How to Volume/Gain Match Subwoofers and Speakers With REW

Achieving a perfectly balanced sound in your home audio system requires precise volume/gain matching between your subwoofers and speakers. Using Room EQ Wizard (REW), you can easily calibrate these components to ensure they work together seamlessly. Here's a step-by-step guide on how to do this using the SPL Meter and Generator/Noise functions in REW.

1. Set Up Your Equipment

Before you begin, ensure you have:

• A calibrated microphone (such as the UMIK-1)
• REW software installed on your computer
• Your subwoofer and speakers connected and ready to play test tones

Position the microphone at the main listening position (MLP), where your ears would typically be during listening sessions. This will help you get the most accurate measurements.

2. Measure and Adjust the Subwoofer First

Start by setting the subwoofer's level before moving on to the speakers. This is crucial because if the subwoofer and speakers are out of phase, one could cancel the other, leading to inaccurate results (we've seen out of phase subwoofers 10dB lower compared to when in phase...!).

1. Open REW’s SPL Meter:

   • Launch REW and select the SPL Meter from the toolbar.
   • Set the weighting to “C” and the speed to “Slow” for a more stable reading.

2. Generate Pink Noise for the Subwoofer:

   • Go to the REW Generator and select “Noise”/Pink random/Sub Cal (30 to 80 Hz) as the signal type.
   • Set the noise to play only through the subwoofer by ensuring the speakers are muted.
   • Adjust the subwoofer’s gain until the SPL Meter reads around 75 dB at the listening position. This is a common reference level, but you can adjust based on your preference.

3. Fine-Tune:

   • Check the SPL Meter reading and make small adjustments to the subwoofer’s gain until you reach your target level.

3. Measure and Adjust the Speakers

Once the subwoofer is set, it’s time to match the speakers to the subwoofer.

1. Generate Pink Noise for the Speakers:

   • Mute the subwoofer and unmute the speakers.
   • Using the REW Generator, play the same pink noise through the speakers.
   • Adjust the speakers' volume (usually via your AV receiver or preamp) until the SPL Meter also reads around 75 dB at the listening position.

2. Check and Adjust:

   • Ensure both speakers are producing the same SPL. If not, adjust their levels until they match.

4. Check Combined Output and Phase Alignment

With both the subwoofer and speakers individually set, it’s time to ensure they work together without phase cancellation.

1. Play Pink Noise through Both:

   • Unmute the subwoofer and play pink noise through both the subwoofer and speakers simultaneously.
   • Observe the SPL Meter reading. If it drops significantly compared to the individual measurements, your subwoofer and speakers might be out of phase.

2. Adjust Phase:

   • Most subwoofers have a phase control (either a switch or a dial). Start by setting it to 0°.
   • If the SPL reading shows a dip at the crossover frequency, switch the phase to 180° or adjust it until you get the smoothest response.

3. Fine-Tuning:

   • Make small adjustments to the phase and gain until the subwoofer and speakers blend seamlessly, producing a smooth frequency response across the crossover region.

5. Final Listening Test

After making all adjustments, sit down and listen to your system. Play a variety of tracks, focusing on how well the bass integrates with the rest of the audio. If necessary, go back and make further tweaks to the gain or phase settings.

Conclusion

Using REW to volume/gain match your subwoofer and speakers ensures that your audio system delivers a balanced, cohesive sound. By carefully measuring and adjusting each component separately and then together, you can avoid common pitfalls like phase cancellation and achieve optimal sound quality. Enjoy the enhanced listening experience!