Resonance Control: The Role of Natural Frequency
Unlike air or watercraft, racecar design is most directly relevant to audio because during primary operation both car and audio component share contact with the ground which transfers vibration. It’s the job any component isolation product (footers, shelves, stands) to protect the supported component from external ground and air vibration interference. Vibration is a variable which must be mastered through proper design and discreet material choices to achieve resonance control for your audio system.
Resonance control starts with the point of contact between your component, or your component on the isolation stand you’ve selected and the floor. When listening to music, speakers are the main source of vibration traveling through the ground and back to your equipment, also termed floor-borne vibration. However there are other sonic interferences from the building, the outside environment, and any resonating source which shares a path of contact to the walls and floor in your sound room. To this floor-born impact add airborne speaker vibration plus the lesser self-generated resonance of your audio components themselves and you have a real sonic challenge, coming and going, which affects your equipment and distorts the purity of sound you were aiming for in the first place.
The problem is your components face a broad ambush of unwanted vibration, and component isolation via low natural frequency intervention is the solution.
- ALL isolation stands, and all audio components for that matter, have a natural frequency which is the result of their unique combination of materials and design; and
- NO isolation stand, regardless of perceived bells and whistles, can control resonance or vibration below its own natural frequency; therefore
- Improved sonic performance is ONLY achieved by lowering the combined natural frequency of whatever is supporting your component—the lower the better!
Notice the word “combined.” You haven’t achieved full sonic advantage if your component rests upon a shelf with low natural frequency, but which is supported by a frame with high natural frequency. Why any of this matters to the customer, is natural frequency provides a useful reference. For component isolation products you want the lowest natural frequency possible because resonance can only be controlled above this limiting point.
Grand Prix Audio has intentionally applied the knowledge and principals of natural frequency to all aspects of our product design, thereby achieving the lowest natural frequency which translates to the greatest resonance control of any similar product on the market today. Our Multi-Stage Isolation™ design approach exploits each and every opportunity from the ground up and throughout the system to reduce natural frequency and maximize your component’s performance.
Hype can only be repackaged and rephrased, but real performance can be measured and quantified. For this reason, Grand Prix Audio performs multiple and varied tests throughout research and development (R&D) for all our products. For a detailed example, see our WHITE PAPER on turntable design. Grand Prix Audio’s R&D uses sophisticated mathematics, engineering and chemistry. Our work is supported by independent laboratory and cross-industry evaluations, plus state of the art in-house testing systems.
FIRST: We use instrumentation to test competing products if there are any. In addition to testing, we deconstruct these products and evaluate quality of component parts. This step provides the baseline the audio industry is accustomed to. Competitive product testing and deconstruction also factually validate positioning Grand Prix Audio’s products as superior in quality and performance—a standard goal and mandatory achievement for each and every product Grand Prix Audio designs.
SECOND: Our technicians apply rigorous testing at each and every phase of our product design process; from testing prototypes to materials evaluations and final design testing. Our testing methods are comprehensive and include a wide array of mechanical and electrical testing apparatus:
Data Precision 2480R
Lab Power Supplies:
Electronic Measurements 20205
Tektronix 465 Option 5, 100MHz analog
LeCroyWaverunner LT344L, 500 Ms/sec Digital Storage 'Scope
Hewlet-Packard 5328AF (Military Version)
w/ Option 010 Ovenized Oscillator,
Option 011 IEEE-488 Interface
Option 030 Channel C Input
Tektronix SG-503 Sine/Square Generator
Tektronix FG-504 Function Generator
Audio Precision System 1A-22A Dual Domain
w/ W&F Analyzer, and AWT, CCIR-468, 2KBP, 3KBP,
Apogee 20KLP filters
Prism dScope III Analog & Digital
A.C. Magnetic Probe, Model EP-101A
Other: High-Sensitivity Accelerometers, Spectral Analyzers, Shaker Tables
EXAMPLE: Before Grand Prix Audio entered the market the industry standard metal frame isolation stand performed so poorly it exceeded standard testing equipment measurements. The isolation stand test conducted involved:
- setting the isolation stand on top of a shaker table with a constant vibration setting equivalent to standard component output;
- adding weight equivalent to a standard component, and
- measuring the DB level (in red) with an accelerometer testing scope anchored to the top shelf.
Figure 1: competitor isolation stand – modified to improve performance
The first test of the original product (not shown) pushed the red line off the chart in both directions so drastically we had to modify the product just to get a baseline reading. In order to achieve a measurable reading as seen above, our technicians had to—after market—add lead shot to the frame of the competitor product to improve performance. The above graph (Figure 1) shows the modified product results in red. Further modification by adding an after-market air bladder, the same size as the shelf, achieved a total 80% reduction in vibration versus the isolation stand sold “as is,” but even the modified result was poor.
Figure 2: Grand Prix Audio - Monaco Modular Isolation Stand
The above graph (Figure 2) is the same test performed on a standard Grand Prix Audio Monaco Modular Isolation Stand which comes fully equipped with Multi-Stage Isolation™ at the point of purchase. The Monaco Modular was the result of hundreds or hours of research and testing, and the final test of the Monaco showed a full 125% improvement in this head-to-head comparison with the competitor product. The Monaco also beat the competitor’s product by 45% even after theirs had been modified with lead shot and an air-bladder suspension. The end result of R&D for the Monaco Modular was a high-performing isolation stand which has passed the test of time and remains a customer favorite.