DIY Tonearm bearing suggestion for a LT TA

[Adelmo]

Hi Vic,

.....I wonder if you had finished, what direction your hifi life would have taken?


That is a good question.

Rgds

Adelmo

[pde2000]

The 7 Hz resonance is probably due to the turntable's suspension.  When I was testing a l78 tonearm on a suspended table it was only once the suspension was defeated that a representative resonance could be driven (by tapping).  The suspension dominated the spectrum otherwise.

[TransFi]

The 7 Hz resonance is probably due to the turntable's suspension.  When I was testing a l78 tonearm on a suspended table it was only once the suspension was defeated that a representative resonance could be driven (by tapping).  The suspension dominated the spectrum otherwise.

Thats real interesting, Paul, and makes sense. Will try to bypass the suspension & test again.....

Cheers

Vic

[Adelmo]

The 7 Hz resonance is probably due to the turntable's suspension.  When I was testing a l78 tonearm on a suspended table it was only once the suspension was defeated that a representative resonance could be driven (by tapping).  The suspension dominated the spectrum otherwise.

Hi Paul,

by tapping you mean that you did tap a non floating or non suspended plinth by hand you heard the noise from the cart?

If so I have a non suspended Lenco and when I knock to the plinth I hear no noise.

Above just to understand better since the topic is interesting.

Tks n rgds

Adelmo

[pde2000]

I tapped the turntable to excite the resonance of the stylus/suspension/arm-mass.  The tapping transferred energy to the spring/mass so that a lateral and vertical resonance could be measured.  This is very low frequency and often visible (jiggle) but can also be seen on a spectrum (audacity).  The turntable was a Kenwood very similar to pioneer pl12, so a sprung top-plate sitting on a wooden box.  This top plate had its own resonant (low) frequency so had to be propped up to bypass the springs.  If you have a combination of spring/mass resonators coupled they interact in a more complex way than you might want but in this case the turntables sprung resonance was very dominant.

[TransFi]

Just tried this. Supported plinth on styrofoam blocks....still 7hz 

From my AT-OC9XML this is the result I get:

[Adelmo]

HI,

Work in progress making a TA lift from left over material, the execution is driven by the available scratch parts and the missing of a lathe so here is how is coming out ( Done ) . Important is that fit to the TA and works well protecting the cart during the cueing.

Remaining works to be done are:

Finish the lighter tonearm wand ( Almost done )

Assemble the new ceramic bearing into the secondary shaft unit ( Done ) . After that above perhaps I am at the end of this project.

Rgds

Adelmo

HI,

while trying to finish a lighter TA wand with the usually bamboo I managed to crack 2 wands while inserting the bamboo dust saw inside it. Actually the cracked itself while drying the wet and glue mixed dust saw, the dried outer bamboo crack.
Strange because I managed to do well with present heavier wand.

Shall take long time before I get other bamboo with good dimension and shape well dry.

Pity as all the other things of the LT TA clone now work very well, I have steady no skating all the tracks without any anti skating, mag shape is well tangent 90 degree, warped or off of center LP are not a problem at all. Means the size of the wire cam and of the mag ii used is good for my TA, setting clearance between the wire and the mag is less than the name card thickness.

Bearings with present TA are to be left as they are, the ceramic pre loaded used lately have improved drastically the precision of the mag unit.

The Lenco TT and LT TA shall keep working for the time being with the present TA wand till I make a wand replacement.

Rgds

Adelmo

[low pitch]

Hi Adelmo, I followed this for your construction but did not understand how it worked. Thanks for your help on the other thread.

I am thinking if I could design one based on a linear slide using same principle. ie a magnetic track that stops the TA advancing past the tangent.  I drew it up in LibreCad and it looks possible but needs to be very accurate.  Do you think a iron wire track can keep the magnet position accurate to less than 1mm?

your LT is a great achievement, I was fascinated when it came out, never thought it could be diyed thanks martin

[Adelmo]

Hi Adelmo, I followed this for your construction but did not understand how it worked. Thanks for your help on the other thread.

I am thinking if I could design one based on a linear slide using same principle. ie a magnetic track that stops the TA advancing past the tangent.  I drew it up in LibreCad and it looks possible but needs to be very accurate.  Do you think a iron wire track can keep the magnet position accurate to less than 1mm?

your LT is a great achievement, I was fascinated when it came out, never thought it could be diyed thanks martin

Trying to send a PM,how can I send?

Rgds

Adelmo

[Adelmo]

Hi Adelmo, I followed this for your construction but did not understand how it worked. Thanks for your help on the other thread.

I am thinking if I could design one based on a linear slide using same principle. ie a magnetic track that stops the TA advancing past the tangent.  I drew it up in LibreCad and it looks possible but needs to be very accurate.  Do you think a iron wire track can keep the magnet position accurate to less than 1mm?

your LT is a great achievement, I was fascinated when it came out, never thought it could be diyed thanks martin

Hi Martin,

I did not figure out how to send you a PM in LH, sorry, so here I am.

The mag slide in my TA it is a curve, not a straight line so I am not able to comment if a straight line works well or not.  I used 2,2mm soft Fe wire and a mag 1,5mm thickness ( but also a mag 2 mm thick worked ) with 5mm diameter but also 4mm diameter worked. The mag auto center its center with the wire center, but you need to consider that almost every vinyl have eccentricity therefore the mag has some movement to follow the eccentricity and that deviate from the theoretical center line. Therefore a too small mag  diameter I think shall not work well as could bring the mag outside its attraction field therefore shall not be able to re auto center again with the wire cam. I did not test3 mm mag diameter. Do not be too keen on the theoretical dimension allowance, but plus minus 1 mm is achievable. When I play the vinyl I stopped the TT keeping the TA on the vinyl and on the track he was playing and I checked with the tools I made if the tangent tracking was correct and it was for the entire vinyl.

Can you help me on how I could send a PM?

Rgds

Adelmo

Adelmo

[wenig watt]

Hi Adelmo,
clic on "low pitch" then you see on the left "send personal message" or Martins email.

Best regards

Arndt

[Adelmo]

Hi Adelmo,
clic on "low pitch" then you see on the left "send personal message" or Martins email.

Best regards

Arndt

Hi Arndt,

Many tks

Rgds
Adelmo

[low pitch]

Thank you Adelmo for responding, I sent you a pm with my email.

My idea is to adapt Frank's idea to a linear slide.  I will modify my existing linear motion slide.  All it needs is a magnetic track like you made.  I have drawn it on LibreCad and it looks possible.  From your reply itseems the magnet keeps accurate position, just needs an accurate track to be made.  I will copy you.

thanks, martin

[Adelmo]

Thank you Adelmo for responding, I sent you a pm with my email.

My idea is to adapt Frank's idea to a linear slide.  I will modify my existing linear motion slide.  All it needs is a magnetic track like you made.  I have drawn it on LibreCad and it looks possible.  From your reply itseems the magnet keeps accurate position, just needs an accurate track to be made.  I will copy you.

thanks, martin

HI,

Just sent a PM, pls check.

Rgds

Adelmo