User manual SUMMIT EQF-100

[. . . ] Proceed by doing the following: · · · Set the line voltage switch to the proper position Determine the proper fuse size by referring to the specifications Check for pilot lamp illumination when powered up The Controls: 1. Frequency Select Selects one of seven frequencies on which the band boost/attenuate and bandwidth controls operate. 2. Bandwidth Determines the amount of boost or cut that takes place. Determines how much of the frequency spectrum is affected by the boost or cut operation. [. . . ] Turn the gain all the way up (for the highest amount of cut) and start narrowing the bandwidth. Use the frequency select and bandwidth to narrow in on the frequency to be attenuated. Decrease the gain knob (decreasing the amount of cut) until the frequency is cut with the least effect on the surrounding frequencies. Low or high shelving: Set the low or high EQ sections to shelving filter. Select the frequency where roll-off or boosting is to begin. Select plus or minus on the Boost/Cut/Bypass switch and turn up the gain knob to cut or boost above the high frequency selected or below the selected low frequency. A Word About Tubes The tubes that are used in the EQF-100 are selected to give the best possible performance in the position that they are in on the printed circuit board. Switching them to different positions will cause performance deterioration on the audio path. Replacing them with "gold" or high end tube types may not be desirable. In cases that we have measured, these tubes have shown higher distortion and noise as compared to the tubes we have selected. In some cases, the so called "gold" or high end tubes have made the unit unusable. The reason for this is some of the "gold type" tubes are selected for high distortion in guitar amplifiers. Using gold tubes is no guarantee of better performance. All of these so called "Brand X" types are selected with 6. 3 volts AC on the heaters, whereas Summit Audio uses 5 volts DC on the heaters for longer tube life and lower noise. The reduced gain can raise the noise floor, increase distortion, and reduce headroom. For proper performance from a tube, the replacements must be selected using 5 volts DC on the filaments. The tubes we use are selected in the circuits that they are used in to ensure proper operation, long life, and low distortion and noise. In at least 50% of the cases we have tested, gear that has been used for several years actually have lower noise and distortion levels than when new. This makes the question of when to replace tubes difficult to answer. If a tube turns micro-phonic, the distortion will be obvious and the tube must be replaced. However, tube life will most likely be greater than 10, 000 hours of operation. Tubes are generally very reliable; don't replace them just because they are old. In the EQF-100 there are gain adjustments that will need to be checked when the tubes are replaced, or else the metering could become inaccurate and the noise floor could change. [. . . ] This filtering was developed so that sound pressure level (SPL) measurements can more nearly match human's non-linear hearing characteristics. However, when used in noise, frequency response, and distortion measurements, weighting will alter the results. Completely flat frequency measurements are key to giving accurate specifications. Summit Audio devices are the highest quality professional audio gear and the specifications below are made with the flattest possible unweighted measurements, giving the most accurate results. [. . . ]