Some of the Chronotron features are rooted in my own usage, others are the result of customer feedback and a few of them are just there for historical reasons. Then, there are those features that every media player must have, which we just take for granted and rarely think about how they actually work.
Examples of the latter are the Balance control and the Graphic Equalizer. Most people are already familiar with balance and equalization so maybe that’s why I seldom, if ever, get any questions about these features. However, while implementing them I did have questions for which I had to figure out the answers. In this post I’m sharing a couple of such questions – and their answers – with you.
The Chronotron Equalizer
What Pan Law to Use for the Balance Control?
In a nutshell, the pan law governs how much you attenuate or amplify the audio signal to compensate for the gradual loss of the left or right channel as you move the balance control in the opposite direction. A lot has been written about pan laws elsewhere so I’m not going to enter into the details.
Chronotron uses a 3dB pan law, which means that it boosts the remaining channel progressively, by up to 3dB, as the fading channel becomes less audible. This keeps the perceived volume reasonably constant during playback and is the same pan law used by many audio equipment.
If you google for articles on pan laws, you may be wondering why I didn’t choose to apply a higher boost, like 4.5dB or 6dB. After all, Chronotron is a media player and not really a mixing app, right?
Well, there are karaoke videos, music lessons and play-along CDs that take advantage of stereo channel separation to let you adjust the level of the backing track vs. the lead instrument just by using the balance control. In Chronotron, balance is applied before the Solo Channel setting, so if you come across this kind of audio material, you can set Solo Channel to MONO to enjoy sound from both speakers while still controlling the mix with the balance control. Handy, isn’t it? In this situation Chronotron behaves like a mixer and the 3dB pan law is still a reasonable tradeoff.
The above example illustrates the well-known fact that the order in which audio controls and effects are applied can sometimes make a big difference, which led me to the following question…
Should the Graphic Equalizer Come Before or After Tempo and Key Manipulation?
I made a case for putting the balance control before any further processing, but what about the equalizer? If we put the equalizer before tempo change and note detection, we cold leverage its effect to prevent some time-stretching artifacts or to improve the accuracy of the detected notes. If we put it after, we could use it to fine-tune the final result for a particular listening environment, for example.
I thought it would be a good idea giving users the choice and that’s what the Pre/Post switch does.
The default position of the switch is Post, which means that equalization occurs – just like in many other media players – at the end of the sound processing chain. In this position the equalizer does its expected job without causing any side effects.
In the Pre position, though, things get more interesting because you can now use the equalizer to make the note detector emphasize a certain frequency range. Also, when using the equalizer as a notch filter, you will notice that its effect will be preserved even after changing pitch.
The choice is yours.
Have Questions? Feel Free to Ask
Ask questions via the Chronotron web site or by posting your comments here. Unfrequently asked ones are welcome!