Why does the Gingko Audio ARCH™ work better than spikes under speakers?
This White Paper explains why the Gingko Audio ARCH works better than conventional speaker spikes in reducing cabinet vibration and improving the sound. We present a theoretical model based on the ARCH’s unique design and construction, as well as vibration measurements that illustrate performance differences between the ARCH and conventional speaker spikes. We also summarize how the different ARCH models can be used to support audio components of different weights.
Introduction
Gingko Audio has been addressing vibration control in audio systems for close to 20 years. Since its introduction in 2002, the patented Cloud vibration control platform has been sold to thousands of satisfied customers. It has made Stereophile’s Recommended Components since 2004. The Cloud platform is made of rubber balls sandwiched between acrylic plates. Although the rubber balls reduce vibrations over a wide range of audio frequencies, their softness creates an unstable base for heavy speakers and allows the speakers to move while the music is playing – a recipe for wooly bass and smeared midrange and high frequencies. This White Paper explains why the ARCH is an effective vibration control device under speakers and why it works better than metal spikes.
Most speakers use spikes as a vibration control device both to transmit vibration from the speaker cabinet to the floor and to isolate vibration coming from the floor to the speaker cabinet. However, spikes create their own problems.
First, the complex vibrations from the speaker cabinet when it is playing music are channeled through the spikes to the floor. Some of the vibration energy, typically out-of-phase with the original vibration from the cabinet, reflects back through the spikes to the cabinet and is again channeled down to the floor. When the music is played loudly, airborne vibration also causes the floor to vibrate, especially suspended wooden floors. Because spikes are excellent transmitters of vibration, they affect the speaker cabinet in a negative way, causing the sound to be smeared. Second, most spikes are made of metallic material, which can add its own resonance.
The ARCH Design and Construction
The ARCH is a curved multilayered band. The material of the band, the number of layers and their thicknesses vary across the different ARCH models to account for the varying weights of speakers and audio components. The ARCH’s efficacy as a vibration control device hinge on the following features:
- The ARCH is made of wood-based materials with excellent absorbing quality – vibration is dissipated and very little is reflected back to the speaker.
- Its constrained-layer design filters vibration at different frequencies thus minimizing what is transmitted.
- Its curved shape acts as a leaf spring to turn vertical vibration into smaller sub-components in the vertical and horizontal dimensions. The horizontal sub-components are not reflected vertically back to the speaker.
- It rests on the floor on an edge thus minimizing transmission both ways – downwards and upwards.
- It provides a stable base to keep the speaker cabinet from moving and allows the speaker drivers to work as intended.
In our experiments, we found that the ARCH works well under spikes but works even better in place of the spikes:
- We removed the spikes from the speaker and used the studs that come with the spikes to attach the ARCH to the speakers. We drilled a hole in the middle of the ARCH slightly smaller than the diameter on the stud and screwed the stud into the hole. The wood-based material of the ARCH embedded the stud securely so that it could be screwed into the threaded hole in the bottom of the speaker cabinet.
- Another option was to drill the hole in the ARCH slightly larger than the diameter of the spike stud. We inserted the stud in the hole and let the bottom of the speaker cabinet rest on top of the ARCH. We found that without the metal stud playing a part in the vibration transmission the sound was improved. Since the ARCH’s base is wider than the spike, it provides a wider footprint for a more stable speaker.
A Theoretical Model for Vibration Effects on Speakers
To understand how the Gingko Audio ARCH works, compared to speaker spikes, consider the vibration model depicted in Figure 1.
The down arrows from the speaker cabinet depict the flow of energy from the cabinet vibrations to the floor. The up arrows show how vibration energy bounces from the floor back to the speaker. Simply put, vibrational energy impinging on an object can do three things: Reflect back to the source, be absorbed by the object, and be transmitted through the object. The primary function of an effective vibration control device is to maximize the absorption and minimize the reflection.
To understand how well the vibration control device in Figure 1 does its job, we can measure the amount of vibration on two points, A and B, and compare the results. We mount identical transducers at each point and, using instrumentation, observe the effects of vibration under controlled circumstances. Each transducer generates a voltage proportional to the vibration at its base and feeds a spectrum analyzer that simultaneously displays the frequency and intensity of vibrations at both points on the screen of a laptop computer.
Measurements to Compare the ARCH and Speaker Spikes
We set up measurement tests using two identical B&K 4366 accelerometers feeding signals through two identical B&K Type 2626 conditioning amplifiers to a PC running Richard Horne’s Spectrogram software. The Spectrogram software can be downloaded from this website.
We run the tests by playing the correlated portion of the Pink Noise track on Stereophile’s Test CD #1, at identical volumes, using a Music Hall Trio integrated amplifier/CD player and a pair of Napa Acoustics Model NA-208S speakers placed on spikes and on Mini-ARCHs (monitor speakers are lighter in weight and can be supported by Mini-ARCHs). Below is a picture of the test setup.
To ensure that our two accelerometers – one with the white top, the other with the blue tape – are identical, we place them side by side on the table and observe the result of the Spectrogram program.
Figure 2 shows the result comparing the measurements of the two nearly identical accelerometers.
The split screen shows two nearly identical side-by-side portions of the graph. The horizontal axis denotes real time as we are using the scrolling function of the software. The vertical axis denotes frequencies in a logarithmic scale from 10 Hz to 22K Hz. The vibration energy is depicted using colors, the hotter the color the more vibration energy: Red denotes the most vibration energy, followed by orange, yellow, green, blue; white denotes insignificant vibration energy. The black line at the top of the graph shows the sum of all the vibration energy across all frequencies. The left side is the accelerometer with the white top and the right side is the accelerometer with the blue tape. The graph indicates that the two accelerometers are nearly identical in measuring vibration across all frequencies, except that the white-top accelerometer seems to register the 60Hz signal more readily than the blue-tape accelerometer (as shown by the solid light blue line at 60Hz).
Next, we place the blue-tape accelerometer on the speaker cabinet resting on three spikes and then on three Mini-ARCHs (two in front and one in the back) and compare the result with the white-top accelerometer on the table.
Here are the results shown on consecutive graphs, Figure 3 (speaker on spikes) and Figure 4 (speaker on Mini-ARCHs). Again, the left side of each graph is the white-top accelerometer (on the table) and the right side is the blue-tape accelerometer (on the speaker). We played a short segment of the Pink Noise track as denoted by the middle section of the graphs.
The graphs show that there are more vibrations in the speaker cabinet than on the table as the Pink Noise is played. Figure 4 confirms that the Mini-ARCH does a better job absorbing vibration than the spikes. This is the case not only during the Pink Noise portion but also in the quiet portions of the graph before and after the Pink Noise. The upward energy seems to add to the cabinet vibration, especially at the lower frequencies. As noted earlier in this paper, the spikes are good transmitters of energy in both directions, which can cause problems to the speaker cabinet.
Lastly, we put the accelerometers on both speaker cabinets to compare vibration control of spikes vs. Mini-ARCH. We mount the white-top accelerometer on the cabinet supported by spikes and the blue-tape accelerometer on the cabinet supported by the Mini-ARCHs. We take care to mount the accelerometers at the same places on the speaker cabinets and to play the correlated portion of the Pink Noise test track so that the left and right speakers are playing exactly the same signal.
Figure 5 shows the result. Again, the left portion of the graph is the white-top accelerometer (on the speaker on spikes) and the right portion is the blue-tape accelerometer (on the speaker on Mini-ARCHs).
The left side (speaker cabinet on spikes) shows more energy in the lower frequencies near the 60HZ region caused by the transformers of the B&K conditioning amps nearby while the Mini-ARCHs do a good job in absorbing that energy on the cabinet.
The right side (speaker cabinet on Mini-ARCHs) shows less overall energy but more in the mid-range frequencies than the left side. Our listening tests verify that the speaker on the Mini-ARCHs sounds clearer than the speaker on spikes in the mid-range with increased clarity, transient attacks, and expansion of the soundstage width and depth.
ARCH Models
Although the original ARCH was conceived for speakers, our tests have indicated that the design works equally well under other audio components such as amplifiers, preamps, CD players, or turntables. The Mini-ARCH is thinner and carries lower weight loads but can be stacked to support heavier weights or to tune the sound to your personal taste. We find that stacked Minis make the suspension stiffer, resulting in a more dynamic, punchier sound. Single Minis provides a softer suspension, resulting in a fuller, richer sound. The new and improved Equipment ARCH and Speaker ARCH are premium versions of the original ARCH for use under speakers and heavier components such as amplifiers, with improved sonic performance and a more finished look.
Please email us at gingko@gingkoaudio.com if you have any questions about the ARCH. We hope to see you at an upcoming audio show where we will feature real-time demos of effects of using the ARCH.