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In Reply to: RE: Calling all mechanical engineers - lever problem ... :-)) posted by stehno on October 09, 2014 at 00:48:05
of rack systems.
That might explain why you have displayed little knowledge of TTs? :-))
Linn (and others) use 3 springs not because they are convinced they can "defy the laws of physics and isolate an object from all sources of vibration simultaneously " but because they feel a sprung TT does not suffer from problems which solid-plinth TTs do.
Those mfrs who make non-sprung TTs rely on some kind of isolation devices to make their TT work well (eg, Vibraplanes, Minus Ks etc.) - not so much against footfalls caused by 400 lb spouses boogie-ing right in front of the turntable but from terrestrial vibrations, such as trains which are adjacent to the building structure. I would suspect that doing as you suggest (replace the springs with some hardwood or better yet metal blocks and then place your massloading weight on it) would produce such problems - however, it is easy enough for me to try this experiment. :-))
Linn (and the other suspended TTs) use springs - or in SME's case, rubber O-rings - to prevent these vibrations from getting to the stylus. AIUI, they only work down to (in Linn's case) about 5Hz - so there still may be a need for some other isolation device down to 1 or 2 Hz - depending on your surroundings.
Re. your comment "Finding the correct formula is moot" ... I find that very strange. :-)) It seems to me the springs will bounce better if the total weight of bearing/platter and 2 arms is shared equally across the 3 springs - rather than, say, the weight being 50% on one, 30% on another and 20% on the 3rd.
Thanks to the help I received here from Bill and Todd, I have been able to slightly adjust the position of the bearing which now - according to my calculations - gives me almost exactly equal loading, when the weight & position of the arms are also taken into account. I will post on this, soon.
Regards,
Andy
Follow Ups:
Hi, Andy. Yes, thank goodness I have very little experience with TT's. Knowing what I think I know about vibrations, their sources, and their behaviors, and most importantly how crippling they are to every last component's precision and accuracy, I wouldn't touch one with a 10 ft. pole. Now I do have a 35 - 40 year old Technics SL-1200 semi-auto buried in a closet that I haven't even viewed in perhaps 15 years just to prove that point.
When I think what gymnastics TT designers have gone through to compound isolation strategy upon isolation strategy upon isolation strategy, I can't help but think what a frickin' nightmare some of them have created. And most importantly how much they've crippled that source's musical potential.
That's why finding the right formula for your dilemma is moot to me.
A local friend who seems to swap out his equipment whenever the season changes had purchased some vintage turntable for which he sent out for a $5k makeover that he seemed proud of at the time and wanted me to listen.
As usual his system sounded like absolute crap even though it's always music to his ears. As he was showing off his custom turntable, I noticed how badly his speaker drivers were warbling, quite severe actually. He expressed his concern too and he only listens at maybe 86 - 88db tops.
Not knowing nor wanting to know anything about turntables but after studying his for a few minutes, I asked him for some paper towels. I created about 8 small wads of paper towels rolled up nicely and pinched them between his free-floating spring-loaded base and the outer chassis. The severity of the drivers warbling was now only about half as intense. Wadded up a bunch more and now he's wadding up a bunch and eventually made the spring-loaded free-floating base quite snug against the chassis and the warble ceased while the sound improved quite a bit.
It's been about a year and I've not inquired but if he still has the TT, I'll bet dollars to donuts that he's still got all those paper towel wads all around the perimeter.
Yes, TT's are a frickin' box of chocolates and the more exotic they are, usually the worse they are engineered from a proper vibration mgmt perspective.
Don't get me wrong, from an aesthetics and intimate engagement perspective I love TT's perhaps more than the next guy and they make some gorgeous ones. But performance-wise they simply cannot hold a candle to what is possible working with non-isolation-based digital sources.
When I exhibited at RMAF 2011, I spent an evening at a very high-end distributor's home listening on what I guess was about a $250k system (add at least another $200k for the gawdy room). He put on Boston on his highly rated TT. Then it was my turn and I pulled out my very best manners and said, "That sounds really nice." and he smiled and nodded with great pride. What I should have said was "Amazing." and left it at that. You know, as in, "Amazing how you could dedicate so much resources and time to a system and room and this is the best you can do?" and as in, "Amazing you are still in business with such untrained ears.", and as in, "Amazing that your customers must all have hearing abilities not too unlike your own."
During the show, because at that time he distributed my amplifier, that distributor was routinely sending his visitors and dealers up to my room, telling his customers, "if you really want to hear what this amp is capable of, go up to Dynamic Contrasts room." I recently downgraded from that joker's $8k amp to a $2k amp and because of a new methodology I employ, the new amp is perhaps 50% more musical than that $8 amp ever was. I think it also worth mentioning that his $6k power cable that he insisted I use was no better than my fully-cryo'ed DIY $100 custom power cable.
The funny thing is that my exhibiting system only retailed for maybe $40k and most important was that at a show my racking system operates at maybe 5% of its full potential (since it takes months to reach its full potential). Truth be told, since my rack does next to nothing at a show, what visitors were hearing mostly were my fabulous Foundation Research line conditioners which by themselves will put my system on an even keel with perhaps the very best of any other system provided they are not employing similar superior line conditioners.
I've certainly had other experiences listening to some fine TT's.
Think of it this way, a given component is really no different than any other sensitive instrument, e.g. an atomic force microscope, and it takes very little in the way of undercontrolled vibrations to absolutely saturate and hence cripple a component's precision and accuracy. That said, now consider the layer upon layer of vibration methodologies employed on any given TT including air bladders and air pumps, etc. Talk about battling the laws of physics? Without stripping the TT and completely reconstructing it by removing all the garbage, there simply is no hope for any major sonic improvements. It's impossible.
But yet we're all aware of experiencing a given TT's minor improvements. How can that be if what I say is true? I can only speculate that when a negative is compounded by another negative there is a possibility of achieving a little positive, e.g. -1 x -1 = -0.5. When it comes to high-end audio I never ever use the term isolation in a positive way because 1) it defies laws of physics, and 2) because of #1, it cannot be considered a valid methodology, but only an extremely gross and inferior version of the one true methodology, resonance energy transfer.
Think about it, the air-borne and internally-generated (motors, power supplies, etc) vibrational energy will always be there and is already trapped inside and if given a few milliseconds to bottleneck it's going to release that energy right then and there post haste. If it can't find an expedient exit path, it will attach itself to objects within and release its energy there. Only now matters are compounded because now you have innards vibrating while at the same time vibrating in sympathy with the vibrations captured.
Hence, if those most exciteable and sensitive internal objects are further isolated within, whoala, a little improvement and the designer pats himself on the back thinking he's done good. And if somebody's pride and joy toward sonic nirvana is a TT, then it's pretty much a given they ain't doing much of anything different at the other components to help control vibrations there either. I mean, if Walker uses air bladders, then so should I. So in the end, having springs in a TT and objects freefloating really isn't that catastrophic after all since the rest of the system is also severely compromised so the music's pretty much guaranteed to be pretty flat and lifeless anyway.
Of course, then there's the problem of friction of the stylus at the groove and there's no getting around that frictional energy.
But to come full circle, perhaps the most common cry of the vinyl lover is, "I hosted a party last night and some 400 lbs. woman dancing by the TT caused my stylus to jump 14 grooves. Please help me so this never happens again." Enter sandboxes, kitty litter, bungie cords, springs, tennis balls, Sorbathane, innertubes, cork, rubber, etc. All the beautiful "high-end" materials that instantaneously trap all crippling vibrations already captured at the TT.
Other than that, I love TT's.
Hi Stehno,
Great post - thank you. :-)) However, it spurred me to comment on a few of the points you raised.
Firstly, I perceive the 'tone' of your discourse as similar to the arguments I see from some "engineering fundamentalists" who, because even good tube amps exhibit much higher levels of distortion than typical ss amps ... say they cannot possibly be as good to listen to! :-)) Whereas those of us with a wider-open mind understand that sound reproduction through tubes offers 'pluses' as well as 'minuses'!
Re. your comment that no TT can (performance-wise) compete with what is possible with non-isolation-based digital sources ... while I can see where you're coming from in terms of vibrations damaging the signal retrieval in a record-playing situation, you seem to have entirely forgotten the electrical aspect. IE. that (in the case of a CD, anyway) a brick wall filter introduced at 20KHz influences the sound lower down in the frequency range ... compared to a playback system which doesn't have this constraint.
Sure, if a digital system involves:
* a much higher sampling rate (say, 192K), and
* comes from memory, not from a computer disk
... then I would agree with you that it would sound much better than any TT. :-))
And re. " When I think what gymnastics TT designers have gone through to compound isolation strategy upon isolation strategy upon isolation strategy, I can't help but think what a frickin' nightmare some of them have created. And most importantly how much they've crippled that source's musical potential. "
I bought an LP12 in about 1979 and have used it until mid last year, when I changed to v1 of my 'SkeletaLinn' (the current thread is because I am now building the chassis for v2). So I know a fair bit about LP12s - but I don't know much about how other mfrs of suspended TTs have gone about their suspensions. I also have friends with non-suspended TTs ... and have seen what they have needed to do, to to make them work well. (As you said " the layer upon layer of vibration methodologies employed on any given TT ... ".
AIUI, the 3-point sprung suspension (AR, Thorens, Ariston, Linn - and preceeding all of these, an Australian TT called the 'Aurora') provides pretty good isolation down to about 5Hz ... so it can't handle terrestrial vibrations (like from a nearby railway track) but does a pretty good job of the rest. Providing, of course, the TT is on a rack or table which rests on a concrete slab; or you sit it on a wall-shelf which is attached to a masonry wall. If what you have is a springy wooden floor - then IMO, a TT is not for you ... particularly if you have a 400lb spouse who likes to boogie.
I like how my LP12 sounds and my current situation is merely the result of deciding I had to use a 12" arm that I fell in love with. :-)) My request for mechanical engineering assistance was simply to see if I could find out whether you could use calculations to find out where the cog would be, rather than finding this out heuristically.
And re. " TT's are a frickin' box of chocolates and the more exotic they are, usually the worse they are engineered from a proper vibration mgmt perspective. " ... I'm not sure if you've come across the Aussie "Continuum" TT but vibration control was an essential part of the design - hence, I guess, the $160K price tag!
And re. " internally-generated (motors, power supplies, etc) vibrational energy will always be there and is already trapped inside and if given a few milliseconds to bottleneck it's going to release that energy right then and there post haste. If it can't find an expedient exit path, it will attach itself to objects within and release its energy there. "
I agree - hence belt-driven TTs have a vibrational advantage, compared to DD TTs! But of course, some negatives come with belt drive. :-))
In an LP12, the motor is attached to the plinth ... but nominally, there is a pathway for vibrations to dissipate. In mine, I have chosen to make the motor external - so the only thing connecting it to the platter is the belt.
Then you said " Of course, then there's the problem of friction of the stylus at the groove and there's no getting around that frictional energy. ". Absolutely! And it never ceases to amaze me how a vinyl playing system actually works at all! To say nothing of the LP manufacturing process!
I certainly do love TT's - 90% of my "serious listening" is done with my TT. But when a 192K system playing from memory appears on the market for, say, $8K ... I will probably switch over. :-))
Regards,
Andy
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