Turntable Isolation - A Different Approach to a Sandbox

I once visited a man cave setup by a hard core audiophile. His turntable was sitting on top of a concret base that extended down below the floor below the house. The concrete base had no contact at all with the floor the speakers and the rest of his equipment was sitting on. I always thought that was a good way to isolate a turntable.
 
I do t think sand can absorb low frecuencies.
But high for sure does.
I prefer rubber (sorbothane) because absorb both pretty nice.
Does the bags need to be shaked once in a while?
AG.
 
I do t think sand can absorb low frecuencies.
But high for sure does.
I prefer rubber (sorbothane) because absorb both pretty nice.
Does the bags need to be shaked once in a while?
AG.

I'm pretty sure sand can absorb low frequencies. It sure absorbs centerfire rifle recoil. I wondered if the sand consolidated over time with vibration and humidity in boxes filled with sand. That would be a messy proposition to fix but it will take 5 minutes to fluff up the bags and re-level the top plate and TT. Side Note: I originally wanted to use the actual ice bags however I couldn't get all the air out (duh!) so my wife came to the rescue and made cloth bags to fit.

I agree for the most part. My only concern is whether the plate is fully damped, seeing as the bags of sand form an uneven support for it. In the old days, nails we're driven through the plate into the loose sand below. This was to ensure the plate was fully engaged in the sand, preventing any resonance anywhere on the plate.

That's the thinking anyway. Removing the top plate removes any possibility of resonance, and shows off the beautiful work in the bags at the same time.

I was concerned about this too. The top plate sitting on just a couple of points would leave a portion sort of floating. My solution was to make (well ask my wife to make!) the bags very uniform and so they'd lie flat with the ice bag closures. That way I'd get as much contact as possible. Before I set the top plate I gently tamped the bags with a board to get them as flat and the same height as possible. Took maybe 5 minutes. By design there will be a gap between bags because @marcmorin and I talked about eliminating interaction between the bags. I bet 75% of the top plate is in contact with a bag weighed down by the TT itself. Maybe not as good as nails but there are other benefits of the top plate just sitting on bags.
 
I'm pretty sure sand can absorb low frequencies. It sure absorbs centerfire rifle recoil. I wondered if the sand consolidated over time with vibration and humidity in boxes filled with sand. That would be a messy proposition to fix but it will take 5 minutes to fluff up the bags and re-level the top plate and TT. Side Note: I originally wanted to use the actual ice bags however I couldn't get all the air out (duh!) so my wife came to the rescue and made cloth bags to fit.



I was concerned about this too. The top plate sitting on just a couple of points would leave a portion sort of floating. My solution was to make (well ask my wife to make!) the bags very uniform and so they'd lie flat with the ice bag closures. That way I'd get as much contact as possible. Before I set the top plate I gently tamped the bags with a board to get them as flat and the same height as possible. Took maybe 5 minutes. By design there will be a gap between bags because @marcmorin and I talked about eliminating interaction between the bags. I bet 75% of the top plate is in contact with a bag weighed down by the TT itself. Maybe not as good as nails but there are other benefits of the top plate just sitting on bags.
Sand does not absorb any frequencies, energy can bot be created or destroyed ie it goes from one form to another for example a match goes from chemical energy to heat. A sandbox transforms some frequencies to other energies like heat but not all. Best solution is a frame with no wood just touching feet bolted to a brick or concrete wall.Any shelf will act like a speaker amplifying the sound ie more surface area picking up more energy. The walls are very big and so transmitted energy is small, like tapping a ships hull or a meal cup. If people have solid walls a skeleton frame and bolted to wall is the best solution as the frame wont pick up much.
Chris
 
I messed with turntable isolation for YEARS when I had various Technics tables (1200's, 1700, SL-D3) as I have wood floors. I tried everything from raquet ball halves to sorbothane to concrete pavers to bicycle inner tubes. A concrete paver was the best I came up with (18"x18"x2"). The better solution (and I'm gonna catch hell for this!) is a Pro-Ject table. I've had a RM 5.1 and now a Debut Carbon DC and it's immune to foot fall. I still have the paver under the Debut as it can't hurt. My two cents blast away.

I own 2 tables. My Music Hall 9.1. It is immune to footfalls. My Marc Morin modded AR XA. It is very susceptible to foot falls. I’ve tried everything I am willing to afford to correct it, but have only had marginal success. Hence, the AR is in my basement system where I have concrete floors.
 
I own 2 tables. My Music Hall 9.1. It is immune to footfalls. My Marc Morin modded AR XA. It is very susceptible to foot falls. I’ve tried everything I am willing to afford to correct it, but have only had marginal success. Hence, the AR is in my basement system where I have concrete floors.
susceptible to floor jounce, footfall is different. The two have been confused to be the same thing. floor jounce causes the table to slosh horizontally and vertically. It's multiplied by the height of the stand. Footfall is, as an example, bouncing a golf ball on a concrete floor. can you hear that? yes!!!!!!. why, because something is vibrating thus putting that mechanical vibration into acoustic vibration. Wearing hard soled shoes and walking down a marble hall, what you hear is footfall.
and then there's LFR. which every house suffers from regardless of construction.
What does Low Frequency mean?

All noise consists of pressure fluctuations in the air. For LFN these fluctuations occur between 20 and 160 times per second. Most everyday sounds fluctuate much faster than this (up to 16 thousand time per second), so the term ‘low frequency’ means that the fluctuations are relatively slow compared with other types of sound. Sounds in this frequency range would typically be heard as a low rumble. Sometimes there is also a sensation of vibration or pressure on the ears. The scientific way of writing the frequency range is 20Hz to 160Hz: -the abbreviation Hz is short for Hertz and means ‘cycles per second’.

How does LFN get into my home?

In the majority of cases where a sound source can be traced, it is ‘airborne’, meaning that it travels through the air as a sound wave and enters the dwelling through windows, roof, etc. In theory sound can also be ‘ground-borne’, meaning that it travels through the ground and is converted into sound in the dwelling, or is sensed as vibration. However, cases of ground-borne LFN seem to be very uncommon.

The nearest industrial site is a long way off. Could this be the source of the sound?

One of the characteristics of low frequency sound is that it can travel relatively long distances without much attenuation (reduction in level). It is not uncommon that a source is traced to a site several kilometres away from the complainant’s property.


Having concrete floors certainly doesn't stop this. velocity in concrete is quite high. The sprung suspension system was designed to reduce that energy from getting to the platter/arm,/cart
besides the energy created in the room due to the acoustic energy being transformed into mechanical energy (acoustic feedback)

the sand bag system employed here is a suspension system to reduce (the above mentioned LFR) and induced structural energy from the acoustic energy applied into the room.
And then there's the issue of the table itself applying energy into the shelf it sits on, and then being reflected back into the table. The last part is where sandbags are superlative in conversion
of mechanical energy into heat, and not reflective energy.
 
....Do you hear any improvement?

I've been using the sandbox for a couple of days and while I thought I was hearing some positive effects I needed to compare a group of records under identical conditions with and without the sandbox. I did that last night and the end result is I hear more instruments clearly with the sandbox than without. To be more specific, with the sandbox I could clearly hear background instruments all the time instead of just occasionally. I expected there would be an improvement in bass quality with the sandbox however, if there was a change, it was minor. I left the volume control the same but the volume, measured with may SPL meter, was louder without the sandbox by 1 to 2dB for all the records.

My gear is in my signature except that I was using a Hashimoto HM-3 SUT with 1:20 turn ratio. My cartridge is a Shelter 501 II retipped with a line contact stylus.

The records I used were:

Tracy Chapman ST (First three songs Side 1). Fast Car has some very deep bass plus lots of acoustic guitar. The bass wasn't much different with or without the sandbox but the guitars were more fluid and easier to hear.

Steely Dan, Gaucho (Gaucho and Time Out of Mind). Again, it wasn't the main instruments that sounded different it was the ones in the background that were easier to hear and follow. The soundstage on this record seemed a bit better with the sandbox.

Dave Matthews Band, Crash (So Much to Say, Two Step). Stefan Lessard's bass has never been all that clear on any of DMB's records/CDs and the sandbox didn't reveal anything different. Just the way its mixed/engineered. However, the violin, acoustic guitar, and some sax that were not the featured instrument were much easier to hear with the sandbox.

Donald Fagen, Morph The Cat (Morph The Cat). I picked this record because it has the most bass of any album I own. It overwhelms, or so I thought. Without the sandbox I just heard vocals, some drums, an occasional other instrument and lots of bass. With the sandbox all the other instruments popped right up. Walter Becker was part of this record and Fagen/Becker are known for their attention to detail. With the sandbox I could hear it.

Lastly, there is an ease to listening to music with the sandbox. I attribute that to not having to work to hear background instruments. Before I'd hear something and then it would fade away but now I hear them all the time. The sandbox stays in my system.

Will the sandbox with sandbags help playback from your non-suspended deck? This really is a YMMV situation as there many variables that may be contributing to what I'm hearing (or not hearing). However, it is a relatively inexpensive project, so if it doesn't improve the sound from your system it isn't a great loss.
 
I've been using the sandbox for a couple of days and while I thought I was hearing some positive effects I needed to compare a group of records under identical conditions with and without the sandbox. I did that last night and the end result is I hear more instruments clearly with the sandbox than without. To be more specific, with the sandbox I could clearly hear background instruments all the time instead of just occasionally. I expected there would be an improvement in bass quality with the sandbox however, if there was a change, it was minor. I left the volume control the same but the volume, measured with may SPL meter, was louder without the sandbox by 1 to 2dB for all the records.

My gear is in my signature except that I was using a Hashimoto HM-3 SUT with 1:20 turn ratio. My cartridge is a Shelter 501 II retipped with a line contact stylus.

The records I used were:

Tracy Chapman ST (First three songs Side 1). Fast Car has some very deep bass plus lots of acoustic guitar. The bass wasn't much different with or without the sandbox but the guitars were more fluid and easier to hear.

Steely Dan, Gaucho (Gaucho and Time Out of Mind). Again, it wasn't the main instruments that sounded different it was the ones in the background that were easier to hear and follow. The soundstage on this record seemed a bit better with the sandbox.

Dave Matthews Band, Crash (So Much to Say, Two Step). Stefan Lessard's bass has never been all that clear on any of DMB's records/CDs and the sandbox didn't reveal anything different. Just the way its mixed/engineered. However, the violin, acoustic guitar, and some sax that were not the featured instrument were much easier to hear with the sandbox.

Donald Fagen, Morph The Cat (Morph The Cat). I picked this record because it has the most bass of any album I own. It overwhelms, or so I thought. Without the sandbox I just heard vocals, some drums, an occasional other instrument and lots of bass. With the sandbox all the other instruments popped right up. Walter Becker was part of this record and Fagen/Becker are known for their attention to detail. With the sandbox I could hear it.

Lastly, there is an ease to listening to music with the sandbox. I attribute that to not having to work to hear background instruments. Before I'd hear something and then it would fade away but now I hear them all the time. The sandbox stays in my system.

Will the sandbox with sandbags help playback from your non-suspended deck? This really is a YMMV situation as there many variables that may be contributing to what I'm hearing (or not hearing). However, it is a relatively inexpensive project, so if it doesn't improve the sound from your system it isn't a great loss.

Nice write up.

I hear the exact same types of audio improvements whenever I improve isolation of components. It always seems to improve the ability to resolve details and instrument placement in the sound stage. I also heard this when I made improvements to my AC power. Less smearing and better resolution, a cleaner presentation. You need good recordings to test this and you need to spend time with the two configurations you're comparing.

I find your SPL measurements to be very interesting. Measure higher volume (higher SPL levels) without the sand box might be the contribution of noise/distortions effects that you eliminated with the better isolation.

Many people do not believe in these tweaks, you do need a good system, set up properly, to hear these incremental improvements.

Congrats on your new component and upgrade.
 
I filled the tubes in my rack with a combination of sand and steel bb's and was extremely pleased with the results. Every component sounded better. I think that if the music begins to sound more engaging with each tweak you're on the right track. Room treatments are the next step for me.
 
I messed with turntable isolation for YEARS when I had various Technics tables (1200's, 1700, SL-D3) as I have wood floors. I tried everything from raquet ball halves to sorbothane to concrete pavers to bicycle inner tubes. A concrete paver was the best I came up with (18"x18"x2"). The better solution (and I'm gonna catch hell for this!) is a Pro-Ject table. I've had a RM 5.1 and now a Debut Carbon DC and it's immune to foot fall. I still have the paver under the Debut as it can't hurt. My two cents blast away.
The concrete paver was the most effective because of its mass, and no other reason. Either a great suspension or great mass will counter the vibrations in the most palpable way imho.
 
Op’s SPL meter measurements are interesting but I’m afraid not very relevant. Everything that’s being discussed here can be quantified. 1dB difference at 70 dB is negligible imho.
Recording the tracks to digital with and without sandbags and superimposing the waves in software would be the Way to go.
Much like someone above saying that installing a power conditioner made a clear difference in the sound...I’m sorry but without any data that is just hearsay. Maybe it did, and maybe it didn’t.
 
Op’s SPL meter measurements are interesting but I’m afraid not very relevant. Everything that’s being discussed here can be quantified. 1dB difference at 70 dB is negligible imho.
Recording the tracks to digital with and without sandbags and superimposing the waves in software would be the Way to go.
Much like someone above saying that installing a power conditioner made a clear difference in the sound...I’m sorry but without any data that is just hearsay. Maybe it did, and maybe it didn’t.

I ascribe to the AK moto: All Audio, No Attitude

I've seen this movie before here on AK and in other forums. The discussion starts out with someone saying that unless an observation can be quantified and verified by others using objective measurements it may or may not be true. Often those demanding objective measurements don't offer to do the analysis but demand those reporting an observation are obligated to justify their observation to the questioner's satisfaction. This argument degrades when observations can't be completed, quantified or are quantified in a ways that are acceptable to everyone. Eventually folks get pissed off, write things they would never say face-to-face and the thread gets locked. I don't want to go there.

I'm an analytic person and I understand the drive for data but there remain many things that are subjective and we, AK members, share subjective observations all the time. You can believe them, or not. I initiated this thread to discuss an alternate approach to the oft used sandbox isolation system and I don't need to perform the analysis as you suggest to know what I heard and to make my decision whether to keep the sandbox in my system. You are more than welcome to do the analysis yourself and if you do please report back on your findings. But please do so in another thread.
 
Op’s SPL meter measurements are interesting but I’m afraid not very relevant. Everything that’s being discussed here can be quantified. 1dB difference at 70 dB is negligible imho.
Recording the tracks to digital with and without sandbags and superimposing the waves in software would be the Way to go.
Much like someone above saying that installing a power conditioner made a clear difference in the sound...I’m sorry but without any data that is just hearsay. Maybe it did, and maybe it didn’t.

1 or 2 dB difference at 70 dB is not relevant to loudness, sure I agree, but the OP never said he heard a volume difference, he heard a difference in quality. Finally, we get someone who does something like improved isolation, says it sounds better, and has some measured data. I am not convinced that you cannot correlate the measured data to what he hears. I will admit that I do not know, but something caused the small drop in SPL. You say you have a better way to measure it, but do you really? Read those waveforms and then tell us what you think “sounds” better. Just like amplifier designers touting super low THD designs and yet some people (actually many people) like the sound of tube amps better, even amps with higher THD and IMD measurements.

I’m the person who said I “improved” my ac power, but I never said how or that it was solely with use of a power conditioner. I simply stated that when I did it improved things. I’m not going to spend a minute collecting data on it. But I hear it and so have others that have been to my house.

This is a hobby to please our ears, so let’s trust them every once in a while.
 
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1 or 2 dB difference at 70 dB is not relevant to loudness, sure I agree, but the OP never said he heard a volume difference, he heard a difference in quality. Finally, we get someone who does something like improved isolation, says it sounds better, and has some measured data. I am not convinced that you cannot correlate his measured data to what he OP hears. I will admit I do not know, but something caused the small drop in SPL. Of course you have a better way to measure it, but do you really? Read those waveforms and then tell us what you think “sounds” better. Just like amplifier designers touting super low THD designs and yet some people (actually many people) like the sound of tube amps better, even amps with higher THD and IMD measurements.

I’m the person who said I “improved” my ac power, but I never said how or that it was solely with use of a power conditioner. I simply stated that when I did it improved things. I’m not going to spend a minute collecting data on it. But I hear it and so have others that have been to my house.

This is a hobby to please our ears, so let’s trust them every once in a while.

Sure, I hear you [no pun intended]. For instance, I just purchased a $100 dac that is touted for its specs on the audiosciencereview forum, and comparing it to a $3000 McIntosh cd player from 1997, I can clearly hear the difference, and the $100 dac easily outperforms the 20 year old McIntosh. I know that my direct comparison of the two dacs side by side is very unscientific, but I do rely on my ears. However, if I didn't compare them directly to each other, how would I be able to pronounce whether one is markedly different from another or not? Our auditory memory is very short-lived, very transient. Within a minute or two it vanishes, and what we are left with is just a belief.
Based on that I find it hard to believe that anyone will be able to definitively say that a turntable sounds markedly different on or off the sandbags. unless the difference is indeed very significant.
 
I ascribe to the AK moto: All Audio, No Attitude

I've seen this movie before here on AK and in other forums. The discussion starts out with someone saying that unless an observation can be quantified and verified by others using objective measurements it may or may not be true. Often those demanding objective measurements don't offer to do the analysis but demand those reporting an observation are obligated to justify their observation to the questioner's satisfaction. This argument degrades when observations can't be completed, quantified or are quantified in a ways that are acceptable to everyone. Eventually folks get pissed off, write things they would never say face-to-face and the thread gets locked. I don't want to go there.

I'm an analytic person and I understand the drive for data but there remain many things that are subjective and we, AK members, share subjective observations all the time. You can believe them, or not. I initiated this thread to discuss an alternate approach to the oft used sandbox isolation system and I don't need to perform the analysis as you suggest to know what I heard and to make my decision whether to keep the sandbox in my system. You are more than welcome to do the analysis yourself and if you do please report back on your findings. But please do so in another thread.

I can see how my last post could be construed as fresh, and I apologize. I know you went through a time-consuming process of making the box and your wife fabricating the bags, so you really want the results to produce a marked change. I still think that the only reliable method of quantifying small changes that don't make us say WOW, is by measuring them. If the difference were significant, like the glass of water and a naked eye, I'd applaud your results. The way things appear to me now, based on your posts is that the difference pre and post sand bags is minute, if at all discernible.
Otoh, your stereo being on a concrete floor puts you in an enviable position visavis many of us, myself included, who have suspended wooden construction underneath our stereos. I wonder if just putting sorbothane pucks under your tt would be enough, without any sandbags, etc. Alternatively, a very heavy concrete paver.
Just a view from my sandbox...no pun intended.
And yes, you are right, I've got no measurements of my own, other than a glass of water test.
 
I think this exchange goes a long way to illustrate the two extremes of measurements vs. impressions:




Whatever your stance, no matter how much you think you know or how much you've spent (or saved) on your system, just be courteous and understanding.
 
The concrete paver was the most effective because of its mass, and no other reason. Either a great suspension or great mass will counter the vibrations in the most palpable way imho.

except for.................

Pressure-pulse or compression-type wave (longitudinal wave) confined to a plane. This is the only type of sound wave that travels in fluids (gases and liquids). A pressure-type wave may also travel in solids, along with other types of waves (transverse waves,

sorbothane acts as a liquid, and has a restorative force.

Transverse wave affecting atoms initially confined to a plane. This additional type of sound wave (additional type of elastic wave) travels only in solids, for it requires a sideways shearing motion which is supported by the presence of elasticity in the solid. The sideways shearing motion may take place in any direction which is at right-angle to the direction of wave-travel (only one shear direction is shown here, at right angles to the plane). Furthermore, the right-angle shear direction may change over time and distance, resulting in different types of polarization of shear-waves

sand acts neither as a solid, nor a liquid, nor has a restorative force. It will not, have nor support a longitudinal wave, it will not have, nor support a transverse wave.

rap a paving stone with a hammer, record the sound from it, rap a sand bag with a hammer, record the sound from it.
 
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