Why does better power = better sound?


Why does improving power quality improve sound quality?

I’m not asking to start an argument about power cords or wall outlets. Please let’s not go there. I’m asking because I’m hoping to learn some technical explanations for the effects of power quality on sound quality. I think I already understand how…

1. greater current availability = greater dynamic range
2. reduction of RFI/EMI = better signal to noise ratio

…but what about these…

3. ???????? = greater perceived resolution
4. ???????? = more realistic instrument timbres
5. ???????? = more precise imaging

Are differences in resolution, instrument timbres, imaging, etc. somehow reducible to current availability and/or powerline noise? If so, HOW are they reducible?

Again, I’m hoping to get into technical specifics, not polemical generalities.

Thanks in advance.

Bryon
bryoncunningham

Showing 13 responses by bryoncunningham

Hi Learsfool - I haven't seen F is for Fake, but I know what it's about and it sounds interesting. I will put it on my Netflix list. Thanks! :-)

Bryon
I agree with you, Lacee. I'm a big believer in improving the quality of AC power. IME, it can have a wide range of positive effects on sound quality, including lower noise, larger dynamic range, greater resolution, more realistic instrument timbres, better imaging focus, etc.. The improvements can be summed up as greater "naturalism."

Bryon
There are many possible pathways by which spurious frequency components riding on the incoming AC may couple into the signal path... Some of those spurious frequency components may instead completely bypass the power supply, and couple into the signal path through stray capacitances that will inevitably exist in a great many places in the circuitry, or they may couple into the signal path via EMI effects, or they may radiate into the signal path as RFI.
Got it. In my last post, I was just trying to limit things as much as possible to a single scenario, so my brain doesn't hurt too much. :-) But I understand that spurii may originate from other sources, like EMI, RFI, stray capacitance, etc..

What particularly confused me was the concept of "frequency intermodulation," -- not so much the "intermodulation" part, but rather the "frequency" part, in light of the fact that we're talking about DC. My naive reasoning goes, "If DC is zero Hertz, then how does DC have a frequency to be intermodulated?" My (admittedly limited) understanding of "frequency intermodulation" is that it results in frequency components that are both the SUM AND DIFFERENCE of the original frequencies. So although I think I understand your comment that...
The net voltage at any instant of time will be the NUMERICAL SUM of the individual amplitudes (voltages) of each frequency component at that instant of time.
...but what about the DIFFERENCE part of intermodulation?

Wait a second. Maybe I just figured it out. (I'm typing as I'm thinking)

I was thinking that the "frequency intermodulation" you've been describing was some kind of intermodulation of the DC VOLTAGE with the NOISE. In other words...

IM = [DC voltage + noise] & [DC voltage - noise]

But maybe you've been talking about the intermodulation of the COMBINED DC VOLTAGE/NOISE with the SIGNAL. So...

IM = ([DC voltage + noise] + signal) & ([DC voltage + noise] - signal)

And maybe THAT is what you meant when you said...
The DC (zero Hertz) component of the combination of DC + noise has no relevance to the sonic effects we are discussing; it is just a possible pathway by which the noise may combine with the signal.

Am I anywhere closer to understanding this, or is it hopeless?

Bryon
Since we're also discussing power line accessories, I'll share what I've done...

--Dedicated 20 amp line with VH Audio's Cryo'd 10 gauge Romex. I routed it myself to minimize distance and to avoid crossing any other AC power lines.
--Shunyata Hydra 8 power conditioner (for preamp, amp)
--PS Audio Duet power conditioner (for computer)
--3 Shunyata Python power cords (hydra, preamp, amp)
--5 PS Audio power cords (everything else)
--Outlets: Shunyata, Synergistic Research, PS Audio, Maestro (winner: Maestro).
--Preamp: custom power supply w/ Rubycon capacitors, custom rectifier, SMD ultra fast diodes
--Preamp: removed IEC filter
--Preamp: replaced internal wiring to power supply with DH Labs 14 gauge silver plated wire
--Preamp: shielded power supply w/ copper, steel, and TI Shield
--Silver Hifi Tuning Fuses for preamp and amp
--6 Highwire Powerwraps on various power cords
--About 70 (!) ferrites all over the house wiring, on all appliances and electronics outside the audio system, and on some devices within the system
--Fairly extensive experimentation with grounding schemes, as described here

I haven't had a manic episode in several months, in case you were concerned.

One of the results of all that insanity is that things sound a lot better: Lower noise, more headroom, more resolution, more realistic timbres, better imaging. Now I'd like to know why the things I've done to address power have resulted in those specific improvements. The conversation about intermodulation is a pretty good explanation of how better power can result in better instrument timbres, in my underinformed opinion.

Maybe I can extrapolate explanations for headroom, noise, resolution, and imaging, though I have to confess a certain amount of mental murkiness. I have a weird thing where I feel like I don't understand something unless I understand it at its lowest level of explanation, which in this case is the level of FLOWING ELECTRONS.

(I know it gets lower, but hopefully we can avoid using the word 'quantum').

Bryon
...the output stage of the amplifier will generate a voltage that at any instant of time is (to a close approximation) proportional to the voltage at the input of the amplifier at that instant... The power supply will then provide to the output, via the output transistors or tubes + transformer, whatever amount of current is necessary to establish that output voltage across the load resistance or impedance, consistent with Ohm's Law.

That is very helpful, Al, and different from how I was thinking about it. Thank you for your heroic patience while explaining these things!

Bryon
It seems like the characteristics I mentioned in the OP -- headroom, noise floor, resolution, timbre, imaging -- are all affected by the AC power line's voltage and noise, in that undervoltage reduces the system's current availability and noise increases the system's distortion.

It's still unclear to me whether there are additional AC power line factors that are relevant. Are all AC power line problems reducible to problems with either under/over voltage or noise?

bc
Hi Raks - Wow, an Audience aR6-TS. I'm envious. Just looking at that thing makes me drool.

I'd love to attend a shootout of top power conditioners like Audience, Shunyata, Synergistic Research, Tripoint, etc.. People have great things to say about all of them. What would make it even more interesting is if you could selectively control the quality of the power going to the conditioner. Ahh... It's a nice day dream. Anyway...
To me its like a white dress shirt. Its either clean or it is not. There is at point at which it technically might be considered cleaner if say inspected under a microscope maybe, but practically, it is clean.
I think there's some truth to this, Mapman. But it's worth mentioning that I've been surprised MANY times with the benefits of improving the quality of power reaching my system. What surprised me the most were improvements to things like instrument timbre. For a long time I thought of noise as being synonymous with the NOISE FLOOR. Because the noise floor of my system was already low, I concluded that I wouldn't benefit much from improving the quality of the power to the system. Boy was I wrong.

Recently I went on a mission to reduce RFI/EMI in my system, which included things like installing croy'd 10 gauge Romex for my dedicated line, trying yet another fancy outlet (my 4th), dressing cables with zip ties with obsessive compulsive attention to detail, and adding ferrites to EVERYTHING in the house that pollutes the power lines (and that's just a few of the things I did). The effects went far beyond simply reducing the noise floor. Everything improved: dynamics, coherence, harmonic accuracy, imaging.

You're probably already aware of most or all of that. But for me it was a real eye opener. No, an ear opener. :-)

Bryon
Oh yeah, and yesterday I measured the voltage of various AC lines around the house. They ranged from 118.3V to 121.2V and fluctuated significantly. But...

The dedicated line feeding the system: 120.0V

It was dead on. And there was no fluctuation beyond .1V (within the +/- of the meter) during the 60 seconds I measured it. A little confirmation that my efforts to improve power around here are paying off.

Bryon
Thanks to everyone. Some very helpful comments.

I understand that the DC power provided by a component’s power supply is the same power that constitutes the component’s signal, and that therefore noise or distortion on the AC power line, if insufficiently filtered by the component's power supply, will become part of the signal.

What I’m unclear about is how SPECIFIC audible characteristics correlate with SPECIFIC AC/DC powerline anomalies. Put simply, HOW does bad power result in bad timbre, or bad imaging, or less resolution, etc.?

04-24-12: Almarg
…any and all of those numerous frequency components could, to some small extent, intermodulate with the audio signal, resulting in new spectral components at frequencies equal to both the sum of and the difference between the frequencies of any or all of the spectral components of the music and the frequencies of any or all of the spectral components of the noise or distortion.

This was extremely helpful, Al. I wasn’t really thinking in terms of frequency intermodulation, but when I do, it’s easier for me to understand how bad power results in less realistic instrument timbres. It's something like...

AC power frequency anomalies -> DC power anomalies -> INTERMODULATION of DC power and signal -> distortion of harmonic content -> less realistic instrument timbres

Because accurate harmonic content is essential to realistic instrument timbres, anything that distorts harmonic content, like the intermodulation of DC power and signal, will make instrument timbres less realistic. Sounds plausible to me.

So filling in the question marks to #3 in the OP is…

3. dc power/signal frequency intermodulation = less realistic instrument timbre

Assuming all this is correct, I’m still unclear about the explanation at the level of voltage and current. In particular, I'm unclear about the concept of "frequency intermodulation" with respect to DC power. Some dumb questions...

--Does "frequency intermodulation" basically mean that there are FLUCTUATIONS to DC voltage/current that are UNRELATED to the signal?

--Why are DC fluctuations described in terms of "frequencies" at all? Is it simply because the fluctuations occur at a certain rate per second? Or does the use of "frequency" to describe fluctuations in DC voltage/current also imply that DC can be understood as a WAVE, just like AC?

I have lots of additional thoughts/questions about resolution and imaging, but it would be helpful to stick to instrument timbres for the moment, or my head might explode.

Thanks,
Bryon
04-26-12: Almarg
My statement that:

...the net voltage at any instant of time will be the NUMERICAL SUM of the individual amplitudes (voltages) of each frequency component at that instant of time...

had nothing to do with intermodulation distortion, or with the sum and difference frequencies that intermodulation distortion results in. It was simply a description of the voltage at any instant of time of DC that is noisy.

Got it! That clears up the confusion (mine, not yours). I was just thrown when, for some reason, I thought you were talking about the frequency intermodulation of DC voltage and noise. Sorry for my misunderstanding!

Your subsequent explanation of frequency intermodulation is very well described, and something I feel like I understand at the level at which you describe it.

What still remains a bit murky to me, as I mentioned in my last post, is the explanation of intermodulation at the level of voltage/current. Is intermodulation better understood as a fluctuation of voltage or a fluctuation of current? I understand that you can't change one without changing the other (Ohm's law), so maybe that question is meaningless. I would just like to have a better mental picture of what those electrons are doing! :-)

Bryon
Thanks for sharing your story, Lacee. I have a similar kind of story with my adventures with AC power over the years, starting with a simple power conditioner and then moving on to fancy power cables and then to even fancier power conditioners and then to dedicated lines and to cryo'd 10 gauge Romex and to magic outlets and to more magic outlets and to custom power supplies and to ferrites ferrites ferrites and to noise harvesters and to powerwraps and to obsessive compulsive cord management and to all kinds of custom shielding and finally to fuses, which brings the whole subject to the level of absurdist satire.

Still, I wouldn't change a thing.

Bryon
Hi Lacee - I too am a believer in dedicated lines and late night listening. I even use fancy fuses. And I agree that the most informed opinions are ones that include personal experience. Having said that, I readily acknowledge that plenty of folks have technical knowledge that I don't, and that many of my opinions are under-informed.

Above all else I am a fallibilist, though I don't always act like it. People can be wrong about anything, including experts. IMO, expertise is something that should be respected and challenged in roughly equal measure. And so I tend to listen to both Skeptics and Believers.

FWIW.

Bryon