http://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2004/October/Experimental_Demo.pdf
IMO the damage is done. Pavel spelled the magic words: “mediocre cables”
George
Thank you.
The bottom drawing depicts an IC in parallel with a solid grounding path such as the safety bonds of the line cords.
This discussion also holds for the internal supply rails of a power amp. Anytime the rails carry current to the pass transistors, and from the pass transistors to the output connection and then returns to the supply via a physically distant star ground, that loop will communicate with the chassis metal, the star ground reference to circuitry, etc. If it communicates with the chassis metal, then THAT can setup a mechanism where external grounding lines like the rca's and the IEC will close a loop. No time to draw it, gotta go pretend I know what I'm talking about..
jn
Huh? What do you mean? A star ground, aren't they too hot? Or do you mean another Elvis? (Oh wait I guess that is a star in the ground.)
In an audio power amplifier the power supply busses not only can impose unwanted voltage on circuit commons, they also have a magnetic field that can impose currents in lots of nasty places. When i get the chance next week I might even post pictures. (Sorry non-pornographic!)
cite please?
from the psychoacoustic book I have, other masking graphs - I don't see how this is possible for harmonic distortions (harmonics == above in frequency)
maybe for a lower frequency tone below a high frequency masking tone/noise band - but not with the masking tones/noise lower in frequency with 100 dB SPL for the test tone/harmonic distortion to be "below"
because for higher, >80 dB SPL, levels the upward masking threshold flattens out, "wipes out" sensitivity to low level tones with frequency above the masker with a far shallower slope than for low level, <60 dB SPL, masker or test tones at lower frequency
only extreme IMD example with excitation tones above any conventional (tonal) musical instrument fundamental frequencies could produce audible low frequency artifacts -100 dB re the stimulus in downward difference IMD tones - say the 19+20 kHz CCIF test
from the psychoacoustic book I have, other masking graphs - I don't see how this is possible for harmonic distortions (harmonics == above in frequency)
maybe for a lower frequency tone below a high frequency masking tone/noise band - but not with the masking tones/noise lower in frequency with 100 dB SPL for the test tone/harmonic distortion to be "below"
because for higher, >80 dB SPL, levels the upward masking threshold flattens out, "wipes out" sensitivity to low level tones with frequency above the masker with a far shallower slope than for low level, <60 dB SPL, masker or test tones at lower frequency
only extreme IMD example with excitation tones above any conventional (tonal) musical instrument fundamental frequencies could produce audible low frequency artifacts -100 dB re the stimulus in downward difference IMD tones - say the 19+20 kHz CCIF test
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Just try 20 hertz and 4000 hertz. I think you read the sentence differently than I did. Fletcher Munson shows 75 db 20 hertz/-5 db 4000 hertz at 10 dbC re 1,000 hertz being equal volume, add even 30 db critical band discrimination for 110 db. Now move up to 60 hertz and see at least 90 db should be detectable.
I have a nice example of a narrow rectangular ground plane that a current path on one narrow end shows up on the other end!
In these examples if there is no masking energy in the signal anywhere near 4000Hz what is making the unwanted distortion (in the context of real music listening). The detection threshold of a 4000Hz tone in the presence of a 20Hz tone is sort of academically interesting.
the plots I can find don't go that low - but figure 12 http://faculty.plattsburgh.edu/roger.hamernik/CDS_344/PDF_Files/Auditory4.pdf
looks like there has got to be some considerable "hook" to the curve to reach 100 dB for the 2nd graph 2 kHz masking tone curve
to do this at home I'd need to reinstall my ESI Juli@, use my etymotic iem - with my Bose QC noise canceling over the top to get the dynamic range over motherboard sound, home heating, fans, refrigerator...
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You are missing the issue. If you record a pipe organ that can have a 20 hertz or so pipe, this will not be reproduced by virtually any sound system accurately. However if the energy is recorded and you have this create a distortion product at 4,000 hertz, the distortion will be heard at even more than 100 db down from the recorded level of the 20 hertz note. This will be much more than 100 db down from the reproduced level.
Now if each stage of the recording, distribution and reproduction system adds harmonics to the prior stages harmonics you can actually reach the threshold.
More common appears to be the interaction of power supply noise and the reproduction chain.
Attached is how...no further explanation given... no more fodder for trolls.
Attachments
you have to be kidding or smoking the good stuff - the only way I can see for (really, really terrible) audio amplifying electronics to create 200th harmonic is to deliberately introduce a deadband/clipper
for instance a >20 year old fet op amp, one step up from TL07x, wrapped around a Unbiased complementary follower stage:
and that incredibly badd example's spray is >120 dB down from even consumer line level:
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First stage just 1 % 2nd harmonic
Second stage 2% 2nd and .01% 4TH!
Third stage 3% 2nd, .02% 4th and .0001% 8th
Fourth stage 4% 2nd, .03% 4th, .0002% 8th and .00001% 16th
Fifth stage 5% 2nd, .04% 4th, .0003% 8th, .00002% 16th and .000001% 32nd
Sixth stage 6% 2nd, .05% 4th, .0004% 8th, .00003% 16th,.000002% 32nd and .00000001% 64th
Now 1% 2nd harmonic you probably won't hear but after 6 stages you are going to hear it.
And yes harmonics don't really add linearly, sometimes they can and sometimes they grow faster due to gain and bandpass limits.
Now stage gain distortion is overstated here, but there are many other points of ingress to add distortion.
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I'm begining to realise that one way of assessing the quality of ones audio system is how clearly one can hear the difference between good & bad recordings.
One reason I started out on DIY Audio is because recorded & reproduced classical music sounded so appallingly bad compared to a live concert.
Having now got my system to a reasonable level it has become apparent that the quality of many recordings is sadly lacking . . . . but not all of them.
Sometimes after listening to various poor classical recordings I begin to think that perhaps my audio is still seriously lacking and then every one in a while one comes across a real gem of a recording that demonstrates that my system is not too far off track and just how good 44.1 / 16 bit digital can be if it's done really well.
Last Night I played for the first time a CD of Handel's Messiah from Decca.
Academy of Ancient Music / Christopher Hogwood
Nelson / Kirkby / Watkinson / Elliot / Thomas
Amazon.com: Handel - Messiah / Nelson, Kirkby, Watkinson, Elliott, Thomas, AAM, Hogwood: Music
If you like this kind classical music & havn't heard this recording it's really worth checking out. It's actually worth checking it out even if you don't like it. The recording quality is amazing. I never heard a classical recording this good.
But sadly, it also highlights just how bad most of the others are. I realise now that recording technique is the major limiting factor in audio reproduction. It's frustrating. No wonder Dave Wilson used his own recordings in his demo room at the RMAF.
DF96, you seem to be arguing that it isn't worth paying attention to the minutiae of audio reproduction in the home because many of the recordings available have not had that kind of care taken with them. Well, I hear what your saying but I do not agree.
My view on this is simple. If enough members of the listening public have systems capable of highlighting the disparity of different recordings the standards will rise. Simple rules of demand & supply.
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mike, my take on this is different. I have total confidence that all, say, classical recordings can be reproduced at a satisfying level, irrespective of their recording quality - bizarrely enough, it is only some of the very latest recordings, over the last few years of so, that have really tested my confidence - and this is only because the sloppiness and lack of care by the recording engineers, at times, has become so bad.
Older recordings have not been that type of problem, but they certainly can test the integrity of the playback system, in its ability not to magnify deficiencies in the recording. So it's most certainly worth worrying about that minutiae - unfortunately the hurdle is that the closer you get to that optimum level the steeper seemingly becomes the slope you have to climb.
I'm able to say this because I've got to that level over and over again, it's always achievable - but the degree of attention to detail has to be of the highest order; the slightest lapse, anywhere, and you drop down dramatically from that level.
Older recordings have not been that type of problem, but they certainly can test the integrity of the playback system, in its ability not to magnify deficiencies in the recording. So it's most certainly worth worrying about that minutiae - unfortunately the hurdle is that the closer you get to that optimum level the steeper seemingly becomes the slope you have to climb.
I'm able to say this because I've got to that level over and over again, it's always achievable - but the degree of attention to detail has to be of the highest order; the slightest lapse, anywhere, and you drop down dramatically from that level.
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Well Frank, my system is at the stage were "good" recordings sound pretty good and "bad" recordings sound better than they used to but still pretty bad. I look forward to the time when my system makes bad recordings sound good but I'm not holding my breath.
I think it is not sensible to think that all recordings are of the same quality - it defies common sense. ( some studios have not been welding their leads
)
If all old recordings sound good. Period. Why did Dave Wilson bother to take his own recordings to RMAF.
I think it is not sensible to think that all recordings are of the same quality - it defies common sense. ( some studios have not been welding their leads
)If all old recordings sound good. Period. Why did Dave Wilson bother to take his own recordings to RMAF.
All recordings are not of the same quality - trivially obvious by listening to 1930's recordings, say. However, what the aim is to do is reduce the critical distortion, added to the mix by the playback chain, such that the mind can filter out, without conscious effort, the signature distortion contributed by the recording technology. This was something I started being able to do some decades ago, when eveything was in alignment - over the years I had a pile of CDs which "couldn't be rescued" and that pile has steadily dwindled to nothing - I always found that if I made sufficient efforts then the recording could be made to come good.
So why do people make specially good recordings? Because, a system in normal tune is just not good enough to guarantee that any particular recording will be convincing on the day - at the moment it takes a lot of dedication and focus to get a system to work at that level, consistently. Irrespective of the expertise of the designer, and the quality of manufacture - all the best brands can sound bloody awful, so easily, this is balancing on a tightrope stuff. The solutions which guarantee optimum results, every time, are just not available in the shops ... only people prepared to go the extra distance in fine tuning will be able to get it happening.
So why do people make specially good recordings? Because, a system in normal tune is just not good enough to guarantee that any particular recording will be convincing on the day - at the moment it takes a lot of dedication and focus to get a system to work at that level, consistently. Irrespective of the expertise of the designer, and the quality of manufacture - all the best brands can sound bloody awful, so easily, this is balancing on a tightrope stuff. The solutions which guarantee optimum results, every time, are just not available in the shops ... only people prepared to go the extra distance in fine tuning will be able to get it happening.
Frank,
The description of your system reminds me of when I heard Susan Parker's system with her Zeus amplifiers & Jordan JX92's set in spherical marble cabinets. Everything we heard sounded very nice indeed and somehow invoked an emotional response very readily but this was somewhat at the expense of rendering of extreme fine detail that can convey some extra character to the final sound.
If your system can accurately render very fine detail AND make bad recordings sound good then I take my hat off to you. My understanding thus far is that one has to choose between these two options and at present I am exploring the ultra fine detail option.
Happy to be corrected if my thinking is erroneous
mike
The description of your system reminds me of when I heard Susan Parker's system with her Zeus amplifiers & Jordan JX92's set in spherical marble cabinets. Everything we heard sounded very nice indeed and somehow invoked an emotional response very readily but this was somewhat at the expense of rendering of extreme fine detail that can convey some extra character to the final sound.
If your system can accurately render very fine detail AND make bad recordings sound good then I take my hat off to you. My understanding thus far is that one has to choose between these two options and at present I am exploring the ultra fine detail option.
Happy to be corrected if my thinking is erroneous
mike
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