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Thread: LP12 Bounce test

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    Default LP12 Bounce test

    Hi,

    I've a humble LP12, I bought it in the mid 90's. It's a pre-Cirkus bearing deck with Hercules 2 PSU and Basik Plus arm / K18mk2 cart.

    I'm soon to be swapping the arm for a refurbished AO Akito arm, will be keeping the cart for the time being as I found a 'new' stylus on eBay only recently. I'm tempted to Mose the Herc' and install a better tonearm cable if funds permit whilst I'm swapping the arm out.

    One thing that's always bothered me, if I do a 'bounce test' of the platter to check the springs, whilst it has a similar number of bounces to any YT video I've watched you can always hear the springs rattling away whilst it settles. Is this how they normally are? I would have thought they'd be silent. Makes the whole thing sound a bit rattly as if there's loads of play everywhere.

    The vids sound fairly silent but it's difficult to tell how they've been mic'ed up.

    Advice on whether I should give them some TLC would be appreciated.

    Thanks

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    My LP12 was all but silent when doing a bounce test, as have all the ones I have heard.... IIRC!

    I can't see why they would be noisy, as they are always under compression and are fitted with rubber grommets top and bottom.

    If it were mine, I'd be having a close look at why they may be 'rattling' AND given that you have a few proposals in mind for updating various components you should probably think about including a new set of springs and grommets (a cheap improvement compared to other parts, especially if your existing ones are of any age) and carrying out a full set-up on completion.

    Check out the vid's and the Linn user / maintainer manual (various documents here) and get the TT on a jig with the bottom plate removed. You should soon determine what is causing your rattle (and it may not even be the springs themselves!)

    G.
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    It sounds to me like the spring coils are touching when compressed. Your deck might still have the older springs fitted in which case a new set would revitalise it. Bear in mind we've been on the new black springs for donkeys years now so even if the deck has a set of those already fitted they could be tired especially if the deck was laid up without removing the platter. I've never had any problems with the grommets but the long bolts may need realigning as the top plate bows and can knock everything out of kilter.
    Just a thought but when I do a bounce test I don't press down on the centre spindle. I press half way across the platter towards the arm board as the subchassis fully kitted out is not evenly balanced.
    Si.

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    Not sure if peeps are doing this, but I usually turn over the outer platter to perform a bounce test, but as others have said new springs, and perhaps new grommets are a no brainer given the cost (J7 knows the price as he can supply) little bit of talcum powder on the springs before fitting will stop any squeaks, and aid in twisting them to get bounce pistonic.

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    Quote Originally Posted by Chops54 View Post
    Just a thought but when I do a bounce test I don't press down on the centre spindle. I press half way across the platter towards the arm board as the subchassis fully kitted out is not evenly balanced.
    Me too... good advice.

    Quote Originally Posted by The Professor View Post
    Not sure if peeps are doing this, but I usually turn over the outer platter to perform a bounce test, but as others have said new springs, and perhaps new grommets are a no brainer given the cost (J7 knows the price as he can supply) little bit of talcum powder on the springs before fitting will stop any squeaks, and aid in twisting them to get bounce pistonic.
    Also excellent knowledge to add to your repertoire. The inversion of the main platter is very useful when setting up the TT to ensure that the belt is running true in the correct position / alignment.
    You can only be young once, but you can be immature for ever.....

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    More reasons to stop me ever owning an LP12. What a palaver! But that's just my opinion. I know it's hard to beat once set up correctly, there just seems so much that can be slightly out that ruins its performance. Like an F1 car, you have to constantly meddle with it.
    Last edited by TIU; 26th March 2015 at 13:10.

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    Quote Originally Posted by TIU View Post
    More reasons to stop me ever owning an LP12. What a palaver! But that's just my opinion. I know it's hard to beat once set up correctly, there just seems so much that can be slightly out that ruins its performance. Like an F1 car, you have to constantly meddle with it.
    Not strictly true Gary.

    If it's set up properly in the first place and NOT meddled with, it will stay true and perfect for a very long time. It's a mechanical device with many paramators that require servicing and tuning every now and then (bit like your F1 car analogy, but not quite as 'constantly'), and it will provide sterling service if left alone to play the vinyl....

    And like any simple mechanical device (which is what it is - 'simple'!), there was always far too much mystery surrounding the set up, portrayed by Linn and their dealers.
    You can only be young once, but you can be immature for ever.....

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    What if you remove the springs and have a solid platform? Less faffing about eh.

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    Quote Originally Posted by TIU View Post
    Less faffing about eh.
    That's true........ but what happens to the music???? Bouncer addicts will tell you there would be less of that too.....

    And if there are no springs... don't consider for one minute that the TT won't suffer from foot fall in many a room...
    Last edited by WullieD20; 26th March 2015 at 13:38.
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    I suppose this tt is only posted about when there's an issue so I only get to hear of that. It all accumulates to give me an impression of it which is, as you point out, not strictly true.

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    At the end of the day it's always going to be 'horses for course' and those that love them will pontificate appropriately. Those that don't will always have a similar substantiating argument for their own preference. Even 'bouncers' have different designs and attract their own following.

    I moved from an LP12 to a Systemdek: both bouncers, but entirely different philosophies. Loved my LP12 for many years (and still do); the Systemdek was just another step up the performance ladder for me. (not a dissimilar debate than the one for tone arms and cartridges, or any other of our wonderful hobby's components for that matter).
    You can only be young once, but you can be immature for ever.....

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    I had a bouncy deck - a Dual 505 Mk1 (well, the top plate was springy and had locking screws for transit), which is different in design again.

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    I'll bounce it and record a vid this eve. I've had the deck 20 years, it's not been 'hassle', I'm just had an itch to improve it. I've a friend with an uber LP12, all direct driven, DC motor, internal amp, sounds insane, I don't have much budget but will strip it down to see what's what.

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    Don't take any notice of my ill-informed comments qube. I've never owned one so should stfu.

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    Here it is: https://www.dropbox.com/s/e6xmxld3sd..._2708.MOV?dl=0

    Gave it a bit of a hard knock to help illustrate the point. Just sounds all loose but all the bolts seemed OK. Will bag some new springs and bushes and see what's what.

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    maybe it is supposed to be like that, this YT one sounds the same https://www.youtube.com/watch?v=UBCQNTy1Kt0

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    Isn't that pron for Linn owners?

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    FFS...!! The Youtube vid is all but kickin' the shit out of it IMHO.

    The springs are there to ISOLATE the running gear / chassis from the plinth and prevent outside influences like foot fall and other vibrations from having an effect on the stylus in the record groove.

    Think of a car being pushed down by your hands with all your strength and see the reaction of the springs - no rattles. Now consider the same thing happening, but a force being applied by an elephant sitting on it!! You may just find that the springs bottom out in this incident - MAYBE!!!!!

    However, I personally think that your own TT sounds as if there is interference occurring between the spring mounted chassis and its associated parts and the top plate of the deck, like something is actually out of alignment somewhere, as in your case you are not forcing the intentional bounce too hard.

    I refer back to one of my other posts and recommend you get the TT suspended in a jig (or safely over two tall piles of books) with the bottom cover removed and repeat the exercise gently to discover where the 'knocking' is coming from. It doesn't sound like the springs causing the problem (unless they are totally sha**ed?) as much as the possibility of the interference of components within the TT assembly. Another analogy: your exhaust is banging somewhere underneath your car! It's not the springs that's causing it, so you get the car up on a ramp and start pushing and pulling on the exhaust system to identify where the knocking is coming from........

    Good luck.
    Last edited by WullieD20; 27th March 2015 at 06:54.
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    The deck is on a reasonably decent Target hi-fi stand so generally the heavy-footed son won't jump the needle but if you stomp across the floor when it's not in use you can always hear it bouncing away.

    Talking of 'out of alignment' the armboard has never sat entirely square with the plinth yet it is square with the top board, which always struck me as being odd

    picture: https://www.dropbox.com/s/q874uh11s5..._2709.jpg?dl=0

    I'll swap the springs out to see if anything looks bent or amiss.

    I've not got access to a jig, I'm sure a Black n Decker Workmate would make a substitute though

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    Quote Originally Posted by qube View Post
    I'm sure a Black n Decker Workmate would make a substitute though
    Of course it would, you can do anything from rebuild an engine to an Apendectomy on those things, according to their adverts

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