Wynton Marsalis – Marsalis Standard Time, Vol. 1

Sounds fantastic with inverted polarity through Deadbeef and a Zen DAC V2

10/20/24

Since the initial version of this review, I've changed music players from Clementine to Strawberry (in supposed bit-perfect mode, although it sounds like it adds an ear-candy EQ, meaning that it probably uses low-grade DSP), then to Deadbeef in bit-perfect mode [1], each a quantum leap in sound quality compared to the previous player. This CD, played with inverted polarity via Deadbeef and the Zen DAC V2 (which I leave powered-up constantly, using a cheap 5V wall-wart, for best SQ), is a good example of how good CDs can sound, and it's all the more remarkable considering that it was recorded in 1987 with a Sony PCM 3324, which was a 24-track, 16-bit deck which used early ΔΣ/ΣΔ converters, a.k.a "1-bit" converters which convert the anaput into "DSD," and then the "DSD" into PCM. The main problem with these converters was a relatively large amounts of output noise at high signal levels for a given clock jitter, back when clocks were relatively jittery. This problem was addressed by taking 5-bit samples instead of 1-bit samples, so that modern converters use "DSD-wide" internally.

The TI/Burr-Brown Advanced Segment DAC-chip (ASD) takes this idea to an extreme, by using a segment-DAC (a "ladder" DAC, but not R2R) for bits 1-6 and a "5-bit" ΔΣ-DAC for bits 7-25, for extremely low output-noise and tight control over low-level detail. Audio Research and Bel Canto use ASDs in their DACs, which are some of the best. The Zen uses ASDs and a femto-clock (a clock with sub-picosecond jitter), and it doubles the 5VDC input and uses differential outputs so that it can produce a hefty signal for driving headphones.

The sound quality of quite a few CDs is evidently deliberately degraded by inverting their audio polarity (which flips the waveform upside-down), probably to reserve the best version for LPs, which sound good but are hardly master-quality, and can't be copied perfectly. There are many ways to degrade recordings, so don't expect to be able to make all CDs sound great by just flipping their polarity. In some cases, flipping the polarity doesn't make much difference, because the recording or playback system, or both, lack sufficient clarity.

Note that the audio media downplays the significance of polarity, although recording engineers pay a great deal of attention to it and can even determine polarity by looking at audio waveforms. Also note that there are very few pieces of consumer gear, except some high-end stuff such as Audio Research preamps and Benchmark DACs, with polarity/invert controls, although some DAC-chips have an invert-function built into them for use in pro-gear, which would make it easy to add an ideal polarity control to consumer digital playback gear.

So, it seems to me that inverting polarity is being used in some cases as a means of degrading the audio put on CDs, and the music industry doesn't want us to have a convenient way to correct it. The polarity of .wav and FLAC files can be inverted by inverting them with an audio-editing program. If your system has ive speakers, it would be fairly easy to add a polarity control to your system, using one DPDT AC power switch per channel, each with its throws cross-connected, with the input applied across the poles and the output taken across the throws, or vice versa. The switches could be mounted in an electrical box. Use audiophile-grade speaker cable, with soldered-on spade lugs for solid connections to the switch-terminals. MUTE THE AUDIO BEFORE FLIPPING THE POLARITY, to avoid potentially damaging the amp or speakers. It might be a good idea to take steps to prevent anyone else from using it, or to label it with a warning to mute the audio before using it.

I gather that the polarity controls in high-end consumer gear and pro-grade gear have built-in soft-mute functions (soft-muting is safer than sudden muting due to lower risk of causing voltage spikes in general), which are also included in DAC-chips which have polarity-control functions. So, when the polarity-control is pressed or flipped, the volume would quickly ramp down to zero, then the polarity would be flipped, and then the volume would quickly ramp up to its previous level.

You can add polarity-control switches to headphones if their cables have four leads (which is rare), but the leads are difficult to work with due to their delicacy. I modified a cheap pair of Philips headphones, and ended up soldering the leads to a "breadboard" PCB (commonly available from electronics-parts sites) to avoid having to do anything to them besides stripping them, tinning them, stuffing them into holes in pads with multiple holes, and soldering them in place. Then I connected easy-to-use wires to the same pads. There is no need to mute the audio when flipping the polarity of headphones, since they run on low-level signals and draw very little current.

Notes

[1] To configure Deadbeef for bit-perfect playback on Linux using a Zen, you would do the following:

(a) Click on the Edit, then Preferences.

(b) In the Preferences window, select the "Sound" tab, set "Output plugin" to "ALSA output plugin" and "Output device" to the relevant device, which in my case was the Zen DAC driver described as "iFi (by AMR) HD USB Audio - Direct hardware device without any conversions" (my Zen DAC V2 was plugged into the PC, so its drivers were added to the list).

(c) Then select the Plugins tab and click on "ALSA output plugin" so that the relevant settings appear on the right side of the window, and then UN-CHECK "Use ALSA resampling." (Resampling to a higher frequency doesn't add information - it just represents the same waveform with a higher sampling rate. At best, the resampling process is transparent, but a high-quality process might consume a significant portion of system resources, and electrical power. So, avoid resampling if possible.)

Deadbeef, when first installed, is very simple, but it can be configured with a wide variety of plugins to provide just about any feature you could want.