60ndown's Merged Subwoofer Thread

[60ndown]

projecting bass forward (not omnidirectional)

ive built maybe 30-40 subs in the last 25 years, all seem to perform better when the driver/s are facing away from me, it seems to me that listening to the reflected wave makes the bass/sub bass smoother/deeper.

im talking typically about 60 hz and down

i want to build a new sub, but i want to have the output aimed directly at me, not reflected.

ill be using (4) 6" subs i pulled from some thrift store speakers i have

im good with a tape measure and tools, and am not afraid of scaling a design intended for 18s

anyone know of a 'great' design and a link to some plans i can build?

 

[jan.didden]

ive built maybe 30-40 subs in the last 25 years, all seem to perform better when the driver/s are facing away from me, it seems to me that listening to the reflected wave makes the bass/sub bass smoother/deeper.

im talking typically about 60 hz and down

i want to build a new sub, but i want to have the output aimed directly at me, not reflected.

ill be using (4) 6" subs i pulled from some thrift store speakers i have

im good with a tape measure and tools, and am not afraid of scaling a design intended for 18s

anyone know of a 'great' design and a link to some plans i can build?

I don't know whether it is physically possible. At bass frequency wavelengths, the driver acts as a point source so will always tend to be omni.
Baffles and reflectors to 'channel' the radiation will necessarily have to have dimensions related to those wavelengths, ie several/many meters. Look at a bass horn: the mouth area is huge.

jan didden

 

[60ndown]

I don't know whether it is physically possible. At bass frequency wavelengths, the driver acts as a point source so will always tend to be omni.
Baffles and reflectors to 'channel' the radiation will necessarily have to have dimensions related to those wavelengths, ie several/many meters. Look at a bass horn: the mouth area is huge.

jan didden

i see subwoofers designed for rock concerts, where all the sound is projected forward,

and subs for the corner in an HT system.

I want to build a small rock concert sub

 

[60ndown]

interesting page


subwoofer horn plans - Google Search

 

[jan.didden]

i see subwoofers designed for rock concerts, where all the sound is projected forward, [snip]

So, how do they do that then? IF they do?
I assume you realize that the fact that the opening is facing forward has nothing to do with the radiation pattern (at sub frequencies)?

jan didden

 

[Peter M.]

I don`t think it is possible to have directivity in the modal region of a room, regardless of how large the horn is.

I suggest you read about Gedlee`s multisub approach:
http://www.diyaudio.com/forums/subwoofers/134568-multiple-small-subs-geddes-approach.html

 

[godfrey]

...subs... all seem to perform better when the driver/s are facing away from me...

Interesting.

At bass frequency wavelengths, the driver acts as a point source so will always tend to be omni.

Yes, the deep bass will be omni-directional. However the speaker also creates distortion and noise ("chuffing" from ports etc) at higher frequencies where radiation is more directional.

So although speaker orientation may not affect the bass itself, it may well be a good idea to have the distortion and noise aimed away from you rather than towards you.

 

[Zero D]

Science & Physics

@ janneman

So, how do they do that then?

Science & Physics

Offset rear facing, out of phase, time delayed sub for every 2 forward firing subs. Variations on the theme are possible & also implemented. Works a treat to reduce bass going backwards, & annoying people, especially outdoors.

 

[Xoc1]

This article on the Void Accoustics website will help explain about directional bass arrays.
http://www.voidaudio.com//pdf/bass guide.pdf
As mentioned by Zero D this involes using drivers in groups of 3.
Some bass arrays use bins in groups of 3 (for example Martin Audio)
Some use 3 drivers in one box with 2 facing forward and one facing to the rear such as D&B Audio
d&b audiotechnik -J-SUB.
To get these arrays to work they use digital speaker management systems.

 

[Zero D]

Yep

@ Xoc1

Dems da ones

 

[kenpeter]

I don't know if it applies to SUBs. Some midbass enclosures can
throw a half vortex that defies the usual patterns of dispersion.

 

[revboden]

i see subwoofers designed for rock concerts, where all the sound is projected forward,

and subs for the corner in an HT system.

I want to build a small rock concert sub

You want to build a time aligned rear canceling array??? with 4 drivers...

ok, I'll need some blue tack, a roll of duct tape, and night vision goggles.

sorry, i had to...

 

[60ndown]

awwwwww come on guys, i HATE reading.

i love my skill-saw and my screw gun and my tape measure.

i need plans !!!!!!!

 

[kenpeter]

Find you the 1955 Radio Electronics "Karlson K15" plan.
Its intended as a full range, but excels at midbass.
Front chamber will throw huge volumes of air.
Reaches down plenty low enough for Rock...

I play bass guitar in Drop D, and this is what I use.
Its also great for drums, and will replicate kickdrum
like no other single cabinet of its size...

Claims wide dispersion, true enough for midrange if that matters.
But midbase kick is a floor hugging vortex thats quite directional.
Aim directly at the audience for optimal loading, this one defies
the usual logic. Does not load better facing into a wall or corner.

Plans here: 1954 Ultra Fidelity plan will do, same thing basically...
http://gainclone.com/Karlson/index.php?topic=790.0
Its also qualifies as a one sheet wonder (Cut from a single 4x8).

 

[60ndown]

looks like its worth a shot and definitely fits my design goals as front firing,

thank you.

http://6vbxkq.blu.livefilestore.com...0_ETqHMTWZ5rP_3zN4g/transductor-bo.jpg?psid=1

 

[60ndown]

hmm, looks like the design has been worked on a bit over the last 40 years and post #50 here is the final design.

ill give it a build and see how it sounds, as a sub

Karlson Plans

 

[freddi]

that was a little cabinet with a curved reflector - the original Karlson K15 was built in the summer of 1951 and sold from 1952 to John Karlson's death in 1973 and is quite adept

 

[60ndown]

that was a little cabinet with a curved reflector - the original Karlson K15 was built in the summer of 1951 and sold from 1952 to John Karlson's death in 1973 and is quite adept

im not sure what your point is? build it? dont build it? plan 1 plan 2?

 

[sek]

There's an application note by loudspeaker manufacturer d&b (not affiliated).

They call it 'cardioid subwoofer array' and make one out of three regular subwoofer enclosures.

Cheers,
Sebastian.

 

[sek]

And here's some free software (also not affiliated) in order to calculate on your own.