Loudspeaker Positioning

Published on: March 7, 2014 @ 7:10 pm

It’s been suggested that the single most common flaw in people’s systems is the position of their loudspeakers – so I thought it could be useful to explain how we do it. It seems to work rather well…..

If your listening room is a regular rectangle, then as a starting point you would be well advised to download the following Room Mode Calculator spreadsheet:

Room Mode Calculator
 
Once you’ve entered the length, width and height of your room, this spreadsheet will tell you what the modes are that occur in your listening room. It’s then a very simple matter to use these results to position your loudspeakers where they are least likely to excite the room’s standing waves. Similarly, you can use this information to choose the optimal listening position in your room, subject to the usual domestic constraints!

The information from the spreadsheet will not provide you with absolutely optimal loudspeaker positions but it will, a) enable you to avoid the worst loudspeaker positions in the room and b) give you an excellent starting point from which to begin the optimisation process.

In order to fully optimise your loudspeaker positions, I’d strongly recommend that you read the section of our website entitled “How to Evaluate a Hi-Fi System”, since unless the concept of the “tune dem” is fully understood, the following technique for loudspeaker positioning isn’t going to get off the ground!

OK. – Begin with both loudspeakers positioned with their backs as close to the chosen wall of your listening room as you can get without any part of the loudspeaker, stand or indeed speaker lead making contact with the wall. For this part of the exercise, you do need to use whichever stand your loudspeaker requires but for the time being, the spikes on the base of the stand can be dispensed with. On a polished wooden floor, a section of carpet placed beneath the loudspeaker stand can facilitate small incremental movements of the loudspeaker and stand without damaging the floor in the process.

Do by the way use a tape measure for checking the amount you’ve moved. Don’t whatever you do just guess or approximate. You’d just be wasting your time.

Certain common sense considerations should be applied when positioning loudspeakers, e.g. very few loudspeakers will function to optimum in the corner of a room. If your pair of speakers is one of the very rare exceptions that is designed to operate in a corner, then you’ll probably be aware of it. If, like most loudspeakers, yours are not designed to work in a corner, then placing them in a corner will result in grossly exaggerated lower registers that smother the rest of the sound.

If your loudspeakers are too far apart, then you’ll experience a distinct left and right effect with a “hole” in the middle whereas if they’re too close together, that will result in an unrealistically narrow soundstage. A loose rule of thumb for the listener/speaker relationship is that they should form an equilateral triangle, so having the loudspeakers two feet apart when your listening position is twenty feet from the loudspeakers will probably not get you an optimised result unless you live in a drainpipe. – In other words, don’t waste time eliminating irrelevant options; some positions are obviously not going to work.

The first parameter to establish is the optimal distance for each loudspeaker from the side walls. Initially, keep the speaker positions symmetrical and move both loudspeakers by the same increment each time you make an adjustment. Try moving them out towards the side walls and also try moving them closer together. Gradually.

N.B. When comparing two different speaker positions, play a few bars of your chosen piece of music and then repeat before you move the speakers to position 2. The human brain will always make more sense of a passage of music at the second hearing, particularly under these conditions, so it’s absolutely crucial to listen to position 1 twice, then move the speakers to position 2 and listen to the same short passage of music again to draw a comparison.

Using the tune dem technique, quite simply listen to the results from position 1 and then decide whether you can more or less easily discern the melodic thread/threads in the music when the speakers are moved to position 2. – Don’t fall into the trap of making subjective “tonal” judgements about the music; forget the imaging; ignore all the “detailed midband, tight controlled bass” guff and just focus on the melodies. You’re not going to get the optimum result at position 2. – More likely you’ll get it somewhere north of position 42 or beyond so relax and go with the flow. At this stage, you’re looking for better or worse, not perfect. It’s that simple. Keep it that way.

As regards music, use whatever floats your boat. Personally, for these purposes I prefer to use relatively simple acoustic music with clear melodies or a piece of classical music with loads of counterpoint. Try “The Arrival of The Queen of Sheba” or maybe the Adagio from Beethoven’s 5th piano concerto. That sort of thing makes the differences (better or worse) really obvious.

What you’re really doing with this technique is “zeroing in” on the optimal position. Start off with fairly large movements, say 200 – 400mm just to get your bearings. If you really “get into the zone” with this technique, you’ll finish up being able to discern differences of 10mm or less. Honest! If you make a change and struggle to immediately decide which is better, try making a bigger change in one direction till you get your bearings again.

Once you’ve established the optimum distance from the side walls to your own satisfaction, then establish the optimum distance from the wall behind the speakers by moving them away from the wall incrementally, as per the method for establishing the side to side position, until you’ve established the ideal distance. Quite simply, keep coming away from the wall in small increments until, using the tune dem technique, you can hear that it’s stopped getting better and started getting worse. Then revert to the previous position – hopefully the optimal distance from the wall – and stop.

At this stage I would recommend that you re-fit the loudspeaker stands’ spikes and level and stabilise the speakers, (absolutely, totally stable – it’s critical).

You will probably find that a degree of “toe in” may help too. The amount you’ll require is affected by (among many other things) the room’s proportions, the room’s reflective characteristics but primarily, by the extent to which the speakers are what I’d describe as phase coherent. – Whatever. Who cares why? Just apply the tune dem technique and make a decision. The best way to execute this part of the process is to rotate the loudspeaker using the front outside spike of the loudspeaker stand as the pivotal point.

It’s unlikely that you’ll need more than 10 – 20 mm of toe-in. You may need none. You may need more. Trust your ears.

Check the speakers are still absolutely stable. They may well need a small amount of adjustment after the last position change. Then take a break and listen to some music. – If it doesn’t sound considerably better (more realistic) than it did before you started, well at least you got some exercise!

The above is a first draft/work in progress btw. It will alter and hopefully improve. I haven’t gone into any detail about asymmetric, non rectangular rooms; the principle’s the same but you have to take things a bit further. In the meantime, any constructive comment might be gratefully received.

© Chris Brooks Audio Ltd – March 2014

  • phil says:

    Hi Chris, how’s tricks?
    Great write up which should be helpful to those who would be ready to listen.
    Just a small constructive comment that I have learned recently which may be of help.
    After carrying out speaker positioning as per above, I’ve been sometimes confused that when ‘spiking up’ the sound sometimes changes for the worse, one loses the tune. I’ve learnt that after getting the approximate position for the speakers, (within 5 or 6 inches or so), to sink the spikes into the carpet and carry out the rest of the fine tuning with spikes. Bit of a pain, but this has proved to be far more consistent.
    Try it; at least you can then tell me if I’m talking bollocks or not….. 🙂
    Best regards to you and yours,
    Phil

  • ChrisBrooksAudio says:

    Hi, Far from being “bollocks”, this is absolutely correct. I’ve yet to come up with anything approaching a rational explanation for this phenomenon since in principle, you’re positioning the loudspeakers relative to the room barriers/listening position in order to minimise the impact of the room’s modes and that being the case, with/without spikes shouldn’t logically affect the result; spiking the speaker stands should logically just complete the job. However, it doesn’t always work out that way. Quite what state your polished parquet floor (and marriage!) will be in if you go the whole hog is a matter for your own conscience but if you want to get it 100% right 100% of the time, do the final zeroing in with the spikes in situ.

  • Alistair McNeill says:

    I have a bass boom problem in my main lounge caused in part (I think) by a springy, suspended wooden floor above a 1.6 metre deep cellar. Trying to tackle this first before moving onto room modes and other issues.

    Used your Room Mode Calculator to see what results it returned but this is complicated by the fact that my room is not rectangular but has a bay window at one end. How do you adjust the results to take account of this?

    The rectangular part is 4.85 x 4.05 while the bay window extends the length to 5.8 i.e. an extra 0.9 section to factor in. Room height is 3.05.

    The speakers fire across the room width to the listening position – is there any benefit moving the speakers to the bay window end and have them firing along the room length.

    Any feedback would be most appreciated.

    • ChrisBrooksAudio says:

      As regards the standing wave calculation, there’s no ideal solution in this situation but the rule of thumb is, if the area of the bay is larger than the areas to its right and left (if they were there as part of the room!), then measure into the bay. If the area of the bay is smaller, them measure up to the edge of the bay.

      Personally, I would always fire down the length of the room where possible. You may well find that positioning your speakers immediately to the left and right of the bay opening, having calculated your distance off the wall using the spreadsheet, will yield the best results.

      That said, while you may markedly reduce the bass boom by exciting the modes less with correct positioning, there are obviously a myriad of other contibutary factors. Positioning “by ear” using the tune dem. method is ultimately by far the most accurate method.- Good luck!

Blog Archives