PAP-C1 Operation

Thank you for purchasing the PAP-C1 Analog Active Crossover that was designed/manufactured by Nelson Pass/PassLabs First Watt.

The PAP-C1 is an upgrade of the legacy First Watt B1 crossover so for general information you are welcome, come to read the B1 manual.

The tuning of the PAP-C1 is made on it’s board that you can access by opening the two upper bolts at the front and the back of the C1, and removing carefully the upper part of the enclosure.

Once connecting the output of your pre-amp to the Input of the PA-C1 and connecting the outputs of the PAP-C1 to the two power amps (Woofers and Center Driver), you can turn the unit on and proceed with the tuning.

On the board of the C1 there are four areas where tuning is made:

  • Low Pass, where the cut-off frequency of the Woofers is set
  • High Pass, where the cut-off frequency of the Center Driver is set
  • Bass Boost, boosting the Bass
  • High Notch, slightly shaving the upper mid frequency

On the front panel of PAP-C1 there are two Volume Control pots, Left and Right, for the woofers only (Low Pass Channels). These controls allows you to set up the balance between the woofers and the center driver. This option is known as Loudness, whereas at low volume you can make the woofers volume a bit higher…

At regular listening scenarios you probably won’t play with these controls after they were set to your favourable position.

Tuning the Cross Frequencies

The Low and High Pass tuning is made with four pots that have to be brought to same position (the desired cross frequency). The reason there are four pots is: there are two channels, left and right, and the signal consists of a positive and negative pole while every pole is controlled by it’s dedicated pot.

See the graphs and the frequencies (writer in white) at the below photos and tune the cut off frequencies to your preferred values.

Our Recommendation:

For Speakers with Voxativ Center Drivers: Start with Low Pass and High Pass at 335hz.

For Speakers with Horn1: Start with Low Pass and High Pass at 550hz.

Use Bass Boost and High Notch as per your personal preference.