Track 7 is a string bass playing a chromatic scale from its lowest note up to around 200 Hz. The goal is to have all notes be equally loud. It’s particularly useful if you have a subwoofer in your system.
There are actually four things to listen for: pitch, volume, fundamental, and pluck.
I thought this would be an easy test. My first try with B&W 802D3’s and JLAudio f113 v.2 showed that the lowest notes lacked the required fundamental (that is, the really deep sound), that two notes had the same pitch, that there was a significant peak in lower mid-bass, and there were a few deep notes where the pluck was not evident. This in a system that always produces smiles and “Wows” from experienced listeners.
Achieving a even scale with fundamentals was a matter of very slight changes in the position of the sub. By “very slight” I mean, at first, inches and finally nudges of less than 1/8". The result was immediately evident as much deeper, more even bass in every recording. It became clear that the mid-bass peak–which made the system have “good bass” was in fact overwhelming bass notes both lower and higher than the peak.
It took more time to figure out the source of the missing pluck. I first realized that it was occurring on the notes where the sub crossed over to the main speakers; and that moving the sub did not restore the missing pluck. I then figured out that the cause was a phase issue–that, in the crossover region, the speakers were slightly out-of-phase. A small adjustment of the phase control on the sub and a couple of Hz change in the crossover frequency achieved a prominent pluck on every note in the track. And an amazing improvement in overall sound–not just in the bass, but in depth, width, and enjoyment.
There are several recommended ways to match the phase of a sub and main speakers. I’ve tried them all with helpful but inconclusive results. Listening for a prominent pluck on every note on track 7 is by far the best and most certain way to achieve a correct phase relationship.
I love this post. It so describes the value and intricacies of fine tuning speaker placement.
See you on the floor!
I thought I had a really good TV once… then I ran some calibration patterns… then some test patterns. I don’t have a really good TV.
I’ve done sweeps on my system but nothing as extensive as The Stereo package that arrived today. It’s really amazing what we don’t know until given an opportunity to actually witness / hear it. For some, it may better to keep your head in the sand and not reveal just how bad things are. I’m ready to dive in though. I already paid for the electronics and cables. Always willing to put in a little more work to optimize and get every little bit out of it.
@jrango Nice write-up. I’ll come back to this when I get to that track for sure.