Break-in adjustments?

hrpschrd said:

I am measuring the bass response of new speakers every month to determine how long it takes for break-in. When I compare graphs (below) it will certainly matter what the offset is between graphs. I am trying to see an increase below 40Hz but each graph is different because of changes to the room over time.

One can use the controls to add offsets to make the graphs overlap better. How do you do select a frequency to overlap which is fair to the rest of the spectrum?

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Great Fun!

Control of the numerous variables that impact room response is difficult and will limit the ability to identify a small change, but it will be interesting to see if any change in response does seem to appear.

To your question, I suggest you select a relative flat (low slope) range that is also comparably smooth and relatively free of room modes. For me, that would be the range from about 90-110 Hz. You could temporarily smooth the curve to 1/3 or 1/6 to accurately adjust the average levels in that range.

Let us know what you discover!

Thanks, John, I will use a smoothing curve and adjust.

By the way, perhaps you have seen the comment by Eric Pflughaupt that smoothing better represents "what you hear, anyway." This seems to contradict what I have been told about using the finest resolution in your room measurements so that you see narrow bands of peaks and troughs. In these narrow bands one can "lose" a clarinet fundamental for example. Are these two statements compatible?

Bob

hrpschrd said:

Thanks, John, I will use a smoothing curve and adjust.

By the way, perhaps you have seen the comment by Eric Pflughaupt that smoothing better represents "what you hear, anyway." This seems to contradict what I have been told about using the finest resolution in your room measurements so that you see narrow bands of peaks and troughs. In these narrow bands one can "lose" a clarinet fundamental for example. Are these two statements compatible?

Bob

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I am not entirely sure, but...

My understanding is that the appropriate amount of smoothing changes with frequency; Less smoothing for LF and more for HF. So 1/3 octave is probably appropriate for HF and maybe 1/24 for LF? I believe JohnM is going to eventually implement a complex smoothing feature within REW. I assume this will be available within the EQ window so it can be used with the auto filter function. I usually just review the predicted response at several different smoothing levels to assure it look reasonable. Keep in mind it’s better to leave a dip than create a significant rise in the response around it.

Very sharp dips are not as big an issue as one might guess. They are not perceived as poorly as they appear to the very small mic capsule. The wider ones are more an issue and those respond better to EQ.

jtalden said:

I am not entirely sure, but...


Very sharp dips are not as big an issue as one might guess. They are not perceived as poorly as they appear to the very small mic capsule. The wider ones are more an issue and those respond better to EQ.

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I understand why wide dips are a problem but it also seems that sharp dips should be significant also. The example I gave of a missing clarinet came from a real example. Before I added traps to remove first reflections, I had a song with a missing vocalist! After traps, the vocalist appears again. This seems to be the result of a narrow dip at the fundamental (or tonic) of her voice.

I'm not an acoustics expert but this seems to support the idea that narrow dips can be very important to "what you hear anyway". Any help with this is appreciated because I would prefer to smooth the curves and not worry about the narrow peaks and dips, right?

hrpschrd said:

I understand why wide dips are a problem but it also seems that sharp dips should be significant also. The example I gave of a missing clarinet came from a real example. Before I added traps to remove first reflections, I had a song with a missing vocalist! After traps, the vocalist appears again. This seems to be the result of a narrow dip at the fundamental (or tonic) of her voice.

I'm not an acoustics expert but this seems to support the idea that narrow dips can be very important to "what you hear anyway". Any help with this is appreciated because I would prefer to smooth the curves and not worry about the narrow peaks and dips, right?

Click to expand...

Yes, as I sure you know, the overall problem is complex and no simple statement is correct for all circumstances. I was only intending to point out that care must be taken in trying to address nulls with EQ because worse issues can easily arise.

In the larger sense, we need to keep in mind that EQ cannot address all types of problems and also that acoustic room treatments do not resolve all types of problems. They do different things but there is overlap between them also. Room size, positions of speakers and LP position and distance are also major factors. Did I mention the speakers themselves yet?

So the problem is complex and a challenge. I like to try to experiment and solve problems so it is a hobby for me. This situation is instead a significant frustration for the person that just want optimized sound with minimal effort. Everyone must choose where they fit on this spectrum (pun intended).

No good simple answers from me.