What's with all this leveling stuff? I level clocks for a nice even tic-tock by ear. Takes about twenty seconds in the dark. I level the LT arm by balancing the arm wand so it stays about horizontal and then set the tube so the carriage does not run one way or the other of its own accord. That's all there is to it. Then set the tracking force. I have mentioned several times how I do that. What I've observed is that once the arm is working nicely the arm will track rather well with no skips when the tube is visibly out of level, either uphill or down hill. Your guess is as good as mine how many degrees. What I'm saying is that in the face of all this effort to level and get things right on the nose, if you are still having problems, you have things to correct other than leveling.
As far as vibrations go, this forum is overflowing with contradictory ideas and beliefs about damping, using spikes, vibration sinks, one material or another etc, etc, etc. If you can hear needle talk from across the room with your hearing aid turned off, yes you have a problem. I built a simple cantus style carriage with a <1" square piece of wood 0.1" thick for a head shell. Then 2 short brass tubes for a wand. My 4 bearings ride on a glass tube firmly glued in a block of hardwood. On a loud Stravinsky recording I must listen close up in a quiet room to hear anything from the needle. I must be converting almost every bit of vibrational energy to electrical energy and on to the preamp. Someday I may try decoupling the tube from the rest of the structure. As of now I do not feel it is necessary.
These are my thoughts and experiences. You and others may have experienced otherwise. This is a good place to get it out in the open and learn from others.
BillG
So I just went back and reread these postings to find out what we are talking about. The first thing that hit me was Chokesrule talking about vibrational energy from tapping on the arm and/or elsewhere. That for starters gives a source for the vibrational energy. Here I am reminded of my small daughter complaining "but it only hurts when I touch it" to which Mommy replies, "so don't touch it". The tap test as far as I know was intended to reveal ringing in the mechanism. Hit anything with a hammer and it will make noise. The "dull thud" is supposed to demonstrate that the vibration is well damped and there is no ringing. So stop tapping and the noise will go away. Now with no impacts from tapping, where is the vibration coming from that reaches the needle? You found a source? Perhaps the approach should be eliminating the vibration right there. If it is a vibrating TT, stop it from vibrating rather than putting ear muffs on the tone arm parts.
We haven't addressed the needle talk issue I mentioned in my previous post. More careful reading of Chokesrule's post leads me to think that is not the issue he is concerned with. So for now, let's put that one aside.
Looking at the laminated plexiglass/perspex base sitting on the granite slab
suggests a test that could be easily made. Move the arm around to the back side of the TT and attach it to some mounting block which is not directly connected to the TT. Also put a brick or other heavy weight on the arm mount. Give it some real mass. Then see how well or poorly the arm performs and do report.
I've pontificated quite enough for tonight. Please give it some thought and do contradict me on any or all points if you take exceptions.
Rgds,
BillG
Bill, Chokesrule,
With the arm as designed I have to put my ear within a foot or two to hear any sound coming from the cartridge without amplification, which means maximum energy is transferred to the coils/magnet structure. This means the carriage is doing its job, but of other importance is energy reaching the carriage, this as designed is dealt with well and honestly the only damping per se on the whole TT and arm is o rings for the arm and constrained layer damping for the motor plinth. Decoupling is of utmost importance, on a side not i did a mod for this on a pair of Martin Logan ESL's for the stator to cabinet which made a remakable improvement, often "damping", really screws it up but one needs to strategically apply both as that time constant thing can come to bite us in the a$&
.
Colin
With the arm as designed I have to put my ear within a foot or two to hear any sound coming from the cartridge without amplification, which means maximum energy is transferred to the coils/magnet structure. This means the carriage is doing its job, but of other importance is energy reaching the carriage, this as designed is dealt with well and honestly the only damping per se on the whole TT and arm is o rings for the arm and constrained layer damping for the motor plinth. Decoupling is of utmost importance, on a side not i did a mod for this on a pair of Martin Logan ESL's for the stator to cabinet which made a remakable improvement, often "damping", really screws it up but one needs to strategically apply both as that time constant thing can come to bite us in the a$&
.Colin
Thanks chokesrule, good pictures- I see the slots in the base for adjusting.
BillG, I had another look at your base on page 34. Is it just the screws in the base that you use to raise and lower the tube? I know you asked what's with all this leveling stuff but everything gets adjusted at some point - so how is yours done?
BillG, I had another look at your base on page 34. Is it just the screws in the base that you use to raise and lower the tube? I know you asked what's with all this leveling stuff but everything gets adjusted at some point - so how is yours done?
Hi Bob,
The 4 screws are stainless steel with reasonably sharp points. They perform the leveling function. Once leveled a bolt in the center of the base will tie the whole thing down with tension. They also provide an energy transfer path.
By no means was I suggesting that leveling the arm was not needed. What I was commenting on was what appears to be excessive concern with leveling techniques, lasers for instance, and excessive twiddling to get it just right.
Now for energy getting back into the cart/stylus. Last night I tried giving my glass rod a couple of good whacks up within a half inch of the tube mounting block and heard nothing at all. The needle was on the record and the volume was set for normal room listening. With the volume set very loud yes there was a discernible tapping. Now at nine inches away at the free end of the tube a low frequency thud could be heard. Right now my arm is being held tightly to the plinth with weight. I haven't wanted to drill the plinth for the tensioning screw yet. So my tapping and banging on the free end needed to be held to a value that wouldn't send the arm flying. So I repeat my question. Where is all this energy coming from that you are guarding against getting back into the cart? And if you can identify that wouldn't you be far better off eliminating that at its source. Floating the glass tube to block it breaks the energy drainage path for cartridge/stylus generated vibration. Sounds like your systems are acting like giant microphones trying to cut modulated grooves back into the record. For that matter, how much energy is being picked up by the record itself acting as a microphone diaphragm and sending energy straight back into the stylus? Take the stylus off the record and see how much. Then place the stylus on a record mat. Imho there are far larger fish to fry than floating the tube.
ENUFF for today!
BillG
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If you send a vibration down the arm then chances are you will hear something. By the very nature of this arm, it's not "isolated" at all parts. If you want that then use an air bearing. As long as there is physical contact of the arm to the rod then there is the possibility of some sort of noise coming from that direction.
Chances are that noise would be coming from your motor as it runs. That being the case, work on the motor. Even if you completely isolate the rod from the rest of the system you haven't achieved anything because the stylus will be touching the record. As said before by another poster, look for what is generating the noise and fix that .... then your problem is solved.
I know that on my Thorens td-150, at 33rpm the motor is quiet as a church mouse. At 45rpm however, you can feel the rumble from the motor if you touch the plinth. Instead of spending too much time with it, I just don't play 45 rpm records on my Thorens. Problem averted.
If you want to have a floating arm "just because", you could think about suspending it with fishing line at both ends, but then you will get into other problems like the torsional forces on the arm from the cart moving.
Chances are that noise would be coming from your motor as it runs. That being the case, work on the motor. Even if you completely isolate the rod from the rest of the system you haven't achieved anything because the stylus will be touching the record. As said before by another poster, look for what is generating the noise and fix that .... then your problem is solved.
I know that on my Thorens td-150, at 33rpm the motor is quiet as a church mouse. At 45rpm however, you can feel the rumble from the motor if you touch the plinth. Instead of spending too much time with it, I just don't play 45 rpm records on my Thorens. Problem averted.
If you want to have a floating arm "just because", you could think about suspending it with fishing line at both ends, but then you will get into other problems like the torsional forces on the arm from the cart moving.
Bob, Sorry, but I didn't answer your question. always hate it when other people do that to me. The 4 screws can give limited vertical adjustment but their primary function is to compensate for any lack of the tube being level. I don't remember if the picture shows it but there is a grub screw in the side of the aluminum cylinder. There is a 3/8" dia rod press fit into the bottom of the wooden block. That rod is a slip fit into larger aluminum cylinder which is part of the base. Vertical height is adjusted by loosening the grub screw and raising or lowering the wood block. Then snug up the grub screw. Sorry for not making that plain.
BillG
I think its all a question of extremes. This are is never being sold as "the best" its just mega good for its money. So air bearings are on a whole other level : if you want to take it that far. It is so cheap to decouple the glass from the arm and so easy to do : its only common sense to do it. Yes Bill and Lexi there is a lot in what you say probably. If cost massive amounts of money to decouple (like making an air bearing set up) you would be right. But in this case why take the chance? If you had a headache would you rather be in a crowded room of people yelling or just a few? I only knew that I had a problem with noise reaching the needle. Decoupling like that has tremendously reduced that noise.MUCH more so than all the numerous thinks I have done to the actual table. Bill from your posts I think my problem was much more severe than yours. So I am definitely looking at using wood now to make an arm and see what happens.
Sorry mortron
Seemingly not well enough.
Regards
nested filters in feedback
Hi Colin, I'm trying to put together my own valve RIAA stage, and could use a hint: I've seen some circuits that nest a passive 2122hz filter within an active 50/500hz feedback loop, and can't help feeling there would be some interaction between the bands in this configuration. Have you seen anything like this? All the other active/passive configurations I've seen do not involve nesting one filter within the feedack path of another. I would like to hear your thoughts on this.Bill,
I must say I'm flattered for any sort of reference to any advancement on Bo's work, judging by clearaudios latest offerings it appears it was seminal not to mention not referred to enough, funny enough we share some heritage in my 1/4th swede
Colin
Hi.
I'm quite new to this sight and have just read through this entire thread.
I am currently building a linear tracker. It is of very different design but the principals are similar.
In my opinion the reason this type of arm sounds so good has little to do with the elimination of LTA errors but is due to the fact that much shorter armtubes can be used. The ridgidity of a tube is proportional to 1/the third power of its length so a tube of 1/3 length is 27 times as ridged, a 1/4 length 64 times and so forth. A more ridgid arm will deflect less due to the forces acting on it by the stylus, holding the cartridge more stablely. As a record play back system is a dynamic system the resonant frequency of the tone arm is even more important than the ridgidity. Resonant frequency is a function of ridgidity and mass, though damping does play a roll. The higher the ridgidity and lower the mass the higher the resonant frequency. With tonearm design the higher the resonant frequency the better. In a ideal arm the resonant frequency would be way above 20khz but this is probably not possible.
The SME V, which is a very good pivoted arm, has a resonant frequency, with average mass cartridge fitted, of about 1khz. My back of an envelpope calculations based on the arm design of this thread, using the types of cartidges you're using, would suggest a frequency of 1 to1.5khz. Not bad at all.
It may be worth considering using a thicker arm tube. Although this will add to the mass of the arm it would also increase the resonant frequency. 2 to 2.5khz should be obtainable with a 12mm od 1mm carbon tube. If the mass is kept to a minimum soley to aid lateral tracking this might not be such a good idea. If the mass is kept low for compliance/effective mass reasons it is worth noteing that the effective mass resonance is tuned in at about 9.5hz as this is the right distance above the highest frequency that significant warps occur, about 6hz. lateral effective mass can be set higher as warps do not effect it. As low frequency musical information is cut only laterally below about 200hz increasing lateral effective mass can have positive gains in low frequency reproduction.
One of the first things I did when designing my arm was build a test rig and measure the actual warp shape of a randomly selected records from my collection both clamped and not clamped. This took weeks but gave me a massive data base from which to work. I agree with Bo that designing an arm to track massive warps is pointless. Its a bit like a formula 1 racing team demonstating their new susspension system by driving their car up a farm track. I'm after formula 1 performance not tractor performance.
I plugged the approx dimensions of your arm into the spread sheets I had developed to ***** the effects of real world warps.
When negatiating the biggest warp on an average record (well clamped) tracking force would increase by about 2%, and on the worst 10% of records by about 3.5%. these are the worst points on those records so variance would be much lower most of the time. A variation in tracking force of this magnitude will probably be inaudile.
More worrying was warp wow. For the average record the peek level of warp wow was 0.2% and for the worst 10% of records 0.45%. Again these are the points and would be much lower averaged over the entire record.
0.1% wow is inaudile (except in a really echoey eviroments)
0.2% wow is about the threshold for normal human hearing
0.3% wow is noticable. You can't hear it as a definate pitch change more as a kind of instability to the sound.
Have any of you who have a working arm of this design noticed this?
A solution would be to lower the track tube to just above the record surface and pass the arm tube above it. This would lower the level of warp wow to below audibility on all but the worst records. The one you wouldn't play anyway.
This would also bring the pivot height of the arm very close to its centre of mass virtually eliminating tracking force variance. The lower track would require to be movable to allow records to be changed, as with the clearaudios. Or is the underslung design neccesary for stability?
The discussions in this thread have helped me improve the design of the wheels in using for my arm though I need to buy a lathe to impliment them. It sound fantastic but mistracks occasionally. The more information I have the better my design will be.
I'm quite new to this sight and have just read through this entire thread.
I am currently building a linear tracker. It is of very different design but the principals are similar.
In my opinion the reason this type of arm sounds so good has little to do with the elimination of LTA errors but is due to the fact that much shorter armtubes can be used. The ridgidity of a tube is proportional to 1/the third power of its length so a tube of 1/3 length is 27 times as ridged, a 1/4 length 64 times and so forth. A more ridgid arm will deflect less due to the forces acting on it by the stylus, holding the cartridge more stablely. As a record play back system is a dynamic system the resonant frequency of the tone arm is even more important than the ridgidity. Resonant frequency is a function of ridgidity and mass, though damping does play a roll. The higher the ridgidity and lower the mass the higher the resonant frequency. With tonearm design the higher the resonant frequency the better. In a ideal arm the resonant frequency would be way above 20khz but this is probably not possible.
The SME V, which is a very good pivoted arm, has a resonant frequency, with average mass cartridge fitted, of about 1khz. My back of an envelpope calculations based on the arm design of this thread, using the types of cartidges you're using, would suggest a frequency of 1 to1.5khz. Not bad at all.
It may be worth considering using a thicker arm tube. Although this will add to the mass of the arm it would also increase the resonant frequency. 2 to 2.5khz should be obtainable with a 12mm od 1mm carbon tube. If the mass is kept to a minimum soley to aid lateral tracking this might not be such a good idea. If the mass is kept low for compliance/effective mass reasons it is worth noteing that the effective mass resonance is tuned in at about 9.5hz as this is the right distance above the highest frequency that significant warps occur, about 6hz. lateral effective mass can be set higher as warps do not effect it. As low frequency musical information is cut only laterally below about 200hz increasing lateral effective mass can have positive gains in low frequency reproduction.
One of the first things I did when designing my arm was build a test rig and measure the actual warp shape of a randomly selected records from my collection both clamped and not clamped. This took weeks but gave me a massive data base from which to work. I agree with Bo that designing an arm to track massive warps is pointless. Its a bit like a formula 1 racing team demonstating their new susspension system by driving their car up a farm track. I'm after formula 1 performance not tractor performance.
I plugged the approx dimensions of your arm into the spread sheets I had developed to ***** the effects of real world warps.
When negatiating the biggest warp on an average record (well clamped) tracking force would increase by about 2%, and on the worst 10% of records by about 3.5%. these are the worst points on those records so variance would be much lower most of the time. A variation in tracking force of this magnitude will probably be inaudile.
More worrying was warp wow. For the average record the peek level of warp wow was 0.2% and for the worst 10% of records 0.45%. Again these are the points and would be much lower averaged over the entire record.
0.1% wow is inaudile (except in a really echoey eviroments)
0.2% wow is about the threshold for normal human hearing
0.3% wow is noticable. You can't hear it as a definate pitch change more as a kind of instability to the sound.
Have any of you who have a working arm of this design noticed this?
A solution would be to lower the track tube to just above the record surface and pass the arm tube above it. This would lower the level of warp wow to below audibility on all but the worst records. The one you wouldn't play anyway.
This would also bring the pivot height of the arm very close to its centre of mass virtually eliminating tracking force variance. The lower track would require to be movable to allow records to be changed, as with the clearaudios. Or is the underslung design neccesary for stability?
The discussions in this thread have helped me improve the design of the wheels in using for my arm though I need to buy a lathe to impliment them. It sound fantastic but mistracks occasionally. The more information I have the better my design will be.
I have approx 150hrs on my 2 different versions of this design.
To my delight I have played some unreplaceable slightly warped albums
over and over, and have not heard a variance in pitch.
I also have some new 180gm pressings that have come out of the sleeve
with a warp or off center hole...These both play amazingly well, so well
that I've not returned them but kept them as proof of performance.....nice.
I dont know if its mentioned, but what type of cartridge/compliance works well
with these types of arms? I have tried many MM type but never a MC.
I have found a cart and needle combo that never miss tracks, and keeps the
VTF proper. Its an older cart and performs multiples better than it has a right to.
So what, if its not a secret......are you guys using for carts on this arm?
To my delight I have played some unreplaceable slightly warped albums
over and over, and have not heard a variance in pitch.
I also have some new 180gm pressings that have come out of the sleeve
with a warp or off center hole...These both play amazingly well, so well
that I've not returned them but kept them as proof of performance.....nice.
I dont know if its mentioned, but what type of cartridge/compliance works well
with these types of arms? I have tried many MM type but never a MC.
I have found a cart and needle combo that never miss tracks, and keeps the
VTF proper. Its an older cart and performs multiples better than it has a right to.
So what, if its not a secret...
...are you guys using for carts on this arm?
This arm was, and is designed, built and tested using the lower to mid compliance Audio Technica at120e mm cartridge. I did and still feel top performance or close to should not be a thing that is out of reach of even the smaller budgets. And really it's not, imho the Audio industry can be a sick industry that has unjustly.inflated itself for the nost part, high prices for some thiings built often around a 2 dollar ic.
Colin
Colin
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I agree Colin......why I DIY almost everything.
Thanks for the Cart type your using......I seem to remember reading that
a while back, I assume lower compliance but wasnt positive.
The one I'm using is an ancient AT13Ea......what a sound it produces.
I have to get a better one....thank goodness its "present season"
I'm already thanking my wife, she just doesnt know what for.....
Thanks for the Cart type your using......I seem to remember reading that
a while back, I assume lower compliance but wasnt positive.
The one I'm using is an ancient AT13Ea......what a sound it produces.
I have to get a better one....thank goodness its "present season"
I'm already thanking my wife, she just doesnt know what for.....
Sorry mortron
Seemingly not well enough.
Regards
After 112 pages I had like 4 questions... thats pretty good given my condition. Thanks tho.
Nah, the energy is still there but the shorter the wand the higher dissipation frequency. Or?
The energy is still there. (energy=force x distance) With a more rigid arm tube the same energy will result in a smaller distance, less flexture of the arm tube. This means the axis of the generator in the cartridge will move less relative to the neutral axis of the record groove for the same driving force. An arm tube with a higher resonant frequency and with the same damping factor , same material shorter tube, will resonate for a shorter period of time after an impulse/transient and if the initial displacemt is also less will resonate for a shorter time still.
The way the armtube behaves below it's resonant frequency is much more linear than above it. Harmonics appear above the fudimental not below it. So with a higher rf the arm behavior is more linear.
I definitely was not knocking the design. Many years ago I built a prototype that was very similar to the one being built here. Except it used a knife edge not a glass tube. I was in the lucky possition to have 2 pink triangle anniversaries and 2 ortofon mc3000 cartridges and an sms v at my disposal. I was therefore able to do direct a-b comparisons. My arm beat the sme hands down. The only problems I encountered were:
Warp wow was noticeable on about 1 in 6 records. Hence my asking if this was a problem anyone had noticed. Apparently it isn't.
The arm constantly drifted out of alignment. Poor armbase design on my part.
Niffy