HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

I actually ordered two of these black stools I got the text from Argos that they were ready to collect whilst waiting for my covid booster so went and picked them up

They are well made and look good which is a good start. They are exactly 30cm diameter at each end which has got me thinking....... I wonder if the steel hemisphere with driver cut out will sit directly on top of the stool. From memory the steel hemisphere is exactly 30cm diameter as well. I would then be using the stool as the enclosure as well.

Polypropylene is not the most rigid material especially compared to a 3mm steel hemisphere but the shape helps. There may be a penalty to pay in the bass but I won't know unless I try it. I will fill the extra interior volume with sand or gravel - gonna try both. I will compare that to the original plan of steel sphere. If the polypropylene stool with steel hemisphere on top shows promise then I will try and strengthen it by lining the interior with fibreglass.

Excited now

Diy supplies just got easier - Screwfix have opened a new store only two miles from my house Result.

Might as well take your bed down there, you'll spend more time in Screwfix than you will at home

Picture of the plastic stool minus the seat



Now with wooden base, a steel hemisphere on top and 15cm ball above the up firing mid bass (just to get an idea). I personally don't like how this version looks and the stool top is ever so slightly wider than the steel hemisphere.



Next up is the stool with the full steel sphere sat in it. This doesn't quite work because the sphere won't go all the way down so there is a gap all the way around where the plastic meets the steel. Apart from that it looks better but the gap is a deal breaker

It is clear now that I have two options. The first is to use just the bottom half of the stool and sit the steel sphere on that. I can't mock that up properly at the moment because of the way the two halves of the stool interlock



It would require some modification to remove the part sticking up so that the bottom of the sphere sits nicely inside the top lip. I don't want to modify it just yet so mocked it up with a short 9cm piece of drainage pipe on top which just allows the bottom of the sphere to clear that bit of the stool that sticks up. This extra pipe won't be there if I decide to go with this version.



So here it is with steel sphere and plastic ball on top. Just imagine the main sphere being lower with the pipe removed. I think that will look good when the drainage pipe is removed and the top of the stool half is cut away.

Turn the stool the other way up, cut the base off, i presume it has a flat base and the sphere being bigger than it should just drop straight into it with no gap. And be more stable as the base would be bigger than the top

The final version would use the whole of the stool like the pic below but with a modification to get rid of the gap between the sphere and stand. Here it is with the gap. Doesn't work .



So the idea is to remove the top 5cm of the stool and that will enable the bottom of the steel sphere to sit snugly in the stand with no gaps and there will be a much better continuation of the curves from the sphere to the stand - that will be better both aesthetically and from the sound wave's point of view I think.

So what ever I do, this stool will need some modification. I am leaning towards this last idea for the reasons above and it gets rid of any abrupt changes in shape, it's smooth curves all the way baby. I am pondering if I should remove the lip at the bottom of the stool where it meets the wooden base so the curve rolls smoothly into the base ?

What is clear is that if I were to try and use the stools inner volume for the driver enclosure then it would need some reinforcement with fibreglass. That is an option if I were to change drivers at any point to one which required more volume. Keep your options open.

Laters.

Vinyl-ant wrote: ↑Tue Jan 25, 2022 3:42 pm Turn the stool the other way up, cut the base off, i presume it has a flat base and the sphere being bigger than it should just drop straight into it with no gap. And be more stable as the base would be bigger than the top

Hi Ant. The stool is identical at both ends in shape and dimensions. There is no flat base, just a lid that will fit on either end. If I turn it upside down I will have exactly the same problem. The only way is to neatly remove 5cm (approx) off the top of the stool and then the steel sphere will sit snugly in the stand with no gaps.

That's the way to go, I don't like the drainage pipe idea, so if you can remove the top piece where it straightens up it would look great, as to the bottom doing the same, i'd probably go with that as well.

antonio66 wrote: ↑Wed Jan 26, 2022 2:15 am That's the way to go, I don't like the drainage pipe idea, so if you can remove the top piece where it straightens up it would look great, as to the bottom doing the same, i'd probably go with that as well.

+1 for this.