NU9N eSSB Audio News Editorial - May, 2010
Do You Voodoo?

NU9N News Blog - May, 2010

Do You Voodoo? “Voodoo” is in the air and on the air. It has become an ongoing trademark for some in how they approach the science and art of outstanding amateur radio audio. What is the mystique with this Voodoo stuff? Or even a better question would be, just what in the heck is Voodoo Audio?


Voodoo Audio History:

The term "Voodoo Audio" was first used in 2000 by KK7TV (Randy) whenever he was referring to audio techniques that were derived from non-scientific and uneducated ways of processing audio. The term "Voodoo Audio" was an inside joke for several years referring to neophyte operators that didn't understand or follow accepted processing techniques.

WZ5Q (Mike) and I were having a light debate one evening regarding low-frequency harmonic processing (i.e. Behringer EX3200, BBE Sonic Maximizer, Aphex Aural Exciter, etc..), tube equipment vs. solid state, and analog vs. digitally based equipment, to achieve richer low-frequency harmonics. WZ5Q was making an argument in favor of these methods, proclaiming that the sonic characteristics would be beneficial and noticeable. I was making the argument that all of these things would not produce any real benefits or noticeable differences on the air, referring to them as "Voodoo".

We both got a good laugh out of the discussion and remain friends to this day. WZ5Q started referring to his station as being "Voodoo" speaking tongue in cheek, and the term has caught on as the trademark for the low frequency harmonic advocates.

But even more than that, something that has been referred to as being "Voodooized" has become a well-known phrase used by those who are referring to Mike's (WZ5Q) work on Kenwood TS-950SDX's and audio processor boxes that he has had his hands on. Improving just about everything imaginable, from audio chip selection, tube selection, modified and reworked circuits, to even the physical attributes of his gorgeous work, Mike leaves no stone unturned in his audio projects!


Are There Any Real Advantages of Analog vs. Digital or Tubes vs. Solid State in the audio processing domain? To Voodoo or Not to Voodoo is the Question!

What differences in sonic characteristics and tonal texture might one expect if they were using all analog processing devices verses all digital? Or with using all tube processors verses all solid state?

The digital and solid state world of audio electronics (for many reasons too complex to discuss here) are sterile and devoid of excessive even harmonic additives that can color an audio signal. Most audiophiles of the purist ilk, that desire a clean and near perfect reproduction of the audio source, without any coloring or harmonic distortion with their stereo amplifier, would probably tell you that they would prefer a solid state amplifier over a tube driven one. They would tell you that they want to hear the source material the way it was recorded—flat and pristine with little or no distortion added for effect or persona. These are the same guys that prefer CD’s over vinyl records.

There are other audiophiles, however, that do not like the “sterile” sounds of digital or solid state devices and prefer the coloring effects of analog devices with tubes in the gain stages. Some of these guys also prefer vinyl records over CD’s claiming that the digital technology makes their coveted music too hard and brittle sounding compared to the rich, harmonic content that soothes their ears, especially in the lower frequencies. Their claim is that the added even harmonic distortion inherent in the tubes and analog circuits fill-in much needed substance that warms the heart and soul of their being at a psycho acoustic level. It’s all about the final product that their ears here, despite what a science nerd graphed on a white paper.

There is much that can be said about both approaches. There are pros and cons with both, and certainly disagreements about both. So which direction should one go?

"Voodoo Audio" does seem to have some merit and may not really be Voodoo after all. It is well known and documented, by true hi-fi audiophiles, that tube and analog technology has some favorable sonic advantages over solid state and digital devices, where soothing even-harmonic resonance is involved. Those involved in the "Voodoo" movement also experiment with rolling their own Op Amp's, using vintage tubes, and performing other sonic modifications such as hi-fi input/output mods, power supply mods that deliver a purer, more consistent voltage to the circuits and so on.

One of the known and annoying problems with digitally processed audio is the quality of the DAC's and the way that the digital transport is designed, resulting in a nasty and brittle sounding high frequency harshness, as well as smeared, out-of-focus sounding mids and lows. This phenomena is caused by poorly timed digital data reconstruction knows as "Digital Jitter".

To understand what "Digital Jitter" would look like on an oscilloscope, where a square wave signal is introduced into the digital domain, see the following illustration.
(...And no, your eyes are not going bad)

(Photo and "Jitter" information source: http://www.lessloss.com/page.html?id=40)

The vibrating effect of the poorly timed digital information is the primary cause of the audio effects described above. For those of you who are interested in learning more about digital jitter, it's adverse effect with audio reproduction, and what can be done about it, click the link given above.


A Simple Experiment

As an experiment, I decided to take the Voodoo challenge by swapping-out my preamp's tube, a modern JAN/Phillips 5751 and replace it with a NOS RCA 5751 Command Series Black Plate, (known for it's low noise and smooth, rich harmonic content). Additionally, I swapped out my preamp's OpAmp, a 4560D, with a higher quality AD823ANZ. To my surprise, there was a noticeable difference! Each swap made a difference, but accumulatively, the differences were simply amazing! The noticeable differences were not just subjective either. I made sure that I recorded the original audio before swapping anything, then made new recordings after each swap. The differences were real and objective. I plan on swapping out the preamp's audio transformer next with a high quality Jensen.

After hearing the differences at just the microphone preamp level, I am now persuaded to evaluate the rest of my audio chain where OpAmp's, power supply voltages, and audio transformers are involved. It makes good sense to me that if higher quality components are used throughout the audio chain, the accumulative results can only improve.


Conclusion

Whether or not you are convinced that the type of tube or OpAmp will produce the sound you are looking for, or that being pro-analog is the only way to go, will depend on what you are looking for, and to some degree, how sensitive your ears are to subtle variations in the complex components of sound. If audio were only a matter of science, I would probably not entertain such notions. But because audio is as much of an art as it is a science, I am inclined to be open minded about the complex components of sound that deliver the final persona or feel of what I am hearing.

The bottom line here is this... Experiment for yourself and see what happens. Some mods are very quick and easy, some are more complex, but you may have some potential fidelity in your system that has yet to be discovered simply because of cheap parts holding back the audio.

I should point out that the accumulative improvements with audio chain mods will probably not be as noticable at narower bandwidths less than 4kHz or so. Obviousely, the greater the bandwidth being used to support fidelity, the greater the noticable differences will be with the perceived details of the audio mods, especially at higher frequencies.

To find out more about "Voodoo Audio", visit WZ5Q's "Voodoo Labs" website at http://www.voodoo-labs.com/.


73,

-John, NU9N