Linn Owners

Sondek.. fast prob. Help!

The Abbot

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Hi folks in this merry corner of The 'Wam. I've kindly been lead here via a link.

I have a speed problem, it seems, with my Lp 12's valhalla. Not excessively OTT fast, at a guess 34 to 35 rpm. But fast enough nevertheless to be a blurred pattern on my outer 33 rpm AO strobe disc.. & everything just audibly a bit fast. Annoying.

I've tried: alchohol cleaning the motor pulley, & setting the 2 motor screws at max tilt. Both these have in fact made no difference.

It's a 89 vintage, had the board's main filter cap replaced about 3 years ago ( it just stopped working prior to this job ).

Only last few Lp's have I noticed the 'slightly fast' musical presentation. I'm fairly sure then, it changed at a recent juncture, rather than a gradual thing over a long time.

Any ideas? Thanks so much for reading, Abbot.
 

Coalboy68

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You can adjust the speed slightly by adjusting the motor screws on the top plate under the platter which allows you to tilt the belt pulley slightly thus altering the speed.
 
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Moomintroll

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I've tried: alchohol cleaning the motor pulley, & setting the 2 motor screws at max tilt. Both these have in fact made no difference.
What do you mean by two screws at max tilt? This should have definitely made a difference one way or the other.

A photo would help.

’troll
 

The Abbot

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What do you mean by two screws at max tilt? This should have definitely made a difference one way or the other.

A photo would help.

’troll
Hi Moomintroll. There are 2 screws either side of motor pulley. You can adjust them so motor pulley is at max tilt in (meant to increace speed) or max tilt out ( decrease speed). In the manual etc.

Ive done the latter, but this has made no difference, well no audible difference ( its sounds identically slightly fast), nor any difference on the strobe disc ( being still just a blur).

[ Edit: this is the Linn site thing! Im getting confused with my other thread, & where exactly I am now.. I just don't understand this Linn site- within- hifiwigwam- site thing: I mean why isn't there just a linn forum ?!]

Thanks, Abbot
 
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The Abbot

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You can adjust the speed slightly by adjusting the motor screws on the top plate under the platter which allows you to tilt the belt pulley slightly thus altering the speed.
(Moomintroll, this ^ is what I meant by adjusting the 2 screws at max tilt).

Thanks Coalboy, yup I did try this as outlined in #1. This seems to be only sufficient for "micro adjusting" tho, like 0.2 rpm max.. something like that figure.

I'm a full 1 rpm fast I'd say.

Thx Abbot
 

Nopiano

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If my memory is correct, then a semitone is 6% difference. Based on 33.33 rpm, then 6% is 2 rpm.

If you’re 1 rpm too fast that’s half a semitone sharp. I’ve not got an adjustable turntable to hand but I’d be surprised it was so obvious. But if you’ve perfect pitch it would very clear I’m sure!

Do you have an incandescent lamp to illuminate your strobe, as they are rare these days? I would expect to see the strobe pattern to appear to be rotating clockwise, but not so much as to be a blur.
 

cre009

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From your prior thread in 2 channel you commented that you had to remove crud from the pulley.

It is most likely that came off your belt in which case your belt may not be in good condition. At the very least clean your belt. The condition of the belt is very important for speed stability.

The method for fine tuning speed on the LP12 is by tilting the motor. There is no doubt that this works over a limited range but I have not seen a clear explanation about why it works. I have read comments that it is down to change of belt tension while others seem to believe it adjusts the position of the belt on the pulley and this causes the change. Make sure you are following the instructions in the service manual when adjusting tilt.

I own a lot of decks (not just LP12s) and for one of them I have a number of old well used belts which had stretched over time and all of them ran fast by varying degrees. Tricks like boiling the belt helped a bit and I made sure they were well cleaned but in the end the best solution is to acquire a new properly specified belt.

There is an issue with the LP12 in that Linn belts are quite costly and there are a lot of cheap after market belts available but they rarely provide the full specification. The spec does matter. A belt that is too thick will run fast if all else is equal. A belt that is the wrong width may not interact correctly with the pulley. A belt that is too tight could stress the motor.
 

Ady

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I think you mentioned in your two channel thread that the belt was 8 yrs old? On the advice of Peter from Cymbiosis I changed mine after 5 yrs. Yes it cost £50.00 but it works. I don't know where you are in the Midlands but if you are within travelling distance of Cymbiosis I would just take it there and let Peter sort it. You may of course be intent on DIY, if so I hope you get it fixed.
Cheers Ady
 
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The Abbot

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@cre009

Thanks for that explanation cre009. Makes much sense. Yes the crud must have come from the belt you're right. What can I clean it with? Maybe isopropyl will eat the rubber?

It was an aftermarket belt yes, but until a week ago ( this is when I noticed the faster aspect to music, from Lp's I know like the back of my hand) it was providing fine service. Maybe 10 years.

Tell me, how physically can a belt's worn aspect, produce -faster- symptoms? My belt before, it's original one, produced gradual -slower- symptoms so I changed to current one. I can understand a tiny stretching, over time, & a slowing as a result. But can't understand the opposite symptoms.

What I want to rule out you see, if I plump for a linn original belt ( if current one was fine for 10 yrs tho.. & £ 1/5th, you might see I could think this isn't such a stupid buy) what I want to rule out begirehand that some capacitor ( IE or a board niggle) isn't the cause of this speed increace. Or I'd have spent £50 for nothing.

Thanks, Abbot
 

The Abbot

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I think you mentioned in your two channel thread that the belt was 8 yrs old? On the advice of Peter from Cymbiosis I changed mine after 5 yrs. Yes it cost £50.00 but it works. I don't know where you are in the Midlands but if you are within travelling distance of Cymbiosis I would just take it there and let Peter sort it. You may of course be intent on DIY, if so I hope you get it fixed.
Cheers Ady

Hi there Ady, sensible advice there thanks. I don't let's say have the disposable income normal lp12 owners have you see- far from it. Mine was a loony £200 mid 90's. But I still had to take arm off & flog, as I wasn't £loaded. Helping alot the akito sold for £280! ( I had to AO service it with 'sticky bearing sydrome' first tho, & really loved that arm). So once my proper-job mission 774 bought for it I effectively had a lp12 for £130. So new £50 belts... are quite a stinger.

It's primarily being confident that this belt - is- the culprit though. I wonder as a test, & thinking this idea as I read your reply, could I buy your old belt off you? Assuming a linn. If this showed slightly slow symptoms (as I assume it did to you) then I've prooved firmly my belt -is- the cause of my speed increace issue.

Grateful for the help chaps, Abbot
 

Ady

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I honestly can't remember if I've still got my old belt in the lp12 box in the loft. I'll check and if I have it you can have it free of charge except for any possible postage costs. At the time it wasn't showing any signs of deterioration I just had it replaced because of age.
Cheers Ady
 

The Abbot

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I honestly can't remember if I've still got my old belt in the lp12 box in the loft. I'll check and if I have it you can have it free of charge except for any possible postage costs. At the time it wasn't showing any signs of deterioration I just had it replaced because of age.
Cheers Ady
Hi Ady. That is fab of you.. actually I was just doing the same looking for my old belt in my boxes, which may have given me a clue to tye current issue, but can't find.

Thanks so much, Abbot.
 

The Abbot

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If my memory is correct, then a semitone is 6% difference. Based on 33.33 rpm, then 6% is 2 rpm.

If you’re 1 rpm too fast that’s half a semitone sharp. I’ve not got an adjustable turntable to hand but I’d be surprised it was so obvious. But if you’ve perfect pitch it would very clear I’m sure!

Do you have an incandescent lamp to illuminate your strobe, as they are rare these days? I would expect to see the strobe pattern to appear to be rotating clockwise, but not so much as to be a blur.
Hi Nopiano. [apologies I didn't see your reply until now]

Hmm.. good observations there. I haven't got perfect pitch, but 2rpm is possibly where I'm at. I'm adamant it's fast anyway.

Incandescent.. not sure. But having an old dual 505 tt I use as my rcm base.. under typical build new led ceiling 'spotslights' I can see this do the usual strobe outer pattern 'freeze' still.

I simply have an led bulb in my anglepoise I use for my Lp12. So I assume this is the same effect as my 'spots' in the workshop next door.

Thanks alot, Abbot.
 
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Moomintroll

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Incandescent.. not sure. But having an old dual 505 tt I use as my rcm base.. under typical build new led ceiling 'spotslights' I can see this do the usual strobe outer pattern 'freeze' still.
An incandescent bulb will ”blink” in relation to the mains frequency, so in the UK with 50Hz mains, it will “blink” at 100Hz. LED lights also blink, but not fixed to the frequency. This probably explains why you see strobe marks as a blur, rather than moving. No idea what speed the freezing strobe on your 505 indicates, but another LED will not, necessarily, give the same reading. You can still pick up “old style” incandescent light bulbs if you look hard enough. These will give a more consistent reading on a strobe disc.

I’ve looked at the Valhalla service manual and all board faults seem to relate to slow running, not fast. That’s not to say it doesn’t need a full service after 30+ years, if you only replaced the large caps previously.

’troll
 
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cre009

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@cre009

Thanks for that explanation cre009. Makes much sense. Yes the crud must have come from the belt you're right. What can I clean it with? Maybe isopropyl will eat the rubber?

It was an aftermarket belt yes, but until a week ago ( this is when I noticed the faster aspect to music, from Lp's I know like the back of my hand) it was providing fine service. Maybe 10 years.

Tell me, how physically can a belt's worn aspect, produce -faster- symptoms? My belt before, it's original one, produced gradual -slower- symptoms so I changed to current one. I can understand a tiny stretching, over time, & a slowing as a result. But can't understand the opposite symptoms.

What I want to rule out you see, if I plump for a linn original belt ( if current one was fine for 10 yrs tho.. & £ 1/5th, you might see I could think this isn't such a stupid buy) what I want to rule out begirehand that some capacitor ( IE or a board niggle) isn't the cause of this speed increace. Or I'd have spent £50 for nothing.

Thanks, Abbot
One of the Linn manuals suggests use of furniture polish to periodically clean the belt though that is controversial for many users. Another Linn manual says

"BELT. The belt should last for at least five years of regular use. The belt can be cleaned at the same time as the pulley is cleaned. The best method of cleaning a belt is by pulling it through a damp cloth".

After motor rpm the main thing that impacts speed is belt thickness. On some turntables (but not the LP12 due to the pulley) this is easy to demonstrate by running the turntable with 2 belts one outside the other. This runs considerably faster than if the outer belt is removed. Approximately half the thickness of the belt is added to the effective diameters of pulley and inner platter. Many people think it is just the pulley and platter diameters that matter but the belt thickness has to be factored in.

Another thing that can influence speed is drag which will be down to the tension and how slick the belt is. This is something I am interested in but not confident about. If a belt stretches over time then there is less drag. The belt may also harden over time and be less grippy. This will be off set to some degree by thinning of the belt and gradual shredding of rubber over time. The belt may also ride slightly differently on the pulley. If the belt becomes uneven through shredding then the speed will become less stable and best to replace the belt.

Are you able to provide an image of how the motor is attached to the top plate? The holes for attaching the motor bolts are elongated and there are a couple of different positions possible. It is only a couple of mm but will matter. For UK the motor should be attached such that on one side the bolt is farthest away from the platter and on the other side closest to the platter.
 
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Nopiano

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Hi Nopiano. [apologies I didn't see your reply until now]

Hmm.. good observations there. I haven't got perfect pitch, but 2rpm is possibly where I'm at. I'm adamant it's fast anyway.

Incandescent.. not sure. But having an old dual 505 tt I use as my rcm base.. under typical build new led ceiling 'spotslights' I can see this do the usual strobe outer pattern 'freeze' still.

I simply have an led bulb in my anglepoise I use for my Lp12. So I assume this is the same effect as my 'spots' in the workshop next door.

Thanks alot, Abbot.
‘troll has covered this better than I could, but let’s eliminate bulb issues first. You need a non-led source to be sure, or you could try a phone app as a back-up though it’d not be my first choice. You can use the Dual as your comparator.
 
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The Abbot

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‘troll has covered this better than I could, but let’s eliminate bulb issues first. You need a non-led source to be sure, or you could try a phone app as a back-up though it’d not be my first choice. You can use the Dual as your comparator.

Hi nopiano. Yes I think I've eliminated the lamp: I cant take the Lp12 to another room/ huge hassle, & can't take the fixed ceiling spots my dual TT is under out to the Lp12 room.

Looking at the Lp12's lamp bulb box, it says theyre "Vs Incandescent". So I asssumed this was a useable bulb for the strobe test.

One thing I haven't tried (as I thought I'd definitively concluded the Lp12 is fast prior to starting the thread), is take the dual TT (rcm) out of plinth (fixed in solid in my workshop as an rcm/ faff to undo it all) out over to my Lp12 lamp. As equal a faff is taking this lamp out you see/ all dug in behind jumble of hifi cables & plugs.

@cre009 thanks for your observations there. Yes I read all issues related to slow running too in the manual. As Im not sure it's a linn belt, I think not, I don't want to clean with something which may deteriorate it. It seems in reasonable condition .

Thanks chaps, Abbot
 

Moomintroll

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Looking at the Lp12's lamp bulb box, it says theyre "Vs Incandescent".
Isn’t this just a comparison of the LED versus incandescent? Otherwise I can’t imagine what “Vs incandescent “ might mean.

BTW - safest thing to clean any belt with is a slightly damp lint free cloth.

’troll
 

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