Rerurn to Romy the Cat's Site

In the Forum: Playback Listening
In the Thread: About speakers Imbedded Macro-Positioning.
Post Subject: 2) Set playback in-wide-phase to room or how to find AEZPosted by Romy the Cat on: 5/22/2007

Ok, how to start. First of all we have to understand that out subject of attention will be a region between approximately 80Hz and 500Hz or something that shape the fundamentals of the “melody range” within your playback. Search my site I have written about the prominence of the upperbass a lot ….

Most of the mid and small size rooms (very large room is a separate subject) have two types of the room modes: narrow modes and wide modes. Your primary task at this point is to find where those wide modes in your room will be. As you understand when I talk about the room modes I mean the modes in the Melody Range. The narrow modes are 1/4 octave wide and you should discard them. You need to search for picks that would be wider then ½ octaves. I have seen some rooms that have plus 5-6dB at 130Hz and 1.5 octaves wide. The smaller room the more room modes might be and the more “problem” the room most likely will have. Do not worry about it – search for the wildest bandwidth and for the highest amplitude of modes in your room and those “problem” will not be problems if you use them properly.

How to search it? It is deepens of many parameters. Your listening expertise and topology of your loudspeakers (the Melody Range channels) are not the last among all variables. Generally a simple RTA with 1/6 octave and higher will do. You do not need any good quality microphone as you do not care about absolute number but rather about the relative values.  Running pink noise with very fast averaging and resetting itself after, I would say, 15 seconds is a good tool. You need to connect one channel of your Melody Range and to let your friend to tango with the speaker (or with a Melody Range substitute this will be even better) across your room. Do not forget moving your microphone and well if it is necessary. You should sit at your desirable listing spot with microphone, looking at your RTA and to listen the sound. The combination of what you hear and what the RTA shows is be a good tool for you to get a sense of directions. Change at least a half of dozen listening positions until you feel that you found the SECOND UGLIEST LOCATION IN YOU ROOM.  What does it mend the “second ugliest”. The first the most ugliest location for your Melody Range will have a maximum amplitude of the narrow modes (Do not approach to the room’s walls closer then 3 feet). Keep looking you need to look for the WIDEST BANDWIDTH, EVEN AT SLIGHTLY LOVER AMPLITUDE.

If you are ability lucks of any sensibility and hearing then you might use you loudspeaker as a microphone. Fill your room with band-pass noise (Melody Range) and look with a meter or scope how much signal you your speaker pick up at their output. It is very erroneous way but it juts a handicapped way for the deaf beginners. Do not forget that in this case you will need to conduct a number of discrete measurements at different very narrow band-pass frequencies in order to determine how wide bandwidth of the room gain. Do not forget also that the position of room noise-filing speaker should be at the position where you will be listening from.

Anyhow, some people might propose to use some kind of modeling software but I personally have no positive experience with software and I considering then superfluous toys. Perhaps it is juts me. You might use whatever means are available in your disposal to found the “boomiest”, across wide bandwidth, spot in your room.

Two important comments. This relatively-wide bandwidth “agilest” spot in your room will not be a spot but rather a quite large space. It is very difficult to make a generalization about it but generally this quite “large bloomy space” will be a space equal to, I would say, 1/8-1/12 of the room dimensions. I call this large bloomy space as ACOUSTICAL EROGENOUS ZONE (AEZ) of your listening room. Now you need to found the AEZ’s dimensions. Mark the found location of your AEZ and move your speakers a few feet in all direction measuring loosing the room gain within the Melody Range. Eventually you will discover an approximate relatively large region in your room that might be considered as AEZ. Now, you need to find the AEZ’s polarity. The AEZ’s polarity is the AEZ’s side where the room gain in the Melody Range would be at maximum. The AEZ might be right-polarized or left-polarized.

So, what to do next? Now you need…. to place both of your loudspeakers in the AEZ, trying to position the right channel in the most polarized region of your AEZ. Regardless speaker’s topology is used your loudspeaker’s Melody Range they, the loudspeakers, must be INSIDE of the AEZ. It is not only because you have extra feed db gain in there – this it beneficial but very secondary. The key is that now your artificial room transducer (speaker) is in-phase with nativity of your listening room and then do not work against each other.

If your Melody Range channel (or live instrument as well) are in AEZ then they are capable of wonderful thing by “TURNING THE ENTIRE ROOM ON” – you can’t not accomplish it with better speakers or better amplifiers. Let dive slightly in the dangers territory. Driving your room by loudspeakers from outside AEZ location is like pleasing different parts of female body – it gives positive and effective atomic (individual, isolated) effects to her gratification. However, but performing necessary actions on women G-spot is capable to create for some women not atomic but a FULL-BODY REACTION. The Melody Range lodging a room from AEZ is very much hits the G-spot of your listening room and allows you get a VERY different and very evolved result of the room loading that is unimaginable if you drive your room from outside of AEZ. I can assure you that if you are not a Moron™ and each time you heard any more or less interesting sound from any playbacks then the loudspeakers, in one way or other and in most of cases completely accidentally, were near the AEZ.

The very next actions will be removing all filters, impedance normalizes, resonators from your upperbass driver (and perhaps your lower midrange driver) and let your upperbass installed in the enclosure-topology of your choose to play full range. In the next my post I will continue describing the next steps…

Romy the Cat

Rerurn to Romy the Cat's Site