What is the tone quality of your audiophile system?
by, 01-22-2012 at 05:43 PM (4384 Views)
Using the chart below, what subjective terms would you use to describe the tone quality (a.k.a. tone color or tone balance or timbre http://en.wikipedia.org/wiki/Timbre) of your sound system at the listening position?
This chart, used by permission from Bob Katz, Mastering Engineer extraordinaire, http://www.digido.com/ shows the subjective terms we use to describe excess or deficiency of the various frequency ranges.
As an aside, there is an important underlying concept here that needs some explanation. That concept is that audio is both an art and a science and that there is correlation between the two. In the case above, the art is the subjective descriptors and the science is the frequency range that the subjective descriptors map to.
It is my belief and experience (more on that later) that shows there is a direct correlation between the art and the science of audio. Put another way, how does it sound using our ears can be mapped to what is being measured and vice versa. I would suggest that this is a balanced view of our hobby where art and science come together and it's not just one or the other extreme.
Looking at the chart also provides us with common terminology in describing our sound systems or the sound of a particular song. So when we say the song sounds "bright" we know that the frequency range for this is likely 3KHz to 10Khz and has been lifted 1 or more decibels relative to the other frequencies on the scale. This can be measured using a real time spectrum analyzer VST plugin http://en.wikipedia.org/wiki/Virtual_Studio_Technology on either the Mac or PC (if your music player software supports VST plugins) using Blue Cat's free FeqAnalyst for example: http://www.bluecataudio.com/Products...t_FreqAnalyst/
Listening to various songs and watching the spectrum analyzer at the same time, you will soon start correlating songs that sound bright with songs that sound warm for example.
Let's get back to tonal quality. How do I train my ears to understand the tonal quality of my sound system? Nothing like experimenting to help assist with what is going on. As mentioned above, if your playback software supports VST plugin's there are literally thousands of plugins available for both the Mac and PC platforms: http://www.kvraudio.com/allpluginsononepage.php Note that most modern recordings and masters have been processed through a Digital Audio Workstation (DAW) and uses the same VST plugin technology. This has been going on since the mid 90's http://en.wikipedia.org/wiki/Digital_audio_workstation and is very likely that most of the music you listen to has been processed through a DAW, with several VST digital plugins and analog processing chain.
With the advent of unprecedented computer processing power for cheap, software designers of music players http://www.jriver.com/audiophile.html can take advantage of 64bit processing that is way beyond our hardware output capability of 24 bits and therefore has 0 impact on sound quality. You should have no fear in using any of these VST plugins as they will not affect the sound quality of the audio signal passing through them.
Here is a free parametric equalizer that is available on the Mac and PC that you can download and install. http://sonimus.com/site/page/downloads/ The beauty is that you can play with the controls while at the same time listening to the sound and hearing the effect in real time. You can then correlate the sound you hear at the frequency range and the corresponding subjective terms as described in Bob's chart above.
With this eq, you can roll off the extreme frequency ranges and listen to the effect on your speakers or headphones. Note the center slider. What I like to do is turn up the boost and sweep the frequency range while listening to the tonal differences in real time. It is a real ear opening experience. Then you can start correlating the sound of your audio system not only with subjective terms but exactly at what frequencies. You can also correlate by flipping back and forth from the eq to the frequency analyst and correlate with what you are adjusting to what you are seeing to what you are hearing all at the same time.
Where is this leading to? Well, the frequency response of your sound system at the listening position not only describes tonal quality (or timbre) but also directly correlates to the sound stage presented at the listening position. This is an important concept to understand. For example if there is too much high frequency arriving at the listening position, not only is it a bit bright sounding or at the frequency extreme more "air", it correlates to the soundstage being "upfront" or too forward or lacking depth. Conversely, if the high frequency roll off (or slope or shelf) is too much, then not only does it sound "dull" but the soundstage is too far back or "distant".
Is there an optimum tonal balance or timbre or frequency response at the listening position that also has the right soundstage depth? Yes there is. Here is an excellent paper, complete with subjective descriptions and scientific measurements describing such a frequency response we should strive for at the listening position: http://www.bksv.com/doc/17-197.pdf
It has been my experience that this target frequency response curve measured at the listening position, not only provides the best tone quality from my sound system (not too bright or dark, but just right) but also the perfect soundstage (not too forward or too far back, but just right).
Sean Olive is another double blind test. (Thanks hulkss for the link!) Interestingly enough, the virtually same target curve as the B&K curve above is the preferred spectral response at the listening position. It is the top curve in this comparison:
And here is the measured frequency response of my system at the listening position:
Using the B&K target curve as reference, my system is easily within +-3db from 20Hz to 20KHz at the listening position. I have experimented with dozens of target curves, including flat, which is etch a sketch bright with the soundstage in our face. I always end up coming back to the B&K curve.
Note all three graphs are virtually identical. This is no coincidence. If you read Bob Katz's excellent book, Mastering Audio - The Art and The Science, you will note the frequency response of his monitors in his mastering studio also exhibit the same target curve. Finally, when I was working as a recording/mixing engineer at several studios, there was always at least one set of monitors "calibrated" to the B&K curve above in each control room.
Point is, if you want the best tone quality and soundstage from your audiophile system, calibrating your speaker to room interface to a reference target, like those described above, will give you the best possible result.
Most people that hear my rock and roll sound system http://www.computeraudiophile.com/bl...e-Sound-System are surprised at the soundstage. Casual listeners comment on how they can easily hear the different layers of sound (i.e. the mix) whereas they cannot hear that on their own sound system. That is the first comment I get before, wow, does it sound clean, or punchy or whatever other subjective terms are used.
I wrote a series of six articles detailing on how I went about achieving perfect timbre in my system starting with: http://www.computeraudiophile.com/bl...roduced-part-1 Given that the speaker to room interface has the biggest impact on tonal quality of your sound system, the best investment you can make to optimizing your existing system is to measure its frequency response at the listening position and compare it to the optimum frequency response as described in the B&K article.
How to do this? For software, REW is fantastic: http://www.hometheatershack.com/roomeq/ and well supported. All you need is a calibrated microphone. It must be calibrated. One such mic is http://www.parts-express.com/pe/show...number=390-801 and another is kit so you don't have to fuss with phantom power: http://www.content.ibf-acoustic.com/...products_id=35 I use the latter and have had excellent results.
What's my point in all of this? Using free tools (save the measurement mic) you can experiment with tone quality to see what frequencies you may have too or too little of and correlate that with what you are seeing in the way of spectrum analysis and frequency response graphs and compare to a known standard. That way you can achieve the best tonal quality of your existing sound investment. Given that the speaker to room interface effects timbre and soundstage the most, with little effort as described in this article, can produce huge returns on your existing sound investment.