Karlson-slotted pipes

[PeteMcK]

My new speakers, 150mmx 1.2M PVC pipe, 2x 4" drivers biamped by small chip amps xover 150Hz. Amazing solidity to acoustic bass & drums, much better than I'd hoped for. Probably would be a good approach for a full range driver.

(attempting to attach jpeg...)


Pete McK

[PeteMcK]

a closer view

[PeteMcK]

I tidied this up later with a glue gun...

[RHosch]

I don't think I'll ever understand the continuing fascination some have with Karlson enclosure designs. To each his own I suppose...

[PeteMcK]

I can understand why some don't like the classic Karlson, but this isn't one of those 'acoustic meat grinders'; this is simply using the slot to 'de-tune' the resonance of the pipe (see the theory on the Karlson forum site). To my amazement, it worked really well....
Pete McK

[Ian J]

Pete,
Did you just 'cut a pipe' or were there some other factors such as driver Q to take into account? How is the baffle fixed in the pipe, and are the driver placements critical?
Thanks
Ian

[PeteMcK]

is my motto..The drivers (&amp/xover)were just what I had on hand. The length of the pipe is 1/4 wavelength at 40Hz, the slot starts at 2/3 the length (well it would if it went to a sharp point, where it ends now is where I could turn the jigsaw around comfortably), and the flare rate was chosen to fit the 6" width of the pipe at the end.
The baffle is simply slipped down the middle of the pipe and screwed in place. I lined the sides of it with felt to fill any gaps.
As it is, it's a bit top heavy, so I need to make a stand of some sort.
I don't know if driver placement would make a difference, I just put them where they are for max pipe length & aesthetics.
As it is though, to my ears it has a smooth response all the way down, no noticable resonances, so I'm happy. (That may just be due to good luck - I'll be doing more listening this weekend & running a sine wave through them to see what happens).

If anyone has suggestions as to what sort of driver Q would be best in this situation, I'd be interested to hear your views.

Cheers,
Pete McK