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A new belt for the Linn LP12

The LP12 belt has progressed through three versions:

Initial prototype - 165mm diameter and 4mm width. IIRC this is the version @flatpopely has.

Mk1 - The length stayed at 165mm diameter but the width was increased to 5mm. IIRC this is the version @linnfomaniac83 has.

It was observed that the 165mm belt ran about 1% slower than the genuine Linn belt on a standard Axis or LP12 set-up. This itself is not a problem at all since the speed can be adjusted back up again marginally. When using a Radikal the speed will automatically always be kept perfect.

Mk2 - I decided to increase the length of the LP12 belt very marginally to 167.5mm. The slightly longer belt creates less 'drag' and runs a fraction faster on a standard set-up and so needs less speed adjustment. It is of little consequence but I wanted to make the belts as perfect as possible.

For people using a Radikal there is no advantage to the Mk2 belt and no disadvantage to the Mk1 (remember the difference is tiny) and so rather than keep people waiting for the Mk2 to come into stock I sent some Radikal users the MK1.

Simon's set-up is non-standard and he is using a longer 170mm belt.
 
My deck is a bit of a hybrid Kuzma Stabi S 12", but uses Lp12 bearing, sub and platter with a Mober Dc motor. The motor pod is fully adjustable for position so i went with a longer belt.

I'd stick with the standard LP12 length on an all Linn spec deck
 
My Lp12 belt arrived today; thanks @Mike P I've not had the chance to try it yet. So this one will be the Mk2 version then? I look forward to giving it a listen!
 
Mine has arrived, how long should I run it before comparing?

On a TD-124 it very obviously breaks in over a couple of night’s listening, I’d say 6-8 hours or so before it is really ‘there’. Very curious a) as to why this is (i.e. what property is changing, and b) whether it is as evident on slower-moving drive systems such as the LP12.

PS I suspect the 124 is a pretty hostile environment for a belt as the motor is so fast-running (about 1450rpm IIRC) and runs the belt against an eddy-brake resistance.
 
I hadn't given a thought to running in tbh, but it would also seem that according to Mike, for the LP12 at least, you should also check the speed too, else if one or the other belt is running faster, then that would bias the listening test.
 
Arrived this morning Mike, thanks. Will report findings on the LBT thread, will give it a few weeks. Cheers, Matt.
 
Forgot to ask, any advice on fitting? I always fit Linn belts smooth side against the platter/pulley? Is this any different?
 
OK let's see some reviews! I'm interested in buying but wouldn't mind hearing from those who are giving it a go!
 
Forgot to ask, any advice on fitting? I always fit Linn belts smooth side against the platter/pulley? Is this any different?


I'm getting a lot of queries about fitting instructions for my belts, so here you go:


Unlike standard belts our belts are moulded 'in the round' as a single continuous circular piece with no glued join. They are 'endless'.

So there is an inside and an outside to the belt. However, to be honest the material is so soft and supple the difference is very subtle.

If you hang the belt from something like a pencil the the bottom of the belt where it turns 180 degrees will form a radius. With the belt the correct way around this radius will be slightly tighter and with it inside out the radius will be larger.

If you can't tell, please don't worry about it. Just install it either way and it'll be fine.

However, please take the time to clean the surface of the pulley surfaces to remove all traces of residue left by the old belt. This is especially important on the Thorens TD124 which often suffers from a lot of build up of residue left by the old belt.

It does make sense to try and keep the belt clean and free from dust and grease when you install it. There's no need to wear a full forensics suit but I would advise at least washing your hands thoroughly before handling the belt.

As many owners have already observed, these belts do take a little while to settle in and they can be a bit noisy at first. This is nothing to be concerned about and once 'bedded in' it should be very quiet and quieter than any standard quality belt by a good margin.

Unless your turntable uses a sophisticated speed controller, such as a Linn Radikal a change of belt may cause a small change to the speed your turntable runs at and you may need to make a small speed adjustment. If you don't have a strobe you can use a App to measure and fine-tune the speed. Top tip: when using a phone App place your phone as centrally as possible on the platter, on top of an upturned bowl or similar, so as to knock the platter out of balance as little as possible.
 
OK let's see some reviews! I'm interested in buying but wouldn't mind hearing from those who are giving it a go!
OK.
Deck is '81/'82 vintage. pre-circkus with Lingo 1 PSU, Trampolin 2 and Tranquility. serviced about four years ago

Used Apps "RPM" and "Turntable Speed" on my iPhone X

Results at 33 1/3 rpm using RPM:
Black Linn Belt yesterday: 33.35 +0.04%, w/f 0.13%
Blue belt today: 32.74 -1.79%, w/f 0.21%
Black Linn Belt reinstated: 33.37 +0.1%, w/f 0.11%

Results at 33 1/3 rpm using Turntable Speed:
Black Linn Belt yesterday: 33.35 +0.04%, w/f (rms) ±0.05%
Blue belt today: 32.55 -1.76%, w/f (rms) ±0.24%
Black Linn Belt reinstated: 33.37 +0.10%, w/f (rms) ±0.05%

Results at 45 rpm using Turntable Speed:
Black Linn Belt yesterday: 45.04 +0.09%, w/f (rms) 0.05%
Blue belt today: would not get up to speed - unable to test.
Black Linn Belt reinstated: 45.06 +0.14%, w/f (rms) 0.04%
 
Last edited:
Shrugs. I'm using the app recommended in post #11.

If the results from multiple runs of a baseline configuration are consistent then one is only looking for deltas which occur following any change to that baseline configuration. Black Linn belt is the baseline configuration. Two tests of the baseline configuration were performed, one before fitting the Blue belt, and one after. The results of those two tests are pretty consistent.

Works for testing spacecraft anyway :)
 
The apps seem pretty good, good enough for Michael Fremer and others to use them. The problem with a suspended deck like a Linn is if the phone isn’t very precisely centred weight-wise wow will be hopeless as the suspension will be following the offset weight.

PS No such issue with my 124, this is with the phone just plonked on one side of the centre spindle:

51949895909_a7e43d1a07_b.jpg


The speed is variable so I could tune it in better (I set it using the built in strobe by eye), the wow and flutter is the important stuff here, and that’s good by any standard.
 
The phone was centred on a cardboard tube of dia. 8cm as "concentric with the spindle" as I could get by eye.

Edit: More thoughts

1. I note that Turntable Speed app recommends putting a disc on with the needle in the groove. Will try that tomorrow

2. I wonder whether the Tranquillity is having an effect?
 


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