What Is a Subsonic Filter on the Project Tube Box II Pre-Amplifier?
The Project Tube pre-amplifier is designed with a dual mono circuit to improve clarity, covered in a metal case to protect the amplifier from both wear and tear and outside distortion. The unit has gold plated sockets, high quality leads, and a subsonic filter to improve sound quality. Subsonic filters are a common device used in amplifiers and similar sound systems to help increase efficiency and reduce distortion.
Other People Are Reading
-
Subsonic Filters
-
Subsonic filters are a type of electronic system that work to filter out unnecessary signals from speakers and amplifiers. The sound passes through this "filter" and comes out cleaner and truer to its original content, which in turn produces more authentic sound from speakers. The filter is subsonic because it deals primarily with low frequencies that sound systems can unnecessarily produce.
Low Frequencies
-
Low frequencies in amplifiers can easily become distorted in their passage to recording or reproduction. This distortion spreads throughout the recording and can create increasingly annoying problems later on. This typically happens with bass instruments or applied distortion that sinks the sound frequencies to very low levels, which amplifiers are not prepared to deal with correctly. The subsonic filter catches this low frequency distortion before it becomes a large problem and regulates the music signal.
-
Operation
-
Technically, most subsonic filters are active Tschebyscheff high pass filters of the fifth order, and have a cut-off of 18 Hz. Generally subsonic filters work below 40 Hz and often a little above, too, to improve bass quality. Most sound filters are constructed of inductors, resistors, and capacitors and work on a passive level, but this becomes impractical when dealing with low frequency sounds, so subsonic filters tend to be active in nature and use an operational amplifier to control sound more accurately.
Power Usage
-
A reason often cited for the inclusion of subsonic filters is power savings and focus. Most of the subsonic interference that the filter removes from the signal is not actually music. At low frequencies, the sound tends to create electrical noise that serves no purpose except to take up the power of the amplifier. When the filter takes care of this noise below the 40 Hz level, the power of the amplifier is left to focus more clearly on intended frequencies.
Stereo Systems
-
For mono systems like the Project Tube Box II, the basic filter system works well. However, stereo systems typically require two separate subsonic filters, one for each channel. In this case, it is important to buy a system that already includes two professionally made filters, because any difference in the filters can affect what low frequencies make it through the speakers, and the stereo system sounds.
-
References
- Photo Credit amplifier image by Darko Draskovic from Fotolia.com
