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Old 29th January 2008, 02:06 PM   #1
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Question Uni project about Turntable design...

Hi all - I am new to these forums, and the whole audiophile scene in general...although I have been interested in hi-fi for many years now, and am building up my system bit-by-bit

Anyways, I'm doing my Final Major Project in Product Design at University, and am basing it around a turntable.

I'm not too sure which direction it will take, as it's only just been started, and a long way to go yet.

Could people help me out, and let me know what the most important features about turntables are, such as weight/balance, tone arm positioning, the 'insides' (techie stuff) and what ever else you think I should know.

This will be great help, as reading through the forums, it seems people know their stuff.

Thanks.
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Old 2nd February 2008, 08:16 PM   #2
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Have a look here for some inspiration:

http://www.krishu.de/de/index.php?id=76

Also browse this site: www.aca.gr for hundreds of turntables.

GD
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Old 3rd February 2008, 12:12 AM   #3
Nanook is offline Nanook  Canada
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Default Funny you should mention this...

as I am involved in a turntable project, but in a commercial sense. For your project is it for industrial design or designed for manufacturing? Or mechanical design? All have different priorities.

Mechanical design would suggest performance first, regardless of the practical considerations in manufacturing. Industrial design is more concerned with the aesthetics and overall look and feel of the project. And design for manufacturing is concerned with ease and cost of manufacturing. Electronic concerns for turntables will be common to all types: motor type (AC or DC voltage operation), and speed control (different methods for different voltage types and different methods for the same voltage type).

Aesthetics should be your last consideration, because you can make something look pretty much the way you want it after you know it is suitable to manufacture, and that it performs well. But don't compromise performance for aesthetics.

Turntable design has taken a complete turnaround in the last few years. Maybe have a look here for some history regarding turntables.

There many approaches, but the goals generally are the same.
  • isolate the turntable from the environment
  • isolate the tonearm from the turntable plinth/bearing and motor
  • isolate the platter from the motor and the plinth
  • isolate the cartridge from all of the above

Nice short list, but tough to solve. There are suspension schemes, tonearm dampening schemes, motor isolation schemes, etc....
It's the combination that can make a great product.

Suspensions are probably the most difficult to design and implement correctly, so massive plinths are an alternative. So too are extremely light weight plinths, but for lack of energy storage rather than using mass as a dampening agent. The list goes on and on.

If it were me doing a project for university, I'd try to develop a product that can be manufactured using easily accessible technologies, and materials to accomplish good performance. Do the basics brilliantly. And don't worry if a completed turntable is not the end result (still haven't touched on tonearm design). When I was in school, my profs were more concerned about the process of the work rather than the absolute outcome. Discuss it with your's and see if the expectation is designing the thing or actually designing it and having a completed prototype as the end result. And read as much as possible.

Some turntables that may suggest inspiration are:
  • Oracle Delphi
  • JA Michell Orb/OrbSE/Techno Deck
  • Nottingham Analogue
  • Linn
  • Scheu
  • Bix
  • Rega
  • Basis
  • VPI
  • Technics (1200 Mklll , SP10, SP15, SP25direct drives)
  • Micro Seiki (direct drive)
and the list can go on and on.....
good luck

stew
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Old 5th February 2008, 12:31 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

I'll just add for a commercial turntable then are a few other things that
are not related to technical performance per se. That is positioning of
the product in the market, its price point, and the users aesthetic and
features expectations, these all seem to effectively take priority.
And to a degree there is also "fashion", aping other designs.

What I'm saying is some design decisions are not based on technical
merit. Some users will not accept a "wobbly" sub-chassis design. Some
will not accept a "boring" box with lid when naked acres of transaparent
acrylic and the like are available.

Knowing the market is just as important as rthe technical details, and
if something different is to be done its probably more important that
the design is targeted / marketed towards a sympathetic user base.

Its no good having a great design not enough people will buy .....

/sreten.
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Old 6th February 2008, 12:15 PM   #5
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put it off and put it off and put it off and on the very last night before it's due quickly bodge up a rega clone
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Old 6th February 2008, 01:10 PM   #6
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I've been having a thunk about this. (cross posted on several fora)

[braindump]
An incomplete list of things that affect the sound of a motor unit (some due to stray vibrations, some due to noise and some due to speed stability, and some due to... ?):

-Main Bearing (quietness, lack of play, amount of friction)
-Platter Mass (speed stability, storage of stray stylus vibrations, isolation of record from bearing)
-Motor (inherent vibrations, torque, power, mechanical isolation, damping, speed stability, inertia)
-Drive Type - Direct, Belt, Idler, 'Indirect' [see Teres rim drive] (Coupling of torque between platter and motor, lack of slippage, elasticity, inertia, isolation of motor vibrations)
-Motor Control (Tacho/ constant voltage/constant frequency/magnetic pickup from platter [see Sony Biotracer] etc can cause subtle shifts in speed stability- the 'hunting' of servo motors for example)
-Plinth (sinking vibrations from the motor/bearing)

This is not to mention the rest of the things affecting the TT's sound:
-plinth (flexing between bearing and tonearm, isolation from external vibrations)
-tonearm (damping, resonance, alignment, quietness of bearings, lack of play in bearings, wiring [believers only], effective mass, length, type [unipivot, gymbal, servo linear or passive linear])
-cartidge (stylus shape, cantilever length, material, suspension type, type [MC, MM, MI, strain Guage], Inductance, resistance, wire material, no of turns)
-phono stage (matching to cart [resonant tank circuit here], transformers, RIAA match)
-platter mat (coupling/isolation of vinyl+platter, damping)

And the rest of the system:
-vinyl (quality, cleanliness, damage)
-amplification (including phono stage amplification)

The main problem with vinyl is the tiny wavelength of the sound recorded thereon- in the region of the wavelength of light (look sideways-ish at the grooves while in sunlight- you can see the spectrum, due to the variations in the wall acting as a diffraction grating). This, IMHO makes the main problem play in the bearings affecting the relative position of the cart relative to the vinyl and also makes very, very small variations of speed much more noticeable- not necessarily ans wow or flutter, but in terms of immediacy as the stylus slows the platter down while traversing a particularly dynamic part of the disc.

All this is IMHO, with what I think affects vinyl reproduction the most.
That it works at all is a constant source of wonder to me. That it sounds good completely befuddles me- it's a lump of rock being dragged down a plastic gutter, at a non-constant speed, with forces and vibrations all over the place.

[/braindump]

Personally, I lean towards the rim drive (indirect drive) system, with a damped, medium-mass platter (around 5-10kG), a heavy, fast spinning flywheel coupled to the platter using an idler-type thing, with the motor controlling the speed through a high-speed servo (IMHO, the servos on DD TTs run at too low a frequency) or fixed frequency controller, or possibly a low-speed servo that normally acts as a fixed-freq controller. A linear air-bearing tonearm and a rigid, damped plinth complete the system.

I just find it fascinating- trying to get a good balance of compromises in an imperfect world. And, of course, everyone's preference is different.

James

Don't just copy it though...
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Old 6th February 2008, 06:44 PM   #7
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Wow - thanks for all the information. I understand some of it, and some of it is a bit too techie for me to understand...I'll get there tho.

As for the priorities of the project, it is more aesthetic design based, than having to create an actually working prototype. Although saying that, I will have to back it up with evidence that it is possible to go to manufacture, and do some stuff on the material/pricing etc.

As for the marketing, that is a big issues, as thats part of the course (Product design with marketing) - and I'm slacking a bit, and am still uncertain about my target market.

Cheers for all the replies
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Old 10th February 2008, 11:36 PM   #8
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calum, with marketing you can be pretty bold cutting the market into segments.

i would suggest, by age, by cost and by lifestyle.

under 20, 20-45, 45+
cost sub 300, 300-1000, then 1k+
lifestyle, fashion, relaxation and music appreciation.

draw that lot up into a 3x3 grid, pick 20-30 currently produced records and place them within the corresponding sectors of the grid.

that should give you a rough analysis of product placement, then pick a few people types from within the grid and go out and quiz them on product performance, specification and aesthetic considerations. once you know your target audience requirements you'll be much better positioned to specifcy and cost out your design.

there isn't much whitespace wtihin the market, ie customers for whom a product doesn't already exist, but maybe you'll find a gap that you can design for.

for serious audiphiles it's mostly about quality and performance with cost and aesthetcis coming in 2nd.

best of luck.
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Old 11th February 2008, 08:05 AM   #9
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Hi,

I'm in Southampton and I am in the process of building a turntable at the moment. This is slowed down by the fact that I do not have access to a machine shop. Maybe we could meet for a chat.

In addition Origin Live are based in Southampton and Mark Baker would be a very interesting person for you to talk to.

Regards BT
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