Salad Bowl Speakers

[Ray P]

With the IKEA ones, I couldn’t glue them together because of whatever they were coated with. I taped a sheet of sandpaper to the floor and put the bowls upside down on it then rubbed them until I had a flat on the rim. Glued easily with pva then

Don’t know what the Wiko bowls are coated with, but I would guess something similar and food grade

Brian

The Wilko ones have a nice flat rim and I plann to do the same as you to sand through to the wood for glueing.

[Ray P]

Inspired by Owston, today i started the project to build a pair of speakers using the Wilko salad bowls. I decided to keep it simple, instead of my rocket based ideas. I've cut the front baffle and a hole for the port at the other end. I've ordered some 1.5mm birch ply to make a flange for joining the bowls together and have designed the port tube in Fusion360 and will get them 3D printed. I may also get a bezel for the drive units 3D printed.

Drive units are Jordan JX29S.

[Ray P]

Here's the bass refelx calculator for the Jordan units using the estimated volume of 8 litres.

Jordan FR Calc.JPG (117.36 KiB) Viewed 1176 times

[Mike H]

[Ray P]

Can I get thoughts/advice from the panel regarding lining/stuffing these speakers?

Cheers

[pre65]

Can I get thoughts/advice from the panel regarding lining/stuffing these speakers?

Cheers

Lettuce ?

Cotton wool ?

https://www.ebay.co.uk/itm/125995373015 ... R8qo29DwYg

[Daniel Quinn]

There look like infinite baffle , therefore I would use a small amount of wool.

[Mike H]

Nope...

I've cut the front baffle and a hole for the port at the other end.

I'd try actual loudspeaker wadding, the white stuff (do Internet search) – and experiment with how much.

Chris has successfully used pillow stuffing, another possibility.

[Daniel Quinn]

In that case bin them

[Ray P]

I'm wondering more about lining the inside than stuffing - for that I'll probably just follow Chris's lead and get a bag of hollowfill from Dunelm and try varying amounts.

[vinylnvalves]

Chris, explained to me how to understand from an impedance sweep, where you need the damping, from the perturbations in the curve. I found I had over stuffed and I took a lot out without any detriment, improving the cooling of the driver.
There is a concept for commercial “ egg” speaker where the rear is divided into a separate chamber to breakup the internal waves, if I can find it on the web again I will post it.
Don’t forget the lowest frequency that needs to be damped is 1/4 wavelength of the longest internal dimension.

[Ray P]

Chris, explained to me how to understand from an impedance sweep, where you need the damping, from the perturbations in the curve. I found I had over stuffed and I took a lot out without any detriment, improving the cooling of the driver.
There is a concept for commercial “ egg” speaker where the rear is divided into a separate chamber to breakup the internal waves, if I can find it on the web again I will post it.
Don’t forget the lowest frequency that needs to be damped is 1/4 wavelength of the longest internal dimension.

Cheers, hopefully down the line I can get some advice from Chris too.

Regarding internal waves, I'm conscious that, although the bowls are, broadly speaking, hemispherical, they have a flat bases. One bowl base is the baffle, and the flat base of the rear bowl is parallel baffle, reflecting straight back to the drive unit. To counter that I plan randomly glue some pyramid shapes to the flat rear panel.

[Ray P]

I knocked this up as a 'deflector' for the rear panel so there will be no surfaces parallel with the front baffle - the intention is to 3D print it - thoughts?

It's 13cm diameter and the ridges are 2cm wide and 1cm high. The hole in the centre is where the port will be located.

Capture.JPG (101.48 KiB) Viewed 856 times

[chris661]

Attached is a before/after of a Faital 10HX230 in a ported cabinet.
I was using 1/2" thick recycled wool underlay to cover the internal panels, adding layers until the ripples in the impedance curve were no longer obvious.

Also visible is the slight alteration in LF alignment. It was down a dB or two there, but the midrange was vastly improved. Since those cabinets often get used with subwoofers, I decided that was an acceptable compromise.


Chris

[Ray P]

Thanks Chris.