Rather pleased with my DIY skills this week :)

[g8ina]

Now I have my new router, a Triton 1500 watt jobbie (not an internet router, but a woodworking type), I can do all those little hifi jobs I've had waiting to be done. This one is the manufacture of a set of hifi turntable platters, made from white Corian, with an 18mm centre hole for Rega TTs. First one (not pictured) is a standalone one which is 24mm thick, 293mm diameter, the second (pictured) is the be stacked so needed to be a little larger at 298mm, 12mm thick. Corian is my all time favourite material for this sort of job, almost completely non resonant, and cuts easily. Also, you can get an almost mirror finish by using 400 grit, then 1000 grit, then T Cut.



This one just sold for 60 quid

[Hoonigan]

Corian is the stuff they make ultra-durable worktops from, isn't it? Never thought I'd see someone using it for a turntable platter!

[g8ina]

Yep, same stuff.... I have a very friendly local manufacturer who sells me his offcuts cheap.... I also make plinths for turntables out of it. A standard plinth weighs in at 9kg

[spacein_vader]

Very impressive work.

Does hi-fi stand for high fidelity? If so is Hifi vinyl not a contradiction in terms?

[g8ina]

Yes and no

Hi Fi = high fidelity

Vinyl is higher resolution than any digital signal as it is purely analogue Use a Linn Sondek LP12 with a decent arm and cart and I challenge anyone to listen and say vinyl is the poor relation

[Saracen999]

I agree with g8ina.

CD and other digital formats/hardware have their place, and I love the convenience but ....given good quality amps, speakers and of course TT/arm/cart, vinyl just has a .... it's hard to define .... a warmth, a 'musicality' I've yet to hear from digital.

But as with anything audio, it's ultimately a beauty that is in the ear of the be-listener.

[DanceswithUnix]

Very nice.

Do you do any related engineering to cope with a platter that heavy? I can imagine a small motor struggling to spin that up to speed, and what kind of bearing does it take to support a slab like that?

[g8ina]

Tools +

Triton 1500 watt router with a half inch bit, goes thru the Corian at about 1 inch per 2 seconds

My past is all electronics since I was about 8 yrs old. All my mechie skills have been self taught over the last 2-3 years, when I started doing this sort of work.

The motor for the heavy Corian platter (3kg) is a very simple Pro-Ject 16VAC 300rpm motor, belt driven around the outer rim of the platter as you can just about see in the photo above. Only takes 3-4 seconds to run up to speed.

The bearings *do* need some work though, the Lenco L75 bearing is OK, as its platter is cast alloy at 3.8kg, but I do have a double platter one in the office, two at 3.8kg, and that bearing certainly did need some extra stuff, a new PEEK thrust pad, a new grade 5 ceramic ball bearing, and some additional mass around the base.

[peterb]

Yes and no

Hi Fi = high fidelity

Vinyl is higher resolution than any digital signal as it is purely analogue Use a Linn Sondek LP12 with a decent arm and cart and I challenge anyone to listen and say vinyl is the poor relation

What do you mean by ‘resolution’? Dynamic range or frequency bandwidth?

[g8ina]

resolution as in purely analogue rather than 16/32 bit digital.

[peterb]

resolution as in purely analogue rather than 16/32 bit digital.

Resolution of what though? There are limitations in digital recordings (and most recording studios use digital mixers and digital mastering equiment) just as there are in analogue recordings on vinyl (notably the dynamic range limitations at high frequencies)

That apart ( ) those decks really are beautiful to behold!

[g8ina]

Resolution of the purity of say, a sine wave, with analogue its a pure sine wave, with digital, even with the best AA filters, it is stepped.

Hmmmm, cant get linked images to load

http://www.ni.com/cms/images/devzone/tut/1fig_qual.gif

Do you see what Im getting at ?

[Zak33]

Corian is the stuff they make ultra-durable worktops from, isn't it? Never thought I'd see someone using it for a turntable platter!

nor I...clever git, isn't he?

[Zak33]

Resolution of the purity of say, a sine wave, with analogue its a pure sine wave, with digital, even with the best AA filters, it is stepped.

Hmmmm, cant get linked images to load

http://www.ni.com/cms/images/devzone/tut/1fig_qual.gif

Do you see what Im getting at ?

I do.. I know exactly what you mean

A wave shape... as a sound wave, has no sharp edges

Cut it into 8 or 16 or even 32 bits ..... each must have a flat top. But not with an anaologue wave form, which is curved.

Resolution is a great word. Best way to explain this is.... looking through a microscope and taking a high pixel count photo of a cell with a digital camera. If you then zoom in with a a PC to see better detail... you get..zoomed in. But not better resolution.
But if you use a higher magification LENSE on the microscope before taking the picture..you get better resolution.
Same with digital sound. Even if it's cut into a lot more "bits" it still has edges.. and an analogue curve has none.

[g8ina]

Nice analogy

[peterb]

Even if it's cut into a lot more "bits" it still has edges.. and an analogue curve has none.

Are you talking about sampling or the 'value' of each sample?

Shannons sampling theory proves that if you sample a signal at at least twice the frequency, it can be reconstructed perfectly so it is instinguishable from the original This can be proved mathematically and demonstrated in the lab.

If you are talking about the amplitude of each slice in a complex waveform, then there is quantisation error in the dynamic range - although whether that is detectable in real life is debatable - but that error exists/is introduced in the recording and mastering processes which will be digital at some point in the process.

A 16 bit word has 65,536 levels so an error is 1/65536 or .00152588% (approximately ). Its not quite that simple, but there is a fuller explanation here.

https://en.wikipedia.org/wiki/Quanti...al_processing)

But...is the digital picture on your television any worse than the anologue picture of years ago?