The good news for TacT owners is that target FR curves are selectable and highly adjustable. Armed with a laptop, we can insert/move/delete filters to our hearts content in search of “the perfect curve”. Adjustment may be made in increments as small as 0.8Hz and 0.1dB. Furthermore, multiple curves are supported and selectable with the push of a remote button, so we can design and use multiple curves as individual mastering and/or the mood suits. Not enough bass on a particular recording? Pick a curve with more bass emphasis. Want more bloom in the midrange? Pick a curve with a touch of midrange push.
Unfortunately, finding the ideal curve isn’t necessarily easy. Sure, the TacT comes with a variety of target curves to try and, if one of them is the perfect fit, you’re done. In my case, and probably in many/most others, that won’t be true and one is left to tweak a supplied curve or to develop one from scratch until nirvana is achieved. Depending upon your temperament, you may find this (generally extended) exercise to be fun – or frustrating, so I thought I’d start this thread with what I believe to be basic principles, a couple of enjoyable curves, and an invitation for fellow users to share their own curves and experiences.
Last year, Harman International conducted a series of preference tests for Room Correction (RC) products. The results were published in an AES paper, but the basics may be found on Sean Olive’s blog here. Of importance to this discussion is that Harman found that “the most preferred room corrections produced the smoothest, most extended amplitude responses measured at the primary listening seat” and that “preferred room corrections have a target response that has a smooth downward slope with increasing frequency”. The former probably requires no explanation while the latter is attributed to the belief that listeners prefer a certain amount of room gain because the recordings were mixed with similar room gain. The most preferred response is the topmost of six shown here on slide 24 of the associated Powerpoint briefing. Note the smooth downward slope and that FR falls roughly 10dB from 20-20KHz.
In a recent thread describing his own experiences with DSP/RC, Marty posted that his target curve approximates a curve resulting from Bruel and Kjaer’s research into room response preferences, presented in a 1974 AES paper*. B&K’s curve looks like this:
And shows a slight 2.5-3dB “hump” (relatively flat) from 20-200Hz, falling off evenly from 200Hz-20KHz and ending at ~-3dB. I wanted to try Marty’s curve and created a TacT target curve approximation, which looks like this
And for which the *.cor file may be found attached as BandK 0dB for WBF 6-9-10.COR.
In my system/room and for my absolutely subjective tastes, I find both the Harman and B&K curves to be a bit rich in upper bass, masking vocals and important spatial detail. Basically, I use a straight slope from 20-20KHz, though much shallower than Harman’s.
The associated TacT *.cor file may be found attached as kensexample for WBF.COR
As with any TacT curve, measured response will vary from the curve actually input and desired, so a bit of filter tweaking must be done in order to achieve the curves shown. Finally, and as mentioned at the outset, I have the various TacT presets set up with variations of "my" desired curve, adding more/less bass, mids or highs so that I can select a curve which sounds satisfying for a particular genre or to “fix” perceived mastering issues. All entirely subjective, of course!
* That paper cannot be directly linked, but may be found here in B&K's library by searching on "Relevant Loudspeaker Tests".