After a year of considering numerous possibilities, I decided to invest in my "last" turntable. I concluded that only one turntable manufacturer -- SME Ltd. -- designs products guaranteed to last more than a decade. So I purchased one -- my last one. After all, I had already invested in a SME Series V tonearm, a wonderful tour de force tonearm that reeks of quality construction, and is the easiest tonearm to configure accurately that I have ever owned. So a couple of emails to a friend, some serious $$ mula $$, a month of anxious waiting, and viola! The SME Model 20/2 turntable has landed! Well now that I have the beast, I ask myself "What are the steps involved in setting up a reference turntable?" Through experience, I have found the following issues to be important:
Creating a level and vibration resistant base/mounting structure for the turntable to sit upon.
Leveling the plinth and disk playing surfaces.
Tuning the turntable suspension.
Mounting the tonearm and adjusting the cartridge.
Calibrating and testing the Cartridge/Tonearm geometry.
Creating a level and vibration resistant base
Turntables work by converting small modulations cut in vinyl into electrical signals, which are then amplified (by an order of magnitude) and re-equalized via a RIAA pre-amp ( bass frequencies, for example, are amplified by +20dB [a Voltage gain of 10 times]). It does not take a genius to recognize that even small perturbations of this electro-mechanical playback system will color or distort the sound. Therefore, mounting in such a way as to help isolate the turntable from air-borne and structure-borne vibrations will result in the best possible extraction of information from the disk -- basically the whole point of owning a "reference turntable." Creating a home for your reference turntable can be almost as important as the selection of the turntable itself.
In order to address airborne vibrations, we need only remember the laws of physics: namely the inverse-square law. In air, sound vibrations will reduce in intensity by the square of the distance from the sound source. So locating your turntable some distance away (the further, the better) from the sound source (the loudspeakers) will greatly reduce its vulnerability to airborne vibrations. When I had an Oracle TT, for example, I installed it in another room -- a somewhat painful exercise when listening to rather short LP's. Unfortunately (or fortunately) this is not practical for me at the moment, as my listening/audio room is small. So I have to depend on the manufacturer to have designed a particularly "resistant-to-vibration" chassis.
The SME is just such a system. The chassis and plinth are made of thick aluminum -- massive, stiff and dense. It is also very small as turntables go -- not really much larger than the record you place on it. It would take a large amount of energy to excite this mass, and there is not much surface area to excite. Also helpful is the fact that the chassis is tuned (via the rubber O-rings) to resonate at around 2Hz. The above rule of distancing your turntable from your loudspeakers still applies, and is desirable, but as my audio room is very small, the turntable is only about five (5) feet away from the left loudspeaker. This is why I went to extreme lengths to help isolate the TT with a good base.
As to structure-borne vibrations and how best to deal with them, I had given some thought to this problem some years ago when I purchased a Merrill Turntable. I came to the conclusion that mass (as in high weight/density) and damping were the most important attributes to consider. I come from the school of thought that mass-loading/mass-damping is the best possible way to dampen and isolate a sound system from vibration. This is based on known physical principles: mass damping is the dissipation of oscillatory or vibratory energy via the absorption capacity of "mass", and the higher the mass, the more energy it can absorb/dissipate. In my apartment, nothing is more massive than the concrete walls from which my audio room is created. This is why I chose a "wall mount" solution for my SME Model 20/2. As the wall is at right angles to the floor, transmission of bass frequencies (and footfalls) are attenuated via this mounting method. To treat the so called 'tympanic effect' of the side walls resonating, I mounted the turntable shelf ( a massive piece of constrained layer damped glass that weighs 40kg) on a set of three Aurios MIB 1.0 isolation bearings. These are in turn isolated from the glass using stiff Audio Technica sorbothane feet. The Aurios are particularly good at isolating a platform from horizontal motion (in my opinion), though its beneficial effects on vertical motion are somewhat dubious to me. Click here for an interesting paper on the Aurios isolation capacity.
I had an interesting converstation with Wally Malewicz, a VERY knowledgable individual on the subject of analogue audio reproduction, concerning the SME Model 20/2. Wally has an SME Model 30/2. "Chucky, the suspension was designed to be put on an English dinning room cabinet and still work appropriately -- it is tunned to 2Hz -- what you are doing is overkill, but won't hurt it." Good bless Wally -- he steppped me through some of the pointers that you will see below. Wally did not like the idea of the Aurios ball bearings -- and he is a mechnical engineer. "Chucky -- you may want to get rid of these things and try the table directly mounted to the "T" mount." Well, these comments inspired me to invest in an piezo-electric accelerometer, and part of this arcticle will include some vibration analysis of the platform that I created as compared with my old piece of 3/4 inch marble. Suffice it to say that I am still evaluating the setup -- mostly based on the sound of it (via a stethoscope).
As I had a month to prepare for the arrival of the SME Model 20/2, I was able to build a "custom" installation for my new turntable. Figure 1 shows the thick industrial glass shelf that I had made, and Figure 2 shows the 1/4" thick steel wall mount (called a French hand) that I had made to support the glass shelf and turntable. I designed it with the Aurious isolation bearings in mind, which accounts for the three point suspension. The 4.1 cm thick glass shelf (made of constrained layer damped sheets) is strong enough and self damping enough so that the large unsupported span of glass does not add to the vibration control problem (were I to do this again, I would probably opt for a four point wall mount -- like the SME TT suspension itself.
Leveling the plinth and disk playing surfaces.
"Leveling" an object turns out to be a rather interesting proposition -- there really is no such thing as "absolutely level" -- at least not in nature. It is an entirely artificial construct -- a matter of the scale, perspective and measurement technique used to "level" the object. Level relative to what? All surfaces in nature are imperfect depending on the scale which is used to examine them. The degree of measurement sensitive in your measuring devices greatly determines the outcome. So what should our objective be here?? -- to my way of thinking, a reference turntable should be leveled to the same degree that a record cutting lathe is leveled to. The only quote I was able to find was 1/1000 (you pick your unit -- degrees?, radians?, inch?, mm?) of levelness.
Just as an aside, I am sure that everyone has experienced the turntable leveling heisenberg phenomena -- every time you try to level your turntable from a particular point ( say the left center portion of the record platter) you get a different (unlevel) result from any other point/position on the table -- talk about affecting your measurements....
Getting back to the point, this "lathe cutter degree of levelness" is not an easy statistic to find. It appears that Neunman and Scully lathes are things of the past; No matter how cleverly I searched the internet using Google or AltaVista (or take your pick of the web sorting/searching algorithm) I could not find a direct refernce. After a bit of thought, I decided to "go for the gusto" and write an Expert -- Stan Ricker. Stan was most kind to respond -- here is what he wrote:
Hi, Charles--------
Thanks for writing! As far as I know, there aren't any hard guidelines about leveling a lathe; I just use a marble or ball-bearing on a blank lacquer on the TT-----if it doesn't roll, it's for sure well-enough leveled.......
This part of your letter----
"What I am really after is a "standard" to which one should aspire to when leveling your reference turntable for playback. Having never seen a record cutting lathe work ( there is an electro-mechanical device that "drives" the cutter head across the record -- right?) I might be chalking up the wrong tree, in that maybe leveling does not affect the cutting of a record as much as the playback of one. "
is totally true--- the playback-leveling is much more critical than is the lacquer-cutting----in fact, in practice, I keep a bit of Right-slant bias on my lathe just to keep the face of the feedscrew threads pre-loaded at all times; otherwise, with good lubrication, it's possible to have some "overshoot" of the cutterhead carriage with sudden speed-changes of the pitchdrive motor........
Or, this could be done with a spring-loading system.
Sure hope this helps a bit!!
Cheers,
stan
> > From: cport > Date: 2006/04/03 Mon PM 01:19:59 PDT > To: stan ricker > Subject: Simple question about a Neumann lathe > > Hello Stan: > > I found this email after reading through the very enjoyable Positive Feedback > interview [http://www.positive-feedback.com/Issue3/ricker3.htm] (and > then looking for you with google) and I had a question for you. > > Basically, what I am after is the following info: > > "Hello Record cutting specialists! > > My question is simple -- does anyone know what the installation > guidelines are from Scully, Neumann (or any other "top flight" record > cutting lathes) relating to "levelness"? As in "the state or quality of > being level (parallel with an [imaginary] horizontal plane)"? > > Is there a quote or citation that someone might pass to me as to the > required degree of levelness to function properly? Or to put it another > way "what is the maximum angle off-level that the product will tolerate > and still work correctly?" > > I need a specification -- hopefully from a manual -- "1/1000 of a degree > off-level" or 0.0001 degrees of level -- something like this -- from a > published set of installation guidelines. > > Regards, > > Charles" > > I posted this on a site called the Record Cutting Forum > (http://web1.vs247224.vserver.de/forum/viewtopic.php?t=56) -- no > response thus far. I love to see if you have an opinion on this. > > What I am really after is a "standard" to which one should aspire to > when leveling your reference turntable for playback. Having never seen a > record cutting lathe work ( there is an electro-mechanical device > that "drives" the cutter head across the record -- right?) I might be > chalking up the wrong tree, in that maybe leveling does not affect the > cutting of a record as much as the playback of one. My idea was that we > should aspire to the same degree of 'levelness" in a turntable as is > used in the cutting system. See my work (in progress) at the following > URL: http://www.resfreq.com > > I love vinyl records and the sound of music reproduced from vinyl, and > your records especially ( like the all Waterlily acoustics records that > you made) -- maybe someday I will send you a DAT recording to convert to > vinyl for me. > > Charles Port > Audiophile
Apparently, this idea of mine will not hold water -- there is no "standard", so the following section really has no usefulness. Though one thing is for certain -> "levelness" has a profound affect on the sound of the system. I found this increabible site in Japanese that seems to provide an analysis of this -> Mr. Yosh (?) [Great site].
Deciding which Sensitivity In order to determine which sensitivity is best for a particular application, it is first necessary to decide how level the product needs to be. Another way of looking at this is to consider what is the maximum angle off-level that the product will still work correctly. Let's say for this example that the product needs to be level within 0.1? (or 6'). The next assumption we need to make is how accurately the user can centre the bubble between the divisions on the vial. We would normally assume that this is possible to within 0.5mm although in some applications it may be more or less than this. Based on these figures, we need a vial that will give at least 0.5mm bubble movement for a 0.1? (6') change in angle. This corresponds to 0.4? (24') for a 2mm bubble movement, so we would say that we need a vial with a sensitivity of 24minutes per 2mm bubble movement.
Tuning the turntable suspension
Tuning the suspension on the SME Model 20/2a was a bit confusing at first, as I have only owned spring loaded turntables which "bounced" -- the SME 20/2a does not bounce -- at all. In fact, the impression one has is that the suspension does not work at all (it does).
The SME installation instructions are somewhat elusive on a couple of points. One point that was not entirely clear to me was the application of the small "height setting guage", which one needs to use to set the appropriate tension/height of the o'ring towers. The problem was the orientation of the tool -- this small tool is meant to be used with the smallest diemnsion inserted into the gap. Coming from the school of bouncy turntable suspensions, I thought the O'Rings needed considerably more extension (in order to bounce freely) than they really do. Once again -- this table will not float or bounce as you may be used to in your Linn/Merril/Oracle type tables. Some basic things to look for are the following:
Is the belt/O'ring (Centralizing belt) which offsets the motor pulley belt pull "level"?
Is a there a uniform space between the column base top and the bottom of the suspended plinth?
Do the towers seem to have similar elastic extension?
Put all the tower elastics in the down and "locked" position -- no gap -- O'rings loose.
Level (using only the base feet) the platter using Stan's ball bearing and unmodulated record technique.
Create the approriate elastic extension using the tower height suspension key (using the smallest possible dimension). Should create a small gap of 3mm.
Re-Level from the platter, again using only the base! feet.
Mounting the tonearm and adjusting the cartridge
With the SME Series V and the SME model 20/2, mounting the tonearm is straight forward, as the TT comes with a pre-drilled mounting board -- you mount the tonearm, screw it in tight to the base using the provided screws , and you are now ready to mount your cartridge and calibrate it for overhang, cartridge alignment, VTA, etc. It is necessary to have some hand tools and some specialized tools in order to mount and calibrate your tonearm/cartridge. Here follows a list of what I consider necessary to do the job.
