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Radical Motor in contact with Trampolin Foot
2018-06-10, 06:12 (This post was last modified: 2018-06-10 06:17 by Tony Tune-age.)
Post: #1
Radical Motor in contact with Trampolin Foot
I've been reading comments regarding the possibility of a Radikal motor being in direct physical contact with a Trampolin foot. Apparently it happens with plinth heights of 64mm, and to some extent with plinths below 66.5mm. And the touching of these two parts can have a negative impact on sonic performance. Since my plinth height is 65mm, I decided to have ThomasOK check-out my deck.

In order to know if the two parts are touching, ThomasOK used a narrow strip pf paper placed between the Radikal motor and Trampolin foot. The paper strip was fed through the Trampolin opening see below.

[Image: IMG_0237.jpg?1528601274950&15286...8601293125]


[Image: IMG_0239.jpg?1528601274950&15286...8601293124]


He then pulled gently on the paper strip, which had some initial resistance. That resistance confirmed the Radikal motor was in fact touching the left back Trampolin foot (when facing the deck). At that point, ThomasOK began installing strips of balsa wood (1.5mm thick) around the inner perimeter of the Trampolin. The wood strips were drilled with holes, that were aligned with the Trampolin screw holes. See below:

[Image: IMG_0240.jpg?1528601274950&15286...8601293125]


[Image: IMG_0242.jpg?1528601274950&15286...8601293125]


[Image: IMG_0241.jpg?1528601274950&15286...8601293125]


Once the wood strips were in place, he installed the Trampolin back onto the plinth.

[Image: IMG_0244.jpg?1528601274950&15286...8601293125]


[Image: IMG_0235.jpg?1528601274950&15286...8601293125]


After assembling the deck, he played an album to make sure everything was operating correctly. My first impression was the vocals seemed to sound better, but I wasn't really sure. That's primarily because my deck was hooked-up to his bench system, which isn't very elaborate.

However, it was much easier to hear the differences on my home system. And although the differences I heard weren't subtle, they weren't obvious either. But the sonic improvement is very real and important! Specifically, the vocals do sound better (more realistic and natural), and the timing has vastly improved as well. In addition, it wasn't until I was listening to the new Jimi Hendrix album "Both Sides of the Sky," that I noticed how the bass notes were now deeper and more defined. Simply put, more musical.

While my deck certainly sounded good prior to this necessary modification, I know exactly how much the Radikal motor touching the Trampolin foot degraded the sound. And needless to say, it surprises me that nobody noticed this particular design flaw until recently. Moving forward, perhaps the Linn plinths will be made taller (i.e., 66.5mm). In addition, it will be interesting to see if Linn takes this issue seriously and finds a fair solution for customers that have this problem.

So, what is the bottom line? My deck sounds better than it has ever sounded, and it's unfortunate that some Sondek owners might not be experiencing the true potential of their deck. It's a krazy world indeed!
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2018-06-10, 11:01
Post: #2
RE: Radical Motor in contact with Trampolin Foot
Your plinth looks relatively new.

Why is there such dreadful variance in plinth height ?

The Source is in 'da groove !!
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2018-06-10, 12:06
Post: #3
RE: Radical Motor in contact with Trampolin Foot
Tony has a Chris Harban plinth which is 65mm, same as Linn aim for. I think Linn allow some variance upwards of 65mm. Both of mine are 65mm. There seem to be relatively few Linn plinths that are 67mm or above - I've only heard report of one on the Lejonklou forum which is almost 68mm and obviously unaffected by this issue.

I would be surprised if Linn ignore this in the background. I hope we see a fractionally shallower Radikal housing or taller plinth sometime in the near future. Officially, the line seems to be that there's no performance impact.
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2018-06-10, 13:12
Post: #4
RE: Radical Motor in contact with Trampolin Foot
Tony,

I have similar results. The mode brought better articulation, timbre, flow, decay. Also some sibilance with some of the vocals disappeared.

A higher plinth will weigh more and it could be a problem with Linn tonearms, unless the walls are slightly thinner or the feet rubber thicker. I guess I’ll have no problems with my Aro.

Emil F
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2018-06-10, 13:21
Post: #5
RE: Radical Motor in contact with Trampolin Foot
(2018-06-10 11:01)Steven Wrote:  Your plinth looks relatively new.

Why is there such dreadful variance in plinth height ?

Thanks for the comment. And as Charlie1 stated, it's a Woodsong plinth made by Chris Harban. Actually, the plinth was purchased and installed around the 2009 - 2010 time frame. The wood is called Movingui, but once installed it just sits on a NOKTable. Nothing comes in contact with the plinth, and nothing ever bumps into the plinth either. In addition, I do put lemon oil on the plinth periodically.
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2018-06-10, 13:31 (This post was last modified: 2018-06-10 13:32 by Tony Tune-age.)
Post: #6
RE: Radical Motor in contact with Trampolin Foot
(2018-06-10 13:12)Amadeus Wrote:  Tony,

I have similar results. The mode brought better articulation, timbre, flow, decay. Also some sibilance with some of the vocals disappeared.

A higher plinth will weigh more and it could be a problem with Linn tonearms, unless the walls are slightly thinner or the feet rubber thicker. I guess I’ll have no problems with my Aro.

Emil F

I'm hearing those types of improvement as well, and not as much "vinyl noise" between the tracks now.

ThomasOK said a height of 66.5 wouldn't be a problem with Linn components. In fact, his Chris Harban Movingui plinth is taller than my plinth, and it
sounds great!

Cheers
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2018-06-10, 14:37
Post: #7
RE: Radical Motor in contact with Trampolin Foot
(2018-06-10 13:21)Tony Tune-age Wrote:  
(2018-06-10 11:01)Steven Wrote:  Your plinth looks relatively new.

Why is there such dreadful variance in plinth height ?

Thanks for the comment. And as Charlie1 stated, it's a Woodsong plinth made by Chris Harban. Actually, the plinth was purchased and installed around the 2009 - 2010 time frame. The wood is called Movingui, but once installed it just sits on a NOKTable. Nothing comes in contact with the plinth, and nothing ever bumps into the plinth either. In addition, I do put lemon oil on the plinth periodically.

Interesting findings and story there.
The timeframe around 2010 actually ties in very well with me finding similar problem As previously reported in a post, When working in Hong Kong for a client. I reported the problem to Chris and indeed used spacing slivers of wood to space the motor away from the trampoline foot. So in my opinion and I’m sure Chris will confirm this it is very unlikely more modern plinths from him would have this issue. Obviously the rotation of the foot by the factory through 45° In production helped quite a lot and avoid sone of the fixing screws contacting the backplate of the motor. All subsequent plinths have been fine with adequate clearance and indeed in my case, the plinth that had caused the problem was replaced the following year when I visited Hong Kong again.
Best regards, Peter

Fettling LP12s since 1980 and member here since 2008
Tel 0333 200 4475
Email - peter@cymbiosis.com
Skype - peteratcymbiosis
Facebook - www.facebook.com/Cymbiosisaudio/
www.cymbiosis.com
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2018-06-10, 15:28 (This post was last modified: 2018-06-10 15:30 by Catweazle.)
Post: #8
RE: Radical Motor in contact with Trampolin Foot
My initial reaction was OMG that's a possible reason to decide in favour of Lingo 4 and against Radikal. (I'm still unsure about the more appropriate investment, as I did'nt find a comparison anywhere.)
But now this appears to be a matter of aftermarket plinths only. Do I understand correctly, that this thread is irrelevant to owners of original Linn plinths? A bit more clarity please! It might help us faint hearted Linnies like yours truly Tongue
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2018-06-10, 15:56
Post: #9
RE: Radical Motor in contact with Trampolin Foot
(2018-06-10 15:28)Catweazle Wrote:  My initial reaction was OMG that's a possible reason to decide in favour of Lingo 4 and against Radikal. (I'm still unsure about the more appropriate investment, as I did'nt find a comparison anywhere.)
But now this appears to be a matter of aftermarket plinths only. Do I understand correctly, that this thread is irrelevant to owners of original Linn plinths? A bit more clarity please! It might help us faint hearted Linnies like yours truly Tongue

Okay, briefly because I’m working out in the garden on this lovely sunny afternoon here in Leicestershire ?

The lingo 4 Vs Radikal demonstration is an easy one to do if you have identical sub chassis, arm and cartridge. It is a demonstration I’m doing here every week for clients and I’m sure many other retailers can offer the same comparison. It is fair to say the lingo 4 is closer to the radikal but there is still a substantial difference in performance between the two.

Regarding the plinths, as I have said before I think it’s fairly uncommon and so far I haven’t really had any issues other than the one I mentioned above and so far no issues with the factory plinths however I note Emil’s comments from before. Personally, I think it is an unlikely scenario with any modern factory plinth but of course if we cast on minds back 20 or 30 years tolerances may not have been quite as good and certainly some of the prints from the 70s were noticeably shallower.

My recommendation remains that if you are in any doubt about your LP 12 you should take it to your specialist Linn retailer for a check over and to put your mind at rest. The rotation of the foot fixings by 45° was the change carried out many years ago but prior to that if there was contact then it should have been relatively easy procedure just to removing the excess screw thread projecting through the trampolin foot. This in my experience so far has allowed for sufficient clearance.
So, you are concerned or in any doubt just get it checked out.

I hope this answers you and apologies in advance for any typos but I am making this post using my iPhone Siri.

Best wishes, Peter

Fettling LP12s since 1980 and member here since 2008
Tel 0333 200 4475
Email - peter@cymbiosis.com
Skype - peteratcymbiosis
Facebook - www.facebook.com/Cymbiosisaudio/
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2018-06-10, 17:17
Post: #10
RE: Radical Motor in contact with Trampolin Foot
(2018-06-10 15:28)Catweazle Wrote:  But now this appears to be a matter of aftermarket plinths only. Do I understand correctly, that this thread is irrelevant to owners of original Linn plinths? A bit more clarity please! It might help us faint hearted Linnies like yours truly Tongue

There was another thread here recently where it was reported that a dealer in Sweden believes there to be approximately 60% of Radikal decks impacted. Fredrik Lejonklou reported similar findings, 3 out or 5 decks he'd worked on. You or your dealer needs to perform a test using paper as Tony describes above. That's the only way I've read to be completely sure.

It really depends on the height of the plinth, not whether it's Linn or third party manufactured. Both my 10-15 year old Linn Maple and new Linn Oak plinth are effected - they are both 65mm high.
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