How to isolate turntable from footstep shake or vibration
Hi lewm9 I have the Airforce V which has an air platter and vacuum suction to hold the record flat. This model doesn’t have the air suspension which the more expensive models have. I have all my equipment in my office which adjoins the lounge in order to reduce the impact of vibration and remove clutter from the room. |
I can almost guarantee you will be as surprised as me. It was easy to see how Pods would improve my turntable. With amps it is harder to understand, but just as easy to hear. Pods are the most economical way, put them right against the bottom of the chassis. This way it totally bypasses the factory feet, which always seem to be the worst part of a component! So much so I have totally removed them from several components over the years. Like freebie rubber power cords and Buss fuses I keep them around and put them back so the next guy can remove them, and store for the next guy.... |
I’ve been following this thread with interest as I’ve just changed from a (fully suspended) Avid Acutus to a Techdas Airforce V which has no suspension. The Techdas is amazing and has near CD silence between tracks and the dynamics and scale of presentation is terrific. However, I’ve been wondering how some sort of isolation might work with the Techdas. I read a lot about the Townshed isolation platform after the comments from @millercarbon and purchased one out of curiosity. The Townshend platform has a spring/pod at each corner and is easy to set up and level. The results are quite startling with a big improvement in the ability to separate vocalists along with improved bass. In fact there just seems to be slightly more of everything. I’m rather surprised at the difference this has made and I’m now wondering what sort of impact this might make under my Atmasphere OTL amp! |
Quote/ esputnix OP16 posts06-15-2021 2:42pmThank you for all your suggestions! I’ve double checked the suspension. And it appeared that the right tonearm side needed a stiffer spring as the aluminum housing was so low that it touched the base. It was simply sitting on the turnable instead of "floating in air". I have replaced the spring with the stiffer one and viola! The effect was instant. The footsteps rattle is gone. Even with the maximum subwoofer volume it is dead silent. It doesn’t even respond to me jumping in a room or shutting the door. It feels like I’ve got a free upgrade as it appears it sounds better!" /unquote Above quote from page one. Aha...the solution was to correctly adjust the suspension of the TT by replacing the spring nearest the tonearm with a stronger one. Perhaps at one point the tonearm had been replaced with a heavier one...(speculation) Those Oracles apparently require a different technique to their adjustment than do the earlier designs based on the original AR. And now he doesn’t have any footfall issues. Probably his floor isn’t as -flexy- as some are known to be...or perhaps the Oracle, when correctly adjusted, is less prone toward footfall.. I don’t know..... Still we don’t know exactly which design the Oracle in question is. A Delphi or Alexandria. Both seem to use a very similar subchassis. agree with ghdprentice , the proper solution is to isolate the turntable from the "trampoline" via wall shelf....That is when you live on a trampoline floor, I know I have. Others on this list have very solid flooring entirely suitable for situating a turntable over...yet...among those that do.... many will insert an isolation device between said turntable and the floor mounted rack it sits on in order to improve overall sonic performance of the TT. I think the idea is to isolate the turntable from its environment as much as is possible.-Steve |
What user510 said. In addition, altering the distance between the platter bearing center and the tonearm pivot must necessarily create a speed anomaly, as the belt must stretch or contract to accommodate changes in the distance between the motor pulley and the platter, where the motor is not mounted on the suspension. |
ghdprentice509 posts07-23-2021 3:18pmI had an AR which I could rap in the the top with my knuckle and it would not skip or have the sound transmitted to the speakers. It did what it was designed to do. When I walked by it would skip every time. The solution was simple, a wall rack… that is the solution for suspended floors. mijostyn4,747 posts07-23-2021 3:34pmuser510, I have intimate experience with both the AR XA and I have owned 2 LP 12s. They are both potentially unstable and do not handle footfalls well just as ghdprentice indicates. A Sota you can rap on the surface and dance the jig on springy floor and it will not care. It is all about the self centering stability of the suspension that count.good feedback and I don't mind being contradicted with factual evidence. There definitely are other suspended subchassis designs which isolate well...and I think mjostyn's suggestion that the "hungie" type of suspension proves to be more stable than is the "sprungie". Where the hungie tends to find center while the sprungie tends to never quite find it. Although you can get close in those adjustment sessions but those conical coil springs always point their load in one direction, which needs to be steered...and the drive belt imposes a horizontal pull which will yank the lighter subchassis in a direction we don't want it to go. Ime with a Td126-III i can say that this design suffers far less from footfall. Even though it is a "sprungie" and needs to be adjusted in order to obtain a vertical oscillation action, it does resist the pull of the belt far better with its larger mass. And the cast chassis does indeed not flex. Btw, I can prove chassis flex on the TD150/TD160. Having checked this using a dial indicator,to see that just the addition of the platter mass alone will cause the subchassis to flex. Now if you put this into a dynamic situation where footfall ripples the suspended floor, which causes the floor supported audio rack to teeter just a little bit and that is enough to put the turntable in motion which excites the suspension components within and then we see even greater chassis flex due to the dynamics of the compression/extension action. And that alters the distance between platter bearing center and pivot center of the tonearm, which skips the needle out of the groove. https://www.theanalogdept.com/subchassis_rigidity.htm -StevePs: have we solved the issues described by the OP yet? |
user510, I have intimate experience with both the AR XA and I have owned 2 LP 12s. They are both potentially unstable and do not handle footfalls well just as ghdprentice indicates. A Sota you can rap on the surface and dance the jig on springy floor and it will not care. It is all about the self centering stability of the suspension that count. |
mijostyn4,740 posts07-22-2021 8:37am"user510, there are well designed turntables suspensions and not so well designed suspensions. Suspended turntables that have their sub chassis sitting on springs like the AR XA, LP 12 and Thorens turntables are inherently unstable and they tend to oscillate laterally when aggravated. They will skip with footfalls sometimes even more readily than unsuspended turntables. Suspended turntables that have their sub chassis hanging from the springs are inherently stable and want to maintain their resting positions. This category includes SME, some Basis and Sota turntables. They will not skip with footfalls. You can put them on a collapsible card table and they will operate fine without any audible consequence. " Agree that some suspended subchassis type turntables are more stable than are others. Also agree that the lighter Thorens models are definitely prone toward footfall. And this is inherent in the design. Particularly the models such as the TD150 and TD16x/TD14x. However the AR-XA was originally quite stable and able to effectively isolate from physical disturbances such as foot fall, or being bumped into, or even have a fist hit the top of the cabinet while the thing was playing a record.....and not skip. This was one of their advertised abilities. And it was proven time after time in public demonstrations. I think I understand why the AR isolated well while the Thorens or Ariston RD-11 or LP-12 did not. It had to do with a combination of things including the mass of the suspended parts as well as stiffness of that suspended subchassis. The Thorens models, along with the LP12 models did suffer some chassis flex when being disturbed into motion. This chassis flex altered distance between platter bearing and the tonearm mounting, effectively causing the stylus to jump out of the groove. Only later, some several decades later, has Linn addressed this issue with the Sole subchassis. Thorens addressed it with their heavier TD125 and TD126 models which have cast aluminum subchassis that are stout enough not to flex while in oscillation. But they knew what they had back in their earliest versions. https://www.theanalogdept.com/td150_history.htm That said, and it is an interesting discussion, I wonder if anyone has actually solved the issue described in the OP.-Steve |
Hanging with magnets would not be a viable option unless the magnetic field strength was meticulously matched to the total mass of the turntable. Even the weight of the LP itself would have to be considered, and you’d have to take care not to rest objects on the plinth surface. Otherwise you would either have the equivalent of an unsuspended state (magnets in physical contact) or the sudden equivalent of nothing holding the turntable up as it crashed to the shelf or earth. Suspending the turntable footers between opposing magnets, top and bottom, might work. |
it sounds more like damping rather than isolation although it probably isolates at certain frequencies. If you want to have some fun put the stylus down on a stationary record and hook your phono stage to an oscilloscope. Then play a sine wave sweep loudly and see what gets through.@mijostyn Its both. I have tested it and the platform has proven remarkably wide band. I'd recommend the platform but the manufacturer went out a long time ago (Ultraresolution Technology). |
@mijostyn - I was thinking more along the lines of actual magnetic feet - not a DIY solution - like these... Maglev HiFi isolation feet | Solid Air Audio And the link to the other Agon discussion has more examples of commercially available magnetic feet I think something like this would be too difficult to DIY Regards - Steve |
@williewonka , Sitting a turntable on opposing magnets is similar to sitting a turntable on springs and would be very unstable without some kind of lateral support. Hanging a turntable from attracting magnets would be an interesting project. My instinct says it would not perform any better than hanging a turntable from springs but would be a lot more expensive. |
user510, there are well designed turntables suspensions and not so well designed suspensions. Suspended turntables that have their sub chassis sitting on springs like the AR XA, LP 12 and Thorens turntables are inherently unstable and they tend to oscillate laterally when aggravated. They will skip with footfalls sometimes even more readily than unsuspended turntables. Suspended turntables that have their sub chassis hanging from the springs are inherently stable and want to maintain their resting positions. This category includes SME, some Basis and Sota turntables. They will not skip with footfalls. You can put them on a collapsible card table and they will operate fine without any audible consequence. |
@atmasphere, it sounds more like damping rather than isolation although it probably isolates at certain frequencies. If you want to have some fun put the stylus down on a stationary record and hook your phono stage to an oscilloscope. Then play a sine wave sweep loudly and see what gets through. I plan on doing this with the Sota when I finally get it. |
@esputnix - I searched through this thread and could not find any mention of Magnetic Feet i.e. each footer uses two magnets positioned to repel each other - the table effectively "floats". Of course there might be a reason for NOT using them i.e. "directly" on a turntable, so you might want to have them located on a secondary plinth between the the TT and the shelf Maybe combining the magnetic feet with another isolation technique would provide the nest solution? Personally, I have not used this type of foot, but considered them many years ago and thought it might be a good solution for very difficult isolation situations such as yours For more info - read this thread Magnetic levitation feet | Audiogon Discussion Forum Regards - Steve |
I made an Isolation platform with a Butchers block at IKEA with Sorbothane pads from Amazon. You can also get wall mount turntable shelf from Amazon. I've also see people with Sorbothane turntable feet from here,
Turntable Phonograph Vinyl Record Player lsolation Feet – Mnpctech
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@atmasphere, isomerically isolated? Does that mean rubber feet? A suspension requires a resonance frequency in and around 3 Hz. Dohmann I think uses 1 Hz vertically and 1.5 Hz laterally. Put your stylus down on a stationary record, close the dust cover and turn up the volume. Then go look at your woofers. Keep an eye on the woofers as you walk around and even tap on things. With my old Sota I could hit the plinth vertically with a hammer and the woofer would not even twitch. Most woofers will be fluttering from the environmental rumble which is due to anything from the washing machine in the other room to the truck running down the street. Mass might change the amplitude a little but it will not stop it like a suspension will. How much does it really matter? Most people would never know it was there. None of us could hear it directly over the music. However if you have subwoofers and room correction with a lot of power it can cause the drivers to bottom out and can increase distortion. For me it is important because I run my subwoofers up to 120 Hz where the distortion would be obvious. I doubt any of us could hear it under 40 Hz. Of course there is the psychological benefit of knowing nothing can get to your turntable. |
Being a perfectionist does not mean you are paralyzed. <<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>> It is my biggest obstacle, GETTING started. I think and think and think. Then pull the trigger. A guy taught me 50% of getting the job done is just starting.. He was right.. The older I get it's closer to 100%. :-) |
There is also another condition that might be the cause of the Sub Woofers exuberance. The Condition if present will be quite easy to resolve, as it simply means checking the Earth Connections are at the correct termination points and ensuring they are clamped effectively. I refer to this as it has happened to myself on occasion over many years, and very recently as well, when I working with a Selection of Phon's SUT's and Head Amp's An Incorrectly Earthed Vinyl chain can produce effects that manifest through the Bass of the Speakers. When I am trialling with Phon's and Ancillaries, I have at times got the Earth connections incorrect at the time of exchanging. An incorrect Earth even though not being a Audible Hum, can react to activity around it and produce noticeable Bass Cone Movement. |
The thread title suggests footfall issues while using a spring suspended subchassis type of turntable. But the text of the opening post suggests an issue with a subwoofer which makes a loud "boom" that seems to be triggered by footsteps. This to me suggests a combination of issues. But the "boom" noise coming out of your subwoofer suggests, to me, acoustic feedback. Is it possible that the turntable and subwoofer are in close proximity to one another? If so the simplest solution might be to move either the turntable or the subwoofer further apart. Or aim the subwoofer differently just to see if this helps to eliminate the "boom"... Otherwise the issue of footfall and spring suspension turntables has been covered within this thread and many others more or less completely over the past 60 or 70 years ever since the AR-XA turntable was introduced in 1961.. I do have some experience dealing with spring suspended turntables, having owned a few Thorens models including the TD150, TD160, TD126, etc. And those will respond well to being parked on a wall rack. The idea being to decouple the turntable from the floor so that the seismic vibration of a footfall on a light flooring system does not reach it. Or there is always the idea of putting your turntable up on a true lab quality isolation shelf such as a Minus-K, or Vibraplane or Herzan. Any of these will decouple the turntable from the floor....for a price. But the wall mounted shelf would be the least expensive way. And this would, no doubt, be of benefit even to non suspended turntable designs. Still, based on the opening post I’m leaning toward this being a problem related to acoustic feedback which can be alleviated by moving either the turntable or the subwoofer. -Steve https://www.theanalogdept.com/what’s_under_your_table.htm |
antigrunge2, Pretty sure you agree with me completely: Listen and learn. The point I was making is not that any old thing will make a fine arm board. The point is anyone can try these things very simply and quickly - listen and learn - as long as they set aside the urge to make it look good. Many times guys agonize over how to do something, spend hours debating this and that, when in far less time they could just go and do it and find out. Listen and learn. This is by the way very similar to what professionals do in designing or improving a component. They build a breadboard, basically just a board with room for all the parts. This makes it real easy to swap out parts and compare. They can even compare things like the same part in a different place, or oriented differently, all kinds of things. Only once they figure this out then they package it nice and neat. They listen and learn. Only at the very end do they make it look good. Same thing. |
I had same situation in 2nd story of our house. It was built in 1929 and we still have the original hardwood flooring. The best approach is wall a mounted turntable platform. You can get them on Amazon. I've also read people here having success with Sorbothane feet from this site,
Turntable Phonograph Vinyl Record Player lsolation Feet – Mnpctech
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they should have maximum dimensional and warp stability relative to the platter and ideally be free of resonance: Brass, acrylic blocks or panzerwood are way preferable to mdf or papp.Off topic, but the arm board should be composed of the same material as the plinth and ideal be the plinth itself, so that any vibration present at the bearing of the platter will be in the same plane at the base of the arm, such that the arm simply can't pick it up. This does assume a rigid and dead plinth... Mass does not solve everything. There is loads of environmental rumble that will transmit through anything. When it gets bad enough buildings fall over. Church bells weight tons and they ring like crazy. The only way to isolate a turntable is to suspend it.I guess that depends on what is meant by 'suspend'. My platforms are isomerically isolated from my equipment stand- does that count? |
A pair of heavy duty shelf brackets I found at a local hardware store, attached to a couple of studs with four lag bolts and a shelf made from a few pieces of pre-finished bamboo flooring did wonders for my Linn LP 12. An outside wall is best for this implementation. This proved to be a splendid, economical solution. There is no need to spend silly money on various other fix-it schemes. The brackets and lag bolts cost about $15.00. I already had the bamboo. A small piece of 3/8" or 1/2" plywood likely would work just as well. But, of course YMMV, to use the cliche.’ |
@millercarbon. ”Engineer you say…”. I was trained as a scientist. I got out of school and needed to get a job to buy a suit and get money to move and look for a job in my profession. I was working at a start up company as a manual laborer. When equipment would break I would run over and fix it and recommend how to change it… I was board to death. The owners saw this and hired me to architect and build a prototype of a new system. I am not a stereotypical engineer… I know I have worked with hundreds of them at corporations like Texas Instruments, Sharp Corp… and others. A good way to become frustrated at getting anything done… they have to re-invent everything and make it perfect. Scream 🙀! I worker at Burr-Brown Corp for 15 years. Don’t know if you recognize the name.. DACs, op amps, and ADCs used in high end audio. Yes, with the exception of one of them, they simply don’t believe in a difference in sound possible or their circuit could sound different… and as a consequence refuse to hear it. |
Darn millercarbon, I am stuck agreeing. In medical school we learn to do things perfectly according to the state of the art at the time by learning from people who already do it perfectly. But, looking back at history it took a lot of baby steps to get there. Perfect is only a perspective in time. As time changes so does perfection. I am sure if da Vinci were alive today he would show you are all the places he made mistakes on the Mona Lisa. Being a perfectionist does not mean you are paralyzed. It certainly means you are never happy with what you do, or what anybody does for that matter. It is not a very happy place to be. |
Engineer, you say. Did they drive you out of the profession? Because all the engineers around here are the worst most tone deaf pontificators of that which does not in reality work I have ever seen. You must be a pariah or something. Welcome! Welcome to the club! The club of real world practical thinkers! Our motto: We get results! 🤣😂😁 |
@millercarbon . First thing I learned out of college. Got a job as electro mechanical engineer. I needed to have a perfect gripping material to coat a rotating drum that was to pull fiberglass. I got out my calculator and tables of coefficients of friction. After a couple hours in the books, I realized I was getting no where. I quickly fabricated a little drum with motor, and went out and bought every brand of PVC tape, adhesive, and Saran Wrap I could find. Then just wrapped the drum and tried it until I found one that worked perfectly. Then I built a 10’ high drum and used the material I found by quick trial and error. A couple years later got into audiophilia… where I quickly learned peak wattage was meaningless… and the watts RMS was nearly so… and that I must try interconnects and power cords in my system. It’s a good lesson to learn. |
If you are in audio, and especially if you are into improvement, then it pays big time to be willing to try stuff out without being overly concerned how perfect it is, how it looks, etc. People ask me this one all the time. What is the best one to do? What is the most important component? What is the weakest link? These are all based on a false premise. Every link is weak, at least in the sense it can always be made stronger. Every component is the most important. Before I came to this realization I was building shelves out of different materials, sanding and finishing, doing all this work that only makes it look good but has nothing to do with how it sounds. Eventually I figured out I can cut a piece of wood, stick it under something, and hear how that wood sounds without going to all that trouble. The perfect example of this is the tone arm board. This can be anything. Could be cardboard cut with scissors. For sure could be MDF, or any piece of wood, acrylic, plastic, aluminum, Corian, whatever. Don't even have to drill holes, because for testing purposes you could stick the arm on there with tape or blu-tack or heck some arms even gravity will do. Nobody ever does this. If they did they could learn a heap in no time flat. But they don't. Why? Who knows. Appearances. Everyone so freaking worried about how it might look. Me, I am concerned with how it will sound. What did Magenta say again? "Risk it!" |
I think it is a bit dependent. One usually prizes perfectionism in a brain surgeon but not in a good manager. I am very pragmatic and can vary my precision based on the task at hand. I my way to the executive level in Corporate IT, so had to deal with many perfectionist programmers that would never finish anything. My best friend is a perfectionist and has spent his life struggling to keep his head above water. He tried to be a Doctor, but just didn’t quite make it. Growing up with him I always felt inferior, I now look back and feel very sad for him… it can be like a disease. |
Jordan Peterson sold me on the idea anything worth doing is worth doing poorly. His point being too many people put off doing until they can figure out how to do it perfectly. In that case it is better to do it poorly, because then at least you learn from experience and maybe make it better next time. If you improve something even if only by a little bit, but keep at it, eventually it will be quite good. Or in any case a helluva lot better than when you started! |
Miller Carbon wrote, "
Mass will solve most problems, if you can get enough of it. That's the
trick. Fortunately mass is dirt cheap. Literally: one or two 50 lb bags
of play sand, in a box several inches deep, put a piece of MDF or
butcher block on top, you are pretty much golden
" That was my thought when I built my turntable stand. I cut a section of a well seasoned white oak log about 20" in diameter after all the bark was removed and 18" tall. Then I sanded it smooth so that it could be nicely finished with walnut stain and mucho coats of polyurethane varnish. I then mounted a large maple butcher block on top of the log section. I enlisted the help of a competitive weight lifting son of a good friend to help me set it on a 15" high brick hearth well away from the fire place. The turntable sits on the butcher block and seems to be impervious to foot falls or other floor transmitted vibrations. This conforms to my philosophy that anything worth doing is worth over doing. |
I have an oscilloscope program so when I get the table I'll have a look and see if there is any unusual distortion at various frequencies.You'll need an LP with test tones. I cut some low frequency stuff on my lathe; its easier to see when lower frequencies are present. Allen Perkins (the designer of the Cosmos) went through the setup of the machine with me. It was suspended pretty well. |
