Hi guys

I want to get my speakers off my desk and put them on stands behind it.

At the moment i have IsoAcoustic desk stands.

Im wondering can i get some cheap floor stands and put the iso acoustic stands on top of them?

Any recommended brands?

I'm about to publish a test of loudspeaker isolation products, and so far I'm not convinced that speaker stand quality matters much if at all. What does matters is where you put the speakers!

--Ethan

The Acoustic Treatment Experts

Is this your "2016 Ethan Winer Make GS Blow Up" thread of the year?

Yes!

This should be interesting. I wonder if @ Northward as ever tested something like this.

The key to speaker stands is that they don't resonate sympathetically. This is what your ISO acoustic stands are trying to mitigate, through the use of physical decoupling. Essentially 'floating' the speaker in theory.

Your cheapest most effective way out is to grab some cinder blocks, or solid concrete blocks from the home improvement store. Cover them with a draped farbic, and your done.

Your stances are always interesting Ethan. I can see from a decoupling pint of veiw if there was a 'perfect' ISO mount where stands wouldn't matter.

What I'll be curious to see is how stands don't play a difference when acoustic power is the cause of resonance. Wouldn't a solid stand vs a hollow stand resonate/interact differently under very high spls/low frequencies, if all other things were equal, and the speakers were floating in free space?

Is it simply that the resonance would be negligeable in proportion to the loud spls?

Would this be the same concept even if the stands and speakers were coupled? For instance a bass wave traveling through the floor? Would the stands interaction just be simply negligeable?

Is there a point of finishing return, where the stand matters more or less? I'm thinking particularly at moderate db levels, where my 'onstage hands' speaker stands rattled with certian notes, because they were both hollow and 2-piece.

Just wondering.

Reason for placing spkrs behind the desk is better Frequency Response. (Of course measure to verify that)

Like Kyle said...Concrete blocks is probably the cheapest foundation.
No resonance... (And heavy too= good)

Place your iso stands on top of these. Done

Almost as cheap is to find some used columns intended to be plant stands, some of which are in marble. Years ago in Paris these were widely available in some used furniture shops, but then apparently some people caught on to the cheap source of marble and they disappeared. So maybe something new and not in marble like this (but I only found this via a quick search and you could do better on the cost):19" Greek Roman Arch Column Home Garden Decor Pedestal AOH Studio | eBay

Yes indeed!

ISO stands are pretty inefficient - as are the Auralex foam pads or "Recoil Stabilizers". In particular in the low frequencies. They do some very marginal work in the mids. ISO have a very high natural frequency with barely any deflection, so basically no decoupling characteristics, just basic damping. Pads and Recoil stabilizers are purely damping and have the disadvantage to allow too much speaker cabinet movement. So create a lot more issues than they solve.

Standards stands are plain okay as long as they don't resonate (metal ones in particular are no good in that area) are structurally sound (multiple legs) and some form of damping is added to them: leg cavities filled with rockwool.

Adding 5 to 6 balls of blu-tack in-between the speakers and stands has proven to be just as effective at damping the plate resonance as anything from ISO or any type of pad.

In all cases, biggest and often only differences measured with ISO, Recoil etc are because height of the speakers is modified by inserting the products in-between the speaker and the stand. Keeping the same sweet-spot height, Early Reflections on desks and nearby equipment are shifting in frequency which creates an audible difference in the midrange.

But it is a difference, not an improvement.

We're working on speaker stands that effectively decouple to a very low natural frequency - based on our in-wall and in-glass decoupling systems - but the issues we are running into are weight per unit (they're crazy heavy) and the dangerous kind of tensions we have in the dummy loading system with up to 50kg / 0.5kN / 110lbs per top springs (4 to 6 units) and... 150kg / 1.5kN / 330lbs for the dummy load spring + Sylomer (1 to 2 units).

Should one of these snap in someone's face while tuning the system, we're in trouble.

Currently working on solutions to make sure they are safe to use. But clearly, it's not going to be a lightweight system. A lightweight, low tension / low pressure system simply cannot work. So don't fall for it.

Low budget: go for Blu-tack and DIY damping!

Thomas, at about what frequencies do simple isolators become "completely useless"? My mains are crossed over at 80 Hz, 24 dB per octave.

At that lower bound, would foam, bluetac or sorbothane be useful at all to minimize multipath radiation of sound via induced vibration in the speaker shelf? The shelf isn't ultra-heavy-duty, but OTOH the 3" thick wood is not exactly light/flimsy either.

If it were not already built and installed, maybe I would have planned some better speaker mounting method.

Thanks

You'll have to wait for my complete report, which I'm hard at work on every day. In the mean time, here's one way to look at this:

Sound is created when a surface vibrates. The more displacement, and the larger the surface, the louder the sound. A typical home studio near field monitor has a speaker cone between 6 and 8 inches in diameter, and that cone can move at least 1/4 inch. Now, compare that with the displacement and surface area of the speaker cabinet, and again for the stand the speaker rests on. Even if a speaker sits on a table with no isolation and the entire table top vibrates in sympathy, what portion of an inch do you think is the table surface displacement?

--Ethan

How bout a 15"-18" subwoofer that has a potential throw of 2"-3". I'm sure studio's mixing movie soundtracks would have to pay close attention to that.

I've been using Blu-tack and was thinking of getting some sorbothane pads.
So do you think there won't be much difference?

All I say is Isoacoustics.. :-)

i though the isoacoustics stuff was to stop a desk or something vibrating whilst the speakers were on it? In hifi land there seems to be non-consensus between the value of squishy mounts (blutac/squashballs, isoacoustics) and hard tiny surface area mounts (spikes, marbles etc). I don't know anything. I have isoacoustics, but the main benefit seems to be height/angling which is very convenient.

Simple Isolators are always useless at decoupling - if not counter productive - and are marginally efficient at damping.

Foam: no decoupling, just surface damping in the higher midrange and too much cabinet oscillations.
Blu-Tack: no decoupling, only some limited surface damping in the higher midrange.
Iso Acoustics: no decoupling, only some limited surface damping in the higher midrange.

If you look at the ISO website, you'll see there is not once the mention of a natural frequency for the system (decoupling) or simple damping performance. The data they posted is:

"Laser Vibrometer Testing

Conducted by the National Research Council in Ottawa, Canada

Illustrated and quantified the attenuation of vibrations down through the speaker stand structure.

(3 photos)

These graphics illustrate 75hz tests on 3 separate stand configurations, with an amplitude of up to 314µ m/s on the front plane of the speaker enclosure."

This is absolutely meaningless. They don't actually provide the slightest clue as to actual performance of the system.

I spoke to them at an AES convention, and they had no idea what I meant by Natural Frequency.

The Auralex and Primacoustics stuff falls in the same category, but at least there is much less pretention in how they present their products.

Sorbothane: can be very efficient if the right type for the load is used. Best is to add a dummy load (heavy blue stone) under the speaker to add mass to the system that needs decoupling and to be able to use stiffer Sorbothane pads to avoid unwanted cabinet movements at higher SPL. You also must pay attention to loading of the Sorbothane since speakers are usually front heavy. Calculating load spreading is a must, unless the weight of the added dummy load is many times fold the one of the speakers at which point the difference becomes negligible.

A key to having all this work well is to also make sure the surface the speakers decouplers are resting on is as stiff as possible - otherwise it will disrupt the behaviour of the system: for example the spring will 'push' downward on a flexible surface when excited, hence the surface will start to bounce too instead of only the spring flexing as intended.

Sylomer and springs + dampers remain by far the best products to use but need fairly heavy loads. With properly implemented systems, you can have a natural frequency as low as 8Hz with Sylomer and 4Hz with springs + dampers, decoupling effectively way below 20Hz.

I can hear a huge difference when having my speakers on isoacoustics, specially now my room is treated properly. The mids and highs are much more present.

Add some Sorbothane under your speaker and you here an even better improvement.

I have tried quite a lot of things, but the combination of both is the best so far.

trying to visualise what you mean... four little squares of sorbothane between the speaker and the four 'suction cups' on the top of the isoacoustics frame?

Yep, exactly that.

I thought mine are 4x2", perfect for my Dynaudio's (depends on kg's)

They are not square though but half sphere with the flat side on the isoacoustics.

oh, domes?... something like this?:

50mm Sorbothane Hemispheres Black Pack of 4: Amazon.co.uk: Electronics

Yep, those are the ones. I got mine from ebay from the UK. I bought eight for 22 euro (with shipping).. (18 pounds?)

Check them on ebay before you buy from Amazon and don't forget the check the weight of your speakers to see how many inch you need.

Edit: Here are the ones I have; http://www.ebay.co.uk/itm/4-x-SORBOT...YAAOxycD9TWUJj

There's a weight table in the description so check that out. ;-)

I tried Isoacoustics on my heavy speaker stands with the Geithain RL906 (coaxial). To compensate for the difference in height, I put the speakers on their sides when on the Isoacoustics. No difference at all.
On the other hand they seem to do very positive things when used on a table. Though I am not sure if it is again only the difference in height that helps with the desk reflections. I think they are not homeopathic, but they do less then what they claim to do.

Using mine on the desk and there's really a big noticeable difference.

One friend came over 3 weeks ago and I showed these. At first I just placed them on the desk without the isoacoustics and then with the isoacoustics + sorbo, his mouth fell open on how different it sounds.

Got no clue how it works, but it does it job, so I'm happy to have bought them.

And now exchange one of them with a book pile and rereport, please!

Funny you said that, cause that's what I used previously to get more height and yes, still a big difference. :-)

I thought the same and am going to try this when my new 'fork type' stands for the RL903K arrive. I hope they (the speakers are bolted to the stands) will load the weakest Sylomer (0,011 N/mm2) correctly, but as I do not have the stands yet, I don't know the total load per mm2 yet. Thanks for your confirmation!

Thanks Thomas for the explanations. After I finally get around to building the cabs for the new coax monitors, guess sorbothane will be as good as its gonna get for now, even if only modestly effective.

Have wondered if maybe a stack of dissimilar-property absorbing materials would have any benefit, but if that were the case most likely someone would have products on the market already. One layer in the stack having a different time-constant than the next layer in the stack, or whatever.

So if IsoAcoustics are not efficient in decoupling a speaker, talking about heavy ones, which lowbudget/DIY solution would you suggest for ATC SCM 150 decoupling? Sound Anchors with properly calculated sorbothane pads or cinder blocks with properly calculated Sylomer pads? Are the Sound Anchors' supporting arms stiff enough to work well with the pads?

It just depends on the design goal. There are many different ways to decouple one speaker, some of them may be inefficient based on how the amount of material versus gain goes. Springs are expensive compared to rubber, and for only a measly 4hz gain? (fairly stated as double performance though) And how does having two or more spring layers improve anything? When you analyze the tradeoffs involved, you'll realize it gets complicated fast.