Never Boost a Null = Voodoo Science

I read over and over to never boost a null.


The first reason given is that you lose amp headroom. The other reason is that nulls do not respond to boosts.


After more extensive reading and my own limited experience I find that the first reason often falls apart after even preliminary analysis. In my case I cut a 12 Db peak and then boosted a 7 Db null. How did that result in a loss of headroom? Especially since the peak was at a lower frequency than the null and therefore takes more amp power to produce. If you have no peaks and then boost a null you will lose headroom. This reasons truthfulness will vary from room to room and will be true maybe half the time and therefore is not even reliable to go by as a "rule of thumb."


The second reason is only true in certain rooms and is the result of the sound waves just cancelling each other more violently (somebody elses description) as power is added and therefore not resulting in any more SPL even though a boost has been added. Once again this is only true in some rooms. Also, this may be true of one of a rooms nulls and not true of another null in the same room. Only attempting the boost and then measuring will tell you whether the null will respond to a boost. For instance, the null in my room responded perfectly well to a boost.


I guess the point of this topic is to say that I believe that "never boost a null" is basically just an old wives tale. It is based on only half the story and stifles people even attempting to make what are reasonable and perfectly acceptable improvements.


Another point. I wonder if any of those who are in the "never boost a null" also have a "house curve" set up in their system. Guess what, you have applied a boost to your entire bass range, including any nulls that you have. (If you follow the guides I have read on the internet you will have set up a very wide filter at a higher frequency that will result in a falloff of SPL from about 30 Hz down to the point of the center of the cut. You then turn up the gain on the sub to match the SPL levels at the point of the crossover. In effect you boosted the entire range of the subwoofer.) Also, if you cut all your peaks and then turn up the gain nob on the sub to rematch your subs level with your main speakers you just boosted a null. Know something else? If you don't own an EQ, have a null in your system response, decide you want some more bass so you turn up the sub-level in the receiver: You just boosted a null.


You may now post your graphs refuting my points that prove beyond a shadow of a doubt that you know how to use Excel.