User manual SUMMIT EQF-100

[. . . ] Frequency Select Selects one of seven frequencies on which the band boost/attenuate and bandwidth controls operate. 2. Determines how much of the frequency spectrum is affected by the boost or cut operation. This switch sets the section for boost or cut; the center position turns the sections off. Shelving-Resonant Changes the high or low band between a shelf or peak type of response curve. [. . . ] 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 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. 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. 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. Replacement should be done on the bench with a distortion analyzer attached to ensure that the distortion levels are proper and it is comprised of second order harmonics. [. . . ] If you have any questions about the operation of your EQF-100, please do not hesitate to call our customer service department at 775782-8838 or contact us on the internet at: sound@summitaudio. com. Specifications: Note on specifications: Summit Audio is uncompromisingly committed to excellence. All of our specifications are made with the latest technology and are UNWEIGHTED measurements. "A" weighted, dB (B), dB C weighted, etc. ), the measurement devices are basically EQed or filtered before the measurement is taken. This filtering was developed so that sound pressure level (SPL) measurements can more nearly match human's non-linear hearing characteristics. [. . . ]