- We help recording engineers transform their monitoring to the industry's highest standards by implementing our PhantomFocus™ technology -

Hi everyone,
Thank you again for joining us for this second episode of the MixRoom Mentor™ series. In Episode Two - New Monitors vs. PhantomFocus™, we'll discuss the destructive console bounce and the high importance of the frequency-response shape.
Carl.

Episode 2 - PhantomFocus™ vs. New Monitors
In the previous episode I described the Allison Effect floor/ceiling bounce, which creates a "Grand Canyon" of missing low-frequency information and is the single reason that everyone has such a difficult time hearing the low end accurately.
In episode two we will discuss the real purpose of subwoofers, the destructive console bounce and the all-important frequency response shape that, along with the Allison Effect floor bounce, contributes to the false notion that new monitors alone will solve your monitoring problems.
Below we'll continue with our case study of a pair of high-end monitors in a well-designed room.

Since corrective EQ would blow your monitor's drivers, the only practical way to begin to fill in the "Grand Canyon" dip is by installing subwoofers (ideally two, front-corner-loaded to ameliorate the 1st and 3rd width axial mode nulls at the listening position - much to discuss here, beyond the scope of this blog). The general conception of the use of subwoofers is that they extend the low end which of course they can; however, the more valuable advantage is that they can actually correct the Allison effect. The trick is to set the low-pass filter on the subs high enough to catch the dip of the monitors, typically around 125Hz. You'll need to experiment with the subwoofer's phase control to find the best marriage between the subs and the monitors. Full disclosure: you will likely not match the PFS frequency response curve seen at the bottom of this episode, which utilizes analyzing software, high- and low- pass filters with slope and phase control, and EQ. You can, however, by applying the tools coming up in the next episode and implementing subwoofers, substancially improve your monitoring experience. Of note, a common practice is to listen to monitors with and without the subs. Once subwoofers are properly integrated into the monitoring system, and knowing what you have learned so far, it's clear that the subs are part of the system, not to be turned on or off.
Next let's look at the dips we see in the graph at approximately 750Hz and 400Hz and the hump between 130Hz and 300Hz. The dips are caused by the console bounce cancelation that occurs when the reflections that bounce off the console arrive at a later time than the direct signal straight to your ears from the monitors - comb-filtering. The humps are the room's effect on the monitors. The obvious effect of these anomalies will be that you will want to boost the dips and cut the humps and in both cases your mixes will fail until you again "learn" your speakers. Unfortunately, shiny new monitors will not be able to do a thing about these room-generated artifacts. Of note, the frequency response from about 1kHz up is unusually smooth in this well-designed room and more often than not the case.

The next element to talk about in this graph that seems to be universally overlooked is the extremely important shape of the frequency response. It's apparent here that the shape is pretty messed up but what should it be? Everyone talks about and it is widely assumed that 'flat" is the goal where all the frequencies are at the same amplitude. It makes sense doesn't it - start out with a blank canvas and paint your sonic masterpiece without any coloration to fool you from control room to car. However, once behind the wheel again, you will experience more low- mid and low frequencies than you heard from your monitors in the control room.
Why? Because as far as the human ear is concerned, flat is not flat as Harvey Fletcher along with Wilden Munson discovered way back in 1933 (physics don't change much). They came up with the Fletcher Munson - Equal Loudness Curves that, briefly stated and very simplified, says that frequencies below 500Hz need to be louder on a frequency descending scale in order to be heard at the same amplitude as the higher frequencies. And this important need for frequency response "shape" dispels another widely accepted myth, that monitors can be tuned with acoustic treatment alone aka bass traps, diffusers, etc. The priority PhantomFocus curve addresses this handily.

- Next installment -
Episode Three - PhantomFocus™ Tools
We'll share two simple but extremely effective procedures that you can perform that will render a big improvement in your monitoring.
Note: Episodes 1& 2 now viewable at carltatzdesign.com/mixroom-mentor
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