P5: Phase Tuning???


I hope some of you will help me understand Phase Tuning. From first impressions, it appears it could be nice fine-tuning tool, but I have no idea why, or if this is specific to my power.

Even after 600 hours burnin, I had difficulty getting the spaciousness, texture and micro detail I wanted from the P5. I did finally get to a really good place, but with so many people finding power plants more plug and play, I kept wondering about wildcards like Phase Tuning. Compared to minimal conditioning before (an Uberbuss and modded Brickwall), the P5 was a breakthrough for voltage regulation, but had for me (all slight) a darkish density, hardish edges, and related micro detail limitations. I craved subtle qualities more complex micro detail can offer.

Having heard phase is a rare issue, and if all the meters display logical info…don’t mess with it, I looked more at cables, feet, room circuit noise cleaners etc. The biggest breakthrough toward more micro information was a DIY 8 gauge cable with many twisted silver on copper teflon wires of various gauges and rhodium ends. The thought again…had this done something good to the Phase.

Another breakthrough was using a Shunyata Defender for a filter in my modded Brickwall and running the tweaked Mac Mini, Tranquility DAC, and linear USB power supply through it, the Brickwall plugged into the same Furutech receptacle as the P5. Through the P5 at this point, the Tranquility is really good, but comparatively, it loses a little too much space reference, harmonics, complexity… Added up, for me, this can make the difference between very, very good sound, and a natural sense of real players in space.

Finally, with the most lively feet I have under the P5 (Synergistic Research MIGs), it was sounding really amazing with my Decware Amp and pre into the P5 and the front end into the Brickwall with Defender.

From this happy zone, with excellent stable power and sound, I have been playing a little with Phase Tuning. In this system/room, set at minus 3-4, I get a more spacious sound that is articulate, but also smooth, complex and textured, and with a nice musical warmth. One of things I work toward is resolving clear differentiation between notes and ambient trails near and far…smooth and natural transitions, the edges made sweet by complexity and spacial ambience that just goes and goes.

At the moment, the P5 meter reads 122.1V in and with it set at 119V, with the Phase at zero, the output voltage says 119.8. With the phase set at minus 4, the output voltage says 119.6V. THD in is 2.5-2.6 and out is .1 both ways.

Can anyone help me to understand this phase thing? Is there a good reason for what I am hearing? Is Phase perhaps an important tool for subtle adjustment? Is the Phase here in my house a reason for some of the difficulty I had getting the sound I needed from the P5? Or any other thoughts?


Welcome, Will

It is rare phase tuning needs to be used. It is there to adjust the P5’s software to better phase lock loop synchronize with the incoming AC in certain odd circumstances. In these few cases it helps lower the THD.

There is no harm playing with it. So try the various settings if you would like and listen for a difference.


Thanks Elk.

It sounds like what I am hearing is outside the scope of the design intent for Phase adjustment. But since “Phase Tuning” changes software settings, even though I have no THD issues, I wonder what the software is doing in this case?

I have been playing with it too short a time to be clear about all the specific sound attributes, or even if it is a definitively useful exploration (only started today), but for fine-tuning, it looks like it could be a useful tool, shifting the tonal focus a little. On first impressions, zero seems to have excellent focus and definition, and this might be the best, but maybe not depending on tastes and system/room? At minus 4, the articulation is there, but it seems to cause my system to soften edges (more texture) and create more sense of space, shifting the ambient focus broader. Though each aspect of the ambience seems a little less defined, the whole of the spacial info seems to have a little more presence. I am thinking it feels more “atmospheric.”

I will keep exploring, but am wondering if you long term power plant users might be able to fill in some gaps for me?

Any thoughts?




I was one of the people that had a phase problem. My power company had problems and the incoming voltage had 14% THD.
The P10 could only reduce it to about 8% THD.
That was not good enough for PS Audio so they came up with the phase adjust. With that I was able to adjust for minimum output THD.
My power company has since fixed their problem but if it ever comes back I will be able to compensate with the phase adjust.

Will said

It sounds like what I am hearing is outside the scope of the design intent for Phase adjustment. But since “Phase Tuning” changes software settings, even though I have no THD issues, I wonder what the software is doing in this case

This is an interesting question. I do not know.

My guess is that it adjust the PPL a little above and below 60HZ and its harmonics to try and line up with what the power company is producing so that the Power Plant can better do its job. But this is literally a guess.


Here is a technical explanation that PS engineering gave me while they were troubleshooting my 14% incoming distortion.

“Sounds like you have some technical background… I am varying the phase shift between the incoming voltage and the output voltage. The regenerator synchronizes with the zero crossings of the incoming voltage. However the peak of the incoming sine wave is usually not perfectly in the middle of the zero crossings, because of the phase of the distortion products. So in practical application the regenerated wave has to be shifted slightly from the input. We haven’t found a good theoretical model to optimize this, so we really appreciate you helping us get some empirical results.”


Thanks folks.

I think I get this. It sounds like the regenerator is syncing with incoming zero crossings, but the sine wave center is not necessarily centered, the wave being a little crooked with distortions. So the peaks and troughs are being shifted (ideally to center) by adjustments?

“I am varying the phase shift between the incoming voltage and the output voltage.” I wonder if this means the phase shift adjustments define the final sine wave shape, or if the wave is processed further to before output?

Though the wave is much better here (around 2.6% THD) than st50 had with 14% incoming THD, there is definitely sound change with Phase adjustments and it would make sense if it were changing the peak shape and crossing point.

Then the question for me becomes: Does the P5 definitively modify the sine wave peaks and troughs to “perfection” if the initial THD is not too haywire? Or with reasonable THD coming in, can the Phase Tuning adjustment actually be used for fine-tuning the wave further, possibly bringing it closer to a perfect wave form if we can figure out what indicates that it is better?

I have not played much more, getting a feel for minus 3 and 4. From this the THD remains .1% and the voltage a few tenths closer to the chosen setting. I can adjust all the way to -9 or plus 9 before the THD goes up from .1%. The voltage reading IN is 122.2 now. Set at 119V, with the Phase set to plus 9, the output says 120.2V. Phase at minus 9, Voltage reads 119.3V. Does this tell us anything?

At this setting, with the reduced edge hardness, and increased spaciousness, texture, and broader ambience, is shifting the phase peak adding some kind of subtle distortion other than THD??? Or is it a noise free phase shift that is allowing more micro information from the gear? And finally, do the adjustment sound changes I get here relate to those of anyone else? Or is it dependent on our exact phase coming in?

Whatever it is, I am pretty sure it has excellent potential for tuning. For example, at least in this room, at minus 3-4, saxes that can be too hard/rigid become more textural…less brass and more reed…and ambient information that seems too consolidated and isolated on zero, integrates more with the rest of the room information. At the same time, the individual player definition in the soundstage goes a little softer, though still very nicely saturated, but with more space, more in-between ambient information and better depth definition.

That said, Phase here set at zero is an excellent, solid sound.

Maybe I will get a chance to listen some on the plus side of Phase later today.


Hi Will,

You haven’t mentioned Multiwave. Have you tried it? I hear more stories about positive sound quality effects from adjustments there, than I have from phase adjustments.



Hey Dave,

I enjoy multiwave, especially on some recordings. On many though, it thickens my sound a bit much for me, so I tend to leave it off. Admittedly, I have not tried hard to make it work though, exploring it with some minor adjustments now and then. I think it is probably to do with my amp. It is a very simple point to point tube amp that is fast, rich, and lucid. Multiwave can saturate the sound too much for my tastes. Perhaps the amp tuning already takes one or more of the tube sets close to ideal limits?