markus
Addicted to Fun and Learning
- Joined
- Sep 8, 2019
- Messages
- 709
- Likes
- 815
Ever so often the question comes up which room correction system (RCS) is "best". In order to explore this topic this thread was created.
First let's see if there's common ground on which we can move forward.
In-room measurements vs. perception vs. equalization
At low frequencies the (acoustically small) room dominates what we hear so the premise is that a steady state measurement lumping together direct and reflected sound highly correlates with what is heard up to the sub/sat crossover region.
Equalization here can improve the frequency response. It can also improve ringing. If used incorrectly it can make ringing worse though.
At higher frequencies reflections have a significant impact on what is measured but not on what is heard (we hear added spaciousness, not coloration). Thus any attempt at equalizing the steady state response would alter the direct signal (and reflections) spectrally and likely would make it sound worse.
Equalization could still be beneficial if reflections could be "removed" from measurements taken at the listening position. The result would be the anechoic response of the speaker hence room correction would become speaker correction. Depending on the quality of the speaker this could improve the response quite a bit.
Reflections can be "removed" from measurements to a certain degree by gating techniques. The problem is that there are very early reflections from objects close to the speaker and the microphone that have a significant impact on the measured results despite gating.
Measuring RCS performance
Based on what has been said above there's performance criteria in two areas:
1. Low frequency performance ("room correction")
1.1. Magnitude response - how good does the equalized result follow the target curve?
1.2. Ringing - has ringing been reduced?
2. High frequency performance ("speaker correction")
2.1. Magnitude response - is the anechoic direct sound from the speaker closer to flat/target curve?
Testing
General
1. Room correction needs to improve ALL points within the listening area so multiple measurements need to be taken before and after a specific room correction system is run. These control points should NOT be the same as the mic positions used by the room correction system. This allows us to assess whever the room correction system improved the whole listening area or just the small number of single points used by the room correction system while other points have been made worse.
2. Mics positioned at control points can't be moved between testing otherwise no comparative assessment between room correction systems can be made. Even small mic location variations will create significantly different results.
3. Anechoic measurements of the speaker need to be performed with and without room correction enabled (for evaluation of higher frequencies).
Evaluation
1. Low frequencies
1.1. How close does each control point follow the target curve? (Magnitude response)
1.2. Has the spread between control points been reduced/made worse? (Magnitude response)
1.3. Has ringing been reduced/made worse? (Waterfalls)
2. Higher frequencies
2.1. Has the direct sound been improved/made worse? (Magnitude response)
2.2. Has the phase relationship between stereo pairs (L/R, Lss/Rss, Lsr/Rsr, etc.) been improved/made worse? (Phase response)
First let's see if there's common ground on which we can move forward.
In-room measurements vs. perception vs. equalization
At low frequencies the (acoustically small) room dominates what we hear so the premise is that a steady state measurement lumping together direct and reflected sound highly correlates with what is heard up to the sub/sat crossover region.
Equalization here can improve the frequency response. It can also improve ringing. If used incorrectly it can make ringing worse though.
At higher frequencies reflections have a significant impact on what is measured but not on what is heard (we hear added spaciousness, not coloration). Thus any attempt at equalizing the steady state response would alter the direct signal (and reflections) spectrally and likely would make it sound worse.
Equalization could still be beneficial if reflections could be "removed" from measurements taken at the listening position. The result would be the anechoic response of the speaker hence room correction would become speaker correction. Depending on the quality of the speaker this could improve the response quite a bit.
Reflections can be "removed" from measurements to a certain degree by gating techniques. The problem is that there are very early reflections from objects close to the speaker and the microphone that have a significant impact on the measured results despite gating.
Measuring RCS performance
Based on what has been said above there's performance criteria in two areas:
1. Low frequency performance ("room correction")
1.1. Magnitude response - how good does the equalized result follow the target curve?
1.2. Ringing - has ringing been reduced?
2. High frequency performance ("speaker correction")
2.1. Magnitude response - is the anechoic direct sound from the speaker closer to flat/target curve?
Testing
General
1. Room correction needs to improve ALL points within the listening area so multiple measurements need to be taken before and after a specific room correction system is run. These control points should NOT be the same as the mic positions used by the room correction system. This allows us to assess whever the room correction system improved the whole listening area or just the small number of single points used by the room correction system while other points have been made worse.
2. Mics positioned at control points can't be moved between testing otherwise no comparative assessment between room correction systems can be made. Even small mic location variations will create significantly different results.
3. Anechoic measurements of the speaker need to be performed with and without room correction enabled (for evaluation of higher frequencies).
Evaluation
1. Low frequencies
1.1. How close does each control point follow the target curve? (Magnitude response)
1.2. Has the spread between control points been reduced/made worse? (Magnitude response)
1.3. Has ringing been reduced/made worse? (Waterfalls)
2. Higher frequencies
2.1. Has the direct sound been improved/made worse? (Magnitude response)
2.2. Has the phase relationship between stereo pairs (L/R, Lss/Rss, Lsr/Rsr, etc.) been improved/made worse? (Phase response)
Last edited: