is flat or smooth room response always correct?

[snickelfritz]

My question is this:
If a given configuration of subwoofer, speakers and room measures smooth and flat, is the measurement even close to being valid without considering the contributions of reverberation and decay?

Low frequency systems are often referred to "minimum phase systems".
ie: if the measured response is flat, the phase must also be correct.

Does this assertion also include the contribution of room effects?
ie: if the room measures flat, then the room effects are mitigated or serendipitous, so to speak.

 

[annunaki]

No room measures flat. If it did it would most likely be an anechoic chamber. The room will always affect response. Each room has its own effect on the sound.

The only way to get a system flat in a room is to consider how the room affects response (through measurement) and correct it from there, usually with eq's.

I believe the "minimum phase" you are referring to is is off axis response. Subwoofer are generally though of as omni-directional or non-localizable below 60hz-80hz.

 

[snickelfritz]

Audible phase anomalies in the upper midrange and high frequencies can exist even if the response is technically flat.
In the low frequency range, the FR and phase are linked to each other.
ie: flat FR = correct phase below a certain frequency.

What happens in actual rooms is that the interaction between the speakers, room and subwoofer can combine to form a response that is measurably smooth, despite the existence of reverberation, ringing, standing waves etc...
Does the continued existence of these room-based phenomena invalidate room response measurements?
For example, even if you flatten the room response via EQ, the room modes are still there, but instead creating large peaks and nulls in the measured response, they are simply "filling in" the peaks and valleys created by the EQ.

ie: Lets say you have a 10db modal peak at 60hz, which is basically the room "ringing" at that frequency. So you create a valley in the response via EQ to compensate for the peak, but the room is still ringing at that frequency, just at a level 10db lower.
Musical instruments that have a strong 60hz component or fundamental will *theoretically* sound "soggy" and lacking in definition, even though the frequency response is technically correct.

Bass response of speakers is often described as being fast, punchy, boomy etc... but this is probably just the room interacting with the speaker, since bass cannot be "fast" or "slow"; it is only the speed or frequency being called for, combined with "blurring effects" from room reflections.
(driver response is orders of magnitude faster than the long delays caused by standing waves in a typical room; the resulting composite should almost always be more dramatically affected by the latter, in terms of "speed")

So the question remains; is it productive in any way to pursue flat response without first reducing or eliminating reflections from the room?
Is the response actually flat, or are reflections and ringing simply lying to the SPL meter?

 

[annunaki]

I see what you are saying. Room treatments (bass traps reflection absorbtion/diffraction, ect.) should be done to achieve a flat in-room response along with an eq. You try to eliminate the problem as best as possible and use the eq to compensate. Once that is achieved you can then tailor the response to your liking as you know that adding xdb at y frequency will yield xyz result.

Reverberation can be handled with room treatments and modes can be helped with bass traps, but you can't fully correct a room less it be turned into an anechoic chamber.

This is also why room placement is so key in getting the best sound in a given room. You will have to compromise at some point. It is just trying to make those compromises as few as possible.

If one can get the room as flat as possible with treatments before adding an eq, it would be ideal.

It is definitely not pointless to shoot for flat in-room reponse though as it does have its benefits.