TAG MCLAREN AUDIO PPA20 User Manual - page 10
The frequency response of the PPA20 has been tailored to fit
precisely the requirements of the RIAA specification.The PPA20
also includes a filter which meets the requirements of the IEC
(1)
extension to the RIAA specification, cutting out low (bass)
frequencies to prevent ‘rumble’. To further enhance your
enjoyment of older recordings, which may be damaged or were
recorded using non-standard methods, the PPA20 also has a
bandpass filter and the capability to be switched to mono.
Use the IEC filter if you hear low-frequency ‘rumbling’ noises that
you might get, for example, from a warped record.
Press the filter selector button marked riaa/iec on the front panel
to switch from riaa to riaa/iec and back. The status of the filter is
shown by an LED on the front panel labelled riaa or riaa/iec.
The riaa LED indicates that the PPA20 is meeting the RIAA
specification while the riaa/iec LED indicates that the IEC
low-frequency filter is switched on as well.
The bandpass filter
(2)
cuts down both high- and low-frequency
noise and is useful for listening to older records. In particular, the
bandpass filter can be used to remove the high-frequency carrier
signal from old quadraphonic recordings.
You can use the bandpass filter and the low-frequency (IEC) filter
at the same time to enhance the rejection of low frequencies.
When you listen to mono recordings you should select the mono
setting. This setting will also enable you to listen to certain types
of non-standard stereo recordings, albeit in mono
(3)
.
The mono setting only works when the bandpass filter is on.
bandpass filter
mono
low-frequency
(IEC) filter
18
19
filter and mono settings
filter and mono settings
1. International Electrotechnical Commission
2. A bandpass filter passes a band of frequencies and cuts out frequencies above
and below the band. The bandpass filter in the PPA20 allows through
frequencies between 40 Hz and 20 kHz
3. You can use the mono setting to check the wiring of your cartridge. Play a stereo
record. If the sound drops to a very low level when you switch to mono, then it is
most likely that the phasing of your stereo channel connections is wrong
riaa/iec
riaa
riaa/iec
GRA00046.1-[CA]PPA20 13/03/01 11:31 Page 19