Tempting Fate?

In terms of attitude, the speakers were fairly close to vertical, suggesting that this was the goal during initial installation. Look at the values for rake angle and azimuth and they are roughly within 0.1/0.05 degrees of vertical – actually within the tolerance of many digital or bubble levels. But as always, bringing more accurate tools to the job can generate more precise results.

Readout from the digital level, transmitted by BluTooth to the phone. This allows the level itself to sit on top of the speaker while you can read the results of adjusting the spikes/cones on your hands and knees.

But the most eye-catching variation in the figures is the distance of each speaker to the virtual centre line and adjacent sidewall, with slightly over six inches of difference. The first order of business was to rectify this imbalance as far as possible, something impeded by the presence of a radiator on the wall outside the left hand speaker. One option would have been to bring the right-hand speaker in towards the centre line, but with the set up already narrow, this wasn’t really an option. A general (but by no means binding) rule of thumb is that the distance between the acoustic centre of the two speakers should be around 85% of the listening distance. As originally installed, the spacing ratio was 63.3%, so reducing that by moving the speakers closer together didn’t look like the sensible choice, even if it meant moving the left-hand speaker (even) closer to a solid boundary when the right-hand speaker was bordered by the void created by the stair well down to the dining room. In practice, it was possible to move the speaker almost the full six inches without the rear corner of the cabinet contacting the radiator. A clear SMT panel previously positioned at the first reflection point was left in place and was clearly helping the left/right balance. At the same time, the right-hand speaker was moved backwards to bring it into line with the left (relative to the virtual baseline).

With both speakers repositioned and precisely levelled, one other thing remained to be done: the bass trim jumper on the rear of the speaker had been set to reduce the low-frequency output – presumably an attempt to control the bottom end in a smallish room and under challenging circumstances. This was restored to the flat position, thus “zeroing out” the speaker both geometrically and electrically.

It’s all in the preparation… Before burying himself in finer and finer adjustments, Stirling prepares the way. Here, not just the adjustable cones but the bosses in which they engage are removed and re-mounted with a layer of CopaSlip to aid both adjustment and energy transfer. The long strip of tape holds positional notes and records shifts.

t was time for a quick assessment and it was instantly apparent that the revised location and increased symmetry between the two speakers had produced a significant improvement in overall coherence, clarity and dynamics. The music was starting to hang together and breathe. But this is where the exacting part of the process really begins…