Turntables DD vs BD vs Idler

[AmDismal]

The laser TT does look fun, but I suspect it has plenty of other issues. Most obvious is noise - the stylus can move dirt out of the way, while a laser will play what is there. Also, vinyl seems rather unsuitable to being laser-read, not least because it is black.

It's also bloody ugly - and you can buy a beautiful TT for that price of one of those!

[Werner]

Just out of interest.. Is anyone building turntables with the newer brushless motors?

SME. Raven (IIRC). Continuum.

But they are generally rare. The commercially-available controllers are worthless for turntable use. The trick is to drive the motor coils directly, using them as a 3-phase motor.

Yes: 'brushless DC' = '3-phase AC'.

I am also not aware of any brushless motors with sleeve bearings. So some customisation is needed.

These solutions tend to be pricey.


To others: please don't confuse with permanent magnet (often coreless) 'real' DC motors as employed by Pink/Funk, Michell, OL, Linn Radikal, ... These are generally very low noise, seemingly easy to drive, but tricky to make with low drift.

[Werner]

vinyl seems rather unsuitable to being laser-read, not least because it is black.

Blackness is relative. What is black to the human eye may not be black when regarded by a piece of silicon.

I have a CDR recorded from the laser TT. It sounds very pure, also very bland. But then I am almost confident that should one ever be capable of engineering-out all of LP replay's flaws the result would be bland.

[pure sound]

I also have that CD and I'd agree. However, having heard one at first hand I thought it sounded pretty good given the rest of the system. I also think there'd be a good deal of scope for improving the analogue electronics.

[kingsxfan]

I think a model is available which has no inbuilt stage, to allow the use of your own? Whether or not improvements could be gained further back inside the unit, not sure?

[SergeAuckland]

Blackness is relative. What is black to the human eye may not be black when regarded by a piece of silicon.

I have a CDR recorded from the laser TT. It sounds very pure, also very bland. But then I am almost confident that should one ever be capable of engineering-out all of LP replay's flaws the result would be bland.

If it were ever possible to engineer-out all of LP replay's flaws, the result would be very close to a CD. In other words, something essentially transparent to the original signal, and acting just as a carrier.

Whether that results in blandness, is probably more a function of whether one finds transparency bland or whether one prefers some sonic character.

S.

[Werner]

If it were ever possible to engineer-out all of LP replay's flaws, the result would be very close to a CD.

No. You'd still be stuck with LP cutting and manufacturing issues, both very lossy processes.

When I wrote "LP replay" this was with some reason.

[SergeAuckland]

No. You'd still be stuck with LP cutting and manufacturing issues, both very lossy processes.

When I wrote "LP replay" this was with some reason.

Agreed. However, engineering out all of LP replay's issues is fiction as they are inherent in the medium, so two impossibilities......

S.

[Werner]

I disagree. I can image a mechanism for blameless LP replay. It does not involve turntables, tonearms, or cartridges, though, and it is likely not much fun.

Oh, at least one research group is going down this route. For archival, of course.

[SergeAuckland]

I disagree. I can image a mechanism for blameless LP replay. It does not involve turntables, tonearms, or cartridges, though, and it is likely not much fun.

Oh, at least one research group is going down this route. For archival, of course.

Interested in knowing more.

S.

[Werner]

Optical scan. No moving parts whatsoever. French national library etc looking into this.

[BobC]

It that a similar technique to the laser scanning we use to take 3D measurements and build virtual 3d models of the as built products?

[SergeAuckland]

Optical scan. No moving parts whatsoever. French national library etc looking into this.

It that a similar technique to the laser scanning we use to take 3D measurements and build virtual 3d models of the as built products?

The Finial laser turntable had the problem of dirt and dust being treated as groove modulation. These days, it should be possible to create a DSP algorithm that distinguishes dirt from modulation, but I wonder what they do about worn or damaged grooves.

S.

[BobC]

I don't know the thechnique that werner is talking about serge, but theoretically it would be possible to create a 3d model of the vinyl surface without translating that to music or in fact follow the groove as the original laser TT did. This 3D image could then be stored and if required a prototype could then be made of that 3d model using fast prototying techniques and a new master disc created. In effect you store an image and not the audio content per se...Like you asked, it would be interesting to see what the French are up to here. This would be a relatively cheap way of storing a lot of copy very quickly, if not necessarily a quick way to access the audio content, unless someone has developed software that can translate a complete scan to audio. Interesting area.

[pure sound]

http://acfnewsource.org.s60463.grids...ing_vinyl.html

http://www.npr.org/templates/story/s...oryId=11851842

[JPG]

Certainly is an interesting idea.

fast prototying techniques

Unforutnately that wouldn't work - rapid prototyping techniques simply don't have the resolution required to print green light. ;) They can do down to maybe ~0.5mm*, but can't reproduce a smooth curve, and the surfaces are always rough and obviously formed of multiple layers of material.

However, I can see that makeing a 3D computerised model of the disc and then extracting the audio from that could work, and would [EDIT: over and above the extant laser TT]: a) eliminate possible issues caused by laser mis-alignnment or rotational inaccuracies; b) allow 'tracking' of a different part of the groove to avoid sections worn by repeated playing, possibly recoving missing high-frequency content; and c) allow easier-to-develop and possibly more effective dust/dirt elimination algorithms.

Not that I'd know where to start coding that.

*SWAG based on seeing/holding a few rapid-prototyped items at Uni. I can't be bothered to look it up, sorry.

EDIT - written before seeing Pure Sound's post.

[BobC]

Interesting stuff, would never of figured that a digitised optical pic would be sufficiently accurate nor quick enough, clever stuff.

As for virtual prototyping...I guess we are a few years away from a replicator then

[JPG]

I guess we are a few years away from a replicator then

'fraid so.

[Chumpy]

Ideally, good DD is best. In reality, despite slewing horizontal gravity, rubber-band sounds bettter.