LP12 Motor @ 7o’clock

[Mr Pig]

Have you tried it on your LP12? Does the bottom of the plinth rest on the frame?

No. I'm scared to! I only built the deck a few months ago and it is immaculate, it looks like brand new. The plinth is fluted and, even with the metal disks, I'm not sure I could fit it without damaging the sides of the plinth. You can imagine how tight the spikes need to be to keep the deck on place.

I haven't measured it but I'm sure the bottom spikes will line up with the front and rear plinth edges. I expect that's the case because the baseboard isn't really structural and a lot of people don't use one.

I'm going to build a second LP12 so I'll try the Clamp on it. That won't have a fluted plinth.

 

[Mr Pig]

Just to be clear, the component does not rest on the frame. It is held up by the six spikes.

 

[david ellwood]

That’s a whole new level of lunacy, well done mana!

 

[John]

Found an interesting discussion of the Star Sounds supports on the Audiogon forum. A couple of folks were discussing how they use their LP12 with the supports upward spikes. Thought this was clever.

“Hi Sc53, I also have a Linn Lp12 and a standard Sistrum Sp 6 rack. What I have found to be most effective for me is as follows. .If you remove the masonite bottom plate you will see 4 corner braces. For the Lp12 to sit on the three Sistrum points you have to make a center rear support. I used marine plywood and glued this into a groove that is around the entire perimeter of the Linn. I used this groove because this is where the corner supports reside as well. You have to make your extra rear support as wide and as deep as a Starsound apcd disc. So from the bottom up you have a shelf a point a apcd disc and then the Linn which has three braces now residing on the discs. This technique does not interfere with the Linn Lp12 suspension.. Tom”

https://forum.audiogon.com/discussions/this-sistrum-stuff-works?page=2

 

[Mr Pig]

Found an interesting discussion of the Star Sounds supports on the Audiogon forum. A couple of folks were discussing how they use their LP12 with the supports upward spikes.

It's a case of pictures being worth a thousands words.

 

[John]

You can imagine the LP12 parts.

this is the APCD disc that contacts the cross brace in the LP12:
http://www.starsoundtechnologies.com/productsDetail.php?APCD2-8

This is a picture of the rack, the top spikes can be moved and situated so that the points contact the APCD disk affixed to the three contact points on the cross braces. The brace in the back of the LP12 put in by the person who modified the deck. The picture is obviously not the turntable but gives you an idea of what the stand looks like. The Sistrum platform, below was in production from 2000 to 2014 and was replaced by the Sistrum Rhythm Platform below that.

Sistrum Rhythm Platform

 

[John]

Seems it would be tricky to not foul the arm cable with the modified cross brace. Placing the LP12 on the spikes would be a challenge as well.

 

[Dowser]

Time to service that Valhalla before it goes bang?

 

[Hermann]

Hi Herman,

How are you?

Yes the photo of your system does appear regularly.

It still looks like an amazing room!

Ian

Hello Ian,
first of all a happy new year. Thank you, I am doing very well. Hope you and your family are too.

Thanks also for the compliment on the setup. The regular appearance of the picture is still astonishing. Anyway, in the meantime I think the setup looks much better in the new room. But I'll be careful not to post any pictures.


Interesting the discussion about LP12, baseboard and 7 o'clock arrangement of the motor. Reminds me of earlier times. So I wanted to build an LP12 again, but unfortunately my rosewood frame broke due to a stupid circumstance. The desire has gone for the time being.

 

[IanW]

Hello Ian,
first of all a happy new year. Thank you, I am doing very well. Hope you and your family are too.

Thanks also for the compliment on the setup. The regular appearance of the picture is still astonishing. Anyway, in the meantime I think the setup looks much better in the new room. But I'll be careful not to post any pictures.


Interesting the discussion about LP12, baseboard and 7 o'clock arrangement of the motor. Reminds me of earlier times. So I wanted to build an LP12 again, but unfortunately my rosewood frame broke due to a stupid circumstance. The desire has gone for the time being.

Hi Herman,

I have responded by PM.

Ian

 

[John]

Found this old post on Audio Asylum regarding drainage from the LP12 plinth. Something I addressed a few years ago by adding brass cones to a solid baseboard.


LP12s need a support arrangement which drains vibrations down and out from the plinth??

• 
  Posted by andyr (M) on December 11, 2004 at 03:30:50
  

A Linnie mate and I recently did some experiments with my LP12 and I'd be interested in other LP12 owner's comments/experiences (JDK need not respond as I know he agrees!).
I thought I had done the right thing by putting my LP12 on an isolation platform ... a 30lb slab of slate resting on racquet balls, making an air isolation platform. This certainly prevented everything except perhaps seismic vibration from coming up from the floor (ground floor concrete slab) and through the record cabinet benchtop but it also seems to have stopped vibrations from being able to drain away from the LP12 plinth - thus degrading my sound!

Our experimental procedure was as follows:

1. We aligned the cartridge using my Wallytractor and made sure the VTA and bias were set as well as we could manage.

2. We played the first track and the last-but-one track of side 1 of an Argo record of Vivaldi's Gloria. The first track has some gorgeous trumpets before the choir starts and the last-but-one track has a lovely cello passage before Janet Baker comes in to sing.

In both these tracks, there are some gorgeous moments where the sound dies away in the Kings College Chapel and you hear several seconds of ambient decay.

3. We recorded these tracks on my Harman-Kardon CD-R unit, to enable us to replay them later and compare the same tracks recorded with the different support arrangements.

4. The first two tracks were recorded with the LP12 sitting on my vibration isolation platform.

5. We then removed this and recorded the two tracks with the plinth sitting directly on the benchtop - without the standard LP12 rubber feet.

6. On the principle of trying to provide a direct path for vibrations to drain away, we then put a 1/4" steel nut under each corner of the plinth.

7. We then inserted a lightweight "Dekstand" under the LP12. This is a low frame made of 1" square-section aluminium tube which was produced from the mid-70s to the mid-80s in Oz, as the preferred lightweight support for LP12s.

The sound in each case was quite different:

#6 was the best - the trumpets sounded like trumpets, the cellos like cellos and it produced the most gorgeous delivery of the ambient sound decay in the chapel.

#5, which didn't have the supporting nuts, was not as good. The sound was similar but the ambient acoustic wasn't there as much.

#7 was simply baaad! The Dekstand produced a very nasal tone, emasculating the trumpets and thinning out the cellos.

#4, recorded with the isolation platform, cut short the ambient acoustic delay although the tone of the instruments was OK.

As a result of these, we concluded that it is necessary to allow vibrations produced in the plinth to drain away. The isolation platform was stopping this; the nuts had the hardest contact with the underlying vibration sink and so if spikes were used instead of nuts, it should improve the vibration drainage and make the sound even better.

Any comments anyone?

Regards,

Andy

 

[jimification]

adding brass cones to a solid baseboard.......
..........On the principle of trying to provide a direct path for vibrations to drain away, we then put a 1/4" steel nut under each corner of the plinth.

Just an idea, but if providing the best possible path for vibration exit is the goal, would it be better to use the same material throughout? (ie: wooden cones) so that the vibration travels through the wood of the plinth, down via the wooden cones and into the wooden benchtop? I was recently watching a lecture where Peter Ledermann of Soundsmith cartridges was talking about vibration and citing a Newton's cradle to demonstrate how effectively vibration transfers through objects of the same material. He made an interesting comment, which was that a Newton's cradle comprised of spheres of differing materials wouldn't work.

 

[IanW]

a 30lb slab of slate resting on racquet balls, making an air isolation platform

If I understand correctly that racquet balls are squash balls, then that will provide some isolation and some coupling (the thick material that makes the squash ball will have some inherent damping and as it is cold (material softens with heat when used to play squash) it will also have a resonant frequency in the area that it is supposed to be isolating).

Would need some accelerometer measurements to determine how effective it is at either function.

Nonetheless an interesting set of experiments.

I have recently started to investigate how to ideally isolate HiFi components that need isolation (the results of the investigation above suggest that the LP12 needs some coupling and would need further investigation and experimentation) .

Mainly driven by having full range loudspeakers that sit on a suspended wooden floor that has a large crawl space underneath it.

I have had the room tuned by an acoustician to make the RT60 a smooth and well balanced curve (i.e. room resonant modes through standing waves are dealt with well) but the floor and crawl space still resonates of course, but the RT60 tuning got rid of a lot of distortion in the 50 to 100Hz region.

I had my previous speakers on Mana Soundstages and I could feel the reduction in vibration as I moved my hand down the stack. But for my current loudspeakers I got rid of the Mana as the speakers were too big to really sit on Mana stacks. But I have been thinking that it would be good to put some form of isolation under the speakers to try and reduce the energy getting into the floor and hence the floor resonance.

 

[jimification]

IanW: My speakers are also on a suspended floor and I found a big benefit from isolating them (the way I saw it they were basically sat on the skin of a giant drum). I think the Townshend seismic springs would be the ideal for this but they're quite expensive, so I "designed" (cobbled together) a small, cheap DIY isolator as a kind of low-pass filter and it works very well indeed. Bass is much less boomy, tighter and better defined and, strangely, the soundstage is improved.

 

[Mike P]

If I understand correctly that racquet balls are squash balls, then that will provide some isolation and some coupling (the thick material that makes the squash ball will have some inherent damping and as it is cold (material softens with heat when used to play squash) it will also have a resonant frequency in the area that it is supposed to be isolating).

Would need some accelerometer measurements to determine how effective it is at either function.

Nonetheless an interesting set of experiments.

I have recently started to investigate how to ideally isolate HiFi components that need isolation (the results of the investigation above suggest that the LP12 needs some coupling and would need further investigation and experimentation) .

Mainly driven by having full range loudspeakers that sit on a suspended wooden floor that has a large crawl space underneath it.

I have had the room tuned by an acoustician to make the RT60 a smooth and well balanced curve (i.e. room resonant modes through standing waves are dealt with well) but the floor and crawl space still resonates of course, but the RT60 tuning got rid of a lot of distortion in the 50 to 100Hz region.

I had my previous speakers on Mana Soundstages and I could feel the reduction in vibration as I moved my hand down the stack. But for my current loudspeakers I got rid of the Mana as the speakers were too big to really sit on Mana stacks. But I have been thinking that it would be good to put some form of isolation under the speakers to try and reduce the energy getting into the floor and hence the floor resonance.

Hi Ian,

My previous house had suspended wooden floors and a large (approximately 3ft) crawl space underneath.

The speakers I was using at the time were IMF RSPM IV, which are a very large transmission line design and are famously capable of reproducing very deep powerful bass.

Unsurprisingly I had a lot of problems with uneven boomy bass.

I tried various remedies recommended to me on PFM including corner 'bass traps', raised speaker stands and fitting extra joists under the speakers.

In desperation, and acting on gut instinct, I eventually reinforced the floor area under and around the speakers with a layer of 25mm MDF. I don't remember the exact measurements but I suppose it was something in the region of around a 1m x 1m area under each speaker. I fixed this MDF above the floorboards with a copious amount of silicone sealant, so as to create a sort of constrained layer dampening matrix, as well as adding considerable mass and increasing the rigidity. This homebrew solution subjectively made a very positive difference.

 

[IanW]

IanW: My speakers are also on a suspended floor and I found a big benefit from isolating them (the way I saw it they were basically sat on the skin of a giant drum). I think the Townshend seismic springs would be the ideal for this but they're quite expensive, so I "designed" (cobbled together) a small, cheap DIY isolator as a kind of low-pass filter and it works very well indeed. Bass is much less boomy, tighter and better defined and, strangely, the soundstage is improved.

Thanks for documenting your experience.

I am doing some experiments in my office system with an inner tube system (to isolate in the vertical domain with a very low resonant frequency) and with ball bearings on a slightly curved surface to isolate in the horizontal and rotational degrees of freedom. This approach has been used for years and years to make buildings safer in earthquake zones and to reduce building response to ground borne energy in other environments.

So far I have tried 4 soft springs (resonant frequency under 10 Hz) under each loudspeaker in my office system, where the speakers sit on a desk and so have a similar resonant problem to the big speakers in the lounge. Objectively (measurement with seismograph on my phone) and subjectively (how did it sound), doing this was a big success with the springs fully isolating the desk from the speaker energy and sounding much clearer and less distorted.

I would like to try the Townshend approach but it is expensive and I am struggling to see how the Podiums deal with energy in the horizontal or rotational degrees of freedom. If what I have works as well as I hope then I will scale it to work on the full range loudspeakers.

 

[IanW]

Hi Ian,

My previous house had suspended wooden floors and a large (approximately 3ft) crawl space underneath.

The speakers I was using at the time were IMF RSPM IV, which are a very large transmission line design and are famously capable of reproducing very deep powerful bass.

Unsurprisingly I had a lot of problems with uneven boomy bass.

I tried various remedies recommended to me on PFM including corner 'bass traps', raised speaker stands and fitting extra joists under the speakers.

In desperation, and acting on gut instinct, I eventually reinforced the floor area under and around the speakers with a layer of 25mm MDF. I don't remember the exact measurements but I suppose it was something in the region of around a 1m x 1m area under each speaker. I fixed this MDF above the floorboards with a copious amount of silicone sealant, so as to create a sort of constrained layer dampening matrix, as well as adding considerable mass and increasing the rigidity. This homebrew solution subjectively made a very positive difference.

Hi Mike,

Thanks for documenting your experience.

Many years ago I tried adding mass to the floor to try and reduce the resonant floor problems, but I did not try under the speakers. I then added many Mana Soundstages under the speakers and this did help.

If my experimental approach of isolating the speakers from the floor does not work as well as I want, then I will look further into constraining the floor, as you have done.

 

[John]

Just an idea, but if providing the best possible path for vibration exit is the goal, would it be better to use the same material throughout? (ie: wooden cones) so that the vibration travels through the wood of the plinth, down via the wooden cones and into the wooden benchtop? I was recently watching a lecture where Peter Ledermann of Soundsmith cartridges was talking about vibration and citing a Newton's cradle to demonstrate how effectively vibration transfers through objects of the same material. He made an interesting comment, which was that a Newton's cradle comprised of spheres of differing materials wouldn't work.

Symposium refers to mechanical impedance matching. I discussed this with Peter when I started using their platforms and wanted to incorporate one of with my LP12. The platforms have a stainless steel outer shell with some type of constrained layer within. He said the rubber feet on the Linn would not be a good interface with the platform, he suggested brass cones if I could figure out how to do that with the turntable. I ended up modifying a solid Linn baseboard by bolting four brass cones and fastened the baseboard to the plinth with the ten screws supplied. That was the best idea I could think of at the time to drain the vibrations from the motor.

 

[John]

Thanks for documenting your experience.

I am doing some experiments in my office system with an inner tube system (to isolate in the vertical domain with a very low resonant frequency) and with ball bearings on a slightly curved surface to isolate in the horizontal and rotational degrees of freedom. This approach has been used for years and years to make buildings safer in earthquake zones and to reduce building response to ground borne energy in other environments.

So far I have tried 4 soft springs (resonant frequency under 10 Hz) under each loudspeaker in my office system, where the speakers sit on a desk and so have a similar resonant problem to the big speakers in the lounge. Objectively (measurement with seismograph on my phone) and subjectively (how did it sound), doing this was a big success with the springs fully isolating the desk from the speaker energy and sounding much clearer and less distorted.

I would like to try the Townshend approach but it is expensive and I am struggling to see how the Podiums deal with energy in the horizontal or rotational degrees of freedom. If what I have works as well as I hope then I will scale it to work on the full range loudspeakers.

Ian, are you familiar with Barry Diamant? He’s a recording engineer who has used a similar technique. He’s participated on a number of forums, one being the Steve Hoffman forum. He had some roller bearings made up similar to what Symposium Acoustics sells. Here’s a link to his website:

http://www.barrydiamentaudio.com/vibration.htm

 

[IanW]

Ian, are you familiar with Barry Diamant? He’s a recording engineer who has used a similar technique. He’s participated on a number of forums, one being the Steve Hoffman forum. He had some roller bearings made up similar to what Symposium Acoustics sells. Here’s a link to his website:

http://www.barrydiamentaudio.com/vibration.htm

John, yes I am familiar with Barry Diamant. I found a long thread on the SHF and after I read that I have been discussing how best to do all this with him.

I am getting some roller bearings machined and want to get a replacement for the layer that sits above the bearings manufactured, but have not decided how to do that (choice of marble slabs is not ideal here and I am sure that the material can be bettered).

I want to test as many aspects as possible in my experimental system and then install the best isolation approach under my full range loudspeakers. And then experiment further with other components, which currently sit on Mana racks and soundstages.