Audio system adjustment with the help of natural sounds

Today I would like to talk about a method for adjusting an audio system with the help of recorded natural sounds. Why natural sound recordings? There are several reasons but the aim is to lighten the process of referring to real life acoustical events. First point is that such records are carried out in an open space – somewhere in the woods or in the fields – which means that they are stripped of any room resonances and reverberations. Though close miked studio recordings also strip most of the environmental acoustic artefacts, resonances and reverberations inherent to the musical instruments themselves might overlap with reverberation modes of the reproduction space, which become relatively hard to distinguish.

Records of pure human voice could be used as well but they are of very limited frequency range and there still might be some residual acoustic reverberation typical for performances in enclosed space. The second point is that as a human beings we have been exposed to the sounds of natural surroundings like forest with singing birds and myriad of buzzing insects, mountain landscapes with running creek, sea or lake shores, falling rain, thunderstorm, etc. as part of our earliest experiences, and we have innate recognition for them developed in the course of human evolution. Another good point for using recordings of natural sounds while adjusting the system is that by prolonged listening sessions the sounds of nature tends to relax us as opposed to sounds originating from musical performances which by continuous repetition might become boring or even annoying.

Right now I am using a record of bubbling brook for creating an illusion that there is a brook inside the listening room. It takes some time and effort until a believable illusion is created. At the beginning it sounds more like a record being played, failing to create any believable illusion. There is a sort of electrical glare that hints towards the use of microphones and other electronic devices like cables and equalizers. Some people can even discern between certain types of microphones and configurations being used during the record, but this is not the case and we don’t want this right now for the system should convey the illusion of being there – on location where the record has been taken.

There are certain steps to be taken to achieve this goal, the first being to let your system reach its optimal conditions, which means to preheat the amplifier and any active electronic devices so that they can reach a constant temperature. A minimum of 30 minutes is usually necessary for the system to play some material in order to enter these optimal conditions. Especially when biased devices such as transistors and vacuum tubes are used the velocity of the bias current is time dependent and this is the reason why in some devices there are time delay circuits implemented in the main circuit. Nelson Pass for example recommends a minimum of 1 hour playback time for his amplifiers before a serious listening could start. I would say that this is a reasonable minimum. Leave your system to play some material for at least 30 minutes and shut the door, it is better to avoid to listen to this initial phase of preheating.

The record of a bubbling brook played in a loop right now is still boomy, I could hear it. Actually the lows are boomy and the impression is that the water is not falling on a solid ground but more like it is falling on a metal can or something. There is some kind of iron sheet tint in the sound, but as I already said it is too early to judge the reproduction so I am closing the door and leave it. And this is really important – to leave your system to preheat properly, subtle changes are inevitable during this phase. I am curious to check out how much of this metallic glare and boominess will depart after the preheating phase is completed. I know I shall leave it for some time before I continue to the second step and start adjusting the speakers for their optimal output.

After one hour has passed I am opening the door with a hope. Well, I am able to discern that the metallic glare has gone, but the boominess is still there. I mean it feels more like a brook running in the toilet, like the flush water falling in the toilet bowl, it is that kind of a brook I have at the moment, not a real brook in the forest running over a rock river bed. I know it is time for the second step that comes after the system has been preheated – the fine positioning of the speakers.

Waterfall Sounds of Nature - Falling Waters White Noise for Relaxation
A rather good selection of natural sounds used for dialing in the system

Usually when the system is not optimally adjusted the brook has, as it is now, some mediocre acoustic qualities. Currently there is a brook in the room but I am able to distinguish certain acoustical traits inherent to the room. As long as a clap with hands in the room does not sound like a clap with hands in an open space there is a room adding to the original sound. There is an echo that is displaced because of the room modes which underline certain frequency bands while partially absorb others. So when you have that kind of stuff applied to the original, the created illusion contains type of echo that hints towards a specific enclosed acoustical environment not present at the time of the recording. We are referring to such alteration as room coloration, meaning adding certain acoustical hints to the original. As long as one haven’t listened to the same system in different acoustical environment he can not properly discern the acoustical footprint of the reproduction space. The room footprint spoils the illusion of “being there” substituting it with sort of “they are here” (the musicians or the creek in this case) which is not convincing due to the scale incongruity and the rational reasoning that just rejects the idea of a brook running in a room. This is a clear sign that the system needs adjustments.

You don’t need to sit in the sweet spot for assessing the reproduction qualities during this phase, it is better to stay aside in an adjacent point to avoid additional imaging information. Imaging is not important at this stage so better don’t try to imagine a creek or any other object. Don’t try to rationally analyze the reproduction as well, you should forget about detail resolution, soundstage dimensions, lows and heights, switch off your brain and relax, the same way you are doing it while being in the nature. Instead of thinking try to observe your feelings and try to match them with the feelings the sound of a real brook somewhere in the woods excites, feelings associated with chilly morning, refreshing dew, wet soil, moss and moisture, force of the nature, relentless flow, cold and slick stones, calming breeze and so on. Such feelings could not arise from a flawed reproduction that is more likely to bring associations of being in a lavatory or something.

When you work on the speaker placement it is really important not to concentrate on imaging but to listen for the tonal purity. The best positioning is achieved when the room is not present and this is the main goal – to eliminate the room influence. One should adjust until the room is gone and there are no more walls and ceiling. This is something that Jim Smith stresses out in his book Get Better Sound but somehow it remains unclear how exactly to achieve this. The main prerequisite should be to use a record that relieves the adjustment process, so if you want to create an illusion that there is no room, a record made outside is the most suitable one. With indoor recordings it is really hard to separate the environment acoustic traits captured in the record from these of the reproduction space.

It is good to remember that certain speaker placement excites certain room modes, especially front to back placement is vital in this regard. When you adjust for tone purity and room elimination you might discover that bringing the speakers closer to the wall behind might gain positive results in this respect. At the beginning I advice to point the speakers straight forward and not to play with the toe. One should first find the best location and later on the toe and the tilt angle come into consideration. It is a step by step process in which complex tasks are broken down to simple consecutively performed chunks of operation. The distance between the speakers is usually proportional to the distance between the speakers and the wall behind, bringing them closer to the wall require increasing of the distance between them, in the opposite when closer to the listener (further from the wall) the distance between them should be decreased, keep this in mind and adjust accordingly when you play. If you have side wall nearby try to keep them as further as possible unless the speakers are meant to be used in the room corners like Audio Note or Klipschorn speakers. At some point the natural sound of the floating river will open up and you will feel immersed in the cold air as your body might shudder by the sensation of the fresh dew. This is a clear sign that the room is gone and you are amid the venue where the record has been taken. The lack of unnatural room resonances will free your brain of reproduction associations and you will have a very relaxed feeling of well being.

Now it is time for fine adjustments and toeing the speakers, it is better to take a seat in the sweet spot but again don’t try to analyze with your brain any soundstage or sonic attributes, just pay attention to the feelings you have, feeling of being nearby a running through the forest water. In non-symmetrical situations like mine a non-symmetrical toe-in adjustment make sense, which means that the toe-in of the speaker closer to the sidewall should be greater than the toe-in of the speaker that is further away, I have described such case here.  The interesting thing is that when the aim is to eliminate the room and achieve emotional realism a very natural and believable soundstage comes as a byproduct. In the context of my system and room situation the soundstage is compact but have density and gravity which are striking. It might be not as wide and detailed as it is when the speakers are further away from the wall, but the tone colors are more vivid and the emotional impact is of another level. This adds greatly to the long-term listening satisfaction and the sheer pleasure of listening to music.

I hope that for some of you the above described method for dialing in the system might render useful. Thank you for stopping by and always happy listening!

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