Hey guys, I was wondering if there is any point in isolating the speaker from the stand in addition to isolating the stand from the floor?
My logic says that if the speaker is isolated from the stand then, there are no vibrations to go to the floor.

Any advice?

Also I hear that 30 duro is reccomended for isolation feet but most audio shops sell 50 duro- does this matter much, how critical is the difference?

many thanks

Just look up the weight of your speaker and chose a hemisphere which has 1/4 of that weight nicely in the middle of it's load spec.
Isolating the stand from the floor is another issue. No need if the top iso is working fine, no harm in any case.

DD

Thanks Dan Dan, much appreciated !

I'm gonna throw another curve ball in there and say what if i use one set of speakers as stands for the other, should I just isolate te ones sitting on the floor instead ?

Basically I want to use floor standing speakers to gauge low end and smaller references that sit approx ear level on top.

Another slightly related question.
I want to build a gobo type enclosure for my vocalist/ musician a bit like real traps quiet zone. However I'm not sure how deep to make them.
I'd like extra soundproofing so my neighbours hear less vocals but I'm concerned about making the vocal area too dead

Any advice?

Cheers

Hard to know with speakers on top of each other. I don't think the floor standers will take much notice of the ones on top unless they are big. Might even be helpful. I would isolate the big ones from the floor though.

Vocal areas cannot be too dead IMO. The singer can have whatever room they want to sing in, fed into the cans.
So the deeper the fibre the better to get a clear pure vocal. Don't expect the volume to drop though. You need the cone of silence for that.....



DD

I build strong and heavy stands, sand filled, heavier than speaker, then floating platform on the top of it. This way I minimize translating vibrations to the floor, and dampen their (stands) own resonances/vibrations too...
Look here (click on image if you want more):




Of course!
It is dependent also on the size of the cross section of the particular vibration damping element, not only on material hardness...

Interesting looking device!

During building my 8 inch deep traps I recognized everything became muffled when I stood behind it, so that is what I was referring to in regards to extra isolation for the vocalist- but it is not sealed so I guess it might not be a significant reduction.

I was also worried that if I surround the vocalist with thick material their vocals may become 'muddy' ? or would the fact that they'll be in an open room negate that?

The ones I was looking at have a diameter of 40mm & can take a load of 16-33kg if I use 5 hemispheres- which I would need as my floor speakers are 18kg each and the references are 8kg each

Those stands are epic!
I took a look through your facebook build pics- It looks awesome, very impressive!

Strangely the opposite happens. Blocking and absorbing early reflections removes all the HF destructive cancellations caused by nearby boundaries. This leads to an unhindered path from mouth to mic, resulting in great clarity, not muffling.

The same happens from speaker to ear in treated rooms. The sound can easily be way brighter than we expect or are used to.

DD

I just rigged up a new desktop stand for my DAW, so I can clear the floor for moving into a bigger room. It uses 3 levels of sorbothane, one between the speaker and the glass brick it sits on, another between that one glass brick and two glass bricks below that, and the third at the bottom of it all to seat on the desk. I am using 70 duro for the first two layers because the speaker is secured to all the bricks with tie-down straps, so I wanted it to handle the extra deflection. I will try to use 30 duro on the bottom but it may be too soft for the entire apparatus.

Sounds logical now that you say it!

I really like your speaker stands!

Very nice photo BTW!

Best

Ake

PS I'll guess the speaker box (alone) is heavy enough to give the needed deflection of the isolators...

Opus, how do you predict/ measure the isolation when you have 3 springs in the resonant system? Just curious…

/ Ake

I didn't, just listened mostly.
Sorbothane has some specs for 30/50/70 duro on their website, with proper deflection and an impulse response measurement. Key thing was just to prevent it from rattling the desk, which is mainly midrange energy that the sorbo takes care of easily.
I liked building it because the only material work I had to do was cut the rubber down, then it was just assembly.

Thank you!
It is not that way... (EDIT: dampers are below speaker platform, above heavy stands, so stands aren't heavy to make speakers heavier, but to make support of "floating" platform and speaker, above them, more closer to the theoretical assumptions)
Mobile(!) stand need to be heavy (heavier than speaker) if we like our vibration dampers to work as expected, because, theoretically, they are always connected to infinitely heavy surface, and all formulas (and vibration dampers manufacturer's suggestions) works this way.

If stands are light (many of them definitely are light, and even lighter than speaker).... formula doesn't work as expected, because we got a system with two (definitely) finite masses tied with one spring... and this is not our starting formula, this is a totally different problem with a different solution, which is not easily predictable without serious analysis.

See attached illustration....

And also it is always needed to remember that the purpose of vibration dampers is prevention of vibration transmission to the supporting surface of stands, which also has a finite mass (contrary to the assumption from the very beginning! The concrete slab is heavy, but not infinite), we still need at least controllable resonant frequency of the whole system if we like that attached stand mass between supporting surface and loudspeaker can't mess up our (simple) formula.

Thanks a lot Boggy for your detailed tutorial !
Makes perfect sense...

Best

Ake

Nice work on the stands Boggy! Did you use hemispheres or a different sorbothane product?

Thank you!
I use stud mounts (not hemispheres) built from natural rubber.
Sorbothane is not easy to import here.