Click title to read one, or click date to read all below it.
04-24-12
Bryon, when you speak of power quality, i assume you are tal ... Jmcgrogan2
04-24-12
All the jumbled up frequency hash in the powerline continues ... Elizabeth
04-24-12
It probably has to do with non-optimal power supplies in equ ... Onhwy61
04-24-12
3 and 4 is same as 1 and 2 - greater dynamic range requires ... Kijanki
04-24-12
i believe that several before me have already hinted strongl ... Bombaywalla
04-24-12
Hi bryon, good comments by everyone above. my take is as f ... Almarg
04-24-12
I've got several cheap furman power conditioners that i have ... Arnettpartners
04-24-12
Al as usual gave a wonderful answer to view it a bit differ ... Uru975
04-24-12
If you accept that better quality components (power supplies ... Meiwan
04-24-12
Great comments -- but what is a practical way to deal with t ... Bifwynne
04-24-12
Bifwynne - i use furman elite 20pfi, a power correcting 20a ... Kijanki
04-25-12
I recently purchased a couple of blue circle sillycone filte ... Nikki
04-25-12
The best (and simplest) explanation i have ever seen is simi ... Djohnson54
04-25-12
A further thought about power regenerators. my guess is tha ... Almarg
04-25-12
Thanks, al. you are a pleasure to read. i wouldn't be afrai ... Arnettpartners
04-25-12
Good basic point al. a solution that truly cleans or smooth ... Mapman
04-25-12
Al, i'm sure i don't have much of a choice about more dedica ... Bifwynne
04-25-12
Hi bruce, if the lights that are dimming are not on the sam ... Almarg
04-25-12
Bifwynne, new elite 20pfi is $1019 at audio advisor. i bou ... Kijanki
04-25-12
Al and kijanki, i have the complete gardner beethoven sympho ... Bifwynne
04-25-12
Al and kijanki, assuming i go forward with installing 3 or 4 ... Bifwynne
04-25-12
Hi bruce, i have no particular knowledge of an audio-orient ... Almarg
04-25-12
Thanks to everyone. some very helpful comments. i understan ... Bryoncunningham
04-25-12: Almarg
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
Almarg (System | Threads | Answers | This Thread)
04-26-12
got it. in my last post, i was just trying to limit things a ... Bryoncunningham
04-26-12
I know this may be just hype from burson audio but they are ... Nonoise
04-26-12
Since we're also discussing power line accessories, i'll sha ... Bryoncunningham
04-26-12
Hi bryon, you're not there yet, but it is by no means hopel ... Almarg
04-26-12
got it! that clears up the confusion (mine, not yours). i w ... Bryoncunningham
04-26-12
Bifwynne, i got my pf15i from audio advisor as an "ope ... Djohnson54
04-26-12
it's best to think of everything i have described in terms o ... Almarg
04-26-12
that is very helpful, al, and different from how i was thin ... Bryoncunningham
04-26-12
Has anyone tried a balanced isolation transformer such as th ... Gsm18439
04-26-12
How do you determine whether to buy a 15 amp or 20 amp power ... Arnettpartners
04-27-12
Hi lynne, what is relevant is the maximum amount of current ... Almarg
04-27-12
It seems like the characteristics i mentioned in the op -- h ... Bryoncunningham
04-27-12
Hi bryon, assuming that "noise" is interpreted br ... Almarg
04-27-12
Arnettpartners, i bought 20a version only because i suspecte ... Kijanki
04-27-12
Ok. thanks, kijanke and al. yes, no subs. i'm reading thi ... Arnettpartners
04-27-12
Kijanke, do you use the same 20a for your digital source(s)? ... Arnettpartners
04-27-12
Yes, it has 12 outlets divided into 3 banks of 4. one bank ... Kijanki
04-27-12
Yes, it has 12 outlets divided into 3 banks of 4. one bank ... Kijanki
04-27-12
Very comprehensive unit. thanks. yes, i still unplug during ... Arnettpartners
04-28-12
I unplug during thunderstorms too when i'm at home. there i ... Kijanki
04-28-12
I've seen the furmans with those tubes and never new exactly ... Arnettpartners
05-03-12
Byron, i think of ac power as just dc power at any one momen ... Cheapmike
05-16-12
I can speak from experience about the effects of the quality ... Lacee
05-16-12
Thanks for sharing your story, lacee. i have a similar kind ... Bryoncunningham
05-17-12
Bryon, it only seems absurd to the folks who are content wit ... Lacee
05-17-12
"they laugh at what we spend to improve the power, yet ... Mapman
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