The third is from europe, it has the german earth connections.
If there s a hole in side where are the plug connectors , which is not visible on the photo, it is french standard compatible....
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Which does not fit on/in a French extension cord.
(time and again i was so silly to buy one in F, got half a dozen idle in the barn. Each time i grab the wrong cord i tell myself to exchange the sockets 'tomorrow')
Answer 88.03 db. Sy you are correct it would take a really screwed up circuit scheme to get this result.
The 18ua really should be across the shield wire connecting the amplifier to the preamplifier. For the 1M cable I measured it was .052 ohms. With connectors it rises to .1056 ohms. There probably is as much resistance inside the amplifier and preamplifier so the total resistance could be .2 ohms. This would produce a hum level of -16.3db at the 12' listening position. The hum would start showing up (0db) at a 2' listening distance. That assumes a dead room. If the critical distance was less than 2' (Not really reasonable) then you would hear hum in the entire room! Of course John with his K horns would be annoyed from the start.
To make things worse there would also be some leakage current from the preamp and the other gear connected to the preamp.
So the conclusion is that leakage current from a power transformer can be clearly heard under some conditions.
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Mind you, i did simply drill a hole in the relevant side to make one
french compatible, but without earth connection, alas....
1990 Walt was in on this too. The assembly change is routinely communicated to customers. None of us heard anything and Adcom did (does) not have a listening room or so was claimed.
The offer to drive down and treat everyone to lunch was refused.
I've been reading Klipsch's paper on FM distortion in speakers.
http://community.klipsch.com/forums/storage/3/1095142/mod_dist1.pdf
Several things are clear. FM distortion in the range of under 1% is inaudible to me. This is based on my ability to discern changes in pitch, the change in a half note tone interval being beteeen 5% and 6% frequency change and my pitch resolution being between a quarter and an eighth note at best.
Sidebands representing oscillating pitch change are the result of both FM and AM distortion and cannot be distinguished. If you are going to sacrifice higher AM distortion to lower FM distortion you get nothing as a net gain.
Klipsch himself admits that using more speakers to reduce the excursion and therefore the velocity of the cone of each of them for a given SPL is a usable solution to the problem (if it actually needs to be solved at all.)
Right that the frequency change from a note to the next one is about 6%,
but the ear perceive a TUNE difference of much less, less than 1HZ variation
for a A 440HZ, for exemple..
Indeed, if you play guitar, for exemple, you surely noticed how
precise must be the tuning when two instruments are playing.
I can't agree with you there, that's less than 0.25% or less than a fiftieth of a half note. There's been debate as to whether orchestras should tune to concert A at 440 or slightly higher to 444. Can you tell which of your recordings are tuned to which? One trick some violinists use is to tune slightly higher than an orchestra if they are playing a concerto. That's to "cut through" the orchestra. String inststruments and human voice in particular are difficult to repeat intonation on that closely. And there is almost invariably some vibrato, often deliberate. BTW, if you think Barbara Streisand sings on key....you don't have to worry about FM distortion.
I can't agree with you there, that's less than 0.25% or less than a fiftieth of a half note. There's been debate as to whether orchestras should tune to concert A at 440 or slightly higher to 444. Can you tell which of your recordings are tuned to which? One trick some violinists use is to tune slightly higher than an orchestra if they are playing a concerto. That's to "cut through" the orchestra. String inststruments and human voice in particular are difficult to repeat intonation on that closely. And there is almost invariably some vibrato, often deliberate. BTW, if you think Barbara Streisand sings on key....you don't have to worry about FM distortion.
The 440/444 debate is irrelevant in respect of the discussion,
but if there were no perceptible difference between these two
frequencies, the said debate would be useless.
The reason a violonist can pitch slightly higher, and remember,
no more than 0.3 hz in reference to 440, is that the instrument tend
to detune with rising temperature of the room , by usual thermal
dilatation of the strings.
Moreover , a very slight positive (higher) pitch is less uncomfortable
to the ear than a negative tuning.
As for the human ear pitch resolution, you seems to not know
the true story, and instead, you present your (uncomplete)
knowledge in that matter as a reference.
For the record, i practice music for more than 30 years,
be it alone or with fellow musicians, and not the kind of
music where everything is saturated.....
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/earsens.html
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I wouldn't necessarily extrapolate steady state pitch change to FM. For a small symetrical modulation the average frequency is unchanged. A DC pitch shift by a speaker would violate causality unless it (or you) was moving by on a train.
AM and FM sidebands can be somewhat separated by phase. Certainly a symbolic solver like Maple could give an answer for small modulations.
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"The normal human ear can detect the difference between 440 Hz and 441 Hz."
I'd like to see a reference to at least one scientific paper by a respected source where a double blind test was performed before I accept that as fact. I don't think I could hear it.
"AM and FM sidebands can be somewhat separated by phase."
And can they be separated by ear to? Would you know if you are hearing sidebands due to FM or AM modulation distortion by listening to it?
Out of curiosity, i just made a test now with a signal generator.
It s clearly audible, and i don t think i have an ear as good as
first rate musicians..
That you do not hear it doesnt mean that others can t as well.
Quote from wikipedia :
Pitch is a subjective sensation in which a listener assigns perceived tones to relative positions on a musical scale based primarily on the frequency of vibration. The just-noticeable difference (jnd, the threshold at which a change is perceived) depends on the tone's frequency and is about 4.3 cents (1 cent = 1 hundredth of a semitone) or about 0.36 Hz in frequency within the octave of 1,000–2,000 Hz but within the octave 62–125 Hz the jnd is much coarser with some 40 cents or about 2 Hz between perceived pitch changes.
http://en.wikipedia.org/wiki/Pitch_(music)
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Do a little bit of searching, it's not very difficult.
For anyone curious, that pitch ratio (440/441) is about 4cents. Here's a nice check on whether or not you can REALLY hear that: Audible Difference in Pitch Blind Test
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