Hsu Research VTF-2 manual Volume fine tuning, Removing buzzes and rattles from the room

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Volume fine tuning

For the most precise integration with your main speakers, go through test tones with a SPL meter. Setting the level using test tones by ear may result in misconfiguration, so please use a meter.An analogue Radio Shack SPL meter is inexpensive and works better for this application than the digital Radio Shack SPL meter. It is available at RadioShack.com. Use the "C" weighting and “SLOW” settings.

Using a test disk with one-third octave filtered pink noise or warble tones, measure from the listening position with the volume at 75 dB with a 50 Hz tone. Test tones are available on the Stereophile Test CD 1, available at Stereophile.com. Do not play the test tones extremely loud as this might damage your speakers. Take measurements of four different tones above the crossover point and four different tones below the crossover point. Note that the Radio Shack meter is down about 12 dB at 16 Hz, 7 dB at 20 Hz, and 3 dB at 30 Hz, 2 dB at 40 Hz, and 1 db at 50 Hz. Add these numbers to the readout to compensate. Average together each set of four measurements and adjust the subwoofer’s volume level to compensate. Repeat the measurements until the subwoofer matches the other speakers.

A less accurate method uses the receiver’s test tones, which are usually not in one-third octave increments. Measure from the listening position and set the subwoofer volume level to match the other speakers.

Removing buzzes and rattles from the room:

Annoying sounds can be fixed by using adhesives, tape, or felt pads in the area where objects are vibrating against each other.

Equalizing the subwoofer

If you have an equalizer, avoid raising dips in the frequency response. Instead, use the equalizer to remove peaks. This will prevent potential speaker damage.