(following is an excerpt from “Optimizing ASC TubeTraps” by J. Peter Moncrieff)
Fine Tuning
Fine tuning of TubeTraps must be done by ear, not by formula. It requires a highly trained, sensitive ear, of someone who knows what to listen for, how to interpret it, and what corrective adjustments to make. Unfortunately, that is something we cannot teach you in a written article. Some professional consultants in the field have a lot of experience with TubeTrap, and you might wish to hire them for final fine tuning. If you can’t afford that, here are some general hints to guide you.
Think of this fine tuning procedure not as serious business, but rather as an exploratory experimental game. Make only one type of change at a time, and learn what each change in itself sounds like. Learn what the sonic difference is when you rotate one TubeTrap (symmetrically on both sides of the room) by 45 degree, then 10 degrees, then I degree if you can learn to hear it. Try moving the location of columns 2 inches one way along a wall, then half an inch another way.
The fine tuning of TubeTrap in the back (listener) half of the room affects mostly the sound of hall ambience from the recording, while the front (speaker) half affects mostly the imaging characteristics of the stage where the musician are performing.
In general, you’ll find that rotating TubeTraps so that the seam points more into the wall (giving more reflection and diffusion into the room) increase ambience and generally improves imaging. But if you do this too much, you might pick up hot spots of midrange glare, some loss of musical coherence, and some unevenness in what should be a continuous curtain of sound across the stage width and depth – so listen carefully for any degradation in these qualities.
Conversely, fine tuning only for the smoothest sound of the room can easily go too far and make the room too dead, thereby degrading ambience richness that come from random incoherent long path reflection – so listen carefully for any degradation in this aspect.
The ideal balance is a room that is neither too live nor too dead. But it would be a bad oversimplifying mistake to think that all you are trying to balance is liveness vs. deadness. You are really trying to make the room dead for short path coherent reflected packets and live for random incoherent long path reverberation, at all frequencies. And even that is only the beginning. The other factor pertain to the manifold intricacies of optimum stereo imaging, as follows.
As you play with the TubeTraps along the back wall, listen for the changes in the sound of hall ambience (from a recording that is rich in this), especially the ambience that seems to come from the back of the hall. This is indicated in figure 6 as rear ambience fine tuning. Play especially with those TubeTraps along the rear wall that are not directly in back of the listener. We suggest that you try pointing the top TubeTrap seam of each column toward the back wall, while leaving the seam of the bottom one pointing toward the listener (for the short path vs. long path reasons discussed above).
The TubeTrap along the rear half of the side wall also affect the perceived hall ambience, especially how large the hall sounds from side to side; this is labelled a side ambience in figure 6.
The TubeTraps along the front half of the side wall affect the perceived width of the stage, and also how seamlessly continuous the solid curtain of music sounds across the entire stage width. With speakers that image well, it should be easy to have the perceived stage extend beyond the speaker width, and even beyond your room side walls (because the absorption of these TubeTraps can help these side walls to effectively disappear for early reflections).
Listen carefully to all factor when doing this fine tuning. Too little absorption along the front half of the side walls will create discrete secondary sources at the side wall, which might seem to enlarge stage width, but won’t do so in a seamless fashion, for there will be hot spots, with too much musical energy seeming to be located in ide the speakers and right at the side walls; you want a continuous, seamless curtain of music across the stage, with instruments located at all points in a good orchestral recording.
The seamless stage curtain i also affected by fine tuning the TubeTraps along the center part of the front wall. The affect mostly the center fill of the stage, as shown in figure 6. Rotating these TubeTrap with their seam toward the front wall so they are more reflective into the room, will solidify the musicians located center stage (including center stage rear), instead of leaving them sounding somewhat ghost-like. It will also allow you to move the speakers farther apart, to obtain better stage width without creating a hole in the middle. Beware though of making the TubeTraps at the rear of the speakers too reflective, for that will cause midrange honk or glare, with loss of stage depth.
The TubeTraps in the front comers can be rotated to affect the perceived depth of the far corners of the stage. Again, be careful not to allow so much reflection that you pick up midrange honk or glare from the room corners.
Throughout this exercise, the goal is to hear less of your listening room walls, while hearing more of the recording stage, hall walls and hall pace.
Finally, the pair of column in between the speaker can be fine tuned to affect the 3D projection of front center stage soloists. This pair of columns is very sensitive to the light test change in rotational alignment and in location, relative to the speakers and relative to each other. When optimized just right, you can achieve a spooky magical quality in which center soloists are not only tactilely solid, but also are holographically projected a 3D entities in this pace between the speakers. You can also try extending this line of columns toward the listener, with three or more columns.
Well, there you have it. I’ve helped you get the best sound out of your room as much as I can – short of personally setting up and fine tuning your listening room with TubeTraps. Happy listening! |
