PreSonus Eris Pro Sub 10

First decide which device will filter the signal reaching the monitors. If they receive audio from the Eris Pro Sub 10 OUTPUT L/R and its HPF is enabled, that path already cuts frequencies below 80 Hz. Check the routing and filter state before adding another cut on the monitors. If the monitors connect directly to the source, the sub’s HPF does not affect them.

HPF and LOW PASS FILTER serve different parts of the system. The 80 Hz HPF sits in the path to the monitors; LOW PASS FILTER sets the upper frequency reproduced by the subwoofer, between 50 and 130 Hz. PreSonus specifies 80 Hz for the low-pass when using its HPF. With the HPF disabled, it says to set the low-pass according to the lowest frequency the monitors can reliably reproduce.

1. With levels low, record the source output, both sub INPUT connections and the OUTPUT connections to each active monitor. For a stereo source, PreSonus requires L and R so the sub receives bass from both channels. A mono or LFE output can use L or R; it does not replace the stereo path to the monitors.
2. Use a single input pair for this check. The manual states that TRS takes priority over XLR when both are connected, and RCA is summed into the balanced input. An extra cable may change the source you are comparing. SUB OUT sends a full-range sum to a second subwoofer; use OUTPUT L/R for the monitors.
3. If you choose the Pro Sub 10 crossover, enable its HPF and set LOW PASS FILTER to 80 Hz. Read the unit’s On/Off labels: two manual drawings reverse the HPF’s illustrated position, so do not use “left” or “right” as an instruction. Check the monitors’ own manual for any active cut before changing it.
4. Compare from the same listening position at a moderate level, first with the intended cut and then with any additional cut you found. Keep level, signal and position constant. If bass weakens around the crossover, record filters and POLARITY; if it changes greatly as you move, investigate room placement before compensating with gain.
5. Check that SUB Bypass is not active: the manual says it bypasses the sub, HPF and SUB OUT, passing the signal to the monitors. A bypass comparison therefore changes more than the presence of the sub. Once relative levels are set, PreSonus recommends adjusting overall volume at the source to retain the balance between sub and monitors.

Compare the unit with and without audio connections, from the same position and with the same power and standby state. If the noise disappears when those connections are removed, reconnect one path at a time to find where it returns. If it remains with all audio inputs and outputs disconnected, record it for support: that observation does not identify the component producing it.

The manual’s Hum section addresses ground loops in the audio chain and recommends balanced connections and separation of signal and power cables. It helps trace noise entering through the signal path; it does not identify an internal part. PreSonus prohibits removing the power cord’s grounding pin or using an adapter that defeats it.

1. Record what you hear, from where, with which cables connected and what changed since the previous setup. The manual describes power saving after more than 40 minutes without audio when STANDBY is enabled, and waking when the signal resumes. Keep the same state when comparing noise; silence in standby is not a repair.
2. Outside the programme, lower levels and switch equipment off before changing connections. Remove the audio connections, keep the normal grounded power connection and switch the sub on to observe it from the same position. Do not open the cabinet or modify the transformer for this check.
3. If the noise disappears in that condition, reconnect one path at a time with levels low. Try a known working balanced cable when the source has a balanced output, and keep it away from power cabling. Record which connection brings the noise back; an interface, computer or cable remains a candidate until checked.
4. If noise persists without audio connections, or seems to come from inside the cabinet, send support the model, serial number, standby state and a recording of the observation. The manual provides no external test that confirms a transformer fault. Power supply and any distribution changes must be reviewed with the person responsible for electrical systems; this page does not specify protective devices or power connections.