sachu888
Well-Known Member
Another DIY TT,great workmanship
Diy TT project - AudioKarma.org Home Audio Stereo Discussion Forums
Regards,
Sachin
Diy TT project - AudioKarma.org Home Audio Stereo Discussion Forums
Regards,
Sachin
DIY TURNTABLE : ideas and comments.
- Thread starter Hiten
- Start date
I will make only one comment. Your assumption about vinyl contacting the platter are wrong. Just wrong.
I will explain. The physics are such that the forces of the needle in the groove are high enough to excite the vinyl and cause waves of energy to disperse across the vinyl. Without contact to sufficient mass to absorb the energy, the waves will eventually reflect back to the needle (delayed) and smear the sound.
A higher mass and isolated platter in full contact with the vinyl surface is the only way to eliminate (as much as praticable) the energy of the vibrations coming from the forces of the groove on the needle. (There are other factors as well such as the transfer of this energy through the bearing to the plinth etc., however for this converstaion we don't have to go there). If you can hear it acoustically from the needle (meaning not through your system) there is certainly enough energy to vibrate the LP. You have to dampen or absorb that energy in some way or it just reflects back and forth until it is disipated (or more correctly stated it is transformed as kinetic energy to heat). Unfortunately, it gets back into your cartridge before the vinyl makes this energy transfer on its own.
We studied this problem ad nauseum at MIT in the late 70's. The study created two main results in the audio industry: Thicker LP's with more vinyl and huge oversized (riduculously so in some cases) platters. A few products were actually developed that absorbed these forces directly. The Oracle Groove Isolator mat was one that comes to mind. It actually was made of a material that electrostatically bonded to vinyl at the surface to make the LP "stick" to the platter, effectively eliminating all vinyl self-induced resonances. It did this very well.
To float the LP is just a bad idea, and contrary to the actual real world physics involved. Of course if your turntable is a block of wood with a bearing, tonearm and platter and no suspension you have too many other problems right there. Every external vibration is gonna head right to the needle anyway. That's why if you yell load enough into any Rega while it's playing you can hear your voice coming out of the loudspeakers. Yeah ... world class "log with a tonearm" right there. So if you do not have an isolated platter this whole coversation is moot anyway.
jrlaudio
I will explain. The physics are such that the forces of the needle in the groove are high enough to excite the vinyl and cause waves of energy to disperse across the vinyl. Without contact to sufficient mass to absorb the energy, the waves will eventually reflect back to the needle (delayed) and smear the sound.
A higher mass and isolated platter in full contact with the vinyl surface is the only way to eliminate (as much as praticable) the energy of the vibrations coming from the forces of the groove on the needle. (There are other factors as well such as the transfer of this energy through the bearing to the plinth etc., however for this converstaion we don't have to go there). If you can hear it acoustically from the needle (meaning not through your system) there is certainly enough energy to vibrate the LP. You have to dampen or absorb that energy in some way or it just reflects back and forth until it is disipated (or more correctly stated it is transformed as kinetic energy to heat). Unfortunately, it gets back into your cartridge before the vinyl makes this energy transfer on its own.
We studied this problem ad nauseum at MIT in the late 70's. The study created two main results in the audio industry: Thicker LP's with more vinyl and huge oversized (riduculously so in some cases) platters. A few products were actually developed that absorbed these forces directly. The Oracle Groove Isolator mat was one that comes to mind. It actually was made of a material that electrostatically bonded to vinyl at the surface to make the LP "stick" to the platter, effectively eliminating all vinyl self-induced resonances. It did this very well.
To float the LP is just a bad idea, and contrary to the actual real world physics involved. Of course if your turntable is a block of wood with a bearing, tonearm and platter and no suspension you have too many other problems right there. Every external vibration is gonna head right to the needle anyway. That's why if you yell load enough into any Rega while it's playing you can hear your voice coming out of the loudspeakers. Yeah ... world class "log with a tonearm" right there. So if you do not have an isolated platter this whole coversation is moot anyway.
jrlaudio
Last edited:
jrlaudio.
welcome to the forum.
Regards
welcome to the forum.
Wouldn't the heavy platter create more pressure on the bearing and increase noise and rumble. The same energy can travel back to needle again. Will also load the motor. Need to look at the whole turntable to make the best compromise out of this. I am not sure but I guess Disc stabilizer of right material would be a good middle path trade off for this.
Regards
@jrlaudio: the above explanation is quite an ear-opener for me.
I seriously need to re-think my support and isolation. I think I need a complete revamp. I hear the acoustic playback all the time, and though it is natural since I have heard it on all my TTs, as well as that of friends.
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