What is the key component of a turntable ?

Mervyn

Thinking about what sort of plinth would best suit my latest 'analogue' acquisition ( a Garrard 401 deck) I was confronted with the question of what is the most important component of a turntable - deck plinth tonearm or cartridge ?
Deck - direct or belt drive ?
What plinth best suits - light or heavyweight ? Wood or slate or acrylic ? If wood which one ?
Tonearm - pivoted unipivot or tangential ?
Cartridge - MM or MC ? Retro or modern ?

Logic says you must have synergy and even dosh but the permutations available are still pretty big.
Answers on a postcard to ................

Jim

I would say the drive system very closely followed by the plinth and support it sits on.  Arms and cartridges are lower down the list IMV.  As I've posted elsewhere here I heard a Townshend Rock many years ago with a modest arm and cartridge which sounded fundamentally better than anything else that day.

I prefer light and rigid for all cases and cabinets; i.e. plinths, amp cases and speakers.  My reasoning is about  energy storage.  The common view that a large and heavy plinth will sink energy is wrong IME.  A heavy object will store energy - this is not just my opinion; it is a fact born out by both engineering and physics.  A heavy plinth will store any energy for a short time and it will re enter the business end of the TT a short time later thus smearing the signal by superimposing the extra energy on the signal.

A light and rigid plinth will not store as much energy because the energy will pass through it quickly on its way to a heavier object such as the wall or floor its connected to.

I have heard many heavy TTs over the years, some commercial some DIY.  They all share a common sound.  They are overdamped, lifeless and lacking at both frequency extremes.

Equally with speakers.  I have heard DIY efforts made of sand panels, concrete lined, 2" thick MDF etc etc.  Again they're dead, lifeless and dramatically hamper dynamics.

A simple test would be to acquire two pieces of wood the right size for the Garrard.  One could be 18mm chipboard and the other 30mm MDF or (the current flavour of the month) birch ply.  Make the cut out for the 401 and arm and stand both pieces on short legs long enough to clear the motor works.  Mount the 401 and arm and cartridge and play.

I'd be quite surprised if the 30mm was preferred.

Re arms and cartridges.  Use the best you can afford.  But if the deck is serviced and working well and plinthed properly it's less of an issue.

Alan

Isn't there a hifi rack & isolation support maker who uses acrylic, because it is light, relatively rigid (give its mass) and disperses energy across it's surface very efficiently?

Edit: it was quadraspire.

Jim

Spot on Alan.  I'd prefer composite wood as I think it sounds more real but acrylic is better than anything that is heavy/massy.

Alan

cooo! I almost know what I'm talking about...

Jim

Although about speaker cabinets this is worth a read even if it's a bit long.

http://www.6moons.com/audioreviews/ocellia3/ocellia.html

Alan

They are lovely things - I would love to have a good long play with them here. What an excellent philosophy.

Mervyn

Jim would acrylic damp better than chipboard ? Assume a good plinth needs both stiffness and damping properties.

Regarding the quadraspire acrylic stands I have a couple of these shelves and they work pretty well. The guy who designed them for Quadraspire has developed 100% acrylic stands as here :

http://www.musicworks-hifi.com/wp-content/uploads/2010/09/ReVokitweb.jpg 

I spoke with him at last years show and reckoned acrylic cased NVA's would work a treat on an acrylic stand. I plan to experiment with my TSS some time with the Quadraspire.  ( its just a pain moving stuff when you use SSP i/connects)

 

 

Jim

I think damping is a red herring mate.  I reckon we want the energy to leave the item as soon as possible and not try to damp it.  Sorry to sound poncy but remember Newton's 2nd law: Energy cannot be created or destroyed, it can only be changed or moved around

For me the ultimate material would be of zero mass and infinite stiffness - given that it in no way exists then it's case of getting as close as possible with avaible materials.

uglymusic

The DAC? (I'll get me coat)  :-D

Jim

The DAC? (I'll get me coat)  :-D

Yeah and hat, scarf, gloves and boots


:-))

uglymusic

I dunno. Excluded from me own community...  :-(

Jim

Get over to the covers thread and bung some stuff in the playlist mate - I know you know some good 'uns!

uglymusic

Yep. But I'm sitting in the bar of the Grosvenor Hotel in Victoria so I can't really give the tracks a listen.

Something for later or tomorrow, I think.

Jim

Ah, thought you'd been quiet today.  Hope your journey back is OK.

uglymusic

Thanks Jim.

I'll be quiet again tomorrow, as I'm off to Guys to have my finalised chompers fitted.

Jim

Blimey mate!  All that time in the big smoke, you'll be speaking cockney next

:-))

uglymusic

Gor blimey, mate, don't I speak cockney already?

Jim

Nah!  You didn't say guvnor

uglymusic

It's wot I say, innit  ;-)

Jim

Safe
:-D

RobHolt

The DAC? (I'll get me coat)  :-D

Hold on, wait for me!

Mervyn

In an attempt to get back to the thread ( not quite sure where it has been ! ) if the aim is to dissipate the energy asap then would you couple not decouple the plinth ? Or am I getting my physics mixed up with my biology ?

uglymusic

Isn't there a hifi rack & isolation support maker who uses acrylic, because it is light, relatively rigid (give its mass) and disperses energy across it's surface very efficiently?

Edit: it was quadraspire.

That's not a hi-fi rack. It's a rather bad design for a commode 

Jim

Yes you would.

I prefer everything coupled as tightly as possible.  Any decoupling allows resonance to creep in through loose joints.  The problem with decoupling is it's almost impossible to predict how the energy is going to behave and it's hard enough with everything coupled!  A good test to prove this is to put an amplifier or CD player on a cushion (the test works even better with a TT but it's really hard to get it level).  Play some music with and without the cushion.  I doubt that anyone would prefer it on the cushion - it will tend to sound soggy and lacking bite.

I re read my answer from yesterday re damping and I need to qualify it a bit.

A material should be well self damped so not as to ring or resonate (think sheet of metal or glass both of which ring badly, or really well if you look at it the other way).  Given that that is impossible (because the material doesn't exist and everything has a resonant frequency - even fresh air!) what we want is for the the material to ring or resonate quickly and most importantly way above the bass region.  If we can shove any resonance up to a few hundred Hz or even kHz then it will have the least detrimental effect.  The best way to achieve this is to make the material as light and rigid as possible.  Loudspeakers cabinets are very often braced internally.  If you have a panel that resonates at, say, 50Hz then putting a brace across or along the length will double the resonance to 100Hz - i.e. halfing the problem (it's not as exact as this, but this is good for an example).  Big cabinets, Isobariks, ATCs the old Kefs, Celestions, Wharfdales etc used this method many years ago.  Smaller boxes suffer less as the panels are smaller to start with.  This is why smaller speakers sound less boomy - but of course make less bass.  Design trade-off decisions.

The French guy in the article I linked to is doing exactly that.  His speaker cabinets use light and stiffly braced timber to that end.

mozza

I can vouch for Jim's light and rigid approach, as I've heard his 401 for myself, coming through his Lowther set-up.

I initially went for a Loricraft clone plinth for my 401, with a sanwich of birch ply suspended on 4 squash balls.  My reasoning was that I live in a flat with a reasonably lively wood floor and wanted to damp some of the possible vibration coming into the plinth from outside.  It's worked well for me, but I suspect Jim's may sound a touch livlier.  Did we do a direct comparison Jim?  I've been planning my own light and rigid plinth for a while but  a Tannoy cabinet build has got in the way....

Re arms and carts, I went for a 10.5 inch Jelco and standard Denon 103 MC cart, neither of which broke the bank.  I was thrilled with the Garrard from the start but what really kicked the sound onto another level for me was the EAR 834p phono stage.  Even my girlfriend noticed that upgrade!

Jim

I believe we did Steve.  I seem to recall you bringing yours over to mine when you still had the Rega arm and Grado cartridge on it.

Mervyn

Thanks for that Jim. Re resonance I read somewhere that chipboard has a low intrinsic resonance but apparently bamboo was twice as good and certain resins 4 times better. Bamboo sounds interesting as it quite light and relatively cheap.

Jim

I read that about bamboo as well.  The best chipboard I've found is flooring grade with the tongue and groove (which can easily be sawn off).  It's made much stronger than the usual stuff for obvious reasons, I think they put a lot more resin/glue in the mixture and pack it all togther under more pressure.  Comes in a bit heavier but it is really stiff - knocking it gives a really quick sound and not the dull thud you get with ply or MDF.

RobHolt

Surely the key has to be the best drive system you can implement.

Without absolute speed stability and low noise you won't get very far IMO.

Jim

Completely agree Rob, I said so in my first reply.  Once the drive system is in place then I reckon it's down to the plinth with the arm and cartridge bringing up the rear.

Mervyn

Being having a look for some bamboo to experiment with but sheets seem hard to come by. Lots of pretty cheap  t&g flooring but that would mean glueing pieces together for top plinth. With the cut-out it might not be strong enough.

Jim

If they are glued along the tongue and groove with a good polyurethane glue and clamped tightly over night it'll be more than strong enough.  The 401 chassis is not that heavy; can't remember the exact weight but the platter is less than 10 pounds so I'd guess the whole thing to be no more than 20 altogether.

Gorilla Glue is fantastic Mervyn, a bit pricey but very little is needed compared to the usual PVA stuff.

Mervyn

Thanks Jim. I had thought about maybe some bracing underneath but with 15mm boards it sounds good.

BTW hope that glue is not made from gorillas !

Jim

It's made from a part of a gorilla, no of course it isn't

As you're using 15mm some thin braces underneath wouldn't hurt.  They wouldn't add much weight and if they're glued and pinned in place they'd be stiff enough.

sq225917

There are 3 key components to any turntable.

1. The stability of the geometric relationship between arm base and main bearing.

2. The highest possible rotational speed stability.

3. Achieving 1 and 2 above with the lowest possible noise.

Everything else is just dressing..

PAC

I can offer some observations from experience on this one.  The 401 can sound either less than ordinary or downright top flight depending on how it's maintained and how it's mounted.  Before starting any comparisons on what lpinth to go for, a few simple checks will soon show up any deficiencies which will show through any mounting option and I've listed these in no particular order:

1.  Check idler wheel for wear:  these tend to last for decades but can sometimes loose their square edge and become rather rumbly. Rather than invest the extra-ordinarily scary price of £140 for a replacement, they can be carefully re-worked square with a little effort and care and specialists exist who can do this for a fraction of the cost of a replacement.

2.  Remove the platter and undo the thrust plate under the spindle housing. remove the thrust pad and check that and the end bearing for wear. Aftermarket replacements are cheap and plentiful just don't buy one of those that claim to use harder than standard materials or uneven or accelerated wear of spindle or thrust pad will result...stick to OE spec if possible.

3.  get yourself down to the nearest haberdashers and buy a small bottle of sewing machine oil.  Its perfect for oiling the bearing (I use it on my Gyro and my 401) and it's cheap.

4.  Leave the motor to spin up for 10 minutes then unplug and feel the motor casing. it should be warm to the touch but not hot, which is an indication that the oil has gone from inside the casing.  If needs be, the motor should be sent off to a Garrard specialist and tht motor disassembled and re-filled with oil.

Right...you're ready to start on the plinth.

I won't get into the arguments for de-coupling etc suffice to say I don't agree with the logic of some of what's been said already in this thread.  Fact is, the 401 to work at it's best definitely DOES need the platter decoupled as much as possible from the motor vibrations (ditto the arm board) or all that lovely rumble will come through to the speakers.  That's why Garrard spring coupled the motor in the first place...to damp down vibration or try to isolate as much as possible.  Trouble is, it isn't that effective.

Don't use MDF for plinths.  MDF is far from acoustically dead and resonates at audible frequencies.  Its only used for speaker box construction as its cheap and easily worked and takes veneer well and  has no other merits or place in critical areas.  Speaker manufacturers use computer simulations to determine the amount of bracing and damping needed to shift those frequencies outside of that which is critical to speaker design.

 

Easiest material for a 401 plinth is birch Ply.  Two methods can be used:

1)  multi-laminated board full depth of required motor housing made by cutting or routing out individual sheets and gluing together;

2) up to 60mm total layer sat within braced timber housing.

Whichever route is used, the most successful mounting is to ditch the OE bolted arrangement as the rubber grommets are next to useless anyway and vibration almost always gets through.  Cut four triangular bracing sections which line up under each mounting hole and use a router or similar tool to machine a hemispherical depression in the braces which will accept a squash ball.  Drop the squash balls into place and drop the whole deck into place.  That's far more effective than bolting it down.

If you fit three (not four) adjustable spikes under the base, you can easily achieve a level.

The whole issue about de-coupling is misunderstood and very fundamentally.

When you read adverts for spikes to decouple a CD player for example, it's to stop the resonant effects from external sources creating microphonics from affecting sensitive electrical components.  Another effective way of reducing microphionics is to add weight to the player, so instead of sitting it on a granite plinth, sit it on sorbothane feet and put the plinth on TOP of the player.  Sitting a player on a cushion won;'t, in theory have one iota of influence on sound...not one jot, except to partially damp external vibrations.  You don't want to do that with a record player even if you could, as modern record players are designed specifically with resonance control in mind and nothing is more sensitive to payback effect than messing up resonance of the platter.  They're designed not to be excited at audio frequencies, in theory, although some very obviously do (glass platters are not my favourite) and over-damping can rob the sound of detail.

Soz for the war and peace response, just though there were a few things that might be helpful sharing.

sq225917

Bugbear:

Spikes don't decouple, they couple. Spiking anything heavy to anything immovable effectively couples them together. Like osmosis noise, vibration, energy, call it whatever you like will sink from the highest to lowest concentration. So only couple energetic things to none energetic things. This is useful for sinking internal vibration, ie when you want to sink motor noise to ground rather than have it find its way to the stylus record interface. 

Don't spikes something superbly quiet and well engineered to something boingy and noisy.

Isolation, you only want to isolate something from sources of noise, hence why something like the Vertex two soft feet and one spike works under a cd player with the spike under the transport. Most decks have isolation built in, typically between the outside environment and the rest of the deck, or more frequently (for people who don't care about speed stability- LP12 users) between plinth/motor and sub-chassis/arm-board.

Most solid state electronics are none -microphonic (pin and peg sub-assembly mounted boards and some phonostages excepted). If you doubt this slap your pre-amp with the volume turned up. The only thing that makes a difference in most hifi is damping the casework itself from things like transformer vibration which ring audibly.

PAC

Agreed Simon.  Spikes couple, they don't de-couple but they do lower vibration amplitudes to the coupled kit.

Agreed RE damping casework which is why I suggested the instead of placing bits of kit on plinths...place something heavy on the kit.  I did this to great effect with my last CD player and it made a difference.

sq225917

Agreed Simon.  Spikes couple, they don't de-couple but they do lower vibration amplitudes to the coupled kit.

Agreed RE damping casework which is why I suggested the instead of placing bits of kit on plinths...place something heavy on the kit.  I did this to great effect with my last CD player and it made a difference.

"lower" the vibration with reference to what level?