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Different companies out there offering subchassis for Linn LP12 and built in different materials.
Some of them are low mass and the other are high mass materials like metal.
So it's good to have low mass or high mass subchassis?? Some even has Balsa wood with carbon fiber. How come they don't use good quality hard wood like purple heart or Ebony for subchassis?? As guitar and violin are using hardwood for certain area.
Is that too heavy?? But those hardwood is pretty rigid and almost impossible to drift for long run.
Any thoughts to share??
Follow Ups:
Part of a sub chassis job is to drain away unwanted vibration from the tonearm and re-distribute it through the plinth. So as these vibrations travel down the arm and are transferred to the sub chassis then through the sub chassis to the plinth. I don't believe you want the sub chassis to be dead but somewhat alive to transfer these vibrations. That is how it was explained to me years ago....
Try it. The metal sub chassis is stamped. It is lightweight compared to a heavily built wood or steel chassis. Beware the porch glider effect from a heavy sub chassis as you will overwork the springs and really get it in motion. I would pick Carbon Fiber over wood for stiffness and lightness as that is the purpose of the Keel. the Keel is Aluminum to decrease mass while stiffening the sub chassis I believe. However, as many of the fans will tell you, it might not be the LP12 that you loved for many years.
PS. Flipping the top plate and putting the motor opposite the tonearm works miracles in the noise department.
So theoretically the aluminium is better, but not for sound.
What about carbon/Balsa?
Theoretically one can use more aluminum to make it stiffer and yet have less mass so it can weigh the same as the steel plate that is not ribbed for rigidity. Aluminum itself would not necessarily sound better. The carbon/balsa would also be more material with less mass for further rigidity. I have no idea if aluminum itself or the balsa/carbon make it sound better, they just increase the stiffness of the sub chassis.
Why do you say an aluminium subchassis doesn't deliver good sound? If that is the case ... then why would Linn choose aluminium for their Keel subchassis?As others have said, due to the spring construction, a subchassis should be lighter ... rather than heavier. However, the subchassis material itself, has an affect on the sound.
I think magnesium & titanium are lighter than aluminium - but I suggest:
* these materials are more difficult to machine, and
* they are certainly more expensive. . . than aluminium. Hence, Linn chose aluminium (however, we don't know whether they ever listened to a magnesium Keel! ;-)) ).
A CF-end grain balsa-CF composite makes a good subchassis - as does the CF-aluminium honeycomb-CF construction started by Cetech in about 2000. The top CF skin is used to mount the bearing housing & spring bolts ... the intermediary material and bottom CF skin act as a dampener for the top CF skin. (The 2 skins must be separate - the sound is terrible if you wrap the balsa all the way round with CF.)
I have no doubt Linn will come out with a better-sounding subchassis made from some different maerial, at some stage. :-))
Regards,Andy
Edits: 09/22/16
has a specific gravity about 2.7 times higher than 7075 T651 aluminum. but it also has tensile strength that is 2.7 times or so of the 7075 aluminum In theory one can make a structure that is the same strength and the same weight form either material. Aluminum will be bulkier will have exactly 2.7 times the volume. a thinner structure of the same strength will have higher resonant frequency as well as other mechanical differences. In comparison common aluminum 6061 T5 is about half of the strength of 7075. Nothing is without compromises.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
So the issue is ... for a subchassis on a sprung TT (LP12, Thorens ...) which is it better to have - a higher resonant frequency or a lower resonant frequency?
Andy
if it is above, inside or below the audible range of frequencies. It is below you want the lowest possible, if it is within you want it most damped if it is above you want it real high. Right?
dee
;-d
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
how do I establish what the resonant frequency of my chassis is? Bcoz I could make another chassis using thicker aluminium if the current resonance is in a bad place.
Here's my "SkeletaLinn":
The bearing and platters are LP12; there are LP12 springs and grommets under each apex of the triangle, sitting on brass pods which provide the levelling mechanism.
Andy
:)
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
It sounds great, too (much better than my LP12 ever did!). :-))
Andy
Great Idea!!
Now I'm considering a different trend by building the same LP12 as you did based on DIYHIFISUPPLY BIX belt drive dual motors with LP12 platter.
I guess it will be wonderful! 2 DC motors driving the platter!! I like it.
Thank you very much!!!
The improvement when I added the 2nd motor was significant but what that BIX TT delivers may not be as good as it can be. It depends how a DC motor works.
With an AC motor, when you have 2 motors and 2 belts driving the platter/subplatter, you need to have a slight difference set up between the 2 motors (call it a 'phase difference'). Essentially, AC motors 'cog' - so there's in effect a period where the motor applies rotational force to the platter ... and a period when it doesn't. You need the 2nd motor to be applying its rotational force during the period which the 1st motor is not - so you need a pretty sophisticated speed controller (I am using a prototype of the "Number9").
If a DC motor doesn't do this but simply applies its rotational force evenly - then the BIX kit will be fine (from that PoV).
Andy
Hmm I agree. However I worries the noise generated by the AC motor will transfer to the bearing.
I come up an idea after talking to my friend. Unlike the BIX with rectangular chassis, I can have the acrylic chassis made in Big Arrow shape, and motor positioning on each corner, the Cirkus bearing is indicated by purple circle, the star will be where the tone arm goes.
That's why AC motor get a very good chance to transfer the noise to the bearing under this arrangement.
Mounting the motors on the same chassis as the bearing is a baaad idea, IMO.
On mine, each motor is bolted to the underside of a approx 4"x4" earthed steel plate - these plates are bolted to the top of 3"D brass cylinders (very heavy).
The cylinders don't rest on the perspex base of the TT (which the brass pods under the springs do) - there's a hole cut in the perspex, so the motor pod rests on the benchtop below and doesn't come into contact with the sides of the hole. So the motors are entirely separate from bearing.
Are you sure DC motors don't have any vibration (for your "arrow chassis")?
Andy
Which one has lower mass? Acrylic vs. Carbon/Balsa?
Also, it seems to me an acrylic subchassis wouldn't be as self-damping as either a CF composite or the carefully engineered aluminium Keel.
Andy
I've considered the Tiger Paw Akula subchassis, but looks like its more heavier than the Keel I guess.
Wouldn't it be advisable to keep the total weight of the suspended subchassis constant? Because the springs were presumably chosen for performing well with the weight of the original subchassis. Within that limit, one could play with stiffness. Seems to me if you change the weight of the suspended element, then you need to alter the springs to suit the alteration in weight. Doing that properly is a complex engineering problem.
means you must stick to one arm, also!
Andy
" How come they don't use good quality hard wood like purple heart or Ebony for subchassis??"
How about because, for many hardwood species ( including Ebony), it is illegal?
It should sound very good I guess with ebony or other hard wood for the sub-chassis. But the mass is a concern as most hardwood are pretty heavy.
I think ebony is more heavier than the aluminium.
I really do not understand why you are having these thoughts. Ebony and many other hardwoods basically can neither be imported nor traded in. It is now illegal. So think of Ebony as unobtainium. That's why neither you nor anyone else can make a subchassis from it irrespective of how suitable it may or may not be.NB: it probably wouldn't be good as it would store energy then release it later (at a higher frequency). Not good. OK for clarinets where it provides (or provided) desired tonal characteristics which, however and in contrast with music production, may not be wanted for music reproduction.
You ideally need a material that is very stiff and with low mass. Hence the choice of milled aluminium (Linn for top of line LP12s) or carbon fibre laminates/aluminium struts (Funk Firm).
Edits: 09/22/16
Would not store energy, low mass and stiff = Titanium
Right??
That sounds like a contender. How practical though I am unsure. I understand that specialist expertise and equipment is required in order to work with it.It reminds me of the fabulous Lockheed SR-71 ( Blackbird) which had an airframe of which 85% was made of titianium. Lockheed had to develop special techniques of fabrication and I recall that even so it still leaked fuel.
Edits: 09/22/16
and that was by design :).
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Whilst I respect your patriotism I can't accept that the leaking was " by design". It was simply an acceptance of the physics because there was no solution to the great expansion of titanium from cold to the extreme temperatures experienced by the SR -17 at full flight speed.
If it had been " by design" the world would be now full of leaking aircraft :-)
but the leak was a design compromise. They also used gel fuel to minimize leakage while on the ground. Very interesting challenges . Another interesting machine was the X-15. it is more about me being a geek than a patriot.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
I don't believe ebony is illegal. It is still eidely used for making instruments. My understanding is only Madagascar ebony is endangered and not to be imported. All others are okay for use. Today most ebony is imported from Indonesia.
Friend's LP12 plinth. Beautiful and one of the best soudning plinth I have heard.
I so wanted the same plinth but Woodsong could not source the same wood any more.
But he found this one: figured gaboon ebony, IIRC.
Density and weight are about the same as my friend's madagascar ebony. Heaviest Sondek plinth I have encountered.
Yes, I think you are correct.
making an LP12 sound like not one :)....Sure you can do it within the limits what the suspension can adjust for. I would not use solid wood, because it moves enough that it can affect the alignment between the arm and the nearing in al directions. If you want one species laminate at least 4 layers in perpendicular directions with epoxy.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
So for one designer mass, another low mass.
it is all in the combination of the way the parts do together
There is not one right way
Other than the LP should spin at 33.33 rpm... It think they all agree on that part.
Seems to spin a bit faster in many cases....
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
that was a deliberate design choice - to make Regas sound 'sharper' than LP12s! :-))
Andy
it sounds that way :)...damn those little Japanese dudes wanting to spin their platter precisely in 1 part per gazillion.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
It's great to be perfect.
My take, Rega makes a great, yes, great turntable.
I enjoy it immensely every day.
I've toned it down with an Eagle and given it the Groovetracer treatment, and you know what?
It still sound fabulous, maybe even more fabulous.
"If people don't want to come, nothing will stop them" - Sol Hurok
.
To work within the limits of the suspension springs, the subchassis must be low mass - or certainly not heavier than Linn's own subchassis.
Rigidity - the subchassis joins the arm and the platter forming a rigid unit to keep them fixed as though they are a single unit so that the record groove and the arm are not moving/vibrating relative to one another at all.
Hence pressed metal (Linn original), die cast alloy, or more rigid and more expensive exotic materials such as carbon fibre composites, even including carbon fibre/balsa wood laminates - light and rigid.
Cheers,
John K
Is it??
To many parts and pieces.
The rack looks good though.
Cheers,
John K
I wouldn't be surprised if like most circumstances when there are multiple possibilities that there are trade offs in both the positive and negatives affects and each user would have to make up their own mind.
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