Glossary

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GLOSSARY MAINPAGE

P

PAL - The picture colour standard used the the UK for televisions and for pre-recorded video tapes, Laserdiscs and DVD's.  
PASSIVE - speakers or sub-woofers that react to an amplified signal from a separate amplifier. They contain no amplification themselves. Active speakers and sub-woofers have built-in amplification and require only a Line Level input signal from a source component or amplifier.  
PCM - Pulse Code Modulation. A type of digital output used on audio sources to transfer high quality digital audio information to an amplifier with a suitable digital DAC. It offers improvements over normal stereo phono interconnects.  
PDC - Programme Delivery Control, a feature of video recorders. A ghost signal is transmitted alongside a television programme that a VCR with PDC can understand. The signal contains programme information. When the VCR is set to record a particular programme, and the PDC feature is active, the VCR will record the programme from the start to the end only when it receives the ghost signal. It will alter the VCR settings to record the correct programme even if it starts or ends late.  
PHONO STAGE - A special input found on most amplifiers that can receive signals from a record player. The signal frequency of a record player is lower than that of other sources (CD, Tuner, etc.) and therefore requires this special input. Amplifiers without a Phono Stage built-in need an external phono stage to convert the record player output into a signal that the amplifier can handle.  
PMPO - Peak Music Power Output. Used by electrical retailers to make dodgy equipment look more powerful. A hi-fi amplifier with a power rating of 50 watts will provide 50 watts to each channel (two channels for stereo, etc.) whereas a mini system with a power rating of 50 watts PMPO will actually output less than 25 watts to each speaker. Avoid PMPO hardware because it's not the true value.  
POWER AMPLIFIER - Takes the low powered output from a Pre Amplifier and drives the speakers. By separating the Pre amplifier stage from the Power amplifier stage, normally contained within the same box in a stereo integrated amplifier, the internal interference is reduces giving a stronger, higher quality sound. The Power amp takes the variable signal and amplifies it by a fixed amount - the volume is controlled by the Pre amplifier.  
POWER HANDLING - The safe power level that a speaker can handle without destroying the drivers. It sounds crazy, but you run more risk of damaging speakers using an amplifier with a power rating (watts) lower than the speaker units. For example, a 100 watt amplifier driving 50 watt speakers is not working very hard so the speakers receive a fairly low-powered, clean signal. A 40 watt amplifier driving the same 50 watt speakers will be working close to its limit to provide a signal strong enough for the speakers. This reduces the quality of the signal, creating distorted electrical currents that speakers don't like.  
PRE AMPLIFIER - The control section of a two-box amplifier system. This section takes the source signal and creates a clean, low-power signal for each channel that is then sent to a Power Amplifier and finally on to the speakers. Separating the Pre and Power stages of an amplifier reduces internal interference and improves sound quality. The Pre amplifier outputs a variable signal strength proportional to the volume required.  
PRO-LOGIC - The Dolby technology used to encode and decode surround sound from home software recorded with a Dolby Surround soundtracks. See Dolby Pro-Logic.