More likely that there is signal cancellation going on; try using unbalanced TS cables for the RMX.
No bass with RMX 1000
If you're experiencing a loss of low-end (bass) frequencies when connecting your RMX-1000 effects unit between your UREI 1620 mixer and amplifier using balanced TRS-XLR cables, there are a few things you can check and try:
1. Cable connections: Double-check that all your cables are securely connected and properly seated in their respective ports. Loose or faulty connections can result in signal loss or altered frequency response.
1. Cable quality: Ensure that you're using high-quality balanced TRS-XLR cables that are suitable for audio signals. Poor-quality cables or cables that are not designed for balanced audio connections can cause signal degradation and affect the frequency response.
1. Check for phase issues: Incorrect wiring or phase issues in the connections can lead to canceled or reduced bass frequencies. Make sure the signal polarity is consistent throughout the signal chain. Check if any of the cables are wired incorrectly or if the phase switch on the mixer or amplifier is set incorrectly.
1. Mixer settings: Verify that the effects loop on your UREI 1620 mixer is configured correctly. Check the settings for the effects loop, including any EQ or filtering options that may be affecting the frequency response. Ensure that any high-pass filters or EQ settings are not cutting off the low-end frequencies.
1. RMX-1000 settings: Review the settings on the RMX-1000 effects unit itself. Some effects units have built-in EQ or filtering options that may need adjustment to retain the desired low-end response. Check the user manual or documentation for the RMX-1000 for any specific settings related to frequency response or EQ.
1. Test with alternate connections: To isolate the issue, try connecting the RMX-1000 directly to the amplifier without passing through the UREI mixer. If the low-end response is restored in this configuration, it could indicate an issue with the mixer's effects loop or settings. Drift Boss
If the problem persists after trying these steps, it may be helpful to consult the user manuals or documentation for your specific equipment or reach out to the manufacturer's support for further assistance. They may provide additional troubleshooting steps or insights specific to your setup.