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
Bryon, when you speak of power quality, I assume you are talking about the quality of the AC line, correct? The age old question about why our systems sound better at night? When there is less stress on the power grids and the electricity is better quality? Or dedicated lines taking things like refrigerators or air compressors off the lines of our audio equipment?

If so, I think the answer is just the equipment is better able to perform to the best of it's ability when it is driven with better, cleaner power. When fed dirty power, any piece of gear can struggle. That is why some manufacturer's believe that a battery supply (DC) is the only way to provide true clean power. I believe the answer to your questions 3,4 and 5 is simply that with cleaner power, the equipment is getting what it needs to reveal it's potential sound quality.

I suppose it is similar to how a car performs using different octane levels of gasoline. Yes, in cars too, some manufacturers believe that a battery is the best source for clean power.

Cheers,
John
All the jumbled up frequency hash in the powerline continues on into the power supply. As the power is changed to use by the electronics, it STILL carries way too much of the garbage into the signal. Remember the signal has to be amplified with that very same power. So the actual grunge comes through as signal.
The power supply power actually becomes the amplified signal. If it is pure and clean then the signal will be that much better.
If it still has all sorts of spurious hash and grung not filtered out, then it will just not be as good.

I use two big conditioners and now would not want to be without them.
It probably has to do with non-optimal power supplies in equipment that cannot fully eliminate harmonic impurities or adequately deal with small scale fluctuations in power line frequency.
If you accept that better quality components (power supplies, caps etc.) lead to better resolution, imaging etc., it is fair to accept that choking or polluting the power required to operate the equipment will diminish the potential. Providing clean power is just allowing equipment to operate at its full potential.

Remember you are trying to retrieve everything from your source. Less 'resistive' components all through the chain will allow that. Better quality just means less bad, since everything takes away.
3 and 4 is same as 1 and 2 - greater dynamic range requires good current delivery and low noise.
Instruments won't have natural timbre thru noisy gear that compresses dynamics.

5 - Imaging is related to noise as well but also to crosstalk, often thru common power supply. Power amp supplies are most likely without line and load regulation with inductive capacitors. Separate power supplies for each channel or even separated amplifiers (monoblocks) will reduce crosstalk.

Jeff Rowland started using sophisticated switching power supplies in latest model 625 (class AB power amp). It switches at 1MHz (easy to filter out) with zero voltage/ zero current switching. It delivers clean voltage that is line and load regulated (not to mention efficiency).

Linear power supply is also a switcher operating at 120Hz where switching appears in worst possible place - at maximum AC voltage. Current is supplied from mains in sharp narrow spikes. Width of these spikes changes with load (switcher's definition). 120Hz ripple is difficult to filter out and requires a lot capacitors. Transformer has to be huge for good performance. In comparison same power transformer operating at 100kHz can be 10x smaller. That's the future in my opinion. Jeff Rowland already uses switching supplies to obtain low noise in preamps (Capri) where efficiency is secondary issue.
…but what about these…

3. ???????? = greater perceived resolution
4. ???????? = more realistic instrument timbres
5. ???????? = more precise imaging
I believe that several before me have already hinted strongly at it - lower distortion equals better resolution, timbres & imaging. So, better power implies "better quality power". It's all about the linearity of the power amp & the ability of the power supply to supply sufficient voltage headroom (so that the voltage excursions do not clip) & dynamic current into the load (so that voltage swings do not clip & sufficient voltage can be created in the drivers so that they in turn can react pistonically assuming that the speakers can handle to volume SPL).
Hi Bryon,

Good comments by everyone above. My take is as follows, the bottom line of which is essentially what Elizabeth said:

"Dirty power" will consist of some combination of harmonic distortion (i.e., frequency components that are at multiples of 60 Hz, sometimes including multiples that reach into the upper treble and beyond), broadband noise (a mix of essentially all frequencies across a wide range), and voltage spikes that occur periodically or intermittently, which in turn will contain a considerable number of spectral components at various frequencies. Inevitably some extremely small but non-zero fraction of all of that spurious frequency content will find its way through or around the power supply of each component and into the signal path.

In addition to perhaps causing a directly perceivable reduction in background blackness, 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. That will occur as a result of non-linearities in the components in the system, and no system is perfectly linear.

Given that the power line spurii and any musical note will BOTH be comprised of a great many different spectral components, the resulting sonic effects as perceived by the listener can be pretty much anything, conceivably including reduced resolution, less accurate reproduction of timbre, and imprecise imaging.

Obviously those kinds of effects will have little if any predictability with respect to either their magnitude or their character, and will be highly dependent on both the design of the system components and the characteristics of the power source.

In principle a power regenerator should eliminate or at least greatly reduce these effects, but as you've probably seen some people report reduced dynamics or other adverse effects when a regenerator is used, especially in the case of power amplifiers.

Best,
-- Al
Great comments -- but what is a practical way to deal with this issue. As a threshold matter, I was thinking of runnning a couple of 20A dedicated Romex lines from my circuit box to feed my gear as soon as my wife visits her mother on the West Coast. But as far as "power gremlins" are concerned, is there a moderately priced solution out there??

I've heard similar comments about power regenerators mentioned by Al -- loss of dynamics. Also power regenerators are da*n expensive. Suggestions would be welcome. Lookin' for quality electrons.
I've got several cheap Furman power conditioners that I have picked up on ebay for under $50. The challenge is how cheap can I get them. They do improve the sound. So would it pay me to upgrade? Would it pay to go for $200 worth? Don't be concerned about restricting the dynamics in my case. I'd probably be happy in an anechoic chamber.
Al as usual gave a wonderful answer

To view it a bit differently think of electricity or power as water and your electronics as living creatures needing it.
Believe it or not there are only 5 water systems in the U.S. that do not need or are required by state or national standards to use chlorine or other items to clean the water(New York City and San Francisco are two of them). When you don't have to spend time getting things cleaned up so that water can be used it is more energy efficient and easier on all around. Power works the same, when it is cleaner either by power cords, conditioners, magic, or whatever everything flows much more easily and the electronics can finally do the job they were designed for with ease.
Bifwynne - I use Furman Elite 20PFi, a power correcting 20A conditioner with non-sacrificial over/under voltage protection. I don't see any difference in dynamics possibly because in addition to large inductor in series with power outputs it also has huge capacitor. They claim 55 amperes of available peak current. There is some change in bass performance making bass more musical (more even), but the biggest improvement is in purity of the midrange. It also gives me sense of security protecting all my components during thunderstorms.
I recently purchased a couple of Blue Circle SillyCone filters. They are a parallel filters which are plugged into any free outlet but their effectiveness is increased the closer they are to the equipment outlet. These filters are built into a silicone filled ABS pipe, they aren't much to look at, but don't let that dissuade you.

I purchased them for my monoblocks as I have always plugged the amps directly into the wall. Since the SillyCone filters are parallel filters, they do not restrict current and dynamics.

What immediately grabbed my attention was the level of refinement these filters brought to my system. Leading transients are less edgy and more natural. Backgrounds are blacker which allows inner detail and texture to flow through. Images are portrayed with greater density and space.

Previously, I had PS Audio Harvesters and at certain times of the day, their LEDs would start flashing so rapidly, that I could hear them buzzing. Even when I added more Harvesters, it didn't make a significant difference to the amount of power line noise as they would all be buzzing away. When I plugged in a single SillyCone 6x filter, the blinking on the Harvesters dropped significantly. Adding a second 6x filter stopped their blinking all together.

I eventually ordered two 18x filters for my amps. I'm thinking of getting more of these pipes, they even make a nice contribution when I plug them into my BPT conditioner.

http://www.bluecircle.com/page26.html
The best (and simplest) explanation I have ever seen is similar to what Elizabeth describes above. The comment that I read said that, ultimately, no matter what conversions, etc. happen in between, the musical signal is modulating the AC power coming into your system. It just makes sense that the cleaner this waveform is, the cleaner the output will be.

I can tell you that I thought I had pretty good power until I bought a Furman 15PFi (a smaller version of Kijanki's model) to clean up the mass of cables behind my system. I was stunned at the difference it made. I don't remember what I was listening to after the install but it was something relatively familiar. My daughter walked through the room and commented that she "never knew that song had a guitar in it." She was right - I had never heard it before either. I can tell you that I'll never be without power conditioning of some sort again. And the Furman is not a super expensive piece.
A further thought about power regenerators. My guess is that the root cause of the reduction in dynamics that they are sometimes reported to cause is simply that the 120VAC or whatever that they put out is different (and most likely lower) than the voltage at the wall outlets.

A voltage reduction can make a difference in several ways, to a greater or lesser extent depending on the design of the particular components, especially the amplifier. It could reduce dynamic headroom, reduce maximum power capability, change internal operating temperatures, change bias points, and increase distortion on high volume peaks that approach the reduced clipping point.

On the other hand, if the line voltage happens to be lower than what the regenerator puts out, the voltage increase provided by the regenerator at those locations could decrease distortion on high volume peaks that approach the clipping point. That decrease in distortion could conceivably be perceived as a reduction in dynamics. In a different context (that of SET amplifiers) Atmasphere has commented in the past that since the 5th, 7th, and 9th harmonics of a note's fundamental frequency are significant determinants of our perception of loudness, an increase in those distortion components that occurs primarily on high volume transients will result in a subjective perception of increased dynamics.

Uru, thanks for your comment. Lynne (Arnettpartners) and Bruce (Bifwynne), given the unpredictability and system dependency of it all, I have no particular suggestions beyond what the others have said. Bruce, dedicated lines certainly seem like a good idea, that is amply backed up by anecdotal evidence. I finally got around to having one installed last year, but I upgraded my amplifier at the same time so I don't know how much difference it may have made, if any.

Best regards,
-- Al
Thanks, Al. You are a pleasure to read. I wouldn't be afraid to spend a few more $ on a power conditioner based on the above testimonials--one which featured a storage capacitor. I still have an old Adcom with a storage capacitor, but it doesn't clean up the signal as well as the intro Furman. The intro Furman does restrict dynamics though unless as you suggest the possibility that eliminating harmonic distortion creates that illusion. I suspect, though, that it is in need of storage. I'm also researching the silicon filter.
Good basic point Al.

A solution that truly cleans or smooths out the power supply in regards to AC frequency but also in conjunction limits basic power parameters like voltage and current may be of marginal benefit or perhaps even be detrimental in the end compared to one that does not or even no solution at all.
Al, I'm sure I don't have much of a choice about more dedicated lines. My entire system is sucking juice from one 20A line, the biggest users being: ARC 130 wpc tube amo; ARC tube phono pre; ARC tube linestage; ARC tube CDP; TT; and the big Daddy of all -- Paradigm Servo Sub (rated at 1500 watts; 4500 watts on peak). What amazes me is that I'm not blowing the breakers, although when playing Beethoven's 6th, the house lights brown out during the thunderstorm in the 3rd movement.

I was thinking about running 3 dedicated Romex 20A lines. The problem is where and how. My wife will flip if I start tearing up the walls; ceiling is not an option. If Code allowable, I was thinking about running a couple of lines through a PCV pipe the length of my basement next to the wall board UNDER my electric wall heater, which I rarely use.

Any thoughts. BTW, how much is your Furman. Would I need one for each line?
Hi Bruce,

If the lights that are dimming are not on the same 20A line as the system, then it suggests that a lot of the voltage drop is occurring in wiring that is upstream of that line, presumably on the input side of the panel. In which case adding additional lines between the panel and the system would not resolve a lot of the problem.

It was some of the others who mentioned the Furmans. I'm using a $259 Brickwall surge suppressor, that also provides a modest amount of EMI/RFI filtering and some degree of isolation between its four dual outlets. I've been happy with the results, although I suspect that I have better than average power quality, as I'm in a fairly small low density town that has no industry and almost no commercial development.

A minor correction: It's the 4th movement that you are referring to, not the 3rd, although the two movements are played with no pause in between. One of my favorite symphonies!

Best regards,
-- Al
Bifwynne, new Elite 20PFi is $1019 at Audio Advisor. I bought used for $600. New Elite 15PFi is about $699, used currently listed at Audiogon for $350.

Al, you know your Beethoven - I'm impressed.
Al and Kijanki, I have the complete Gardner Beethoven symphony collection. Recorded on the Archiv CD label. Playback is quite good. Gardner uses a tazer to keep the orchestra really hopping! One of the better redbood CD in my collection.
Al and Kijanki, assuming I go forward with installing 3 or 4 dedicated lines, will I need a power conditioner for each line? Just talking out loud here, I wonder if there's a single device that I can install at the circuit box that will condition and filter the AC power for multiple dedicated lines.
Hi Bruce,

I have no particular knowledge of an audio-oriented conditioner that would handle multiple lines at the panel. But in any event I would expect that installing conditioners at the system end of the runs would be preferable, because they would then be able to filter out RFI that may be picked up by the wiring between the panel and the outlets.

It would probably make sense to purchase one conditioner initially, and try it out on each of the different lines.

Not familiar with the Gardner "Pastorale"; thanks for mentioning it. My "go to" version is an imported Japanese CBS/Sony remastering, on LP, of Bruno Walter's famous 1958(!) performance with the Columbia Symphony. I purchased it during the 1980's. Wonderful performance, of course, and remarkably pleasing sonics aside from a bit of steeliness in the strings at times.

Best regards,
-- Al
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
Hi Bryon,

The effects I was describing do not necessarily relate to the DC outputs of the power supply at all. There are many possible pathways by which spurious frequency components riding on the incoming AC may couple into the signal path. To the extent that the filtering in the power supply is not perfect at all frequencies, the spurious frequency components may couple into the signal path by "riding" on the DC outputs of the supply. 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.

Once the signal, at any given point in the signal path, combines with spurious frequency components that may be picked up at that point via any of those pathways, non-linearities in circuitry that is downstream of that point will result in the spurious sum and difference frequencies I referred to. See this Wikipedia writeup on Intermodulation Distortion.

To answer your specific questions:
Does "frequency intermodulation" basically mean that there are FLUCTUATIONS to DC voltage/current that are UNRELATED to the signal?
If the pathway by which AC line spurii enter the signal path is via the DC outputs of the power supply, then yes, there would be fluctuations in those DC voltages, unrelated to the signal. The value of those voltages at any instant of time would be equal to the numerical sum of the DC voltage and the value at that same instant of time of the fluctuating noise voltage that is riding on it.

However, that is not what is significant. What is significant is the noise coupling onto the signal, and subsequently intermodulating with it at downstream circuit points.
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?
When DC is fluctuating as a result of noise that is riding on it, it can be viewed as having multiple frequency components that are added together. One component, the DC itself, is at a frequency of zero Hertz and has an amplitude equal to the particular DC voltage. Other components will be present at each of the many frequencies that comprise the noise, with the frequency components of the noise having far smaller amplitudes than the amplitude of the DC. 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.

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.

Best,
-- Al
I know this may be just hype from Burson Audio but they are big on power regulation and use only their own proprietary design, claiming it has a major effect on how the music sounds. Anything more involved is way above my head.

I do know, and appreciate, the results I get (from my Burson PI-160) which mirror what Bryon asks about.
Oh, and I use a Brickwall surge protector as well as it appears to have no negative effect on my music while deploying minimal filtering and maximum protection.

Either that or I'm tone deaf.
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
Bifwynne,

I got my PF15i from Audio Advisor as an "open box" item (look under their clearance section) for $519. The box had indeed been opened but I'd swear it had never been out of the plastic wrap inside. I suspect "open box" is a ploy to get around manufacturer restrictions.
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
Hi Bryon,

You're not there yet, but it is by no means hopeless :-)

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.

As long as they are reasonably small, fluctuations in the DC voltages will IN THEMSELVES have no effect on anything. It is only when the frequency components corresponding to those fluctuations combine with the signal that a problem arises. The DC will not combine with the signal (in a properly functioning circuit). But the noise frequencies might, because they can couple from one circuit point to another via the various means I described.

Envision a musical note consisting of a 1 kHz fundamental frequency, and a harmonic of lesser amplitude at 9 kHz. (A real musical note would contain many other harmonics as well, such as 2 kHz, 3 kHz, etc. but I'm simplifying). And imagine that a noise frequency of 11 kHz, having some small but significant amplitude, couples onto that signal.

So far all that has happened is that a small 11 kHz signal has been added on to the signal having 1 and 9 kHz frequency components. That is probably not a major issue, assuming that the amplitude of the 11 kHz is not too great.

Now envision that the signal containing those three frequency components is passed through an amplification stage that has some degree of non-linearity, meaning that its output is not perfectly proportional to its input. Intermodulation caused by that non-linearity will result in many new frequencies, corresponding to the sums and differences between those three frequencies, and various other multiples of them. Perhaps most significantly, a 2 kHz frequency will be created as a result of intermodulation of the 9 and 11 kHz components. (20 kHz will also be created, among other new high frequencies, but that is obviously less significant). To the extent that the amplitude of that 2 kHz frequency is significant, it will alter the perceived timbre.

Now envision that a real-world musical note is present, consisting of a great many frequency components, and that noise also present, consisting of vastly more frequency components. Put all of that through a significant non-linearity and what you have is an unpredictable mess, having sonic attributes that can probably differ from those of the original signal in just about any way that is imaginable, including resolution, timbre, and imaging.

Best,
-- Al
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
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! :-)
It's best to think of everything I have described in terms of voltage. The current at any given point in the signal path is what it is, based on Ohm's Law.

One reason that all of this tends to be confusing is that the statement which is sometimes seen that the power supply is in the signal path, since it supplies the current that drives the next component in the chain, is a bit misleading.

Yes, in addition to powering the internal circuitry of an amplifier the power supply supplies the current that drives the speakers (supplying it via the transistors or tubes + transformer in the output stage of the amplifier). But a better way to think of it, IMO, is that 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 (actually, slightly before that instant, because it takes a very small but non-zero amount of time for the signal to propagate through the amplifier). 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.

Best,
-- Al
...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
Has anyone tried a balanced isolation transformer such as the KECES PT-111?
How do you determine whether to buy a 15 amp or 20 amp power conditioner? Simply by the size of the AC circuit it is plugged into or are there other factors like the demands of the audio system?
Hi Lynne,

What is relevant is the maximum amount of current that is demanded by the audio system. As long as a 15A rating would provide a reasonable amount of margin with respect to that demand (and I suspect that it will in your case, assuming that you will not be using a powered sub), there is no problem using a 15A conditioner on a 20A line.

Best regards,
-- Al
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 Bryon,

Assuming that "noise" is interpreted broadly, to include distortion and perhaps also DC offset, the only other things I can think of would be:

1)Dynamic fluctuations in voltage resulting from resistance in the AC wiring, as current demands fluctuate with the music.

2)Wiring inductance possibly limiting how quickly the supply of current can change, in response to abrupt changes in demand.

I don't have any particular quantitative feel for how much significance those factors may have, if any, and I suspect that in many cases they will be of no significance. Particularly if the power amp is Class A, and hence draws essentially constant current all the time. But those are the only other possible factors that occur to me.

Best,
-- Al
Arnettpartners, I bought 20A version only because I suspected that it might affect loss of dynamics (if any) a little bit less (smaller voltage drops) and to be ready for larger amp in distant future.
OK. Thanks, Kijanke and Al. Yes, no subs. I'm reading this fantastic review of the Furman Elite 15 something--15 amp rating, I think.
Kijanke, do you use the same 20a for your digital source(s)?
Lynne
Yes, It has 12 outlets divided into 3 banks of 4. One bank for power amps or subs(Rowland 102), another for video (HDTV, DVR, Bluray) and third for audio (Benchmark DAC1, Airport Express, Toslik/coax converter). Two of each four outlets are 12V switchable. In addition there are overvoltage protectors for the coax - I use one but perhaps not much help for my roof antenna - in direct hit everything will fry anyway (including house). For cable TV it is a must.
Yes, It has 12 outlets divided into 3 banks of 4. One bank for power amps or subs(Rowland 102), another for video (HDTV, DVR, Bluray) and third for audio (Benchmark DAC1, Airport Express, Toslik/coax converter). Two of each four outlets are 12V switchable. In addition there are overvoltage protectors for the coax - I use one but perhaps not much help for my roof antenna - in direct hit everything will fry anyway (including house). For cable TV it is a must. Make sure this Elite is PFi since I think this Power Factor correction provides this big capacitor and 55amps of peak current.
Very comprehensive unit. Thanks. Yes, I still unplug during thunderstorms.
OK. Will make sure it is a PFi. I'm probably going with a 20. It might be overkill, but I have a high current amp with 120 amps instantaneous not that I ever use all of it. If I get the 20, though, I won't have to wonder if the system is ever limited by its power source.
I unplug during thunderstorms too when I'm at home. There is one feature of PFi20 that is strange. It has two black plastic tubes with strong LED lights inside that you can pull and direct. It is intended to be on the upper shelf of the audio cabinet shining light down on other elements of the system. For me it is useless (bottom shelf of TV rack) making it larger than necessary. I don't mind width (standard) but it is a little deep. Perhaps not more than typical audio rack/cabinet can handle but still.

http://www.furmansound.com/product.php?div=02&id=ELITE-20PFi
I've seen the Furmans with those tubes and never new exactly the purpose til now. They would be useless to me too. But, oh well. My stand can handle the depth. Thanks so much.
There's a used 20 on ebay right now.
Lynne
Byron, I think of AC power as just DC power at any one moment in time. We all know that current reverses 60 times a second and has zero volts/current 120 times a second. Your amp, etc. is not at the end of the power chain but is actually at the center of it in series. Any non-linear defect in this series circut with all the starting and stopping before we even consider the changes of modulating this current with music is an arithmetical mess. Consider that each connection is not just a little resistance but also has a diode effect with current flowing better in one direction than another. And we havent even gotten to your Wi-Fi impressing it's signal onto the house wiring acting as an antenna. Mind boggling, Mike
I can speak from experience about the effects of the quality of the power on the performance of your gear.

Back in the late 1990's I moved into a brand new home, but in an older subdivision.

I had Quad 63 and Meitner mono block power amps.

During my first summer my amps shut down.

I sent them to Ed,he fixed them, sent them back, and in the next day or so, they shut down again.

He said there was nothing wrong with the amps, and that I should consult my power provider.

To make a long story short,a new transformer was attached to the pole and I never had another issue with the amps shutting down.

The sound also improved,things opened up, it was faster,more detail, all the good stuff.

It was around this time that I replaced my power cords going to the Quads with DIY made from 12 guage Romex.

How much of an improvement was that?

The fellow who bought my Quads asked if the DIY power cords were also for sale.

It was ten years later or more that a friend of mine got into balanced power and upgraded power cords and dedicated lines.
I heard what they did to improve his sound which was already much better than mine, and much more expensive.

His system did things that mine was incapable of doing.

It got out of the way of the music.

I've since implimented many of his power upgrades and added a few others like designer fuses to the mix.

The results are that eventhough I have a complete system that doesn't cost as much as his Scarlatti digital set up does, I have narrowed the performance gap .

For me I don't wonder why or how this should be, it is what it is.
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
Bryon, it only seems absurd to the folks who are content with the kind of sound they get with stock fuses, no power conditioning,dime store multi plug outlets and everything plugged into a one buck wall receptacle.

They laugh at what we spend to improve the power, yet they aren't getting the sound from their gear that they paid good money for.
They would rather flip amps and gear on a continuing basis,never having really heard the gear they own running the way it should.

I was fortunate to hear the results of power upgrades in my friend's system, and then followed suit with the same results-improved sound with the gear I already have.

I didn't have to spend another 10 grand for a new power amp, I made my old one sound like the ten grand amp for a lot less money.
Why spend thousands when all you have to spend is a few hundred in the right places.

That's absurd to me.
"They laugh at what we spend to improve the power, yet they aren't getting the sound from their gear that they paid good money for.
They would rather flip amps and gear on a continuing basis,never having really heard the gear they own running the way it should."

Agree clean power only helps and it can be a very cost effective tweak.

I would not go so far as to say that all power related tweaks are necessarily good nor cost effective though.

Like everything involving technology, usually, the devil is in the details. Many may not understand what works and what doesn't when it comes to clean power and shy away. Others that are more educated on the topic probably do.

Buying and selling used certainly can help take a lot of the risk out of trying something just to see even if you have no idea what to expect.