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A new belt for the Linn LP12

I have a new motor on my LP12 and an excellent condition black liner pre Cirkus bearing...

The 167.5mm belt I purchased from Mike is know almost silent and running at 33.23rpm with 0.07 wow RMS. Also, I've reset the motor position to standard just as it was running with the Linn belt. I had issues with noise and low speed when initially fitted and this persisted despite having run the belt in excess of 36 hours.

How did I achieve this? Well, I talced the belt and then I removed excess talc with half a dozen or so paper tissues - no longer a sticky clammy texture to the belt now. Talc is a lubricant yes, as evidenced if too much is left on the belt - it won't drive! But it also prevents stickiness in the right amount, if hardly any is present on the belt.

It's now also behaving more like a Linn belt on start up. Not saying the start up is important as I usually give the platter a spin up anyhow. But my God the blue belt certainly has an effect on music. Transients are almost explosive, electric bass notes start and end on a sixpence, piano notes decay beautifully with no hint of waver and stand up bass is gloriously woody. I've also noticed a huge improvement in subtle detail, backing singers appear to be playing a bigger part in the mix than ever before. Jazz drum brush work is now very detailed much more than just a "tisshh, tisshh" as I heard before. Now I'm not just hearing the initial strike (tisshh) but also the draw across the drum head too - awesome!

These blue belts are something really special, great work Mike!
 
Good evening folks,

I may have been a bit absent from this thread for the last day or two but behind the scenes I've been frantically trying to get to the bottom of the problems that a small minority of people have experienced with the LP12 belt. Problems that did not show up in pre-production testing!

The compound that the bluebelt is made from takes some time to fully cure after manufacture. We estimate typically 2-3 weeks are sufficient in ambient room temperature.

Until the belt is properly aged and cured the belt can be too tacky and this is the root cause of the issues that some have experienced.

Running the belt on a turntable 'works' the belt and does speed up the process, which is why many have observed that the belts improve significantly after a bit of bedding in. However on a deck such as an LP12, which is quite gentle on belts, this could take a considerable amount of time.

This problem didn't show up in testing because the belts being tested were old enough. However in our haste to get the new LP12 belt out to waiting customers we rushed to get them posted out just days after being made. They were therefore still very fresh and still very tacky.

There are three solutions:

1) Let the belts age for plenty of time before using them.

2) Apply a very minimal dusting of talc. Just enough to get rid of the tacky feel.

3) Briefly boil the belt in water for a few minutes which rapidly finishes the curing process.


Obviously the long-term plan is to only deliver fully aged belts from now on but for those people who've already taken delivery of a belt that is not playing ball the solution is either the talc or the boil.

I'm massively grateful to a few PFM members who've been very supportive over the last couple of days and agreed to take part in various testing for me. Notably @Voyd the Voyd and @matfff amongst others.
 
Mike P said:
for those people who've already taken delivery of a belt that is not playing ball the solution is either the talc or the boil
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Thanks, Mike! I'm using my blue belt with a Radikal and haven't had any problems, even though the belt was indeed a bit "tacky" to the touch. Should I give 'er a boil just in case?
 
I’ve yet to listen but after a boil in water and running overnight it still takes an age for the Radikal LED to dim compared to the Linn belt.

This has got me thinking about how the elasticity of a belt could be a factor in a servo system even once it’s reached a ‘stable’ speed. Given the way a servo-controlled motor works there will always be small changes in the torque (as a function of speed changes) from the motor to compensate for any change in the platter speed. The part of the belt that’s ‘returning’ from the sun-platter to the pulley will be stretched to a degree by the torque change and, too much elasticity would be a bad thing as it might induce an oscillation albeit one that would be damped pretty quickly as the belt moved to the pulley. On reflection this also applies equally to the other part of the belt that’s not in contact with the sub-platter. I’d never really given it any thought but it’s clearly a complex system and more so perhaps than one with the motor running at a constant torque.
 
joe9407 said:
Thanks, Mike! I'm using my blue belt with a Radikal and haven't had any problems, even though the belt was indeed a bit "tacky" to the touch. Should I give 'er a boil just in case?
Click to expand...
If your belt is running fine already I wouldn't bother. It will naturally only get better with use anyway.
 
Got my LP12 belt yesterday, popped it on after cleaning the pulley, started the deck up, & within a few seconds, the Radikal's light dimmed. I've not had a chance to have an extended listen but the couple of sides of The Beautiful South's "Choke" I listened to sounded pretty damn good.

Thanks Mike!
 
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My blue belt was delivered this morning and after sitting in boiling water for a few minutes it is now rotating the platter on my LP12.

My old Linn belt was old worn out and would not get up of the angled part of the pulley and so cannot be compared against. Interestingly on the angled part of the pulley it measured 31.37 RPM and 0.06% wow with the speed and wow app.

Will check and adjust the speed tomorrow and then try listening to the system, albeit with no recent memory of what my LP12 sounded like (for many reasons I predominantly listened to flac files, but am going to get back to playing records more often).
 
Thanks for that update Mike. I hadn’t reported on mine yet but I suspected curing might be the issue

I bought three of the new batch from Mike and they were super tacky at first. I could hear them ‘roar’ from the other side of the room when I first tried them all on a deck with a Naim Armageddon PSU and standard (recent) motor. They were also running at a slow speed. I ran one of them in for 5 days turning 24/7 and it really improved over time though even now it’s still a bit too noisy yet. I couldn’t really detect much of a difference in sound though to be honest but I’ll return to listening tests on this deck when I dial the speed in. For now I’m using this deck to run the belts in.

The second belt that came out of the pack was noticeably less tacky now and had clearly cured some more since when I first got it a week ago and was much less noisy after an initial trial. So I agree, the rubber is still curing.

I took the first belt that had been run in and transferred it to a deck using a Radikal. No issues with speed and it’s working well on that deck. Still a little noisy for me and I haven’t detected any difference in the SQ so far but it’s early days.

I will try a third belt when it’s had a run in period on a Lingo 4 deck and will report back later.
 
<moderating>

Thread pruned. This is a thread about a very specific blue belt. There are plenty of threads about the general pros and cons of the LP12 elsewhere on the forum should folk wish to participate.
 
Further feedback on my blue belts. Curing seems to have carried on for some time but I still think these remain a little bit sticky and therefore a little noisy. Speed stability seems good on my Radikal and Lingo 4 powered decks. Both seem to have enough auto adjustment to their motor to get the speed spot on.

With a different deck that used a standard motor powered via a Naim Armageddon however I cannot get the speed set correctly. It seems the belt is slightly too long and as you close in on 33.33 rpm the belt starts to rub on the top of the belt guide.

As an aside I have been setting the speed using a strobe and disc and not an iPhone app because they are in accurate. If I set the speed with the strobe and recheck with the RPM app on a couple of different iPhone models I find the app is about 10% fast.

I will be trying these on Valhalla and Majik powered decks in the coming weeks and will report back on those.
 
Tony L said:
Has anyone got a theory as to why the blue belt seems to run a little slower on the LP12? To my mind there are only two possible reasons; a) it is slightly thinner in cross-section*, or b) it may be a little ‘sticky’ from new and add a little drag (this being my best theory to date for the initial noise on the 124 that recedes so dramatically after ‘break-in’).

*I have no idea if this is true or not, but I do understand that when a material bends around a curved surface it does so at the mid-point of its thickness, i.e. the outer surface stretches, the inner surface contracts, the middle stays where it was, so replacing a thick belt with a thin belt, or vice versa, actually effects the drive ratio and therefore the speed. Again this is very obvious with fast-running drive systems like the TD-124. This is also why accurately sizing a pair of JR149 grilles isn’t as simple as one might think!
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I received my blue belt today. I was using a 10 year old genuine LP12 belt and had the speed running at 33.32. I have a new LP12 belt that I put on next, it was running at 33.38. I put the Blue belt on and it was rubbing against the bottom part of the belt guide, speed was 32.00. At this point I just went ahead and let it sit in boiling water for 10 minutes. I retested and the speed went up slightly to 32.04, still rubbing.

I have a Lingo 1 so in order to increase the speed one is to loosen the back screw closest to the rear of the turntable and tighten the forward screw. Once I got it at 33.33RPM the belt was riding in the proper position on the pulley centered at the crown. Initially it stayed down near the bottom of the pulley, hence rubbing against the belt guide.

I would surmise from my experience that once the speed is adjusted properly, the belt should be riding at the crown and well away from the belt guide.
 
Hi folks,

Please can a clarify a few points:

1) The boiling recommendation applies to the very first batch of LP12 belts sent out only. All subsequent batches are supplied pre-aged and do not need boiling.

2) You will almost certainly need to adjust the motor tilt when changing from a genuine Linn belt to the bluebelt. This is to be expected.
 
Mike P said:
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.
Click to expand...

Just to be clear, are you saying B is the better orientation?

juoJGaE.jpg
 
John said:
Just to be clear, are you saying B is the better orientation?

juoJGaE.jpg
Click to expand...

Hi John,

Normal belts are made from a strip which is closed with a glued join. Our belts are moulded as single continuous circular piece. They have no join and are 'endless'. When they're on the mould they do have an inside and an outside.

Theoretically the belt will hang more like 'B' when it is in the same orientation as it was made. However, the material is so soft and pliable that the difference is negligible and very hard to discern.

Just give it a quick test in both orientations and just keep it in the orientation that you think runs more quietly and/or sounds better to you.
 
The Blue belt is noisy. I ran it overnight and it’s not any better, tried reversing it as as well. The armboard also jimmy’s during startup, the new Linn belt starts up faster with no shaking of the armboard. It’s also dead quite. I was hoping the Blue belt would be good based on the reviews. Maybe it’s more appropriate for a DC motor.
 
John said:
The Blue belt is noisy. I ran it overnight and it’s not any better, tried reversing it as as well. The armboard also jimmy’s during startup, the new Linn belt starts up faster with no shaking of the armboard. It’s also dead quite. I was hoping the Blue belt would be good based on the reviews. Maybe it’s more appropriate for a DC motor.
Click to expand...

Did you adjust the motor position?
 
paulski said:
Did you adjust the motor position?
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I adjusted the tilt screws to get the speed correct, it was running at 32RPM initially.

The belt was centered right at the crown of the pulley and running at the correct speed. I think it being smaller than a Linn belt places more pressure on the motor causing the noise.
 
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