New Methods for Quantifying Sonic Performance: Part Two

Part Two: How to Use Subjective and Objective Methods to Quantify System Performance

Equipment report
Solid-state power amplifiers,
Tubed power amplifiers,
Solid-state preamplifiers,
Tubed preamplifiers,
Digital-to-analog converters,
Music servers and computer audio,
New Methods for Quantifying Sonic Performance: Part Two

After doing the BB sequence comparison noted in Table 1, we explored the positioning impact of BBs under the DAC. We removed all BB boxes—this resulted in a soprano position of 39" (our previous baseline without BBs as noted at position 0 in Table 1). We then added two boxes only at positions 4 and 5 on top of the DAC. This resulted in a soprano position of 56" (44" to the ceiling +12" projected forward along the ceiling) and a very noticeable improvement in SQ. We then removed all BBs from the top of the DAC and positioned the same two boxes at positions 8 and 9 under the DAC. As before, we added spacers (empty CD cases) under the BB boxes to obtain the closest proximity to the bottom of the DAC and the internal electronics. This BB positioning resulted in an increase in soprano height to 72" (44"+28") and an even greater SQ improvement compared to two boxes placed on top of the DAC. Characteristics such as clarity, focus, sweetness and emotion were all improved. We suspect the greater SQ improvement achieved by the bottom BBs was due to the closer proximity of the BBs to the circuit boards and power supply of the DAC, which are nearer to the bottom of the enclosure. When using BBs, it is important to try positioning under electronics as well as on top, although trial and error will be needed to determine the best BB positioning for each piece of electronics in your system. We show an example of the placement and number of wooden BB containers on a BSG qøl processor In Figure 3.

Lastly, there are two other aspects of these results that we would like to point out. On some pieces of equipment we have tested, the position of BBs in certain areas can actually degrade the sound (for example, the middle top areas of the PS Audio Power Plant Premier and the Esoteric K-01 CD/SACD player,) so care must be taken to conduct listening evaluations during placement of each container of BBs. We have found that even a 1" change in position can be audible. Moreover, it is possible to overdo the number of BB containers on a given piece of equipment, which can have the effect of reducing musical dynamics and subtle overtone reproduction while still retaining perceived clarity. When perusing the results shown in Table 1 the reader will note in column 2 that for the addition of BBs at positions 7 through 9, we reached the maximum height value for the sopranos. As we have discussed earlier in Part 1 of this article, we have left these results to stand, on purpose, in order to emphasize the importance of sonically handicapping a system to a great enough extent that all height measurements fall within the limits of the recording itself. In this case we underestimated the required range.

Cones, Cones, and More Cones— Mechanical Decoupling and Vibration Control
The benefits of isolating equipment from external vibration have been known for several decades. One of the earliest specialty products introduced over 30 years ago were the ubiquitous Tiptoes (circa 1984) commercialized by Steve McCormick of the Mod Squad. These devices were machined from aluminum in both tall and short conical versions. Some audiophiles noted improved definition with the use of Tiptoes (usually three or four placed under electronics and speakers). Gradually, it was recognized that these cones had a resonance in the upper midrange that imparted an unnatural and annoying harshness to music. A later refinement of this concept was introduced in the form of Goldmund Cones that implemented a “mechanical diode” principle claimed to drain away spurious mechanical vibrations generated within an equipment chassis while resisting the external influence of structure-borne vibrations in the opposite direction back into the equipment, hence the mechanical diode analogy. Goldmund Cones are no longer manufactured, but at the time, they were a sophisticated product, consisting of a machined-steel body terminated with a higher-density steel tip. Whatever natural resonant frequency that remained in the device was suppressed by a central filling of an elastomeric damping material. Placing the equipment on cones on top of a high mass substrate (for example, a 2–3cm-thick granite shelf) further optimized the beneficial effects. In direct comparisons to Tiptoes and other isolation devices of that era, the Goldmund Cones offered a significant improvement in overall sound quality with improved imaging, wider soundstage, tighter bass response (especially when placed under speakers), and better detailing. For many years these cones bettered many newly-introduced types of footers we evaluated. But finally they were surpassed by both Nordost Sort Kones and Stillpoints.

Initially we chose to compare three examples of product in this category that were comparably priced and that we already owned: our older, now-discontinued Goldmund Cones, along with the current Nordost BC Sort Kones in Bronze and Stillpoint Ultra Mini SS footers. We decided that it would also be a good idea to try footers at a higher price point. Through the kind auspices of Bruce Jacobs of the Stillpoints company and Paul Ritchotte at Nordost Corporation, we obtained samples of Stillpoints Ultra SS footers and Nordost TC Sort Kones (titanium) for testing. It is worth noting that all of these footers, except the original Goldmund Cones, use small ceramic balls (from 1 to 3 for each footer) as part of their isolation concept.

In Table 2, we show the comparative results of both our subjective and objective methods for evaluating the effects of various equipment support devices. Although Goldmund always recommended a tip-down orientation for its cones, Nordost and Stillpoints consistently recommend a point-up orientation. We tried the footers in both orientations and chose that which sounded and scored best. Accordingly, the best-sounding footer orientation is also indicated in Table 2. It came as some surprise to us that we frequently disagreed with the manufacturer’s orientation advice.2 We rank the degree of sonic improvement in order of increasing quality in the table. The retail cost is included as a purchasing aid for those inclined to act on our findings.

In System 1, where all of this testing was done, the two NuForce monoblock amplifiers and BSG qøl processor were placed on Nordost Bronze Sort Kones. System sound quality was sensitive to footers placed under the PS Audio AC regenerator/line filter, so an extra available set of Nordost Titanium Sort Kones in a point-down orientation was used for this piece of equipment. The B&W 802 speakers were fitted with the manufacturer’s support spikes. Given this system configuration, the PS Audio PWD DAC was used as the variable to test the effect of each set of isolation devices. With this experimental setup the ability to detect significant differences and create a rank order of merit was easily accomplished using the objective height method.

Without the application of cones or BBs (intentionally removed from the DAC for this comparison), the PS Audio PWD had satisfying SQ, but it did not reach the levels of musicality of which it is capable. With Goldmund Cones, our prior isolation standard, a very substantial jump in the sound quality of the PWD was observed coincident with a large increase in the height measurement. The Nordost Sort Kones BC improved the sound further by removing a slightly harsh quality exhibited when using the Goldmund Cones, while simultaneously increasing clarity, attack, and harmonic overtone structure. This improvement was similar to that heard when moving from no cones to the Goldmund Cones. Switching to the Stillpoints Ultra Mini SS footers resulted in another level of improvement, conservatively at least as large an increment as that between the Goldmund and Nordost cones. Yet, this last upgrade seemed to lock in a harmonic correctness and complexity that created an immediate increase in emotional connection to the music and the soloist. In all of these comparisons, it was amazing to hear immediate improvements in SQ that were obvious in a single A/B sonic comparison and which were even more apparent in the height measurements.

We then began to test the higher-priced tier of footers. Of the two types of footers tested, the Nordost Titanium Sort Kones and the Stillpoints Ultra constituted one of the rare cases where we could not distinguish any difference between the top two performers. The Titanium and Brass Sort Kones look identical except for the construction material, but in direct comparison the Titanium Kones easily achieved a 30 point SQ improvement over the Brass Kones.

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