The LEDR tests come in three distinct patterns: Up, Over and Lateral.
The Up test starts low and behind the left speaker and the pulses should climb evenly and vertically to well above tweeter height. The pattern is repeated on the right. The Up test gives a clear indication of sound-stage height and side and upper-wall/ceiling reflections. Don’t be surprised if, to start with, the pulse seems anchored to the floor behind your speakers, before it starts to rise (more or less) vertically, before bending inwards above the tweeter. Welcome to the real-world of speaker/room interaction and acoustic effects.
The Over test runs the pulse in an arc from the left speaker, up, over and then down to the right – and back again. The arc should be symmetrical and have decent height. The lower it is the stronger the ceiling reflection. Likewise, if it leans one way or the other it suggests non-symmetrical reflections on the side walls. If the pulse moves unevenly, either hanging up at the peak of the arc, or suddenly skipping across it, then you’ll need to be looking at toe-in – which brings us to…
The Lateral LEDR tests. If Up and over are mainly concerned with acoustic symmetry or positional aberrations, the Lateral tests are all about speaker toe-in and lateral spacing. There are four lateral tests: the first moves from the left speaker to the right, the second from outside the right speaker to outside the left, before both patterns are reversed and repeated. Look for an uneven passage across the centre of the stage and adjust toe-in accordingly. If that fails to correct the flaw and achieve a clear, even progression, or if the sound doesn’t extend outside the speakers when it should, you’ll need to adjust the lateral spacing of the speakers.
No other source material gives this unambiguous feedback on both room reflections and toe-in. Once used, the LEDR tests become an invaluable part of the set-up process. Nor does it matter where you source them. The LEDR tests are the LEDR tests, so any of the discs listed above (and any others I’ve forgotten or never knew about) will satisfy your requirement. Having said that, just as it offers the all-important LEDR tests, the Nordost set also offers some other unique and uniquely useful tools, especially when it comes to low-frequency set-up, making its purchase about way more than just the LEDR tests. I particularly like the Timed Low-Frequency Sweep, but that’s a whole different story…
Track 3 – The First Movement, Beethoven Piano Concerto No. 1
Arturo Benedetti Michelangeli, Carlo maria Giulini, Wiener Symphoniker,
Deutsche Grammophon DGG 2531 302 LP, Speakers Corner 2531 302 (180g LP), DGG 419 248-2 (CD), DGG 480 5888 UCGG-9044 (UHM SACD)
Having said that these three discs are all about what you hear rather than whether you like it, what’s the ABM/Giulini Beethoven First Piano Concerto recording doing here? This legendary live-concert recording is sonically excellent and musically speaking, quite possibly without peer. So yes, this is a wonderful and wonderfully enjoyable disc. But therein lies its efficacy as a set-up tool. If you want the sense of real musicians in a real space: if you want to ‘hear’ the conductor controlling the orchestral accompaniment: if you want to hear a soloist commanding the respect of both audience and orchestra, this disc can do all of that for you. But the operative is ‘can’! This is no gimme disc that just sounds great on any system you put it on. Granted, it never, ever sounds bad, but the difference between ‘good’ and ‘jaw-droppingly, compellingly captivating’ is big and just how far a system reaches across that chasm tells you a whole lot about just how close to dialled-in it really is.
