Speaker Stands - Couple or Decouple

[CnoEvil]

This was linked to in another forum and thought it might be of interest as it includes measurements:

http://www.stereophile.com/features/806/index.html

 

[nopiano]

Fascinating, Cno, thanks for posting the link. I used to enjoy JA's writing when he was HiFi News editor, which was of course before he crossed the pond to the US.

He handed over my prize of Celestion SL600s after one of the Heathrow shows in the mid-80s. He was quite a fan of that series I recall, and interesting that he used a derivative in these tests. I'm bound to conclude that those of us who have been long-time blutak users are probably not wrong!

Hope you are keeping well, btw.

 

[Vladimir]

Thanks for sharing it, this is my first read despite its age. What I was missing in the comparison is mounting the speakers on stands firmly with screws.

 

[Overdose]

The results simply show how the resonant frequencies and the amplitude of the box changes with regard to how it is mounted and what it is mounted on. This should be of no suprise, as everything resonates at some frequency or another and changes to the mass and rigidity of the object affect this to a greater or lesser degree.

What is not determined (and is highly unlikely anyway) is if there was any audible effect of the change of the resonance. In fact the conclusion/summary specifically states that it moves into 'conjecture' when hypothesising that the changes may be audible.

If it was truly audible, it would be possible to measure and therefore state with some authority, that these changes in speaker mounting actually had a tangible effect on the sound quality.

Nothing to see here I'm affraid, another non issue that some manufacturers will tell you needs a solution.

Speaker cabinet resonance is only something that needs to be taken care of in the design of the speaker. Once this has been done, fret no more.

 

[ChrisIRL]

I place my Kef LS50s using the rubber feet supplied with them directly on Concept 20 stands, which have a "gelcore" top plate. Works very well, the LS50's and the concept 20 stands are as if made for eachother. Perfect fit and both finished in gloss black for a good visual match too.

 

[CnoEvil]

Fascinating, Cno, thanks for posting the link. I used to enjoy JA's writing when he was HiFi News editor, which was of course before he crossed the pond to the US.

He handed over my prize of Celestion SL600s after one of the Heathrow shows in the mid-80s. He was quite a fan of that series I recall, and interesting that he used a derivative in these tests. I'm bound to conclude that those of us who have been long-time blutak users are probably not wrong!

Hope you are keeping well, btw.

Thank you for asking...

I'm the best I've been for many years, since getting the back op 2 years ago. It has been a long road, but all the work in the gym is paying off. Have played Golf for the first time in 3 years and am planning to go skiing again after a 4 year gap.

 

[nopiano]

Fascinating, Cno, thanks for posting the link. I used to enjoy JA's writing when he was HiFi News editor, which was of course before he crossed the pond to the US.

He handed over my prize of Celestion SL600s after one of the Heathrow shows in the mid-80s. He was quite a fan of that series I recall, and interesting that he used a derivative in these tests. I'm bound to conclude that those of us who have been long-time blutak users are probably not wrong!

Hope you are keeping well, btw.

Thank you for asking...

I'm the best I've been for many years, since getting the back op 2 years ago. It has been a long road, but all the work in the gym is paying off. Have played Golf for the first time in 3 years and am planning to go skiing again after a 4 year gap.

Delighted to read that, Cno. Hats off to you for sticking at it. And hope no more power cuts...!

 

[Jota180]

Thanks for the linky!

In my case my old, very old, Nexus 6 stands were wobbly (front to back) and nothing I did like tightening screws etc had much of an impact. I was having an issue with the bass on my LS50's on certain tracks at louder volumes. The bass would lose focus and merge into one long droning sound. I took a chance on it being the stands and bought a different set which, when put together, were so solid you could build bloody bridges out of them! Anyhow, no more bass issues for me.

I use the supplied feet from KEF on blutack.

 

[CnoEvil]

Thanks for the linky!

In my case my old, very old, Nexus 6 stands were wobbly (front to back) and nothing I did like tightening screws etc had much of an impact. I was having an issue with the bass on my LS50's on certain tracks at louder volumes. The bass would lose focus and merge into one long droning sound. I took a chance on it being the stands and bought a different set which, when put together, were so solid you could build bloody bridges out of them! Anyhow, no more bass issues for me.

I use the supplied feet from KEF on blutack.

If you don't mind me asking, what stands did you buy - did you fill them; if so, how far and with what?

IME Stands can make or break the LS50s with regards to their bass.

 

[iceman16]

Im also using blutak bet. ls50 and top plate of atacama nexus 7i filled with atabytes about 80 percent in the center tube.

 

[unsleepable]

Same here—Atacama 7i filled with one bucket of Atabites.

To get the best sound, I played quite a bit with their placement, the spikes, floor shoes, etc. At the end, I got the best sound by buying a rug, putting the spikes on, not using floor shoes, and letting the spikes cross the rug and rest on the floor beneath. I've checked and it's leaving marks on the wooden floor—damn, I'll have to pay for that when I leave this place, but it really makes a difference versus not using the spikes, using the shoes or not letting the spikes go all the way down.

I haven't tried with rubber shoes, though. That's something pending to do.

The Atacama are solid, but not as very solid as I would really like. I've checked Dynaudio stands and I had the feeling that they were more solid than my Atacama 7i.

 

[Vladimir]

I used silicon pads, bluetack and felt pads. Best solution ever was screwing the speakers tightly to the stands. Anchoring gave best result in deminishing cabinet resonance and general loss of efficiency due to speakers wasting energy to move back and forward slightly.

Second best thing was the bluetack.

 

[unsleepable]

I used silicon pads, bluetack and felt pads. Best solution ever was screwing the speakers tightly to the stands. Anchoring gave best result in deminishing cabinet resonance and general loss of efficiency due to speakers wasting energy to move back and forward slightly.

Second best thing was the bluetack.

I think it's a very good thing that the CM-1 come with nuts so that they can be screwed to the stands. I use the Atacama gel pads that came with the stands—don't know if I should give blu-tack a go.

Do you use spikes? Or are the screws enough to make the speakers stand solidly on the stands?

 

[Vladimir]

I think it's a very good thing that the CM-1 come with nuts so that they can be screwed to the stands. I use the Atacama gel pads that came with the stands—don't know if I should give blu-tack a go.

Do you use spikes? Or are the screws enough to make the speakers stand solidly on the stands?

I use the factory spikes that come with the FS-700/CM. Those I added because the stands are over thick carpets and because I'm 188cm tall and needed to get tweeter axis closer to ear height. By adding spikes, you are effectively making all the speaker+stand mass to be pushed in 4 small points, increasing kg/mm. The effect is better coupling of the stand to the ground, just like a football player or mountain climber using crampons to grip to the wet and slippery surface. You can use spikes between the speaker and the stand as very effective coupling if you can't use machine screws.

I also filled the pillars with sand and that reduced the vibration through the hollow aluminium profiles. I simply filled one stand with sand and used my hand to test how much it resonates compared to the empty stand. The results were very good so I have them both filled. The stand bottom base is cast iron and has no issues.

You can do the water glass test or use your hand, try the silicon gel pads (half-domes) and then try bluetack. There are differences.

When you have the speaker on the gel pads you can grab it with your hand and shake it a bit, it will wiggle a bit. That means the whole cabinet will move very slightly while playing strong bass passages. This will create high and mid frequency time and resolution smearing, which effectively sounded warmer and with greater imaging to my ears. It will also make the speakers less loud because they are using some of the energy to move the cabinets, which results with drop of speaker efficiency, to me quite audible.

The bluetack on the other hand grips the cabinet to the base and you can't wiggle it that much, meaning it gives better coupling to the stand, speaker+stand act more as one body with greater mass than those separated inidvidualy. The better the friction, the better the coupling, higher the mass, less ability for the woofer to push the cabinet, better pistonic work of the drivers. Same effect (even greater) with spikes between the speaker and the stand top plate. Pushing more mass on smaller surface. Try to wiggle the speaker cabinet and at best you will just scratch the top plat of the stand. The cabinets will not wiggle like on gel pads.

With machine screws we get the best coupling possible simply because speaker and stand are one body. The woofer has to move the mass of the cabinet + the stand with sand + the house floor + the house + the planet. *smile* Not gonna happen Mr. It's forced to move in straight pistonic manner back and forward.

Decoupling is useful when you have a hi-fi rack which vibrates from the speakers playing in the room. You need to decouple it from the floor because the coupled speakers transfer the vibration to the floor. The speaker will also shake the rack through the air, so you need to decouple each hi-fi separate from the rack. I've put CD players and turntables in large pans full of sand as decoupling.

Decoupling = Isolation. Coupling = Joining mass.

If you have very big speakers that simply remain planted despite woofer pushing thunderous bass, you may decide to decouple them and not bother decoupling the whole hi-fi rack, just each separate component.

It's all basic physics, Newton's laws of motion.

Some audiophiles "tune" the sound by selectively coupling and decoupling, filling the stands half way with sand etc. They want the appealing time and smear and added imaging, but as a spice, not the main course. You will often read advice how you shouldn't fill the stands too much or with higher damping compound because "that will kill the sound". Also some audiophiles have their systems badly set, clipping from with too loud and exciting sound, introducing higher order harmonic distortion, so they prefer a smeared speaker setup to battle the brightness and harshness.

What I'm hinting at is, reducing vibration in your speaker and stand is always a good thing. If it reveals some nasties, look for solutions elsewhere in the system. You don't cure Ghonorea by killing the patient with Ebola.

I came to realisation of this through heavy experimentation (had great fun) and by cheating because I read this article: Speaker Spikes and Cones – What’s the point?

 

[CnoEvil]

Another take on things:

http://www.zenn.com.sg/Speakerstands.htm

 

[unsleepable]

Thanks for that long reply! I'm thinking of changing speakers, and you have definitely raised a few very good points to look at when a new set comes. With new speakers I'll likely have to change also the stands due to height.

Today I was in an audio show and they had the new white LS50 with blue drivers, on top of white Dynaudio stands. Gorgeous thing to look at. And yes, these Dynaudio definitely felt more solid than my Atacama.

 

[CnoEvil]

Today I was in an audio show and they had the new white LS50 with blue drivers, on top of white Dynaudio stands. Gorgeous thing to look at. And yes, these Dynaudio definitely felt more solid than my Atacama.

Did you get a listen...and if so, what was the rest of the system.

White and Blue Eh!......very nice.

 

[unsleepable]

Very, very nice indeed.

Well, these white ones were not connected. But I asked and they said they are exactly like the regular ones, just in a different color.

They had another pair of regular LS50 connected to an Arcam A49, and I did listen to those. Well, I think an audio show it's hardly the place to draw conclusions regarding sound—unless you are looking for party equipment, that is. It was a full sound, midrange in its place, and while the bass did not go very deep it was extremely well defined. I couldn't say about the HF or the soundstage—again, it was an audio show with lots of other things playing around. But regarding those aspects I heard well, it's the best I've the heard the LS50 so far.

 

[CnoEvil]

Very, very nice indeed.

Well, these white ones were not connected. But I asked and they said they are exactly like the regular ones, just in a different color.

They had another pair of regular LS50 connected to an Arcam A49, and I did listen to those. Well, I think an audio show it's hardly the place to draw conclusions regarding sound—unless you are looking for party equipment, that is. It was a full sound, midrange in its place, and while the bass did not go very deep it was extremely well defined. I couldn't say about the HF or the soundstage—again, it was an audio show with lots of other things playing around. But regarding those aspects I heard well, it's the best I've the heard the LS50 so far.

I have the LS50s driven by the Class G AVR600, so I have an idea how they sounded....though the A49 should be a good step up.