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Custom Speaker stands


astrostar59
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Hi Guys

I got some horn speakers about 8 months back. They are floor standers, and naturally I sat them on the floor. But found they were slightly too low for my desk system. I thus raised them on ceramic house bricks to 20 cm off the floor, which worked ok but looked awful.

Anyway, I finally got around to replacing the bricks with custom black marble plinths. They look better but interestingly the bass now is less bloated and goes lower and jus more tuneful. Odly I think the imaging and treble are cleaner as well, I think I am not imagining that. Maybe the whole speaker being sat on a wobbly mount of fowl and bricks was not so hot?

It think the ceramic bricks were vibrating to some extent or / or the holes in them were interacting with the energy from the down firing 12 inch bass unit. I filled the leg cavities with expanding foam to remove and resonances, and fitted adhesive backed neoprene tape to the base of the legs, and epoxy glued the legs to the top plate. On top of the plate I used thin foam packing film, about 2 mm think. It has resulted in a super solid and movement / resonance free mount from speaker case to floor. Each plinth is about 50 kilos.

 

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Edited by astrostar59
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Thanks. Fortunately they sound better than the bricks. No way of knowing before if they would! Speakers might seem easier to use / set up than HPs but I think they are more complicated, as they interact with the room and furniture, the floor and the walls, standing wave. It is a bit of a hit and miss in a domestic situation. Lets face it, who wants egg boxes all over the walls? Well the miss's doesn't...

Playing loud today, reggae, trance material, the bass definitely is going deeper and is more tuneful. The bricks boosted the mid bass but drowned out the sub bass.

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Damn, son, those are both beautiful, the speakers and the stands.

I'm fully a believe in speaker stands, but not sure where I stand, in the 'decouple' camp, where the speakers are intended to be decoupled from the floor so that floor-borne vibrations don't transmit back to the speaker through conduction, or the other camp, where you start with the assumption the floor is the most inert thing, and ...couple?  Whatever the opposite of decouple is...the speakers to the floor.  It sounds like from what you say that the speaker stands are inert enough that you coupled your speakers to the stands.

Honestly, I would have them as forward on the stands as possible.  You know, edge effect.  It's less noticeable near the bass driver, so you may be fine, but I always want my drivers to be the most forward thing in the vicinity.

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1 hour ago, luvdunhill said:

I have never found a situation where coupling things together as in the picture sounds best. Spikes somewhere in the chain pointing at he ground, all the way.

I do have spikes for the speakers. But there is a whole debate about about whether spikes (being metal and hard) are the same as any other coupled method. I have no idea or a view on it. I may try the spikes to see what happens.

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4 hours ago, luvdunhill said:

I have never found a situation where coupling things together as in the picture sounds best. Spikes somewhere in the chain pointing at he ground, all the way.

Isn't that coupling?  Decoupling is blu-tak, cork, foam, or the like.  The idea being if there are any floor-borne vibrations, they stop at the decoupling.  Coupling is an entirely different school of thought, where you assume the earth is the most inert and try to keep as strong a coupling from there to the speakers to feed off that inertness.
Supposedly the best decoupling method (conducts the least vibration) is sand, but that would still require other parts (a rigid stand on top of the sand or something).

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4 hours ago, Dusty Chalk said:

Damn, son, those are both beautiful, the speakers and the stands.

I'm fully a believe in speaker stands, but not sure where I stand, in the 'decouple' camp, where the speakers are intended to be decoupled from the floor so that floor-borne vibrations don't transmit back to the speaker through conduction, or the other camp, where you start with the assumption the floor is the most inert thing, and ...couple?  

I have my speakers decoupled (granite slabs resting on sorbothane pads, then the speakers are on spikes on top of the slabs).  I've only lived in old houses with bouncy wooden floors, while owning these speakers, and decoupling substantially improves bass quality in that situation, and helps prevent bothering neighbors.  Without decoupling, these old trampoline floors vibrate horribly.

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1 minute ago, EdipisReks1 said:

I have my speakers decoupled (granite slabs resting on sorbothane pads, then the speakers are on spikes on top of the slabs).  I've only lived in old houses with bouncy wooden floors, while owning these speakers, and decoupling substantially improves bass quality in that situation, and helps prevent bothering neighbors.  Without decoupling, these old trampoline floors vibrate horribly.

Exactly, I think it's environment-specific.

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2 minutes ago, Dusty Chalk said:

Isn't that coupling?  Decoupling is blu-tak, cork, foam, or the like.  The idea being if there are any floor-borne vibrations, they stop at the decoupling.
Supposedly the best decoupling method (conducts the least vibration) is sand, but that would still require other parts (a rigid stand on top of the sand or something).

Decoupling is minimizing surface area between the components.  Spikes do that.  Blu-tack does the opposite; as a tacky material, it couples the speakers to whatever they are on.  Sand doesn't decouple, it dampens. 

Those Zingalis are beautiful, by the way.

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Just now, EdipisReks1 said:

Decoupling is minimizing surface area between the components.  Spikes do that.  Blu-tack does the opposite; as a tacky material, it couples the speakers to whatever they are on.  Sand doesn't decouple, it dampens. 

That wasn't my understanding -- a spike would couple the speaker to whatever the speaker was on (speaker stand, floor, or, in your case, granite slabs).  In your case, the decoupling occurs at the sorbothane pads.  Think of it as insulation.

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No worries, I have to admit, I never researched Blu-Tack, so was willing to be corrected, but it appears according to Stereophile that it dampens somewhat (Wikipedia cited this as a source, Blu-Tack is introduced on page 3):  link.  (I'll have to read the whole article later, seems interesting.)

I was just going on intuition -- the best vibration conductor is going to be solid (resonances may actually amplify vibrations at certain frequencies) -- anything that "gives" is going to dampen somewhat, and ... I can just imagine trying to listen "through" Blu-Tack -- it would probably be extremely muffled.  Hence I just assumed it was a dampener.

Now, you may still be right -- maybe a thin enough amount would act as a conductor by keeping the two surfaces "glued" together -- I.E. coupled, but then the answer would be to use more.  Or maybe at low frequencies it stops absorbing/dampening and starts acting like a conductor (all insulators would be frequency dependent, based on my research into soundproofing and sound insulation).  I think more research is warranted.

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Big subject. I also think spikes transmit vibration throughout the end of the spike. It makes sense, wide feet, sharp feet, it will still transmit the vibration as it is a solid object.

I have sorbethane tape under the marble feet, 5mm x 5mm around the full perimeter. I will try some more under the speaker bases, but not full perimeter. I think it I add too much it will increase the resistance to movements. Maybe 50% of the edge will work. I can't use blue-tac as it will compress under the weight (50 kilos). Cork squares may work.

I think the objective here is to 'decouple' the speaker vibrations to the supporting device and thus the floor. A concrete floor is good, but will I guess have a certain resonance albeit at a low frequency and low level. A wood floor is the absolute worst I would say.

Edited by astrostar59
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Yes, a spike reduces the contact area but will still transmit some vibration through the spike, like a drill effect. I would say it raises the frequency of the vibration transmitted so might be good on speakers, and less so on turntables? I am thinking I need some form of point or pad isolation, as at the moment the entire base is sat of 1 mm foam sheet, so too much contact. I will try rubber mats and cork pads and see what happens.

Anyone tried Herbies Feet?

http://herbiesaudiolab.net/spkrfeet.htm

Edited by astrostar59
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10 hours ago, EdipisReks1 said:

I have my speakers decoupled (granite slabs resting on sorbothane pads, then the speakers are on spikes on top of the slabs).  I've only lived in old houses with bouncy wooden floors, while owning these speakers, and decoupling substantially improves bass quality in that situation, and helps prevent bothering neighbors.  Without decoupling, these old trampoline floors vibrate horribly.

 

10 hours ago, Dusty Chalk said:

Exactly, I think it's environment-specific.

This is my opinion too. On a very rigid stone/concrete floor you can do what most pleases you, so it's quite likely that decoupling with spikes helps to drain speaker cabinet vibration onto the floor, which will absorb them and take them away from the speakers. On elastic vibrating floors like wooden floorboards, you need to avoid the own floor vibrations (or its resonances from the speakers' vibration) getting into the speakers and messing with the sounds they're producing. Jacob's approach is what I'd use.

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The whole vibration thing is interesting. Suppose you put a mass on something that is springy, and the other end is coupled to something rigid, like a floor. What is the resonance frequency? It is dead easy to calculate - if the spring compresses by delta x metres, the resonance frequency is (1/2pi) x root(g/delta x).  You do not need to know the mass and spring constant - just the deflection. So suppose the speaker compresses (say) sorbothane feet by 2mm, the resonant frequency is (1/2pi) x root(9.81/2E-3) = 11Hz. So at frequencies higher than 11Hz the speaker stays (vertically) stationary, and at frequencies lower than 11Hz, the speaker bounces up and down. Of course if it is actually sorbothane, there is high loss, so there is not a resonant peak, but the basic motion remains.

Of course it is more complex than that, because the cones have substantial mass, so there will be a tendency for the speakers to rock like a pendulum as well as the cones move back and forth. In this case it depends on where the C of G of the speakers lie, where the drivers are (particularly the bass driver), and how far apart the springy bits (sorbothane for example) are. That in general will be a low frequency, certainly lower than the vertical 11Hz. Try rocking the speaker and see what happens - probably 1 to 2Hz.

If you use spikes there is a gotcha. The spikes need to be very, very seriously locked in place. Because of the cone motion, particularly at low frequency, and tendency to pendulum rock, it the spikes are not locked absolutely solid, the speaker can rock on the spikes. Most easily diagnosed with swept sine. Got the badge on that one - testing a homebrew sub I wondered what the god awful noises were as I swept a sine wave - sounded like the worst sort of distortion. Loose spikes.

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Ooh this is getting more complex as does so many things in thus hobby Ha Ha.

I am wondering guys, if a composite of say rubber sandwich with cork inner would work best as the link provided by a post earlier. It is used in machine shops to remove as much vibration (vertical) and lateral movements as possible. If we have say rubber on it's own it will have a peak resonance of lets say 11hz, but the cork being harder will have a higher resonance of say 80hz. If bass energy tries to communicate with the floor under the speaker it will get killed at 2 different frequencies, 11hz say -50db in the rubber, then 80hz -50db in the cork. Voila! A simple cheap and effective vibration decoupling device.

To me, any fancy crazy money single material support will fail as it will HAVE to have a peak resonance at some frequency. Only the ones with multiple material types will negate those peaks IMO. I have no scientific data to back this up, only what I figured from various reading on this subject.

I am talking concrete / tiled solid floors for this type of support. I can see a wood floor may need max (ganite plates) and more to overcome the resonance of wood, and the void below that floor. My previous house had a suspended wooden floor and it was a boom box of the highest order. I could prove that as when the volume was turned up the worse it got. In that case is was not just vibration transmitted through the speaker cabinet, but also vibration in the air from the music, technically the whole floor became a live element.

Edited by astrostar59
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Ok, I had some rubber honey comb door mat in the house, so I cut a 4 hole section (about 6cm square) piece. It is around 3 cm thick with small nodule underneath, then a central hole and 4 columns of rubber at each corner. I placed 4 under the speaker base, one each corner.

I ran my 200hz to 10hz sine wave text and it transmits NO energy at all to the top panel of my marble stands, zero. At any frequency. So it is physically dead as regards vibrations.

Next a played a batch of well known dance tracks and reggae with tuneful bass line. The bass is very slightly lower in level than before, BUT is totally linear, i.e. goes much deeper and is more tuneful. There was a slight bass hump at maybe 100hz before possibly the loudspeaker case sending energy down into the plinth below. The other odd thing is the midrange has tightened up and the soundstage is more stable and 3D. I understand this as the speaker cabinet in now 'free' or 'floating' in space sonically.

If I touch the top of the speakers they wobble slightly then settle. They are I guess as floating as I can make them without using the bike inner tube technique?

I can't press down on the speakers and make then defend at all, so downward movement is not exaggerated.

This decoupling mount cost me zero dollars, and seems to do the trick. My speaker dealer recommended some isolation devices ranging from 800 - 3K USD. Ha Ha, no way.

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Edited by astrostar59
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They don't move at all in any direction even played very loud. After having ran with the cheap rubber door mat supports, I am convinced the 'float' method is best for a hard floor. If a wooden floor then a different approach would be require IMO, to further isolate the 'live' floor from the energy of both the cabinets and the sound waves itself, so a difficult task in my view.

Which makes me come full circle and the crazy array of high priced spikes, metal cones and cups, ball bearings, I am glad I seem to have not got sucked into that sector of the hobby TBH. 

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