P simulator but in many ways it has grown up since then.
In context, the point is well taken.
However I wonder about hornresp being the ideal example. hornresp may have had it's beginnings as a 1P simulator but in many ways it has grown up since then.
Post #14,462:
"BR with a long straight flare port (might have more volume than the Coupling Chamber) can be a BR or TL."
After giving it some thought, how about the formula below as perhaps a better ROT?
It is reasonably conservative and hopefully a bit easier to remember
.Lpt <= 1000 / fr
Where:
Lpt is the port tube length in centimetres
<= means less than or equal to
fr is the bass reflex system Helmholtz resonance frequency in hertz
Assuming that the speed of sound is 344 metres per second:
If fr = 40 Hz then maximum Lpt = 25 cm
If fr = 50 Hz then maximum Lpt = 20 cm
Somethings are never going to change, and unfortunately some are. Drag racing should remain in mph forever. 50,000 kph just sounds stupid.
BTW why aren't my 18" drivers 1.5' drivers?
It certainly does - since when has a dragster been able to achieve a terminal speed of 31,000 mph?
Even though Hornresp sometimes uses isophase wavefront models it is still essentially a 1P (one parameter) simulation program meaning that directivity results in particular are indicative only, being calculated using relatively simple empirical models. Finite element techniques would need to be used to accurately predict directivity characteristics.
After giving it some thought, how about the formula below as perhaps a better ROT?
It is reasonably conservative and hopefully a bit easier to remember
Lpt <= 1000 / fr
Where:
Lpt is the port tube length in centimetres
<= means less than or equal to
fr is the bass reflex system Helmholtz resonance frequency in hertz
Assuming that the speed of sound is 344 metres per second:
If fr = 40 Hz then maximum Lpt = 25 cm
If fr = 50 Hz then maximum Lpt = 20 cm
So, a BR tuned to 40 hertz and has a port longer than 10 inches (25.4cm) equals a TL?