Conjecture really. The mat I sent a link for I suspect is about 4 mm in two sections. One section seems to be a possible sweat spot of where dymanics and magnetic damping should could exist. 2 sections might be where other factors come in.
I have always found the stock TD124 sounds like something is lightly rubbing on the platter as a resonant sound when the zinc platter. The Cork-Rubber mat seems to cure that without adding new colouration. Having never used the iron platter I can only guess. I was told it was a non magnetic grade. Seems that is untrue or partly true. The addition of very little chromium ( etc ) can make iron non magnetic. Body scanners use this grade. As far as I know it isn't required it be perfect for that. When building them I had a big magnet and made sure we had the right grade. PU hardware also.
It is very interesting to think about metal alloys. Iron in >90% propotions that is hardly magnetic. Lead and tin togehter that melt below the temperature of either metal.
If one measures the vibration of these motors they are both the rotational speed plus as you say double the line frequency. The output looks like older books showing AM radio modulation. I have doubts the potting is a good idea. The problem that remains is output shaft to belt to idler. The TD124 is very good in this area. What is worth looking at is the motor mountings. Very careful tightening or sometimes loosening of the motor makes it quieter. Finger tight can be very good if the laminations are tight. If the bearings are gummed up that can make for noise. When free to move they become quiet. Also when free to move and hot the shaft sits best in the bearing.
Wax is worth a try. It might just take the heat. It might be slightly the better damping idea. My old Trix train set used wax. When I used the transformer to run other things the wax came out.
Wax is worth a try. It might just take the heat. It might be slightly the better damping idea. My old Trix train set used wax. When I used the transformer to run other things the wax came out.
increase distance above the iron
It is so simple to experiment with mats. I've diy'ed many out of various materials, including rubberized cork. At the moment I'm using the stock rubber mat on the stock alu clutch platter. But with the 5mm thick Boston Audio Mat 2 on top. The Mat 2 is a machined graphite mat.
This drops the noise floor and improves clarity audibly.
The plinth is a rough prototype but more than it appears to be. The plinth was partially built within a casting form, then polyurethane foam liquid was poured in up to a predertermined level, then the top layer was glued, fitted and clamped in place. After cure, and after the foam squeeze-out was trimmed away I had a tight foam-filled plinth. Actually the effect radically changed the resonant character of the box. A much faster, shorter resonant sustain.
I'm using fresh mushrooms. for the armboard I'm using modified finger-flex poly grommets to isolate the 1/4" thick armboard from the chassis. Care must be taken to get the armboard level to the chassis. I used automotive feeler gages for that.
The cartridge is the underappreciated but very competant Technics EPC 205C mkII moving magnet with elliptical diamond on a titanium pipe cantilever.
The arm is the Infinity Black Widow. Arm and cartridge resonate at 11hz on the hfn001 test record track 2 side 2. On side one the arm/cartridge tracked successfully all of the torture tracks except the last where there was only a slight buzz. damping fluid in use.
With the moving magnet cartridge there is little concern about magnetic pull toward the iron flywheel underneath. However with the additional 5mm altitude achieved with use of the mat2, moving coil cartridges should benefit as well.
It really seems that once you get the drive train sorted on one of these, and I feel that I have on mine, the next area of focus is on the clutch operated aluminum platter and just how high to make it. Of course one would need to modify the bearing shaft in order to get a longer spindle pin to hold the record. But there are some possibilities here, I'd think.
-Steve
It is so simple to experiment with mats. I've diy'ed many out of various materials, including rubberized cork. At the moment I'm using the stock rubber mat on the stock alu clutch platter. But with the 5mm thick Boston Audio Mat 2 on top. The Mat 2 is a machined graphite mat.
This drops the noise floor and improves clarity audibly.
The plinth is a rough prototype but more than it appears to be. The plinth was partially built within a casting form, then polyurethane foam liquid was poured in up to a predertermined level, then the top layer was glued, fitted and clamped in place. After cure, and after the foam squeeze-out was trimmed away I had a tight foam-filled plinth. Actually the effect radically changed the resonant character of the box. A much faster, shorter resonant sustain.
I'm using fresh mushrooms. for the armboard I'm using modified finger-flex poly grommets to isolate the 1/4" thick armboard from the chassis. Care must be taken to get the armboard level to the chassis. I used automotive feeler gages for that.
The cartridge is the underappreciated but very competant Technics EPC 205C mkII moving magnet with elliptical diamond on a titanium pipe cantilever.
The arm is the Infinity Black Widow. Arm and cartridge resonate at 11hz on the hfn001 test record track 2 side 2. On side one the arm/cartridge tracked successfully all of the torture tracks except the last where there was only a slight buzz. damping fluid in use.
With the moving magnet cartridge there is little concern about magnetic pull toward the iron flywheel underneath. However with the additional 5mm altitude achieved with use of the mat2, moving coil cartridges should benefit as well.
It really seems that once you get the drive train sorted on one of these, and I feel that I have on mine, the next area of focus is on the clutch operated aluminum platter and just how high to make it. Of course one would need to modify the bearing shaft in order to get a longer spindle pin to hold the record. But there are some possibilities here, I'd think.
-Steve
Yes I have done that with the same measurable results results as without potting , best way to decouple the motor is with springs imho.
Yes, I might try wax with a high melting point on my TD-121 motor. Other potting alternatives made for the express purpose might function better, but wax would be more reversible. (I had been considering it for a SL-1200 but that is for another thread.)
@Volken - I would probably also use springs to mount the motor, in addition to potting with wax.
You might want to read Volken's comment above very carefully. I don't think you make an appreciable improvement with wax or anything else outside of the springs.. The windings are wound pretty tightly and impregnated with varnish, they don't really buzz as long as they fit tightly on the core.
Possibly Simone Luchetti's coils (audiosilente) would be a better way to go than wax particularly if we are talking about the version of the E50 in the MKII table which seems to run worse than the others. (I have a 124 and a MKII, never a problem with the E50 in the 124, and almost never not a problem in the MKII)
Possibly Simone Luchetti's coils (audiosilente) would be a better way to go than wax particularly if we are talking about the version of the E50 in the MKII table which seems to run worse than the others. (I have a 124 and a MKII, never a problem with the E50 in the 124, and almost never not a problem in the MKII)
11 Hz to some peoples thinking is a bit high ( Roy Gandy of Rega thought so many years ago ). As the Black Widow needs only added mass to find out it is worth trying. What you might hear is a more open mid range. 6Hz tends to be a bit low. All this depends on how the cartridge works. One of the best sound I ever heard was a Black Widow with Sonus Blue Label ( ADC ? ) at 0.7g on the big Denon DD. Russ Kaufmann later of Morel was insistant that 1g was too much. My ears said he was right. His business partner Norman Solomon said the Denon did not like high tracking weights. It came to pass others thought similar things ( servo's and cogging ). It should be said Denon and JVC DD's can be exceptionally good.
I was thinking more in the realm of the coil vibrating within the core vs the individual wraps of wire. I seem to recall someone had vibration trouble that the solved with cardboard shims or similar to keep the coils from moving.
like a Garrard 301/401, only just three springs.
what if.....you did have a Garrard style cage to hold the motor with springs and especially to hold against all force vectors, including torque action. !
just an idle thought.
-Steve
Have always wondered about spring suspension. If a particular motor has particular frequency vibration band how does one calculate compliance of springs so that it absorbs them ?
Garrard motors have unique suspension. they are at 45 degrees* and if I remember three on top and three on bottom. So more no. of springs means more compliant (soft) springs can be used so would be beneficial. Right ?
* Any reason why they are at 45 degrees ?
Regards.
Garrard motors have unique suspension. they are at 45 degrees* and if I remember three on top and three on bottom. So more no. of springs means more compliant (soft) springs can be used so would be beneficial. Right ?
* Any reason why they are at 45 degrees ?
Regards.
Popular Science - Google Books
Whilst this didn't answer the question I sure want a Scott 710 Turntable now. Seems to be a Lenco only more so. See the Heath active speaker crossover also.
Whilst this didn't answer the question I sure want a Scott 710 Turntable now. Seems to be a Lenco only more so. See the Heath active speaker crossover also.
Any vibration will resolve to a horizontal and vertical coponent, unless it's a purely rotational force that will result in a rotational couple.
But the motor mounting is a vertical mount. Whether grommets or springs, the compliance is mainly in the vertical.
It would seem that a three spring mount would allow little compliance on the rotational, or , because the springs are not designed to offer any rotational or horizontal compliance, might behave outside their design parameter once subjected to a rotational force, providing there is enough rotational force. I'm thinking of torque under load.
It would be interesting to do some further analysis on this subject.
-Steve
I guess major vibrations would be from minor play in bushes and uneven mass in rotating bodies and probably magnetic flux. So suppose we have a worn out idler and little play in the bushings the motor will vibrate like its rocking; which may add to vertical vibrations. how much 45 degree springs control/absorbs that need to be measured.
Will a little vertical play in the idler holding shaft contribute to vertical vibrations ? From cheap record changers experience I suppose the force with which idler connects to motor and platter is tremendous due to its position.
Regards.
Will a little vertical play in the idler holding shaft contribute to vertical vibrations ? From cheap record changers experience I suppose the force with which idler connects to motor and platter is tremendous due to its position.
Regards.
The ball bearing in the motor is the cause of much of this vibration. When the shaft is new it is less. As a TD124 has good decoupling it is mostly a curious thing rather than a problem. I did have graphs for this which someone lost. We did it at Greenwich University, it's author got a 2-1. It was for my motor design.