Small active 3-way floor stander with a punch

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Damping?

How would you dampen such a cabinet as this?
I know the best result will be from trial and error, but I have to start somewhere :p

This picture show what I imagined. The green outline is the Sub-cabinet. The blue outline is the mid-cabinet. The orange lines i 8 mm felt. The white lines are 30 mm acoustalux/polyester.
WgN52M2.jpg



Additionally, I will ad 8 mm felt to the curved sides of the mid-cabinet.


The sub-cabinet is where I am mostly in doubt. The subs will play from 80-150 Hz and down. Will there be any effect of egg-crate foam, felt or similar on top and bottom?
The longest distance in the cabinet is 67 cm from the top corner to the bottom front corner. From the flat top to bottom is 40 cm. From what I know I won't risk standing waves before 250-400 Hz.
Will the accoustalux then have any other effect than Q adjustment?
 
I need advice!

I have also been playing with the side bending - without glue so far. It will be a challange..
4 mm birch ply is very easy to bend along the grains of the outer layers (it has 3 layers). It is way stiffer across the grains.

I did test that i could bend it to a radius of 10 cm in both directions and my design has a radius of 25 cm.



I would like to have vertical grains on the outer most layer. I thought it would be a good idea to change so that every second layer would have vertical grains and the others horizontal grains. This will give equally many layers in each direction. As i have 6 layers on each side this would result in the following layup:
Horizontal(stiff), Vertical(soft), Horizontal, Vertical, Horizontal, Vertical.


I regret this choice. now i would have prefered all to be vertical as it is easier to work with. I already cut all the plates though and i am out of wood..
So now i was thinking of dooing this layup:
Vertical, vertical, horizontal, horizontal, horizontal, verical.

This way i can get the first layer secured better. also i will have two layers supporting each other before the stiffer layers.


I made two bending "forms" to distribute the pressure more evenly. Originally i had the cross bars on the outside, facing the clamp bands. Tha tilted the bars when the bands were tightened and was a mess..
So now this is what i do.

hLyUbRL.jpg
ioh1VY4.jpg
ILMq4l8.jpg




As you can see i had to ad some blocks under the bands to get proper pressure at the start of my radius. Otherwise the plate will float like on the other side.
Both these plates are with horizontal grains (when the speaker is standing) so they are stiff. I didn't try the vertical grains yet - will do tonight.



As you see the plate with the blocks is pretty much in position, but there are huge forces in play here..


Do you have any tips to soften the plates?
I heard that boiled towels can work?
Should i boil some towels on a couple of plates and pree-bend them first?
How loong does it take for them to dry before i can glue?


Should i use something stronger than normal white glue for the first layer? Like PU glue?
I dont have any experience using PU glue. Can i use it on the wood as is, or should i moisten it first?
What is the drying time of the PU glue?


Hope some of you guys have some tips :/
 
My DSP has up to 19Ms time delay (I think both + and minus).
The slanted baffle is mostly for style. I like the look and I think it feels less intrusive in the room. Furthermore, the speakers are only 80 cm tall so in order for the drivers to be pointed at ear height in listening position i need some tilt.


Sorry to be annoying - but I doubt that your DSP can move forward in time ;)
 
Thor, No ofcourse not, that was a brain fart xD
But I can confirm the 19 ms. :)

I think i managed to find a solution yesterday. In short, the solution involves a 600 degree heatgun, water sprayer, fine tuned bending "forms" and a very specific clamping sequence.
I glued the frist side this morning with water resistent pva glue, and lots of it! ... Fingers crossed!
Will let it dry 24 hours before I remove the clamps.
 
Done with the sides!

Finally all 6 layers on each side is glued! 12 layers in total = 24 mm side walls.

5W0Wir4.jpg




DwcGzzY.jpg



When i got the hang of it it took 30 min to trim the previous layer down and glue on the next. No need for heat or anything.



It is getting heavy xD
And it grew a little now.

syJWgmK.jpg






I am very happy with the result and am ready to cut a bunch of holes tomorrow!
 
Cutting Subwoofer holes

I measured and marked the center point of the woofers. Then i drew 3 circles. The outer one represents the woofer outer diameter. The second is the thru hole for the driver. The smallest is the part i cut out by hand.
CXFymNE.jpg



Set the depth on the router to just barely penetrate the bended sides:
LYaIbxO.jpg1




Dig out the whole inner circle by hand - Lots of dust xD
This reveals my flat squares on the sides of the skeleton.

F7nrM0b.jpg1




Spacer block screwed on and center marked up
FXvrKQA.jpg1




Circle support installed

lhjvZPh.jpg1




Normal circle jig used

gbNcj5A.jpg1






First the counter-sunk
dwre0VU.jpg1






Then the trhu hole

xF40v1R.jpg1




Voila!:
eQMVdCK.jpg1






I do not know if it was the easiest way, but it was how i could think of it xD
 
Nice work ! Surprised no one else has commented ?

My wood working skills and tools need an upgrade :)

I'm hovering up ideas and inspiration at the moment for a future build along the similar lines* so thanks for sharing your project.

*3 or 4 way active compact floor stander with a down firing 10" sub'*
 
Hello you two!
Sorry, but i didn't realize anyone commented on this thread. And i have been super busy, also trying to make the speaker ready for a local event this weekend!

Thanks for the nayz words!
Looking forward to see that build Andy :D


I also managed to kiind of finish the speaker (still missing the side panels - which will be a pain) with a, by all means not perfect, but acceptable crossover for a short teaser demonstration this weekend. I will post some pictures later today or tomorrow :)

I am convinced the will sound great in the end. They sure have power!
 
Nicely done Danner. I'm looking forward to some more pictures. And with 4 of those 10" SB woofers in total, I figured in the end you were going to be seriously impressed with these speakers' potential output. Me thinks you have some serious :censored: fun ahead of you as you get them more and more dialed in. :emoticon:

As an aside, I'm wondering if this thread doesn't have some kind of little technical glitch to it as email notifications of new posts mysteriously stopped for me more than a few weeks ago. :scratch:

Best of luck at your weekend event. And perhaps listen closely to any criticisms cause those are the things you are going to want to correct.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.