The mass you are measuring has no effect on the force at the stylus LP interface. There is not 30g more force on the LP from the stylus, if tracking force is set at 1.5g for both arms 1.5g is the force the stylus will impart on the LP.
This mass you measured will be part of the moment of inertia calculation that will impact tonearm effective mass.
To my humble standards it is superb, altough i listened to it on a home made tonearm with twice the weight of the original B&O tonearm and 1.2 inch longer .I can't say it's better than shure v15type3, it's just that it's not worse.I don't have a Jico stylus on Shure, i have no idea of the difference though...
Last edited:
No Effective mass (EM) does not cause damage to vinyl. You match the arm EM to the cartridges compliance to have resonance around 10Hz. Unless this match is so bad it causes miss tracking it will not damage the vinyl
Vertical warps and sideways movement caused by vinyl hole eccentricity will definitely make that effective mass inertia dangerous otherwise we wouldn't already have a clash about your SAT toneram. https://www.diyaudio.com/forums/ana...t-pseudo-magnetic-levitation.html#post6713752
Well, longer tonearm length need not increase effective mass. By coincidence of maths, contribution from tonearm tube simply relates to its mass. So if yer can arrange for the tube to be of the same mass, yer ends up with the same effective mass. Give or take adjustment for new counterweight position, that comes out in the wash.
Mass at the headshell end is what it is. Ta da long tonearms can be similar effective mass to standard lengths. Check it out.
ttfn LD
Mass at the headshell end is what it is. Ta da long tonearms can be similar effective mass to standard lengths. Check it out.
ttfn LD
I found this blast from the past that explains, amongst other things how to measure the effective mass of a tonearm.
Principle: To measure actual tonearm effective mass, all one needs to do is determine the moment of inertia of the tonearm about the pivot, then calculate the equivalent mass required at the effective tonearm length to provide the same moment of inertia, and that mass is then the effective mass of the tonearm.
Step1 The tonearm is a lever balanced about the pivot. The vast majority of mass on one side of the lever is a lump mass in the form of the counterweight. So weigh the counterweight (mass m [kg]) measure the distance from the centre of the balanced counterweight to the pivot with a ruler (r [m]), and then calculate moment of inertia from I=m*r^2 [kgm^2]
Step2 To evaluate MOI of the cartridge side of the tonearm, remove the counterbalance and cartridge (inc mountings), then use a weighing scale to measure the weight W of the tonearm at the headshell end, with the tonearm parallel to the platter. W is half the weight of the cartridge side of the tonearam (less a small bit for the stub - ignore), so the mass Z of the cartridge side of the tonearm Z = 2*W (kgf), and since it is vertical Z is also the mass in kg. The effective length L can either be measured (between stylus tip and pivot) or looked up from published figures for the tonearm. Then calculate moment of inertia from I = Z*(L^2)/3 [kgm^2]
Step 3 Calculate the total moment of inertia I(tot)
I(tot) = [m*(r^2)] + [Z*(L^2)/3] kgm^2
Then effective mass M at effective length L is given by
M*L^2 = [m*(r^2)] + [Z*(L^2)/3] kgm^2
So M = ([m*(r^2)] + [Z*(L^2)/3])/(L^2) kg
which reduces to
M = [m*(r^2/L^2)] + [Z/3] kg
In itself, this is an interesting result. It shows the contribution to effective mass from each side of the tonearm, mostly it comes from the cartridge side. It shows what to vary if one seeks to increase/decrease effective mass, principally the mass of the cartridge side of the tonearm, Z. But some influence is also possible from a heavier counterweight, and in a non-intuitive direction perhaps (heavier = lower M because balancing distance r influences M as power of 2).
For S shaped tonearms, would need to evaluate the MOI differently. Same for tapering mass/length arms. For tubular arms with detachable headshells, MOI of arm and headshell can be evaluated seperately and added together, that is a principle of MOI, contributions of coupled parts can simply be added. The stub is relative low mass and close to the pivot. One could correct, but i think it only makes a few % difference and is OK to ignore. All of these measurements/ calcs are just for tonearm, no cartridge or fixtures fitted. Add the cartridge/fixture mass in the normal way to obtain total effective mass.
LD
Principle: To measure actual tonearm effective mass, all one needs to do is determine the moment of inertia of the tonearm about the pivot, then calculate the equivalent mass required at the effective tonearm length to provide the same moment of inertia, and that mass is then the effective mass of the tonearm.
Step1 The tonearm is a lever balanced about the pivot. The vast majority of mass on one side of the lever is a lump mass in the form of the counterweight. So weigh the counterweight (mass m [kg]) measure the distance from the centre of the balanced counterweight to the pivot with a ruler (r [m]), and then calculate moment of inertia from I=m*r^2 [kgm^2]
Step2 To evaluate MOI of the cartridge side of the tonearm, remove the counterbalance and cartridge (inc mountings), then use a weighing scale to measure the weight W of the tonearm at the headshell end, with the tonearm parallel to the platter. W is half the weight of the cartridge side of the tonearam (less a small bit for the stub - ignore), so the mass Z of the cartridge side of the tonearm Z = 2*W (kgf), and since it is vertical Z is also the mass in kg. The effective length L can either be measured (between stylus tip and pivot) or looked up from published figures for the tonearm. Then calculate moment of inertia from I = Z*(L^2)/3 [kgm^2]
Step 3 Calculate the total moment of inertia I(tot)
I(tot) = [m*(r^2)] + [Z*(L^2)/3] kgm^2
Then effective mass M at effective length L is given by
M*L^2 = [m*(r^2)] + [Z*(L^2)/3] kgm^2
So M = ([m*(r^2)] + [Z*(L^2)/3])/(L^2) kg
which reduces to
M = [m*(r^2/L^2)] + [Z/3] kg
In itself, this is an interesting result. It shows the contribution to effective mass from each side of the tonearm, mostly it comes from the cartridge side. It shows what to vary if one seeks to increase/decrease effective mass, principally the mass of the cartridge side of the tonearm, Z. But some influence is also possible from a heavier counterweight, and in a non-intuitive direction perhaps (heavier = lower M because balancing distance r influences M as power of 2).
For S shaped tonearms, would need to evaluate the MOI differently. Same for tapering mass/length arms. For tubular arms with detachable headshells, MOI of arm and headshell can be evaluated seperately and added together, that is a principle of MOI, contributions of coupled parts can simply be added. The stub is relative low mass and close to the pivot. One could correct, but i think it only makes a few % difference and is OK to ignore. All of these measurements/ calcs are just for tonearm, no cartridge or fixtures fitted. Add the cartridge/fixture mass in the normal way to obtain total effective mass.
LD
Three ways to help reduce vibration in long arms -
Use cheep alloy ( I think this was previously a tent pole.
Drill holes in it, I coped the pattern from a modified Rega arm.
Machine it to ( three, in this case ) diameters, I guess you could do something similar with a drill and emery paper if you didn't have access to a lathe.
"Archery arrow shafts... Range of mass and stiffness and anti vibe coatings LD"
It's what i used first, actually one of the best and it prooved to be a terrible idea...Its alloy is brittle and trying to drill big holes in it can cause it to split or break, then it became a singing object by itself, a true resonating box .Maybe laser cutting would work better in that avionics 0.3mm thick wall alloy tube .Flat pcb tonearm is 100 times less prone to vibrations while 2...5 times less heavier than usual tonearms and you only need a good pair of scissors to cut it.Unfortunately the cart mass is 10 times higer than the tonearm's so the longer the tonearm, the higher contribution of cartridge, no matter the weight of the tonearm itself.
It's what i used first, actually one of the best and it prooved to be a terrible idea...Its alloy is brittle and trying to drill big holes in it can cause it to split or break, then it became a singing object by itself, a true resonating box .Maybe laser cutting would work better in that avionics 0.3mm thick wall alloy tube .Flat pcb tonearm is 100 times less prone to vibrations while 2...5 times less heavier than usual tonearms and you only need a good pair of scissors to cut it.Unfortunately the cart mass is 10 times higer than the tonearm's so the longer the tonearm, the higher contribution of cartridge, no matter the weight of the tonearm itself.
Last edited:
Hi, dreamyh
If you have access to a lathe, the Easton 2712 aluminum arrow shaft can make an excellent tonearm tube. This is the max legal diameter arrow shaft for competition matches. The OD is aprox .440" with .012 wall thickness. To damp any resonances I made from magnesium 2 hourglass shaped "washers" that were about .4" long. Picture 2 .177 cal. flat nose pellets glued face to face. These washers were made a snug fit for the ID of the shaft. I drilled a 3mm hole through both and used thin wall teflon tubing to go all the the tube, for the wires to fit through. I then used powdered cork to fill the space between washers for dampening. You can put these washers at any arbitrary place in the tube. This procedure sounds harder then it actually is, but it works.
Good luck.
Joe
Meet Joe, and his amazing DIY horn speakers - YouTube
If you have access to a lathe, the Easton 2712 aluminum arrow shaft can make an excellent tonearm tube. This is the max legal diameter arrow shaft for competition matches. The OD is aprox .440" with .012 wall thickness. To damp any resonances I made from magnesium 2 hourglass shaped "washers" that were about .4" long. Picture 2 .177 cal. flat nose pellets glued face to face. These washers were made a snug fit for the ID of the shaft. I drilled a 3mm hole through both and used thin wall teflon tubing to go all the the tube, for the wires to fit through. I then used powdered cork to fill the space between washers for dampening. You can put these washers at any arbitrary place in the tube. This procedure sounds harder then it actually is, but it works.
Good luck.
Joe
Meet Joe, and his amazing DIY horn speakers - YouTube
Hy Joe!
I think i made smth a bit similar in principle around 2017...2018, a tangential tonearm floating on water made of two carbon fiber cones one into another fixed with polyurethanic foam tape working on a floating structure on watter.I coppied the idea from an old gentleman that seem to have died or just dissapeared along with its youtube video and blog.Unfortunately i don't know any conical arrow made out of that alloy.A friend of mine uggested to use some polyurethanie spacers to keep the wires in the middle of the alloy tube just to get rid of the interaction between the wires and tube but there was more to it and i just needed some very light tonearm so i changed to flat tonearms idea and i'm not ready to look back because i consider now Jiri Janda flabby flat tonearms far superior to tube ones.
I saw your youtube clip and the way you built damping those horns seem to have the key to improve te Avantgade speakers.I liked it!
I think i made smth a bit similar in principle around 2017...2018, a tangential tonearm floating on water made of two carbon fiber cones one into another fixed with polyurethanic foam tape working on a floating structure on watter.I coppied the idea from an old gentleman that seem to have died or just dissapeared along with its youtube video and blog.Unfortunately i don't know any conical arrow made out of that alloy.A friend of mine uggested to use some polyurethanie spacers to keep the wires in the middle of the alloy tube just to get rid of the interaction between the wires and tube but there was more to it and i just needed some very light tonearm so i changed to flat tonearms idea and i'm not ready to look back because i consider now Jiri Janda flabby flat tonearms far superior to tube ones.
I saw your youtube clip and the way you built damping those horns seem to have the key to improve te Avantgade speakers.I liked it!
Attachments
Last edited:
Yup all interesting stuff. Tonearm tube is basically a windchime and how natural resonances are managed is the crux be it holes coatings internal damping etc etc. Physics of it says the outer coating is the place to have a damping layer, ie a material which is lossly when it flexes and only has to be thin. LD