LP12 Radikal problem

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LP12 Radikal problem

Post by lejonklou » 2018-04-16 20:23

Everyone who has a Radikal motor on their LP12 and either a Trampolin or a Urika needs to read this. If your retailer does the service, specifically ask him about this issue! If you service it yourself, check this!

The Radikal motor is housed in a big can, which is very deep. Below the can is the left rear trampolin foot and the distance between these two is very small. On some LP12's (currently 2 out of 4 that I have checked), the can actually rests on the foot. This causes the LP12's musical performance to drop significantly. Bass gets sluggish and untimed, music becomes a bit "seasick" instead of rock steady. The following picture was taken with a GoPro camera by Erik:
Radikalhousing.JPG
Radikalhousing.JPG (164.2 KiB) Viewed 12548 times
What you see in the picture above is
To the left: Part of the left suspension spring,
Upper middle and right: Keel subchassis,
In the middle: Radikal motor can with its aluminium lid at the bottom,
Below the can and its bottom lid, on the left side: The rear left Trampolin foot assembly.

If you have Radikal and Trampolin, there is also a screw on the Trampolin foot that protrudes right below the can. Unless this screw has been grinded down in length, it's guaranteed to press against the motor can. On the Urika, the feet are rotated 45 degrees to move this screw away from the Radikal can.

One way to test if the can touches the foot is to make a long piece of thin paper that gets more narrow on one side and protrudes through the hole below the arm pillar (picture by Paolo below). Place it on the Trampolin/Urika, install it below the LP12 with a few screws and then place the LP12 on a table, standing on its Trampolin feet. Now pull on the piece of paper to the right of the arm. Is it stuck? Then you have a problem.
Papertest2.jpg
Papertest2.jpg (132.67 KiB) Viewed 12548 times
If you have the problem, your Trampolin/Urika needs to be moved down, away from the can. I have grinded down the outer perimeter of the Trampolin foot slightly and thought that was enough, but when I did the paper test, it turned out it wasn't - the can and foot were touching. So I have added some wooden strips between the plinth and the Trampolin, which I bought from a hobby store. They had lots of varieties there, so I bought two of every kind. What's needed is a width of 8-10 mm and a thickness of 1-2 mm. On most LP12's I suspect 1 mm will be enough, but there are no such thin strips in my newly acquired collection. With 2 mm, you might begin to get problems with the screws not gripping as well in the holes of the plinth (in which case you can use a longer screw). While I'm sure that different types of wood are likely to sound a bit different, the ones I have which are most uniform in thickness are 8x1.5 mm strips of Lime-tree. They're quite light and soft, so I have removed the old felt strips (the purpose of which I believe is to prevent rattling). I wanted to try Balsa as well, but they varied so much in thickness; 1.2 to 1.6 mm. I don't really know what is optimal, perhaps we can help eachother find out what is?

Wood type?
Thickness?
Original felt strips - in place or removed?

Please note that all plinths are a bit different, so you will need to verify the dimensions on yours. I have a Linn original in maple and used the following measurements when cutting and drilling my four pieces of strips. These strips are for my Trampolin. The front and rear strips are 410 mm long and the left and right are 305 mm. Please note that when drilling, the strip easily cracks. If you clamp it between two other pieces of wood, you can prevent this. Or you might make it by being very slow and gentle. It's good to have more strips than you need, in case you break them.
Stripes2.jpg
Stripes2.jpg (136.61 KiB) Viewed 12548 times
EDIT: I see now that I forgot to draw the hole in the middle of the rear strip.

I didn't use any glue when installing the Trampolin with the strips lying on each of its four edges. Glue would surely have made it easier, but I felt a bit sceptical of it and the installation is doable anyway. After the installation, the Trampolin sits 1.5 mm lower than before. And the result is a completely transformed musicality of the LP12. Much, much better.
Trampolin.jpg
Trampolin.jpg (199.87 KiB) Viewed 12548 times

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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-16 22:34

Thanks for sharing Fredrik.

Is there any possibility that Linn has quietly increased the height of their plinths (at some point in time) and the current lineup do not exhibit this issue? 1.5 - 2mm increase might be hard to spot by eye.

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Re: LP12 Radikal problem

Post by beck » 2018-04-16 23:05

Charlie1 wrote:Thanks for sharing Fredrik.

Is there any possibility that Linn has quietly increased the height of their plinths (at some point in time) and the current lineup do not exhibit this issue? 1.5 - 2mm increase might be hard to spot by eye.


My 1990 plinth is exactly 6.5 cm high.

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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 08:44

beck wrote:My 1990 plinth is exactly 6.5 cm high.
Thanks Beck. Just need someone with a relatively new plinth to measure theirs. Mine is 1990s like yours, plus I buggered my knee up and can't bend down to measure it today.

I mentioned this to a friend with Klimax LP12. His dealer removed the Urika Tramp feet for "better groove and timing" - i.e. using original feet instead. Not sure if his dealer never liked the Tramp or just moved away from it since Radikal came out.

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Re: LP12 Radikal problem

Post by mrco99 » 2018-04-17 09:08

Thank you Fredrik for bringing this up, and your meticulous description of how to solve this.
As I also own (AK) Radikal and Tramp2 I´d better check this - who knows what I´ve been missing out...
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Re: LP12 Radikal problem

Post by Freddy » 2018-04-17 10:23

This is important information, thanks! Maybe this is the reason you sometimes hear about "bad sounding" Radikals. I´m puzzeled that this hasn´t been observed previously.
I will check mine with the paper trick. It should be possible to measure a safe distance. In that case I think you need to measure the depth on the inside from the plinth edge that the Trampolin is resting on to the top plate?

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Re: LP12 Radikal problem

Post by Matteo » 2018-04-17 10:53

Thanks Fredrik

I'll check with my dealer.

I would solve the problem swapping the Trampolin with the solid base.

M.
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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 11:16

Matteo wrote:I would solve the problem swapping the Trampolin with the solid base.
As mentioned above, you could keep the Tramp base, which should be better than the old solid base, but just remove the Tramp feet (they are screwed on and easily removed). Then put back the old-school feet under the plinth itself.

How old is your plinth Matteo? If it's quite new then please can you measure the height?

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Re: LP12 Radikal problem

Post by Matteo » 2018-04-17 11:21

Charlie1 wrote: How old is your plinth Matteo? If it's quite new then please can you measure the height?
Mine is from 2014.

I'll measure the height when I come back home this evening

M.
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Re: LP12 Radikal problem

Post by Matteo » 2018-04-17 11:33

Charlie1 wrote: As mentioned above, you could keep the Tramp base, which should be better than the old solid base, but just remove the Tramp feet (they are screwed on and easily removed). Then put back the old-school feet under the plinth itself.
According to the Linn website:

https://www.linn.co.uk/hifi-separates/t ... solid-base

"The Solid Base provides a fixed, rigid platform for your deck and comes as standard on our introductory level Majik LP12 turntable.
If your turntable is placed on a cabinet or shelf that provides its own isolation from vibrations, then this is the perfect base board for you. Alternatively, choose the Trampolin base board to benefit from the integrated vibration isolation this provides to the LP12.
Manufactured from high quality aluminium and fixed directly to the wooden plinth of the turntable, the Solid Base can be specified on all new Sondek LP12 turntables and can also be used to upgrade your existing Sondek LP12 if it has an older non-aluminium base
".
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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 11:49

Matteo wrote:I'll measure the height when I come back home this evening
Brilliant - thanks Matteo.

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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 11:52

Matteo wrote:Manufactured from high quality aluminium and fixed directly to the wooden plinth of the turntable, the Solid Base can be specified on all new Sondek LP12 turntables and can also be used to upgrade your existing Sondek LP12 if it has an older non-aluminium base[/i]".
Didn't realise that. Thanks.

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Re: LP12 Radikal problem

Post by Freddy » 2018-04-17 12:36

From Fredriks image it also looks like the cables are touching the motor on the right side. They shouldn´t do that I suppuse?

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Re: LP12 Radikal problem

Post by k_numigl » 2018-04-17 13:11

Thanks for the alert!
Immediately checked the situation here, and there is no problem.

A 40 cm ruler held in place of the trampolin shows that there is more space between
the top (=inside) face of the trampolin and the motor case than the thickness of the
trampolin feet (3 mm). A 3 mm thick metal plate on top of the ruler leaves about 2 mm
space to the motor case. The paper test with a load of 1 LP plus some weight (ca. 200 g)
is also positive, nothing gets stuck. My plinth is Linn 058430, and the trampolin
is with feet oriented north-south/east-west parallel to the plinth rim. Thus, no problem with
the screw.

BR, Klaus

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Re: LP12 Radikal problem

Post by k_numigl » 2018-04-17 13:42

Now checked my Urika, too:
Screws are oriented 45 deg against those of the Trampolin, BUT the
screws are different and do not protrude through the rim of the feet.
So total thickness is here 3 mm, too. No problem, again.

BR, Klaus

P.S.: I find it hard to believe that tolerances of the LP12 wooden parts
(not to speak of the metal parts like the motor case)
are of the order of an entire millimetre or more. Perhaps we can check the
total height of our plinths to get a clue what is happening here.
Outer height of mine: 66 mm.
Last edited by k_numigl on 2018-04-17 13:52, edited 2 times in total.

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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 13:47

Thanks for feedback Klaus. Glad yours is fine.

I wonder if the reveal/cutout for the baseboard/tramp is deeper on older plinths, thereby pushing the tramp higher up into the plinth. Perhaps the old melamine baseboard was thicker than the current aluminium baseboard/Trampolin and so it required more depth.

Or, perhaps the felt strips have varied in thickness over the years.

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Re: LP12 Radikal problem

Post by Matteo » 2018-04-17 21:23

Mine is exactly 7 cm
(2014 black ash plinth)

M
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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-17 22:11

Matteo wrote:Mine is exactly 7 cm
(2014 black ash plinth)
That's a surprise.

Mine is late 90s / early 00s Maple and same as Klaus' at 66mm, also similar to Beck's from the 90s.

Perhaps the depth went up a bit when they last changed supplier. It would be good if someone else could measure a new or newish one so that we can confirm.

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Re: LP12 Radikal problem

Post by ThomasOK » 2018-04-18 00:01

This is not a new thing but it appears it may be more prevalent than I thought. I have had to machine down the edge of the ring, and the screw tip on Trampolin 2s, to fit the Radikal properly to some turntables. There was a report on the other forum a couple of years back where the Trampolin was pushing so hard on the Radikal motor it was pushing the top plate up.

https://forums.linn.co.uk/bb/showthread ... +motor+fit

I measured every Linn LP12 plinth here and they are mostly 65mm. Interestingly the newest one, a 2017 cherry plinth with the internal metal corner brackets is 64.5mm. So it doesn't appear that Linn are now making them a little higher. There has always been a bit of variation in the dimensions of the plinth and as wood is not a precise material this is to be expected. It should also be noted that the height of the wood strips and blocks that hold the top plate up can vary slightly. So there are two places that can change the space the motor has to fit in. Looks like something that will have to be checked more carefully on Radikal installations.
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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-18 09:58

ThomasOK wrote:I measured every Linn LP12 plinth here and they are mostly 65mm. Interestingly the newest one, a 2017 cherry plinth with the internal metal corner brackets is 64.5mm.
Good to know - thanks Tom!

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Re: LP12 Radikal problem

Post by matss » 2018-04-18 22:36

Just measured my CH fluted ebony plinth - 66 mm, plus a few tenth as I try to measure in different spots.

Also talked with the Swedish retailer High Fidelity tonight, and they actually suggested to dismount the trampolin feet and remount them on the underside of the baseboard. Gives enough clearance and maybe less of a hassle than working with spacers.

BR/ mats
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Re: LP12 Radikal problem

Post by k_numigl » 2018-04-19 08:52

> remount them on the underside of the baseboard

Not a good idea unless you considerably enlarge the diameter of the foot cutout in the base plate.

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Re: LP12 Radikal problem

Post by matss » 2018-04-19 11:01

k_numigl wrote:> remount them on the underside of the baseboard

Not a good idea unless you considerably enlarge the diameter of the foot cutout in the base plate.
As far as I could see on a Urika II baseboard, the modification was easy. The trampolin feet are by default mounted with screws on the inside of the baseboard. The feet with their rubber suspension then protrudes through the baseboard. The retailer just remounted the feet with suspension on the outside of the baseboard instead. The foot and suspension has a metal rim to grip the screws when fastening. As far as I could see this rim together with the size of the original foot cutout gave enough clearance for the foot plus suspension to work as intended from the outside. Only difference was an increased clearance between the underside of the plinth and the supporting turntable shelf.

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Re: LP12 Radikal problem

Post by Charlie1 » 2018-04-19 11:07

The holes are much smaller than the overall foot construction though. Therefore, I don't see how the feet can have the same degree of travel when mounted on the underside. Bear in mind the entire area of the foot will balloon upwards as weight bears down on the foot - i.e. it's not just the smaller area in the centre that moves:

https://www.brianandtrevors.com/uploade ... 00x900.jpg

https://www.brianandtrevors.com/uploade ... 00x900.jpg

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Re: LP12 Radikal problem

Post by matss » 2018-04-19 11:49

Yes, I understand the issue. As far as I could examine briefly and according to the retailer it works. They seemed happy with the result when they tried. It's an easy modification so it could be worth to try out as an option to solve the original clearance issue. Comparing with spacer alternatives.

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