Thursday, March 1, 2012

Avstomusic Gear Tech. Specs Vs Good Sound


The eternal debate of technical specification of audio gear and the resulting quality of sound has been argued since the beginning of professional recordings. Unfortunately the nature of the topic always leaves the parties of the discussion in suspense, without getting to any conclusive, objective benchmarks. Here are some highlights to consider, which if not solving the dilemma, at least may give you an idea why the problem has no resolution.

I’m talking about how certain pieces of gear have great technical specifications in comparison to others and yet they may not sound as pleasing. On the other hand it is not uncommon to use some old “crappy” gear in the recording studio, which in comparison to modern technologies doesn’t measure up, and yet sometimes there’s something “sweet” about it’s sound or tone.

First lets look at transformers versus transformer-less gear. Due to the high DC (direct current) voltage requirements in vacuum tubes, which before 1955 were the heart of all electronic devices, transformers were widely used well in to the 60s and 70s. With the invention of the transistor, the use of transformers in audio gear became optional and today many manufacturers are going back to the roots, because transformers have some “magic” properties. Transformers work on a phenomenon called inductance. It is a process of transferring electromagnetic energy through the air or magnetic materials. The discrepancy with technical specification and the quality of sound of transformers comes from the fact that most measurements of audio equipment like Frequency response, Gain, THD (Total Harmonic Distortion) etc., are done using sine-wave signals:


Due to the induction process transformers when tested with sine-waves tend to show pretty linear characteristics for a limited bandwidth. When transformers deal with square-waves:





They tend to “distort” them and change the way they sound, due to damping or ringing and the above-mentioned limited bandwidth. 







Technically that means transformers don’t have as good of a slew rate as transformer-less gear, which also automatically means a higher THD (Total Harmonic Distortion). In other words on paper some transformer gear may look horrible, but what it comes down to is how it sounds. When listening to music we don’t look at music charts or chords progression to get an idea of the music piece. Music is a real time art and certain types of harmonic distortion actually sound musical or ear pleasing. Just like with another endless debate of digital versus analog audio, some of the sweetness of certain pieces of audio equipment comes from it’s basic design’s shortcomings, and it’s inability to represent the source signal “accurately”.
If we evaluate modern transformer-less designs of audio gear using discrete transistors, or ICs, then the comparison would be more fair, in which case a poor S/N (signal to noise) ratio for example, simply means - poor signal to noise ratio.
In other words we cannot compare apples and oranges and pick one over the other simply based on their color for example. If taste is what we are concerned with, we have to try both the apple and the orange before we show a preference. Which brings me to the question: Which piece of audio gear is best for you? Which one tastes better - an orange or an apple? A good orange or an OK apple, an average orange or an excellent apple, a bad orange or a spoiled apple? And who says you’re deciding between those two for eating? What if you are making some hard-sider? I bet a spoiled apple would be your best choice.
Audio gear is so distinctive and subjective, that good sound engineers always use their own ears when deciding what to use or purchase.

References:

Transformers – A few Basics, Retrieved March 1 2012 from:
Vacuum Tube, Retrieved March 1 2012 from: 
Transistor, Retrieved March 1 2012 from: 
Inductance, Retrieved March 1 2012 from: 
Total Harmonic Distortion, Retrieved March 1 2012 from: 
Damping ringing in LC circuits, Retrieved March 1 2012 from: 
Slew Rate, Retrieved March 1 2012 from: 

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