8 Adjust the P1 to the cartridge
For each cartridge connected to a P1 input, the phonostage provides several wizards to help set up the system. Users are advised to
take the following steps:
1. Select the type of P1 input the cartridge will be connected to.
2. If the voltage mode MM/MC input is used, select an initial loading value.
3. Select the optimal gain with the help of the gain selection wizard and the provided 45 RPM record.
4. If the voltage mode MM/MC input is used, run the loading wizard in conjunction with the provided test record to optimize
the loading of the cartridge.
The following paragraphs will explain in more detail each of these steps
8.1 Input type selection
High quality low output low internal resistance moving coil cartridges usually work best at delivering current than voltage. When
such a cartridge is directly connected to the P1, MC current mode input should be used.
In most other cases (moving magnet, moving iron, high output moving coil, and even low output low internal resistance moving
coil connected through a step-up transformer), the MM/MC voltage mode input should be used. In that case, optimal loading
should be selected to flatten the voltage frequency response of the cartridge.
8.2 Initial loading selection
For cartridges connected to the MM/MC voltage mode input of the P1, the amount of loading applied to the cartridge by the P1 can
greatly influence not only the frequency response of the cartridge, but also the level of the signal. This is why a reasonably
accurate loading must be selected prior to any gain selection. If the cartridge manufacturer advises on a particular loading value, it
should be set (AUDIO SETTINGS > MM/MC LOADING) as a starting point. If a range of values is provided by the cartridge
manufacturer, the highest value should be set. If no guidance can be found, 100 kOhm should be selected as initial loading value.
8.3 Optimal gain selection
In order to obtain the best signal-to-noise ratio and a P1 output level close to line level sources (such as the CH Precision C1 DAC),
a gain wizard has been programmed into the P1. It can be found in FACTORY SETTINGS > GAIN SELECTION WIZARD.
It is designed to be used in conjunction with track 1 of side 2 of the provided CH Precision P1 phonostage calibration record. Simply
follow the steps described in the P1 wizard screens.
8.4 Refined loading selection
Once the gain has been properly selected, the loading of the MM/MC voltage mode input can be further fine-tuned using the
loading wizard found in FACTORY SETTINGS > MM/MC LOADING WIZARD. This procedure performs more than 20 frequency
response curve acquisition per run, each time with a different loading value spread evenly on a user-defined range of values. Once
these acquisitions are completed, you can scroll across all analyzed loading value. For each value, the frequency response curve of
the entire system is displayed on the P1 screen, along with level attenuation and curve flatness. Based on this information and
auditory feedback (each loading being applied in real time, you can play your favorite reference record as you scroll across
measurements), the loading that provides best results among all measurement can be selected. This wizard can be run more than
once, each time refining the measured loading range around the new optimal value.
Rev 1.1 P1 User Manual 31
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