How to set up a three-spring suspended TT really well.
by Tim Bailey
Not the arm! Thorens arms? (shudder!) Smile!
Do look at the TT set-up article - at the Van den Hul site – or at the Audio Asylum’s FAQ - before going any further. Remember that you are trying to extract information that is a thousand times thinner than one of your hairs is. I was particularly impressed by this as my hairs are very fine.
Brands / models that can be done via this approach include all AR’s, most Ariston, Linn LP12, Systemdeks, and Thorens’ - TD125, 145, 147, 150, and the 160’s. Do visit the TD 125 part of this site if you have a125 or 126, you will need to.
These turntables all use three springs to isolate the record playing process from the sound of your speakers and some other vibrations. The weight of the sub-chassis and integral arm board, and the, usually two piece, platter and bearing sits above the top of the springs. (ed. note: mouse left click to enlarge picture)
But, there are actually two further suspension elements: the drive belt and the arm lead. This will become more important or apparent as we work through the steps.
These elements along with the mass of the sub-chassis platter and arm / board together form a low-pass filter –
ie only frequencies below the resonant frequency will enter the system. The major corollary is that the lower this frequency is, and the higher the ‘q’ - the better. Another reason for dropping the foam inserts, as is suggested below.
These are a distinct group of TT’s, different from those TT’s that hang the masses from the bottom of the springs, often using 4 springs. Most American high end TT’s, the Michells, Oracles, and the Kuzma Stabi.
The SME 30 and 20, are the most obvious of this type.
Generally, with this type the isolation is better and the set-ups last longer than on the TT’s we are going to visit with.
So, you will have to do this again, less often if you use the nylock nuts, - see JIGS.
But, ours are cheaper! :-).
Support and Vibration aka Mounting yr Turntable
Is yr TT sitting on top of a rack that stands against the wall, but it’s on carpet with underlay under that? Yes, well just stop right now and forgeddabahdit!
Wobble of this type is even more destructive of the sound than an aging soprano’s excess vibrato!
diy concept in steel tube, diy concept in wood.
(note the potential for open access to underside of turntable on these racks )
You must mount the TT on a proper support that stops footfall and other mechanical vibrations and holds it relatively still.
The top of a rack like I have described is the worst place for any TT, and even worse for a suspended TT, as it will be in oscillation nearly all the time!
Suspended wooden floors are a bad basis for 'sprungies' of any kind.
A concrete slab floor is an answer only if you spike the stand to the concrete in the slab floor. Sorry, physics.
NB - Spikes do not damage carpet. Well, no more than a safety pin through your dry cleaned blouse does.
(NB = " Nota Bene", in English: "take note")
Don’t bother going further until this is done. What follows is a waste of time otherwise.
When we achieve some initial stability we will find that the suspension can isolate quite well.
And that the sound improves quite a bit, too.
Tools and Equipment, Safety
Vital: 1You will need a residual current detection device in the AC line. AKA safety switch, or ELB - earth leakage breaker. This may save your life!
If only for the set-up work. Just for that period when you are getting the bounce totally right.
2. A level bench or shelf.
An effective stylus cover – especially if you have an MC cartridge sitting in the arm and in a fixed headshell!
A small spanner, tube spanners are ideal (looks like a cylinder with the hexagons for nuts at either end). About 2 or more inches long, and not a ratchet driver. Usually has a hole through both sides for a rod, allowing you to twist it. 3 of are even better.
Three ‘permanent marker’ pens in distinct and dark colors. Black, red and green?
A decent ruler - with millimeters on it. Or a gauge.
Four clear plastic containers with seal-able lids.
Some cleaning fluid - I use Mr. Sheen.
A gentle (plastic wire) scourer.
Paper towels and (nose type) tissues.
An old but clean tooth brush.
Some q-tips or cotton buds.
Some pure water for rinsing.
Cotton gloves, buy them at a hosiery counter!
Some blue tack or similar to stop your platter revolving - and to stopper the bearing hole.
A capacity for stepping back, and walking away. Not quite Zen but you get the idea.
A ‘jig’ would be really nice - see separate section at the end.
Invert outer platter with a mat, an LP, and your clamp on top, measure height to the platter from top of plinth, this is a useful guide for setting up, write it down.
Remove outer platter. Measure height again, write it down.
Put on gloves, remove belt, place in first plastic container and close lid. Take off gloves and put somewhere where they’ll stay clean. In another container?
Remove inner platter or hub and plug hole with some blutak. The sub-chassis should be almost touching the top of the plinth by now.
Find safety device and check that you can plug the TT in to it. Do not turn the TT back on! Yet.
Remove base and put it and its screws and feet somewhere safe and away from the work space.
Remove all three nuts noting where each one went, a dab from a different marker pen, and a dab on the matching bolt hanging down in the plinth from the motor plate. If they are loose, tighten them up, this is very important. You will need a screwdriver and a small spanner. See tube spanners.
Remove springs washers, foam inserts and the grommets at the top of the springs. These last fit into circular cut-outs in the sub-chassis.
Clean both the top and bottom edge surfaces of the cut-outs in the sub-chassis, as mentioned above, rinse and wipe down.
NB You should first check these cut-outs for burrs, with a finger gently, (sand off). OUCH! Thanks Steve.
Take a break!
Cleaning the belt – stage 3
Put on gloves; hold belt with tissues, spray belt and pull through the tissues, until you think it is clean. The tissues will tell you anyway.
Rinse off and dry it with more tissues.
Place in a separate container that has some talcum powder in it.
Cleaning the other rubber bits- stage 4
Spray them and then clean them thoroughly but gently, of all gooey sticky crap.
Especially in the grooves where the spring ends sit and where the subchassis slots in.
Use paper towels, scourer etc.
Rinse off in water.
Put on gloves to dry with paper towel or tissues.
Pop all the bits into the talc container with the belt.
NB Clean the metal washers that go at the bottom of the spring assembly in the same way.
Toss to coat with talc !
NB clean the inner hub’s running surface and the drive spindle on the motor, buds are great for this. Wash, rinse and talc!
Reassembly – stage 5
Do this with gloves on. At least while assembling and replacing the assemblies!
Reassemble one set of top and bottom grommets, washer, and spring, noting its colour marking. Replace on matching bolt and secure with one new Ny-lock nut, or the original. Twist top grommet into place, slowly and gently.
Repeat for all springs.
Replace inner hub, and adjust height with the nuts to approx. yr second measurement.
Take a break!
Reassembly cont’d – stage 6
Replacing and adjusting the belt. Early centering.
Put on gloves again and replace the belt.
If it has stretched a little try putting a twist in it on either side of the drive spindle. This will shorten it a little and help it release from the spindle and hub. NB The Well Tempered range of TT's adopted this idea quite early on.
Get together the outer platter and mat and an old LP. But invert the outer platter and put it on the other bits on top too - include yr clamp or record weight -if you use one.
You can now adjust the angle / height of the motor spindle this affects where the belt runs. There is a? screw with a spring beneath it beside the motor for this.
NB you will find that there are three screws for this motor two of which do not affect the angle of the spindle, but they do need to be loosened off to allow this and then you tighten them again. On many aThorens sprungie these and the suspension bolts are loose. Motor noise usually goes away after this has been done, otherwise – damn, a new motor!
You will need to do a basic adjust on the suspension for height and level and subchassis centring at this point, remember the first measurement we did.
Centering? You twist the suspension units, by pressing them up and away from the nuts, so as not to change the level.
You will need to turn the TT on .
The belt is running correctly when it is on the fattest part of the spindle for 33.33.
You can now start centering and leveling for serious, but for the moment turn the TT off. Safer, eh!
NB - when setting height, esp. if you have added mass (damping) to the sub-chassis or platter/s you may find that a lower height setting compresses the springs less, and you may be able to adjust this.
A slightly freer bounce just might result.
Remember that there isn’t much range because of the speed change lever that moves the belt. Does yours still work?
If you ever go to an electronically regenerated supply or DC the kit may have two speeds and can ditch that lever. AND yr set-up can only be optimal for the one setting of the belt-run.
Apologies to all the popular music vinylists with lots of 45’s.
Try to get a good bounce - with the platter inverted - first. Later, with the system more stable, the final adjustments should be easier and closer to optimum.
A slightly lower height may help here. See above.
Check belt-run once more.
If you are fitting a new arm, then you also have to arrange the lead so that it is long enough to allow free suspension movement and yet placed so that it doesn't get in the way of the movement, as well.
Thorens' own arms do at least have very thin wire here, and so this isn't usually a problem. Do check that the arm leads are free and are not rubbing
NB it is best to do this after aligning the arm and cartridge as this can affect the needed lead length. And around we go again - with another iteration of the set-up process.
Stage 7 - Centering and final bounce
(Editors note: above illustration is taken from the LP-12 setup manual. Rather Thorens-like, don't ya' think..?)
NB keep everything on the platter, that is usually there, now right way up, eg. do up the clamp.
You twist the suspension units, pressing them up and away from the nuts……. Until the chassis is centred and then adjust with the nuts to level it. Iteratively.
The little bulls-eye level is very handy here. Vital?
Check again that the TT itself is level at this point. Use the long level.
Take breaks from here on in. You may get lucky and you may not.
NB the TT must be on and going around now. Now you know for vy ve haff the safety switch – oi vey!
Keep going until you have a nice smooth and quiet vertical bounce to taps with one finger. Where? Tap just to the right side of the centre spindle and a bit towards the arm, but still within the label area.
Once you have found a good bounce, and if you are going to replace the base and screws and feet, there is a bit to do still, and you will have to be very careful.
Remove the platter, and hub, first, stopper the hole too. Then replace the base.
Otherwise be very slow and gentle while replacing the base.
Check that the TT is level on its mounting and…
Apart from listening!
You should notice a substantial improvement in noise floor. Surface noise/display--it should now resolve in another plane than does the music.Bass should not only be deeper but also much more articulate. Fingers on strings and frets, different pluckings etc. etc. Dynamics will be a whole lot better, macro and micro. Depth is wow. You SO will love it!
WHY a JIG?
If you are going to stay with yr ‘sprungie’ / Thorens', you will be doing a set-up once a year or so. More often if you use a threaded record clamp, like my GB clamp!
After you’ve done it once, the job does get easier, and smoother.
Still, a jig - to hold the chassis and wooden plinth level and steady, while working from underneath, is a great idea.
Use some speed frame and some clamps as well.
The frame needs to be high enough so that when used on a bench, you can work underneath and see up inside, without having to contort too much!
Lockable leveling screws in the bottom of each leg might be nice too, level it with a long level, add a bullseye level and a safety switch and there you are.
I have another path in mind,……., later....