The Incredible Technics SP-10 Thread

Turntable power supply

In my quest to outboard the electronics from my SP-10 MK2 I enlisted the help of David at Landfall Systems.com to build the chassis.

To make the transition somewhat easier and to not reinvent the wheel so to speak, the chassis David is making for me is one chassis, two sections, via a front to back divider. Also the top and bottom covers are split along this line. The chassis measures 17" w x 3 1/4" t x 14" d. The center divider is 4 3/8" over, measured from left to right. The chassis will be brushed anodized black.

The left side will receive the original power supply, basically intact, less the original chassis. The power switch and light will carry over as well. The right side will take the under table electronics basically as a whole. I will mount the boards intact to the bottom of the chassis lid, as they are under the table. I am mounting the stop/start switch and speed selector whole to the front panel of the chassis. In my system this new power supply will sit on the next shelf below the TT to allow as short of an umbilical as possible. By having the covers split I can easily access the trim pots on both the power supply and turntable electronics easily with only having minimal covers removed.

The strobe and platter brake will not be a part of the new build.

Besides the cutouts on the front for the switch, light, speed selector and start/stop, the back has cutouts for the IEC receptacle, and umbilical receptacle, along with 6 ventilation slots. I'm hoping the chassis will retain a little SP10'ish look and feel.

Dave CNC'd the cut outs this morning and sent me this pic.

ImageUploadedByTapatalk1420397184.098230.jpg

This is what I ordered from Mouser, and what the parts look like. The contacts are gold plated, rated for 3 amps, up to 20ga wire and solder connection. BTW, I ordered two different size collars as I'm not sure what the final diameter of the cable will be.

ImageUploadedByTapatalk1420397243.874892.jpg

ImageUploadedByTapatalk1420397264.218113.jpg

The chassis should be anodized and be ready to ship Friday. Really excited the have all the openings in the chassis done and anodized after. Should look really nice.
 
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6L6

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I don't think omitting the platter brake is a good idea - the TT conrtoller sends a momentary reverse signal to the motor and engages the brake when the stop button is engaged.

Ask Dave Cawley if that can be disabled or the amplitude turned way down... If not, you might want to consider keeping it.

Also, is there enough room on the faceplate to mount the start/stop button assembly? It's significantly taller inside than out.

Seeing the photo from Dave at Landfall reminds me that I need to order no less than 4 enclosures from him... :) :) :) (I have 2 two-chassis phonostages in the works right now.)
His enclosures are always so amazingly nice. Yours will look incredible.
 
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Sorry, a little late addition. We can also increase the mass of single material cap to drain the noise.
Regards.

That is a great idea.
I would not use the same cap.
I would copy it's thread and recess dimensions and use a wider and longer
one just to add mass.
In the DP-80 i do exactly that - only that the mass is two parts with sorbothane insert between to add even more damping.
2.5 kilos added in this specific area.
 
I don't think omitting the platter brake is a good idea - the TT conrtoller sends a momentary reverse signal to the motor and engages the brake when the stop button is engaged.

Ask Dave Cawley if that can be disabled or the amplitude turned way down... If not, you might want to consider keeping it.

Also, is there enough room on the faceplate to mount the start/stop button assembly? It's significantly taller inside than out.

Seeing the photo from Dave at Landfall reminds me that I need to order no less than 4 enclosures from him... :) :) :) (I have 2 two-chassis phonostages in the works right now.)
His enclosures are always so amazingly nice. Yours will look incredible.
6L6, thanks for commenting.

I have read posts on each side of the idea of removing the brake. When I put mine back together after the recap, I omitted the brake to check for myself. On an operational basis I do not notice any issues. With the brake removed the platter makes 2 1/3 rotations before stopping. It looks like both OMA and Artisan Fidelity both remove the brake in some of their builds. Open to ideas on modifying or adjusting electronics related to removing the brake though, as the brake is gone!

And yes, as built the board and supporting bracketry is actually about 3 1/4" tall, same as the chassis faceplate. A little modification on the bracket (other) is in my future! I didn't want to go to the next size up on the chassis which is 4 1/4". I positioned the cutouts with the button assembly fitting, but tight, to the bottom.

David's chassis(s) are perfect! Usually when you assemble anything that has multiple pieces/screws you have to start all the screws first then start adjusting and tightening as you get everything to line up. With the Landfall enclosures you can tighten every screw as you put together and when you get to the last screw it will still be exactly lined up and panels perfect. This will be my 4th from him. Glad he started being able to make the cut outs via CNC too!
 

PKI

Member
Joined 2011
Paid Member
That is a great idea.

I would not use the same cap.

I would copy it's thread and recess dimensions and use a wider and longer

one just to add mass.

In the DP-80 i do exactly that - only that the mass is two parts with sorbothane insert between to add even more damping.

2.5 kilos added in this specific area.


What cup are we talking about again, guys? If it is about that small one on the shaft... We can only increase its dimensions by increasing the length, diameter is fixed. So from practical standpoint we can change the shaft and make it from the same polymer material (all shaft or big part it). However, I don't think it is worth it. I haven't listened to this TT yet, but I don't think that the noise from the bearing assembly is that critical.

From the theoretical point of view we need to understand how acoustic waves propagate in polymers. If we are looking for a polymer with very "tough" mechanical properties, it will most likely be quite transparent for acoustic waves (well of course because of the polymers nature it will shape the spectrum compare to a crystal material). So, personally, I would do couple this "stiff" end cup by just putting a much "soft" washer between it and the shaft.

However, these are all just speculations...
I think that everything but putting a cup on the end of the shaft is a pretty difficult for an ordinary DIYer project.
So i would only go that complicated way if we, at least do some Google search and back of an envelope calculations, AND do some experiments to measure what are the real numbers in reducing the noise. P
Again, it is mostly interesting from scientific point of view for me, I doubt we will improve things a lot... Especially doubt it will be audible.
 
What cup are we talking about again, guys? If it is about that small one on the shaft... We can only increase its dimensions by increasing the length, diameter is fixed. So from practical standpoint we can change the shaft and make it from the same polymer material (all shaft or big part it). However, I don't think it is worth it. I haven't listened to this TT yet, but I don't think that the noise from the bearing assembly is that critical.

From the theoretical point of view we need to understand how acoustic waves propagate in polymers. If we are looking for a polymer with very "tough" mechanical properties, it will most likely be quite transparent for acoustic waves (well of course because of the polymers nature it will shape the spectrum compare to a crystal material). So, personally, I would do couple this "stiff" end cup by just putting a much "soft" washer between it and the shaft.

However, these are all just speculations...
I think that everything but putting a cup on the end of the shaft is a pretty difficult for an ordinary DIYer project.
So i would only go that complicated way if we, at least do some Google search and back of an envelope calculations, AND do some experiments to measure what are the real numbers in reducing the noise. P
Again, it is mostly interesting from scientific point of view for me, I doubt we will improve things a lot... Especially doubt it will be audible.
PKI. A couple of the guys that have spent years perfecting this table, and make some of their living by selling their services, have added a "bearing drain" to their build.

Since I don't have any personal experience I can't claim that it's the best thing since sliced bread or Snake Oil. But I am adding to my build as it makes sense in my mind.

I have a 4 3/8" x 6 3/8" x 1 1/4" block of cast iron that weighs 10 lbs that I will drill and tap for a piece of 3/8" x 24 thread, threaded brass rod. After everything is put together the threaded rod will be run through the block of iron and kiss the bottom of the bearing cap.

So the motor/platter shaft has the thrust pad on the bottom that runs on one side of the ball bearing. The other side of the ball bearing is held tight to the bottom of the bearing cap, the thickness of the aluminum bearing cap separates the brass rod from the ball bearing. And then into the cast iron block.

image.jpg

So quite a few different materials all working together to disapate the unwanted energy.

I met with my CAD guy Friday to take my sketches and turn them into a program for the CNC. My final Panzerholz plinth will be comprised of 4ea 1" layers. To keep from making a mistake on the Panzer I will make first run with 1" MDF. Hoping to make the first run this week.
 

PKI

Member
Joined 2011
Paid Member
I am not criticizing anyone's work and thought :). That was all in my opinion, and as I sad I am not an engineer and especially not a TT expert :).

Could you please post some of your sketches, I did not quite get how you are going to arrange motor/bearing section.

BTW, I really admire amount of work you do with the table! I would newer being able to do so!
 
I am not criticizing anyone's work and thought :). That was all in my opinion, and as I sad I am not an engineer and especially not a TT expert :).

Could you please post some of your sketches, I did not quite get how you are going to arrange motor/bearing section.

BTW, I really admire amount of work you do with the table! I would newer being able to do so!
PKI, I am really sorry if any of my comments, or that I did comment, gave you reason to think that I thought you were being critical or had a wrong opinion.

But if so, that is my mistake in my post. I am the very last person to have an opinion strong enough to criticize anyone on this forum.

Since I'm new to the DIY Audio world, I like to post what I learn and build from this perspective.
 
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Mmmmmmmmmm Time Zoned again ! :snail: So from the UK : I have removed several brake mechanisms for customers, it doesn't do any harm. But I simply cannot see why. It does not deteriorate the operation in any way, but it does allow you to change records much more quickly.

As for the bearing, I'm beginning to think it's all about noise and not wear. I have seen the bearing drains, but if you listen to it with a stethoscope there is no noise, only of the motor rotation. But I'm open to any suggestions here as I haven't properly investigated or measured it.

Dave
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I could suggest that if someone is going to use CNC work for this specific point it can do it a lot better.
Adding just weight is a good measure.
Adding weight AND damping through a compliant layer (eg sorbothane) makes the area a true black hole.
The boards that surround the cap are making it difficult but not impossible to do this.