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Adjust+ Part II
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From Hi-Fi World - October 2008 issue

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Right Angle

drfeickert_test_level

 

Modern technology comes to the aid of the LP with Adjust+, a way of adjusting the vertical alignment of your cartridge for better sound. In the second and final part of his review, Noel Keywood delves deeper into its capabilities...

 

Last month I looked in detail at the primary functions of the Adjust+ software, namely that of setting cartridge verticality (or horizontal tracking angle), as well as vertical tracking angle. Getting them right significantly improves sound quality. If you missed this feature in the September issue, this is available in electronic form on our website, for £1.90. In Part II this month I am looking at other measurements Adjust+ can make. They don't facilitate adjustment, but can tell you how well your record deck is performing.


FREQUENCY RESPONSE

I was intrigued by this option within Adjust+. Measuring cartridge frequency response is difficult and the problems obscure. Few test discs have ever been accurate enough in themselves to give a meaningful result, so I doubted Adjust+ could manage better. One professional test disc, cut at half speed, is accepted as accurate worldwide: JVC TRS-1007. We have two samples, bought from Japan at high cost long ago, that we use for our cartridge tests. TRS-1007 is now out of production and unavailable.


jvctrs1007frtestd


JVC TRS-1007 test disc offers accurate frequency response measurement.


Amazingly, the Adjust+ disc gave similar results to TRS-1007, although that is not to say "the same". Look at the graphs of Ortofon's 2M Black with JVC and Adjust's discs. The Adjust disc shows raised bass, and treble that looks ragged, but reaches 20kHz within one dB or so. JVC TRS-1007 superficially looks a lot different - although to my eye it looks similar. The reason is that below 1kHz cartridge generators are flat, ignoring arm resonance which occurs very low at 12Hz or so. So the Adjust+ plot is wrong (explanation later) and you can safely draw a straight line in your mind from 40Hz up to 1kHz.


It is at high frequencies that test discs have traditionally been inaccurate, and here the Adjust+ disc gave a result similar, if not the same, as TRS-1007 - impressive. So you can measure the real frequency response of your cartridge to a useful degree of accuracy. But why would you want to? The reason is that many cartridge preamps, including the Trichord Diablo we used within this review, possess switchable capacitance that modifies the high frequency response of Moving Magnet cartridges (but not MCs). Adjust+ will show you how things change as you do this and whether the response gets better or worse. It will also show just how flat, or otherwise, your cartridge is.



2mblackiscfr


Frequency response of Ortofon 2M Black with Adjust+ disc.


As LP playing makes a comeback, the emergence of the Adjust+ test LP is good news, but there are problems. For good reason, test discs never use RIAA correction, but custom equalisation that demands a special preamplifier, which means you can't measure frequency response through an ordinary phono preamp at home. RIAA boosts treble during cutting, and cuts bass, and the treble boost increases both velocity and acceleration of the cutter.


2mblackjvctrs1007fr


Frequency response of Ortofon 2M Black with JVC TRS-1007 disc.



To keep both of these high frequency parameters within acceptable limits for the cutter and playback stylus, signal level on the Adjust+ LP has been kept down, resulting in a poor signal-to-noise ratio at low frequencies. As a result of this, warps start to contribute to the test results, explaining the low frequency lift in the response graph. It may be possible for Adjust+ to lessen this with narrower FFT bins, but there is a trade off against measurement times.


At the other end of the scale, our Goldring 1012GX got decidedly shaky at high frequencies tracking the Adjust+ disc, mistracking above about 4kHz, although it stayed in the groove. So it appears that high velocities are reached all the same and some cartridges will object, likely giving ragged treble under measurement. The Ortofon 2M Black also looks uncertain at high frequencies, our response shows, compared to its behaviour on the JVC disc, likely for this reason. Ultimately, then, the Adjust+ disc gives a good result providing you ignore the low frequency part of the graph.




 

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