valveitude said:I believe it is the assembly as a whole, rather than the material, resonating, as it is sitting atop a "spongy" bench. I think it's a question of geometry, in that, the motor is hanging out on a shelf approx. 6" from the nearest foot. I believe it is using this as a fulcrum (sic) to flex the rest of the plinth. It actually feels like its vibrating harder the further you get away from the motor. I think I will try the bracing first..this may cure it. If not...
Congrats on your phono pre by the way
-Casey
Trying a foot under the motor extension sounds like a good idea.
Hmm, if you are not planning to run it on that bench, maybe your problem is not so severe.
Thanks on the pre. A few more bits and my entire system will be DIY, or at least every piece will have some DIY element.
Sheldon
Sheldon-
I'm starting to think that this may well be the case. Writing things out helps me organize my thoughts, and after reading what I wrote above, it seems likely that my very heavy table sitting on the 24"x48"x1/2" plywood top of my work area has formed a very loose suspension. I will test this out by setting it up on the concrete floor, seeing how it behaves before I do anything rash. I spent a lot of time thinking about internal resonances when I constructed it...which is why I have been so flumexed about my current "perceived" problem.
As far as the intended TT stand this is my planned top plate
Very cool
, currently my system consists of highly modded commercial pieces..the table being the first truly diy. I plan to be 100% diy by the time I'm through.
-Casey
I'm starting to think that this may well be the case. Writing things out helps me organize my thoughts, and after reading what I wrote above, it seems likely that my very heavy table sitting on the 24"x48"x1/2" plywood top of my work area has formed a very loose suspension. I will test this out by setting it up on the concrete floor, seeing how it behaves before I do anything rash. I spent a lot of time thinking about internal resonances when I constructed it...which is why I have been so flumexed about my current "perceived" problem.
As far as the intended TT stand this is my planned top plate
Very cool
, currently my system consists of highly modded commercial pieces..the table being the first truly diy. I plan to be 100% diy by the time I'm through.-Casey
valveitude said:As far as the intended TT stand this is my planned top plate
That's amazingly cheap. Shipping's got to be the biggest part of the cost.
cool
[/B]
At this point, all my amps are completely DIY, as are the speakers. The turntable is a Teres, so all I did is finish and assemble. No point in completely redoing that, as it would be hard to beat without major effort. I do plan to make a DIY tone arm - probably some sort of unipivot, though not certain on that direction. I have taken note of your motor musings and will probably do some mods in that area. The way I listen for noise is to attach a small metal angle to the side of the turntable that bends just over the platter. Then I run the platter and set the stylus on the little angle while the table is running and listen to the output through headphones. The little platform transmits all the motor and other vibrations to the cartridge. Definately a little work to be done here. The belt splice is audible, as is some motor related noise.
The only items not DIY are the CD player. I will do something here, but more in the kit type area. Not feasible to build a transport, and I don't need an D/A converter, as I'm using a DEQX as the main preamp. At some point in the future I may replace that with an analog crossover ala Linkwitz's Orion, we'll see. If I do, I'd build a DAC too. But that's further off. Or I may go the other direction. If the PC stuff keeps getting better and, more importantly easier, that could replace the DEQX and CD transport. One real nice thing about that approach is that all the music can be stored at full resolution, maybe even the vinyl.
Sheldon
Sheldon-
Yes and yes..truck freight's gotta smart.
As to whether or not I “beat” (or for that matter, equal) the Teres remains to be seen, but I’ve got the major effort angle covered. Actually, I followed the original Teres project on the web years ago..it’s my inspiration.
Neat..I might have to implement that. On the other hand, I may have access to an Audio Precision One for wow/flutter & rumble numbers…I just need to source a test record
The splice has me worried. What is your pulley size? In other words, how acute of a bend does the splice have to deal with. I suspect the smaller the pulley, the bigger the problem. As far as the motor noise goes, what I’ve done WORKS!
On another note, I don’t remember smoking the crack, but I tried to duplicate my problem, and couldn’t! The only things I’ve identified that’s different than when I first heard it is a) the motor now has a pre-load. b) I’ve moved the junk on my bench around, redistributing the weight, and c)the temperature is about 30 deg. cooler. What the Hades? Oh well, I think I’ll just reinforce the motor shelf and call it good…I really don’t need to be chasing a non-problem. It’ll just give me a headache trying to figure out why the problem I apparently don’t have, seemed to be present before.
-Casey
Yes and yes..truck freight's gotta smart.
As to whether or not I “beat” (or for that matter, equal) the Teres remains to be seen, but I’ve got the major effort angle covered.
Actually, I followed the original Teres project on the web years ago..it’s my inspiration.Neat..I might have to implement that. On the other hand, I may have access to an Audio Precision One for wow/flutter & rumble numbers…I just need to source a test record
The splice has me worried. What is your pulley size? In other words, how acute of a bend does the splice have to deal with. I suspect the smaller the pulley, the bigger the problem. As far as the motor noise goes, what I’ve done WORKS!
On another note, I don’t remember smoking the crack, but I tried to duplicate my problem, and couldn’t! The only things I’ve identified that’s different than when I first heard it is a) the motor now has a pre-load. b) I’ve moved the junk on my bench around, redistributing the weight, and c)the temperature is about 30 deg. cooler. What the Hades? Oh well, I think I’ll just reinforce the motor shelf and call it good…I really don’t need to be chasing a non-problem. It’ll just give me a headache trying to figure out why the problem I apparently don’t have, seemed to be present before.
-Casey
valveitude said:
My pulley is about 1cm. Originally the Teres motor shipped with a somewhat larger pulley and used a silk string. Problem with the silk is that the knot is going to cause a slight blip each time around. They have since gone to a Mylar (polyester) belt. The belt is (was) spliced with a small section of and adhesive tape. Mine lasted about 6 months before the adhesive failed. So I made my own.
I took clear shipping tape, cut it to the width I wanted, butted the ends (but at an angle, not perpendicular - to create a less abrupt change in flex) and joined them with about a 2cm section of tape - adhesive to adhesive. Then I coated the exposed adhesive with baby powder, turned the belt so adhesive side is out and installed it. Been using it for over a year now.
But, I think I'm going to look for some very thin polyester tape and make a belt with maybe two or three layers. That way I can make an even more gradual transition with the splice regions.
Sheldon
Sheldon-
I thought that might be the case from what I remember from the Teres project. This was actually one of the reasons I opted for the low rpm motor approach..it uses a larger pulley(.65" OD in my case with the 600rpm motor). I see the advantage as two fold 1) it makes for an easier job for the splice to roll around it (the splice takes up a smaller percentage of the belt on the pulley as it rolls around), and 2) all things being equal, it requires less belt tension for the same amount of pulley adhesion (more surface area to grab hold of), thus , putting less strain on the splice. In my earlier attempts I hadn't noticed any splice noise, but you have raised a flag.
Might I suggest a VHS splicing block? I cringed when I priced them, but after attempting a splice without one, I took the plunge. Essentially it's a tape "miter block" that keeps the tape ends lined up, and provides for a perfect cut. I got the "real" splicing tape at the same time, but found Scotch brand celophane tape to work and look nicer. I've ruined several belts in my adventure, but have'nt had a splice fail.
-Casey
I thought that might be the case from what I remember from the Teres project. This was actually one of the reasons I opted for the low rpm motor approach..it uses a larger pulley(.65" OD in my case with the 600rpm motor). I see the advantage as two fold 1) it makes for an easier job for the splice to roll around it (the splice takes up a smaller percentage of the belt on the pulley as it rolls around), and 2) all things being equal, it requires less belt tension for the same amount of pulley adhesion (more surface area to grab hold of), thus , putting less strain on the splice. In my earlier attempts I hadn't noticed any splice noise, but you have raised a flag.
Might I suggest a VHS splicing block? I cringed when I priced them, but after attempting a splice without one, I took the plunge. Essentially it's a tape "miter block" that keeps the tape ends lined up, and provides for a perfect cut. I got the "real" splicing tape at the same time, but found Scotch brand celophane tape to work and look nicer. I've ruined several belts in my adventure, but have'nt had a splice fail.
-Casey
Valvy, in your opnion, haveing gotten so far.
Do you think I would need lots of training to figure out how to make my platter and bearing assemblies etc on my lathe... also its not very highly accurate, Are there things one could do diffirently that you thought of that would provide an easier construction etc, even if at the price of some of the performance gains you made.
I.e. do you reccon a noob turner could make something that plays records better than a fleamarket TT?
Last time I worked on a lathe was in high school during the previous century, and those were wood lathes.
I watched some online movies on turning metal and it doesn't look too bad, working with wood still teaches you not to try to remove material on the wrong side of the turn etc, and some basic safety precautions...
Do you think I would need lots of training to figure out how to make my platter and bearing assemblies etc on my lathe... also its not very highly accurate, Are there things one could do diffirently that you thought of that would provide an easier construction etc, even if at the price of some of the performance gains you made.
I.e. do you reccon a noob turner could make something that plays records better than a fleamarket TT?
Last time I worked on a lathe was in high school during the previous century, and those were wood lathes.
I watched some online movies on turning metal and it doesn't look too bad, working with wood still teaches you not to try to remove material on the wrong side of the turn etc, and some basic safety precautions...
Hey Nordic
Jump in, the waters fine. Just make sure you have a large scrap box for all the pieces you'll roach before you get it right. Teaching your head is the easy part, teaching your hands is a question of time and doing.
To start with, I would download a book or 2 from the beginning of the last century, such as
this one , a good catalog like this one , and I can't recommend this series of books from the late Dave Gingery strongly enough...he will show you how to make and use anything you could ever need. I have them, and though I never built his machines, I learned more practical how-to from him than any other source.
If you decide to go for it, email me, and I'll help where I can.
-Casey
Jump in, the waters fine.
Just make sure you have a large scrap box for all the pieces you'll roach before you get it right. Teaching your head is the easy part, teaching your hands is a question of time and doing.To start with, I would download a book or 2 from the beginning of the last century, such as
this one , a good catalog like this one , and I can't recommend this series of books from the late Dave Gingery strongly enough...he will show you how to make and use anything you could ever need. I have them, and though I never built his machines, I learned more practical how-to from him than any other source.
If you decide to go for it, email me, and I'll help where I can.
-Casey
I've been reading through your thread - lovely work. I'm not sure if I'm clear on what your current motor assembly is like, but I have a thought for you.
The motor vibrates because its torque isn't perfectly smooth. If you can't smooth the torque, you need to filter it. You've added a massive flywheel to your pulley and then a flexible coupler to the motor. In this way, you aim to filter the motor noise from reaching the pulley. There's another approach you might want to consider. Couple the motor solidly to the flywheel but mount the motor body really compliantly so that instead of the motor being fixed and driving vibration into the pulley, the pulley/flywheel is fixed and the motor drives its vibration into its own (much smaller mass). The filtering will be down to the ratio of the two masses. As a motor suspension, I'd suggest a sheet of latex taken from the palm of a surgical glove (chemist's shop) or a from a latex bicycle inner tube (upmarket bicycle shop). The current to your motor is minuscule, so you could use pick-up arm wires inside your housing to avoid bridging the suspension and to couple between the motor wires and the thicker wires from your power supply.
The motor vibrates because its torque isn't perfectly smooth. If you can't smooth the torque, you need to filter it. You've added a massive flywheel to your pulley and then a flexible coupler to the motor. In this way, you aim to filter the motor noise from reaching the pulley. There's another approach you might want to consider. Couple the motor solidly to the flywheel but mount the motor body really compliantly so that instead of the motor being fixed and driving vibration into the pulley, the pulley/flywheel is fixed and the motor drives its vibration into its own (much smaller mass). The filtering will be down to the ratio of the two masses. As a motor suspension, I'd suggest a sheet of latex taken from the palm of a surgical glove (chemist's shop) or a from a latex bicycle inner tube (upmarket bicycle shop). The current to your motor is minuscule, so you could use pick-up arm wires inside your housing to avoid bridging the suspension and to couple between the motor wires and the thicker wires from your power supply.
Hello EC8010,
Thank you kind sir.
The “real time” nature of this thread has a down side at times, the narrative can become disjointed. I explained the theory of my new motor mount in this post, 11 pages back (I have since dumped the caged bearings). I believe, other than semantics and material choices, it matches up pretty well with your suggestion. The final construction is described in this post.
The next five pages covers me whining about a problem that actually doesn’t exist. While I was repositioning the motor to try (unsuccessfully) to hear any noise with my mechanics stethoscope, I inadvertently pinched the motor leads between the housing and the bottom plinth. When this happened, the bottom plinth started vibrating bad enough to actually hear it standing above it. I mistakenly believed the mechanical vibration of the wires was enough to set up a resonance in the plinth, I have since been unable to duplicate the problem. I now believe that when I pinched the wires, I put enough tension on them to pull the motor over enough to make contact with the housing..bypassing the isolation. Regardless of the root cause of my “one off” noise problem, it is, as it turns out, a non problem.
The fine wire pigtail suggestion is a good one, and it’s on deck as plan “B”. I am first going to wind the wires into a coil (spring), and couple them to the housing with a grommet fashioned from Sorbothane.
Bottom line…my “energy prison” of a motor mount has lowered any noise/vibration to the point that it isn’t possible to hear it with mechanics stethoscope anywhere on the motor housing, or the plinth it is sitting on. I realize this to be a pretty large claim, in fact, I continue to call :bs: on myself, and try again in vain to hear anything..there simply isn’t anything to hear.
In the beginning, I stated that I believe a synchronous ac motor has the advantage of a dc motor in the speed stability dept., and IF I could get one to run as quietly as the best dc motors, I would have the best of both worlds..I now do
-Casey
Thank you kind sir.
The “real time” nature of this thread has a down side at times, the narrative can become disjointed. I explained the theory of my new motor mount in this post, 11 pages back (I have since dumped the caged bearings). I believe, other than semantics and material choices, it matches up pretty well with your suggestion. The final construction is described in this post.
The next five pages covers me whining about a problem that actually doesn’t exist. While I was repositioning the motor to try (unsuccessfully) to hear any noise with my mechanics stethoscope, I inadvertently pinched the motor leads between the housing and the bottom plinth. When this happened, the bottom plinth started vibrating bad enough to actually hear it standing above it. I mistakenly believed the mechanical vibration of the wires was enough to set up a resonance in the plinth, I have since been unable to duplicate the problem. I now believe that when I pinched the wires, I put enough tension on them to pull the motor over enough to make contact with the housing..bypassing the isolation. Regardless of the root cause of my “one off” noise problem, it is, as it turns out, a non problem.
The fine wire pigtail suggestion is a good one, and it’s on deck as plan “B”. I am first going to wind the wires into a coil (spring), and couple them to the housing with a grommet fashioned from Sorbothane.
Bottom line…my “energy prison” of a motor mount has lowered any noise/vibration to the point that it isn’t possible to hear it with mechanics stethoscope anywhere on the motor housing, or the plinth it is sitting on. I realize this to be a pretty large claim, in fact, I continue to call :bs: on myself, and try again in vain to hear anything..there simply isn’t anything to hear.
In the beginning, I stated that I believe a synchronous ac motor has the advantage of a dc motor in the speed stability dept., and IF I could get one to run as quietly as the best dc motors, I would have the best of both worlds..I now do
-Casey
I'm glad to hear the vibration problems have been resolved - clearly I hadn't been paying sufficient attention as I read through. Accidentally short-circuiting your suspension sounds highly likely. I must say I'm most impressed with your improvised tools. I haven't made a turntable, although I've made arms (bought a lathe specifically for the last one). I might have to consider making a turntable...
EC8010-
That makes two of us brother . Killing the blasted motor noise was far and away the biggest challenge of this project. Up until this point in the project, I was pretty much winging it with a general idea of what I wanted to do, and some hand scribbled drafts. The noise problem required some actual engineering, and a whole lot of experimentation. In retrospect, It’s easy to see why most ultra-fi table projects opted for the challenges of getting a stable speed from dc, as opposed to trying to get quiet ac.
Agreed. The psychological bruising I took from the many failed ideas I had come up with to eliminate my noise, predisposed me to suspecting the worst. Looking back, this really is the only explanation that makes sense.
Thanx. I have to give a lot of credit to Dave Gingery, and his books I recommended to Nordic. This guy figured out how to build a whole series of machine tools, starting from hand tools and garden supplies. I learned the concept of “making the tool to make the tool” from him. He learned it by reviewing the history of the evolution of the metal working industry.
It has been my experience that the little stuff is far more difficult than the larger (my battle with my motor spindle being the latest example). Not only do your tolerances shrink with the scale, but, the materials have a harder time withstanding the forces involved with peeling off metal. If you can make all the little bits involved in the construction of an arm, you surely have the skills to take on a table.
-Casey
That makes two of us brother
. Killing the blasted motor noise was far and away the biggest challenge of this project. Up until this point in the project, I was pretty much winging it with a general idea of what I wanted to do, and some hand scribbled drafts. The noise problem required some actual engineering, and a whole lot of experimentation. In retrospect, It’s easy to see why most ultra-fi table projects opted for the challenges of getting a stable speed from dc, as opposed to trying to get quiet ac.Agreed. The psychological bruising I took from the many failed ideas I had come up with to eliminate my noise, predisposed me to suspecting the worst. Looking back, this really is the only explanation that makes sense.
Thanx. I have to give a lot of credit to Dave Gingery, and his books I recommended to Nordic. This guy figured out how to build a whole series of machine tools, starting from hand tools and garden supplies. I learned the concept of “making the tool to make the tool” from him. He learned it by reviewing the history of the evolution of the metal working industry.
It has been my experience that the little stuff is far more difficult than the larger (my battle with my motor spindle being the latest example). Not only do your tolerances shrink with the scale, but, the materials have a harder time withstanding the forces involved with peeling off metal. If you can make all the little bits involved in the construction of an arm, you surely have the skills to take on a table.
-Casey
valveitude said:
A college friends father was a retired tool maker from General Dynamics in San Diego (they made thousands of B-24' during WWII). He had a lath, a drill press, and and some x/y tables he could rig for milling. From that he made pretty much anything you could imagine. If he needed some hard to get screw size, he made em. Big deal right? Well, if he needed more than a couple, he'd make a tool to ROLL them. He made a 32' powerboat in his backyard. Started with a model he floated in the bathtub, built a full sized male plug, layed up a female mold, flipped it over and layed up a fiberglass hull. Half the hardware on the boat was titanium that he got from the Convair (the newer name for GD) weekend surpluss sales. Built pretty much everything himself, including the steering hydraulics. DIY fanatic for sure.
Update on the belt thump issue: I ordered some 3M 850 polyester tape from McMaster Carr. It's 1/4" wide and the film is 1mil (0.025mm) thick. Spliced up a belt as I described before. I also ordered a small piece of Sorbathane and, following your lead - in a halfdonkeyed way, put small pieces under the motor. The good news is that there is no noise discernible from the motor or tape splice. Bad news is that I now have to come up with a more permanent solution. The problem with this is that, besides being hokey, the pull of the belt gradually tips the motor a little - still works, but I don't like it. I'll think about it some more.
Sheldon
Sheldon-
Somtimes half a donkey is all one needs. Where did you source the Sorbothane? I have only seen it at Edmund Scientifics, and athletic stores in the form of running shoe insoles. When the stuff hit the scene in the early 80's, I thought it would become more widely used..alas the digital thingies came out about the same time, relagating it's life to pampering abused feet.
Egg-suh-lent.
You are witnessing the unique properties of Sorbothane. It's "liquid like" properties "flow" rather than stretch or compress. The first suggestion that comes to mind, is to make a "guy line" out of thread opposite of the platter. This would offset the belt pull, allowing the motor to "sink" square to the platter. You can un-hokey the cludge after you work out the mechanics.
-Casey
Somtimes half a donkey is all one needs
. Where did you source the Sorbothane? I have only seen it at Edmund Scientifics, and athletic stores in the form of running shoe insoles. When the stuff hit the scene in the early 80's, I thought it would become more widely used..alas the digital thingies came out about the same time, relagating it's life to pampering abused feet.Egg-suh-lent.
You are witnessing the unique properties of Sorbothane. It's "liquid like" properties "flow" rather than stretch or compress. The first suggestion that comes to mind, is to make a "guy line" out of thread opposite of the platter. This would offset the belt pull, allowing the motor to "sink" square to the platter. You can un-hokey the cludge after you work out the mechanics.
-Casey
Hi Everyone ! 
, and remember one thing above all else ..... N Joy the Musik !!! 
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