Increasing Accuracy
In part one of this speaker setup series I covered basic system symmetry. In essence making sure the left and right sides of your room, setup and furnishings are roughly the same. But many enthusiasts want to go further than this, and there are two elements to work on:
Fine tuning the energy envelope.
Accessing the stereo image.
When we first adjust a setup for basic symmetry (part one), we start to get the idea of tonal balance being partially dependent on positioning, furniture and so-on. But when we want to move to more accurate reproduction, we always find that changes in the overall frequency response, tonal balance and the decay of the energy envelope are clearly effected by even quite small changes in room layout, speaker positioning and seating position. So these aspects become more important for accurate reproduction.
And then regarding stereo image, notice I don't say creating it. It's vital to appreciate that the image is present on a two-channel recording as subtle cues, time shifts and phase information differences between the left and right channel, and that's what we want to reproduce. It's never about throwing sound out the sides of speakers to reverberate around the listening room. We use the word 'soundstage' more these days, to reflect that we're after reproducing the venue space with reverberation and decay, plus the width dept and height of the performance.
So where to start? Fundamentally you aim to create a triangle between your listening position and speakers. And in essence, the more precise this triangle is, the better. But should it be an equilateral triangle, a wide isosceles, or a narrow isosceles? Well, for me I've always found a slightly narrow Isosceles works best, with a ratio of about 2 to 3. So speakers 8 ft apart, distance to listening position about 12ft. I find that when the triangle is significantly wider, you suffer with the ability to get the best tonal response and create an integrated soundstage.
Okay, we need more detail on that. Of course it is room dependant to start with. You might have to go a bit wide if there is a chimney breast to get round for example. The thing is to work towards the best triangle you can achieve – as a starting point. I haven't mentioned the speaker's distance from the rear wall, or the seating position from the back wall yet either, and as we start tuning, movement back and forth may change the ratio of your triangle too.
Now it's experimenting time. You should probably plan a few days to make adjustments and listen, taking time to assess changes to frequency response, integration, timing and sound stage. Don't forget toe-in as well. So move your speakers wider a bit, then narrower a bit and assess. Go forwards and back to check how bass re-enforcement changes. Try moving your seating back and forth too. No room is perfect of course so you might find you end up with some slight trade-offs – say with the speakers well away from the rear wall imaging is a bit better but bass is too light so you might need to move back and compromise. I find it best to make notes, and have a checklist to go through each of the imaging, timing and frequency response parameters, perhaps scoring them. Sometimes I've seen folks using small pieces of insulation tape on the floor to mark the speaker positions they are moving between, as they make their adjustments.
So at the start of this blog I referred to tuning the energy envelope and accessing the stereo imagery on the recording, and this is what you are doing with all the adjustments of your triangle. It's usually a very enlightening experience if you've not done it before and I think it becomes part of the hobby. One important thing to remember is that your final position is the best one for the electronics and speakers you are currently using. Alway, and I mean always, re-check positioning when you change any component. You can't hope to make a proper assessment of a new more powerful amp say, when your speakers were adjusted for the old one.
Right. That will do for now. In my next speaker blog I will go into a few bits a little deeper with some fine tweaking tips that might surprise you!
