The Common Sense of High Resolution Audio
Here in Chicago, it is well known that we like our women dirty and our music even dirtier. So is it really worth it to record and produce music in Chicago or anywhere else at a high resolution when it is meant to sound raw and lo-fi, like hip hop and rap. While many audio engineers and producers would say there is just simply no need to, more and more of them are beginning to realize the benefits of higher resolution recording such as 96kHz and 192kHz. And I too realized it after eating two Chicago style hot dogs and one polish. You can too, so listen up!
Wandering away from the times of DADC (digital audio data compression), collectively the questions of why high sample rates could benefit the consumer delivery platform becomes increasingly important. We inside this audio community struggle with the notion of using sample rates that improve fidelity outside the limits of our ears. Why can’t we just stop at the 16 bit, 44.1 kHz digital format. 16 bit gives us the dynamic range to mask the noise floor while 44.1 kHz gives us the full 20 Hz – 20kHz frequency spectrum our ears can discern. Wasn’t the conclusion Phillips and Sony made back in the day good enough? A CD’s sampling rate and bit depth delivered the best sound possible over any other digital product. The answer today in the year 2014/2015 would be no.
High-Resolution Audio systems offer the assurance of an extended high-frequency range. These digital systems now operate at 2 to 4 times the sample rate of the standard CD. This means that these systems have the ability to extend the playback frequency range well above the 22 kHz limit of the standard CD. Does this added high-frequency range really improve the quality our listening experience? Yes, it definitely will. The problem is that High-Resolution Audio will only arrive when all the components in the playback chain can equal the resolution of playback.
For example, lets consider a digital audio playback system consisting of a CD player, preamp, power amp, and speakers. If each component has a frequency response of 20 Hz to 20 kHz, is this good enough to reproduce all the frequencies we humans can hear? The quick answer is no, and here is why.
An audio system’s real frequency response can be understood by adding together the frequency response of each component in the audio systems chain. If we look at our example above, we have four components total in the chain: CD player, pre amp, power amp, and speakers. If each component is -3 dB at 20 kHz, then in total, we have a system that is -12 dB at 20 kHz. Because this collective curve is so steep, it will begin to affect the audible high frequency information we humans hear, measuring at -4 dB at 10 kHz, -.66 at 5 khz, etc. In conclusion, this system will not even come close to matching the performance of what our ears can do.
So, if we want to accurately reproduce audio at 20 kHz, the frequency response of each component must continue well past 20 kHz. Is this what you call excessive and unnecessary? To argue this, let’s change each of the four components in our example above with components that have a 200 kHz bandwidth. Combined, the audio system now measures – 4 dB at 100 kHz, – 0.8 dB at 50 kHz, and close to – 0.2 dB at 20 kHz. This simple 4-component signal chain achieves a 100 kHz bandwidth and is consistent with the 96 kHz bandwidth of a 192 kHz digital sample rate. It can be argued that the region between 20 kHz and 100 kHz may offer little musical content, and even if it does, the only living thing in your house that could possibly hear it is the family dog or cat. The real asset is that we have preserved the entire 20 Hz to 20 kHz bandwidth after passing through four audio components in a typical playback system.
Nowadays, professional audio systems usually have analog signal chains that are much longer than 4 components. These operations place difficult requirements on the frequency response of each analog component in the chain. A chain of 16 analog components total, each with a bandwidth of 20 kHz, will produce an overall frequency response of about -48 dB at 20 kHz, 16 dB at 10 kHz and – 3 dB at 5 kHz. This really is telephone quality at best if you look at the curve on frequency graph! If the same system is built with 200 kHz components, the overall response will be – 3 dB at 50 kHz, about -1 dB at 20 kHz, and -.33 dB at 10 kHz.
All together, very high bandwidth is required of each component in the audio chain if we want to assemble a High-Resolution system that can handle sampling rates such as 192kHz. The proposed benefit of high resolution audio is not inaudible content, but better performance of digital systems within the 20 Hz – 20 kHz range. The idea of high resolution has now branched out to not only recording studio playback systems but consumer playback systems as well. Neil Young’s popular consumer playback system ‘PONO’ offers response all the way up to 250 kHz.
How does this all relate to recording and producing one of these lo-fi Chicago sounding record’s on a high-resolution system. Well if you think about it now after what was mentioned above, it’s going to be a better lo-fi sound. Not in the fact that it’s going to magically sound better because of the high resolution, but in the fact that it’s going to translate better across the consumer market because of the high resolution. What this means is for the first time, people are going to be able to hear the same sound at their home as what the artist heard when making the record in the studio. This is because from recording to mixing, mastering to final print and consumer playback, the full 20 Hz – 20 kHz spectrum will have been entirely preserved. This means the sound is accurate and unaffected from the process of making the record to hearing it. To all you audio engineers out there, take it into consideration, even if you’re recording lo-fi music such as hip hop and rap, especially hip hop and rap from Chicago.
So don’t be afraid to make those high-resolution records in 192kHz, that is, if your system can hack it. The consumer market is finally picking up the pace on affordable high resolution, or high definition playback systems. Really all we need now for high-resolution consumer audio to take hold is for a significant market progression away from the mp3 format. Lets keep our fingers crossed guys and girls!