Speaker De-coupling

[dasdoing]

put a glass of water on you speakers and play them loud. if the water doesn´t move, there is nothing to absorb

 

[MattHooper]

I don't doubt they do a lot for turntables,
but, as Ethan explained, speakers don't even vibrate enough to cause issues. else he would have found significant diferences even with the might be inferior stuff

Yes I can see that point.

On the other hand, at least my speakers are clearly moving enough that, during loud or bass heavy music, I can easily feel the floor vibrations under my feet or if I put my hand down on the floor near the speakers. When I put the springs underneath, the vibration of the floor effectively stops.

 

[dasdoing]

Yes I can see that point.

On the other hand, at least my speakers are clearly moving enough that, during loud or bass heavy music, I can easily feel the floor vibrations under my feet or if I put my hand down on the floor near the speakers. When I put the springs underneath, the vibration of the floor effectively stops.

I just hope it is no placebo effect. but I give you the benefit of doubt

 

[kyle_neuron]

Yes I can see that point.

On the other hand, at least my speakers are clearly moving enough that, during loud or bass heavy music, I can easily feel the floor vibrations under my feet or if I put my hand down on the floor near the speakers. When I put the springs underneath, the vibration of the floor effectively stops.

Have you considered that by spacing the speakers off the floor, you’re creating a Helmholtz resonator between the acoustic centre and the wall(s)? Depending on distances involved, this could account for a cancellation that ‘cleans up’ the VLF response enough to avoid excitation of surfaces.

It would be interesting to compare the ‘decoupling’ methods out there at equal placement and positioning to determine the contribution of this effect on the acoustic impedance versus the dampening of energy transference.

I’ll add this to my list of ‘would be nice to study if I didn’t have 8 million other things to do first’

 

[f1shb0n3]

I love my IsoAcoustics speaker stands for bookshelf speakers on my desk - look awesome and does isolate vibrations for loud bass-heavy music. Objectivists can be extremists too - for example Ethan is measuring frequency response and shows no difference, but that's not the whole point - if you measure vibrations at the surface below you will definitely find a meaningful measurable difference.

 

[MattHooper]

Have you considered that by spacing the speakers off the floor, you’re creating a Helmholtz resonator between the acoustic centre and the wall(s)? Depending on distances involved, this could account for a cancellation that ‘cleans up’ the VLF response enough to avoid excitation of surfaces.

It would be interesting to compare the ‘decoupling’ methods out there at equal placement and positioning to determine the contribution of this effect on the acoustic impedance versus the dampening of energy transference.

I’ll add this to my list of ‘would be nice to study if I didn’t have 8 million other things to do first’

Yes, I've mentioned before that simply raising the speakers higher could be contributing to the effect. And as I mentioned earlier too, I'll be trying out the Townshend isolation bars, which will allow me to try the speakers with and without the spring isolation, while maintaining the same height.

 

[Thomas_A]

I don't doubt they do a lot for turntables,
but, as Ethan explained, speakers don't even vibrate enough to cause issues. else he would have found significant diferences even with the might be inferior stuff

Well then I proved that Ethans claim was wrong. That speakers can vibrate and that hard coupling may transmit vibrations to the support and give rise to distortion is no news, known for many years. However, there is also no news that in most cases, there will be no or only very small differences regarding distortion.

 

[Thomas_A]

speaker isolation is a basicly a huge ocean of snakeoil http://ethanwiner.com/speaker_isolation.htm

I would say that the so-called "spikes" and "cones" that came to the market 30-40 years ago, claiming the benefits of a speaker being more secured and fixed during playing, were the biggest snake-oil. Not only were these companies wrong about that in theory, but they also caused potentials to increase distortion by transmitting vibrations.

 

[dasdoing]

Yes, I've mentioned before that simply raising the speakers higher could be contributing to the effect. And as I mentioned earlier too, I'll be trying out the Townshend isolation bars, which will allow me to try the speakers with and without the spring isolation, while maintaining the same height.

Well then I proved that Ethans claim was wrong. That speakers can vibrate and that hard coupling may transmit vibrations to the support and give rise to distortion is no news, known for many years. However, there is also no news that in most cases, there will be no or only very small differences regarding distortion.

I would conclude this way: when there is vibration it is caused by the soundwave. if you make the distance of the woofer to the vibrating surface bigger, there is less energy hitting it.
If you think about it: if the cabinat vibrates enough to transmit vibrations, the loudest thing you would hear is it's own resonant frequencies. and that is the reason good cabinats wont realy vibrate

 

[Thomas_A]

I would conclude this way: when there is vibration it is caused by the soundwave. if you make the distance of the woofer to the vibrating surface bigger, there is less energy hitting it.
If you think about it: if the cabinat vibrates enough to transmit vibrations, the loudest thing you would hear is it's own resonant frequencies. and that is the reason good cabinats wont realy vibrate

Again, see my measurements. The distortion in the 800-1000 Hz and 2000 Hz regions are not from the driver or cabinet. These are sufficiently high i level to colour the sound of the ≈130 Hz signal that is feeding the loudspeaker.

 

[Purité Audio]

Yes I can see that point.

On the other hand, at least my speakers are clearly moving enough that, during loud or bass heavy music, I can easily feel the floor vibrations under my feet or if I put my hand down on the floor near the speakers. When I put the springs underneath, the vibration of the floor effectively stops.

Remember structural borne and air borne , good for turntables but you still have to deal with air borne of course most effective to remove TT from the room, if objects are resonating in the room then stick them down.
Keith

 

[dasdoing]

A case with coupling vs. decoupling.

you mean this messurement?
how is it possible the decoupling solved comb-filtering issues between 700-2000Hz? it doesn't seam to be a before/after of only decoupling

 

[Thomas_A]

you mean this messurement?
how is it possible the decoupling solved comb-filtering issues between 700-2000Hz? it doesn't seam to be a before/after of only decoupling

It is distortion from a vibrating support where the speaker is situated, not comb-filtering.

 

[dasdoing]

It is distortion from a vibrating support where the speaker is situated, not comb-filtering.

there are a series of cancelations happening in the before

 

[Thomas_A]

there are a series of cancelations happening in the before

I don't understand the issue. There are excitations of resonances in the support when the speaker is coupled to the support (here by three metal bars in a tripod). These are related to the resonant character of the support which is excited when suitable frequencies are transferred.

 

[dasdoing]

I don't understand the issue. There are excitations of resonances in the support when the speaker is coupled to the support (here by three metal bars in a tripod). These are related to the resonant character of the support which is excited when suitable frequencies are transferred.

we are just trying to find out what happend, right?

that tripod was removed in the after?
If so, looking from the above it was visable?

 

[Thomas_A]

we are just trying to find out what happend, right?

that tripod was removed in the after?
If so, looking from the above it was visable?

Ok, understand.

Speaker on a bench with three metal bars between speaker and support (hard coupling) vs. the same speaker at the same position with isolating pads (Sonic Design). Not visible from above. Speaker is a small monitor with cabinet built with constrained layer damping (9 mm MDF-Swedac DGA2 glue - 9 mm MDF).

Microphone measured a sweep from the speaker; at 125-130 Hz there is an audible distortion happening with hard coupling. Analysis shows distortion components in the 700-2000 Hz range when hitting around 130 Hz.

 

[dasdoing]

Ok, understand.

Speaker on a bench with three metal bars between speaker and support (hard coupling) vs. the same speaker at the same position with isolating pads (Sonic Design). Not visible from above. Speaker is a small monitor with cabinet built with constrained layer damping (9 mm MDF-Swedac DGA2 glue - 9 mm MDF).

Microphone measured a sweep from the speaker; at 125-130 Hz there is an audible distortion happening with hard coupling. Analysis shows distortion components in the 700-2000 Hz range when hitting around 130 Hz.

ooh; the graph shows a single sine at 130Hz. now I understand.
well, I belive you that you can hear the diference with the sine tone, but hearing the diference in a masking context is questionable. that distorsion is what, minus 50dBFS?

 

[Thomas_A]

ooh; the graph shows a single sine at 130Hz. now I understand.
well, I belive you that you can hear the diference with the sine tone, but hearing the diference in a masking context is questionable. that distorsion is what, minus 50dBFS?

Sure, masking is a factor. But high order distortion components that are way off the harmonics of a tone are much more audible.

And the point being, why risk to introduce putative distortion components in the chain by using spikes and such on hard floors when you can just put the speaker on a carpet or soft pads for peanut money?

 

[MattHooper]

Remember structural borne and air borne , good for turntables but you still have to deal with air borne of course most effective to remove TT from the room, if objects are resonating in the room then stick them down.
Keith

Thanks Keith.

As it happens, my turntable, along with my amplifiers and source gear, are actually in a separate room from my listening room (down the hall a little bit). Originally I wondered if this would be unworkable for using a turntable, after all it makes sense ergonomically to have it in the listening room.

But it turned out just fine. I've found that when I lower the arm, by the time the music actually starts playing I'm usually in my seat. It would be essentially the same if the turntable where in the room as I'd have to get up and down when I wanted to change LPs or tracks. So it's been no hassle at all, and some peace of mind in terms of air-born resonances from the speakers.

(Though someone, I forget on this website or another, measured the feedback effect on the signal with turntables from the speakers, and said it can slightly alter the sound in a way some people like).