Perfect combination
(2nd of a series)
The thought of coming out with a tutorial on analog music is greatly inspired by relentless readers who want to get started with an all-analog stereo system. It was quite surprising for me because most of them are in their early 20s; giving us a general view of how far this wonderful devolution in music reproduction has gone. Since my technical knowledge may be limited, I thought of inviting from the audio community prominent orthopedic surgeon and analog guru Doctor Lito Gozum to help me spell out in simple terms just how to get started with this crazy, yet very rewarding, hobby.
We have already discussed how a poor quality cartridge can result in inaccurate music reproduction. Very telling is its inability to reproduce impulses and transient in music. Passages with drums and percussion will sound bad, with cymbals sounding either shrill or muffled. Synergy or the perfect combination of all components in the analog chain should thus be the hobbyist’s main focus. There shouldn’t be a weak link. Everything should work in precise cadence.
Here is Doc. Lito’s explanation:
“In the digital domain, the music is stored in a CD or hard drive via a series of 1’s & 0’s.
In vinyl, the music is stored in the cut grooves. Playback will require converting mechanically what is stored in the wavy grooves into electrical current. This is accomplished by using a cartridge or pick-up. The part of the cartridge in contact with the vinyl is the stylus or needle which is a small cut diamond. The stylus is glued to the tip of the cantilever or spar. At the other end of the cantilever (inside the cartridge body) is either a magnet or a wire coil. This stylus/cantilever/generator complex is usually suspended within the cartridge body by a carefully designed rubber suspension. As the stylus traces the wavy patterns of the grooves, the moving magnet (MM) or moving coil (MC) generates minute electrical currents. It is this small electrical signal which must be eventually amplified by a phonostage to make it useable for your pre-amplifier.
“The amount of voltage that a cartridge churns out will classify it as a high-output, medium-output or low-output cartridge. Most phonostages can handle high- to medium-output cartridges. A low-output cartridge may require an additional device called a Step-Up Transformer (SUT) to further amplify the signal. Likewise, the flexibility or compliance of the cantilever/suspension complex will classify a cartridge as being of high, medium or low compliance. The more flexible or compliant the cantilever/suspension system is, the better it will follow the grooves.
“Taking into account the design of the stylus/cantilever/suspension, different cartridge manufacturers specify a particular range of vertical tracking force (VTF) for their particular cartridges for optimum performance. Set too light, the stylus may jump grooves which can cause damage to both record and cantilever. Set too heavy, the suspension may collapse causing damage to the cartridge itself. To set this accurately, a stylus force gauge (balance scale) will be required. There are analog and digital/electronic versions of this. The VTF of modern carts is between 1.25 grams and 2.5 grams on the average.
“Of critical importance is the choice of tonearm which supports the cartridge as it does its job of tracing the grooves. Just like cartridges, tonearms are of various designs and have a particular compliance. There are no hard and fast rules here, but you generally match a high- compliance cartridge with a high-compliance tonearm, a low-compliance cartridge with a low-compliance tonearm, and so forth. Like a couple in a ballroom dance, the two must complement each other well, or their performance suffers.
“There are many designs of tonearms. They come in different lengths: 9 inches, 10 inches and 12 inches being the popular ones. They are classified by their bearing design. The more common designs are the gimbal design wherein a set of ball races allows the tonearm to move in both vertical and horizontal planes. Another is the uni-pivot tonearm which relies on a needle point to balance the tonearm, allowing the same degrees of freedom.
“More exotic is the air-bearing tonearm in which the tonearm rides on a cushion of air provided by an electrical pump with a reservoir. In this particular design, the cart/tonearm moves horizontally across the record surface vs. the gimbal and uni-pivot designs which trace an arc across the record. The travel of the air-bearing tonearm mimics the cutting lathe which cut the grooves in the vinyl master disc.
“There are many pros and cons for each design. The bottom line is: It has to be adjustable to the needs of your cartridge settings. You should be able to adjust VTF, Vertical Tracking Angle (VTA or tonearm height) and anti-skate (mechanism by which you counter the outward force of travel by the tonearm if this feature is present). The tonearm should enhance the performance of your cartridge rather than limit it.” (To be continued)
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For comments or questions, please e-mail me at audioglow@yahoo.com or at vphl@hotmail.com. You can also visit www.wiredstate.com or http://bikini-bottom.proboards80.com for quick answers to your audio concerns.
