Its raining vintage TTs

[sachu888]

I have received POM thrustpads and ISO 32 grade fully synthetic Compressor oil from Spain today.Now searching for a Ceramic bearing ball.

Regards,
Sachin

 

[sann]

Wow Sachin, the Man eating leopard staring at the synthetic oil.

This leopard killed 125 humans and was hunted down by the legendary man-eater hunter Jim Corbett in 1925.
I salute the great man!

 

[sachu888]

Wow Sachin, the Man eating leopard staring at the synthetic oil.

This leopard killed 125 humans and was hunted down by the legendary man-eater hunter Jim Corbett in 1925.
I salute the great man!

Thanks for the nice book.I really liked it.

Regards,
Sachin

 

[jls001]

Now searching for a Ceramic bearing ball.

If you know the correct diameter, magma is your best bet to help source it as he sources ceramic balls for his footers.

The thrust pads are POM? As far as I know, one of the commercial names for POM is delrin. Supposed to be good material for such applications. Another possible material is plain old stainless steel as it is much stronger than brass.

Now you have the compressor oil and grease so I guess your overhauling can begin

 

[sachu888]

Hi Joshua,
I read on Lencoheaven,its White Polyoxymethylene (POM, Acetal).Bearing ball size is 5mm.I will contact Magma.I have free time next week,so hopefully will complete bearing and motor maintenance.

Regards,
Sachin

 

[sachu888]

Update

I received Pioneer tonearm from FM raghunath,Thanks Raghu.So I have rewired motor and roughly fit this tonearm in Lenco's stock position.It is not perfectly fit,but I didn't bother much.It is sounding good even in this position.I did not even align tonearm as I know mounting distance is wrong.It is sounding miles ahead from my belt drive Micro Seiki.Joshua sent me mounting template for my arm,and I will follow that for my final build.I am very impressed with L-75.My two cents to Fms,buy Lenco as prices are still reasonable and every part is available.Few pics:

Regards,
Sachin

 

[omishra]

Sachin, smaller weight could be antiskate or VTF? fitted in direction of toneram headshell. Is that reversed now if VTF?

 

[sachu888]

Sachin, smaller weight could be antiskate or VTF? fitted in direction of toneram headshell. Is that reversed now if VTF?

Hi Om,
I think its for anti skate,but nothing mentioned in Pioneer manual.

Regards,
Sachin

 

[anilva]

Can we do a group buy for a simple design yet multilayer plinth for L75?

Cheers.

 

[sachu888]

Can we do a group buy for a simple design yet multilayer plinth for L75?

Cheers.

That would be great :clapping:

Regards,
Sachin

 

[sann]

Can we do a group buy for a simple design yet multilayer plinth for L75?

:clapping:
I am in, but being a little impatient, need CLD a bit quickly.

 

[arj]

:clapping:
I am in, but being a little impatient, need CLD a bit quickly.

As sachu888 has done, remove it from the current plinth and mount in on any solid pillars..you will be 70% there anyway !

a group buy is a great idea..worth waiting for. do finalize the design..it would be interesting.
My suggestion is to keep the topmost layers as MDF (from all I have read) and to a depth such that it completely couples into the top plate. you can always put damping material on the top plate and screw it into this layer..supposed to take the resonance in the top plate out of the equation

rest can be hardwood etc.

 

[jls001]

My suggestion is to keep the topmost layers as MDF (from all I have read) and to a depth such that it completely couples into the top plate. you can always put damping material on the top plate and screw it into this layer..supposed to take the resonance in the top plate out of the equation

Having the top layer of correct thickness is very important. I used 12 mm since I couldn't get 10 mm thick MDF or plywood. So this leads to poor coupling of top plate to plinth. There is 12 - 10 = 2 mm gap between the pan of the platter and the layer 2 of the plinth. The top plate rests on the topmost layer only on the edges of the top plate, which is not much coupling area (around 1 mm thick plate). The bottom of the platter pan has a much larger area. Remember, the whole high-mass plinth concept for the Lenco heavy platters is based on direct coupling between top plate and the heavy plinth below it.

My temporary solution is to use hard cardboards as fillers between the bottom of the pan and the layer 2 of the plinth. But a paper cardboard is probably acting as a damping layer, and probably this is not the right place for a damping layer (even assuming a pseudo-CLD structure). Besides it is not easy to get the thickness of the cardboard right. So last night I ended up buying an acrylic sheet of 2' x 2' of 2 mm thickness. Cutting this to shape is another project by itself

So whatever you do to your plinth, use 10 mm thick top layer. It is CRITICAL.

 

[arj]

Having the top layer of correct thickness is very important. I used 12 mm since I couldn't get 10 mm thick MDF or plywood. ..
So whatever you do to your plinth, use 10 mm thick top layer. It is CRITICAL.

Good point !
i believe there is also an issue of variances in this depth..hence needs to be customized !

 

[omishra]

Can we do a group buy for a simple design yet multilayer plinth for L75?

Cheers.

I am also in.

 

[quad]

I am also in.

You should definitely get it done on a CNC machine, for accuracy and consistency,
and also ease of final assembly.

One of the FMs from Bangalore posted that he had got the GR speaker cabinet made on CNC.

 

[sann]

@arj, I followed your advice, took out the top plate from the plinth, placed it on two mdf boards resting on the four bolts.

This changed the sound completely, sounded more focused and cleaner but the bass was compromised.
So, I again placed the top plate on the plinth without the springs, resting on four wood blocked meant for housing the spring assembly with folded cardboard for separator and damping. Now the bass is back, and it definitely sounds better.

 

[jls001]

@sann & sachu888: this is what Santhosh had used a temporary mount for his L75.

 

[arj]

The heavier the base used below the top plate, the better the sound . the reason for the bass suckout is MDF ! put it on stone/granite/bricks and you will hear the difference

 

[Hiten]

Since group buy is suggested, why not attempt to make a good plinth ? With kind permission from Sachin am posting a plinth design which I think will work in most idlers wheel turntables. Criticism are most welcome as it will help betterment.

For plinth we have to deal with three sources of interfering vibrations from floor, acoustic vibrations from room to plinth and inherent vibration from motor and spindle. Above plinth is of MDF sandwiched between two aluminum sheets. The idea is different materials presents varying impedance to vibrations plus whole plinth becomes inert to flexing. Rigidity is required for plinth. The top plate should have as much coupling as possible with turntable chassis plate to dissipate vibrations.
Vibrations from floor are controlled with felt>Sorbothane>metal puck on which spike feet are placed. Three would be enough for low contact and stability.
A side panel is added to prevent room acoustic vibrations reaching the plinth. As music have various frequencies I believe a bare plinth either reflects, absorbs or transmit these waves. The panel is separated by sorbothane strip.
Also added; around motor and spindle bearing are few holes (3/4 inch) to fill with small steel ball bearing or non compacting sand to dampen the vibrations at the source itself. How much heavy(Mass) the plinth should be is little difficult to comprehend, also the design I have made may have shortcomings or negative side to it so suggestion would be highly appreciated.
Regards