Re: Two interesting projects
Thank you Brian.? I knew about the different number of strings but this the first time I've seen it explained.? Fascinating.?
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Re: Two interesting projects
Hello Jeff, Though J S Bach set up the equally-tempered scale in about 1720,
he did not establish the basic pitch of instruments. The beauty of the
equally-tempered scale is that when a piece of music required several keys, the
musicians did not need separate instruments or to retune for each key change.
However, when bands of musicians or orchestras travelled to other auditoria, in
their own countries or overseas, if they were accompanying a local impresario,
such as a pianist or organist, the whole orchestra would need to retune to the
local pitch. In the 18th and 19th centuries, ‘Standard
pitch’ varied between 420 and 450 Hz.?
For some brass instruments tuned to the higher pitch, there just
wasn’t enough tubing to reach the lower, local ‘standard pitch’. Take for instance
a trumpet designed for A = 450 Hz; its total length from mouthpiece to the end
of the bell would be about 50” (1.28 m). To retune to A =420 Hz, the tuning
slide would need to be extended about 1.8” (nearly 45 mm). Not all instrument
makers allowed for this much retuning. There were worse problems for some
stringed instruments whose strings and tuning pegs had been designed for the
local standard pitch range. Establishing an international standard pitch made
music production, international travel of musicians, and musical instrument
manufacture much easier. Nonetheless, there are still groups of string players
who will only play instruments designed for the original ‘classical pitch’ of A
= 422 Hz.?
On my piano, the upper 60 notes (soprano and tenor) have three
strings each , the next lower 20 (alto) have two strings each and the 8 lowest
(bass) notes are produced by just one string per note. The pitch of each string
is determined by its length, its mass per unit length and the string’s tension
– remember the f = √(k/m) formula? When pianos were first produced they had
just one string per note. So, the piano’s harp was very long to accommodate the
bass notes, perhaps 8 to 10’. To reduce the size of the harp, in the late 19th
century, piano manufacturers wound copper around the steel inner string to
increase the mass per unit length of the bass notes and some of the tenor
notes. Such over-winding increased the vibrating area of the string thus
lowering the impedance mis-match between the surrounding air, the sound board
and the human ear. As a first approximation, when the hammer velocity is kept
constant, the loudness of a piano note is determined by its vibrating area. So,
the over-wound lower notes started to sound much louder. To get a more balanced
loudness throughout the piano’s range, piano manufacturers added more strings
per note in the upper ranges. This increases the amount of air vibrated. One
manufacturer, Bosendorfer, employs four strings per note in the upper register.?
Fender, with its Rhodes piano, used a normal grand piano action
with the hammers striking one steel tuning fork per note. Adjacent to the free
end of each tuning fork there was a pickup coil whose electrical signal was fed
to a preamplifier with suitable electronic filtering to ensure even loudness
throughout the piano’s range. (I’ve used the past tense because I dealt with
Fender Rhodes pianos over 50 years ago – Fender may have changed the design
since.)?
The usual way string players achieve harmonics is by lightly
touching the string, not pressing the string hard down on the finger board
(violin family) or fret board (guitar). If you play a fretless acoustic guitar,
you can achieve any pitch you want, including the disharmonious ones.?
Cheers, Brian, VK2GCE
Brian Clarke BE, MBA, PhD, CPEng,?APEC Engineer, IntPE(Aus),?FIEAust?
From: [email protected]
[mailto:[email protected]] On Behalf Of Jeff
Green
Sent: Friday, 25 November 2022 3:59 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Two interesting
projects
?
To the group owner, sorry about
the thread drift, we are getting way down in the weeds.
?
Thank you for clarifying that. <snip>
?
Your explanation makes perfect
sense.
[For extra credit, read the Treaty of Versailles , it has a codicil specifying the
frequency for either middle A or C. I remembered that from the one required political
science class I took as an undergrad.
I'm still not sure how setting an international standard for A or C had anything
to do with WWI.]?
I “play” guitar, acoustic and I’m
mainly into folk music. You’d have to have much longer fingers then I to
produce those “disharmonious” harmonics.
?
Since you tune your piano,
perhaps you can answer this question.
Why
does each note have 3 strings?
Email sent using Optus Webmail
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Re: Two interesting projects
The issue on HF is how to generate flat “white” noise , band limited to 2-32 or 2-60 MHz with? notch(s) at some ham bands of sufficient depth to be at least 10 db better than the best NPR you want to see. ? I know it can be done with a very expensive AWG.? Does anyone have a good enough D/A for such? ? Lester B Veenstra? K1YCM? M?YCM? W8YCM?? 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1) lester@... ? 452 Stable Ln Keyser WV 26726 USA ? GPS: 39.336826 N? 78.982287 W (Google) GPS: 39.33682 N? 78.9823741 W (GPSDO) ? ? Telephones: Home:????????????+1-304-289-6057 US cell??????????+1-304-790-9192 Jamaica cell:??? +1-876-456-8898 ?
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From: [email protected] [mailto:[email protected]] On Behalf Of tgerbic
Sent: Thursday, November 24, 2022 6:12 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Two interesting projects? While the terms total harmonic distortion or just harmonic distortion pop up pretty regularly. I seldom hear intermodulation distortion discussed or tested with audio or HF amplifiers.? It too is an interesting area to test. I was reading articles about IM distortion a few years ago and ran across this youtube demonstration of IM distortion. While shown with a huge amount of distortion added to the sound, it really drives home what IM is and how it affects a signal passing through a circuit with distortions or imbalances. Seeing it on a spectrum analyzer or scope screen does not provide the same impact.
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Re: Two interesting projects
>? It was loud.? The magic smoke came out of the speakers.
They were just ahead of the tech.?
Modern active speakers have IEC inlets and I guess even ethernet signal inputs.?
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Re: Two interesting projects
Although a bit OT there is a history? to Harmonic Distortion and
Inter Modulation Distortion? measurements. The major need for
distortion measurements was in sound reproduction, the transducers
were often the weak links. HD was easy, a low distortion source
and a very sharp notch filter was simple to implement. The sine
signal? was filtered out completely leaving the distortion and
noise which was then expressed as a ratio to the un-notched
signal.
When audio waves were recorded on disc or on film ( from the
start of the talkies) there was a lot of wow and flutter which
frequency and phase modulated the sine wave carrier so it was
impossible to notch out all of the tone energy now spread each
side of the carrier.
So the SMPTE came up with intermodulation testing, a high
frequency carrier was added to a low frequency ( 50 or 60 Hz)
signal and sent through the recording system. The LF signal was
removed by high-pass filtering and the high frequency tone was
then demodulated as an amplitude modulated signal, low pass
filtered to eliminate the carrier and then displayed as IMD.
There is a subtle difference between the tests, HD depends on
notch depth, ideally at least 20dB below the lowest HD to be
indicated so even with 0.1% distortion the notch should be at
least 80dB down, this is quite deep! Automatic balance bridges
were produced to avoid manual twiddling.? The HD measurement is a
"Whole Wave" one, the distortion waveform gives some data on where
the distortion is happening in the time domain.
IMD measurements normally use a large LF tone and around a
quarter amplitude HF signal. Essentially the LF signal sweeps the
HF carrier through the transfer characteristic of the system,
local changes in slope modulate the carrier amplitude so again the
recovered IMD can be related to the transfer curve.
Now that we can easily do spectral curves using accurate ADC's
and FFT's it is easy to plot the harmonic structure of the
distortion products. By using very narrow bandwidths and averaging
it is possible to reach much lower levels than earlier methods
which had much broader measurement bandwidths.
There was a unique early method that could be used with inverting
amplifiers, the amplifier output was nulled against a sample of
the input signal by very careful attenuation and phase adjustments
leaving the distortion residuals. This had the advantage of being
relatively frequency insensitive and very simple.
As for the audibility of distortion, I would never underestimate
the superpowers of some to hear the inaudible. There are people
who claim they can hear the difference between very good
operational amplifiers yet it is very probable that they could not
detect 1% second harmonics nor could they tell the difference
between sine and square short tonebursts.
Regards, Alan G8LCO
?
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Re: PCB making software, What do you use?
FWIW, years and years ago (version 4, I think) the Eagle folks were kind enough to give me the 4-layer, 4x6 license for the $150 "hobbiest" price because I was designing products for a non-profit group. However, when AutoCad switched to the subscription model, they said I had to pay the full "professional" (or whatever it's called now) subscription fee.
I can't really complain because I got years of use out of that inexpensive license, but the full-bore subscription cost plus my dislike of subscription software in general pushed me to KiCad. And I haven't really looked back -- particularly since KiCad now does a reasonably decent job of importing Eagle files (But for the old Eagle format, you have to use Eagle 7.x to convert to the new format, then import to KiCad. Annoying, but it works.)
John
----
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On 11/24/22 21:17, Harvey White wrote: For the sake of explaining this (a bit) in terms of EAGLE:
The original license for "standard" (also known as "free") was two layers, one sheet of schematic, maximum of 4 by 3 board (half of a eurocard).? No others need to apply.
The professional license was (IIRC), 6 to 8 layers, 4 by 6 inch board, multiple sheets of schematic.? This was also the hobbiest (mine) license, with the restriction that the design not be used in any way for profit.
The "unlimited" license was? layers over 20, (I think) unlimited board size.
The advantage with EAGLE was that the libraries, autorouter, and tools were much the same, just limited.
No idea what they did for later versions (may be to change 4x3 to "12 square inches", but I have no idea since the versions 8 and up are on a subscription model.
My 7.x license is still valid, and remains without any extra charge.
I suspect that many "for profit" products have similar limits.
Harvey
On 11/24/2022 8:59 PM, Radu Bogdan Dicher via groups.io wrote:
I think it's pretty clear in the "semi-pro," "turbo hobbyist" market KiCad is by far, currently, the norm.
I'm not sure what challenges other programs bridge in the "actual pro" market - making the expense (whatever $ value that may be) worthwhile - but I just assume there must be some gaps needing bridging.
Radu.
On Thu, Nov 24, 2022 at 3:43 PM Morris Odell <vilgotch1@...> wrote:
I used? Protel Easytrax with a DOS emulator for many years but now
I've moved to Sprint PCB. It's not free but not too expensive
either and produces Gerber files that can be sent to a PCB
fabrication service. It has a comprehensive library and you can
also make custom templates for new devices etc.
All new software requires a learning curve of some sort and Sprint
wasn't too hard to get into. There's also a user group on
groups.io <> but traffic is very low.
Morris
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Re: PCB making software, What do you use?
For the sake of explaining this (a bit) in terms of EAGLE:
The original license for "standard" (also known as "free") was
two layers, one sheet of schematic, maximum of 4 by 3 board (half
of a eurocard).? No others need to apply.
The professional license was (IIRC), 6 to 8 layers, 4 by 6 inch
board, multiple sheets of schematic.? This was also the hobbiest
(mine) license, with the restriction that the design not be used
in any way for profit.?
The "unlimited" license was? layers over 20, (I think) unlimited
board size.
The advantage with EAGLE was that the libraries, autorouter, and
tools were much the same, just limited.
No idea what they did for later versions (may be to change 4x3 to
"12 square inches", but I have no idea since the versions 8 and up
are on a subscription model.
My 7.x license is still valid, and remains without any extra
charge.
I suspect that many "for profit" products have similar limits.
Harvey
On 11/24/2022 8:59 PM, Radu Bogdan
Dicher via groups.io wrote:
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Show quoted text
I think it's pretty clear in the "semi-pro," "turbo
hobbyist" market KiCad is by far, currently, the norm.?
I'm not sure what challenges other programs bridge in the
"actual pro" market - making the expense (whatever $ value
that may be) worthwhile - but I just assume there must be some
gaps needing bridging.?
Radu.?
On Thu, Nov 24, 2022 at 3:43
PM Morris Odell < vilgotch1@...>
wrote:
I
used? Protel Easytrax with a DOS emulator for many years but
now I've moved to Sprint PCB. It's not free but not too
expensive either and produces Gerber files that can be sent to
a PCB fabrication service. It has a comprehensive library and
you can also make custom templates for new devices etc.
All new software requires a learning curve of some sort and
Sprint wasn't too hard to get into. There's also a user group
on but traffic is very
low.
Morris
|
Re: PCB making software, What do you use?
I think it's pretty clear in the "semi-pro," "turbo hobbyist" market KiCad is by far, currently, the norm.? I'm not sure what challenges other programs bridge in the "actual pro" market - making the expense (whatever $ value that may be) worthwhile - but I just assume there must be some gaps needing bridging.? Radu.?
On Thu, Nov 24, 2022 at 3:43 PM Morris Odell < vilgotch1@...> wrote: I used? Protel Easytrax with a DOS emulator for many years but now I've moved to Sprint PCB. It's not free but not too expensive either and produces Gerber files that can be sent to a PCB fabrication service. It has a comprehensive library and you can also make custom templates for new devices etc.
All new software requires a learning curve of some sort and Sprint wasn't too hard to get into. There's also a user group on but traffic is very low.
Morris
|
Re: Two interesting projects
On Wed, Nov 23, 2022 at 03:58 PM, Jeff Green wrote:
A friend showed me a crazy ad for adapters to convert the wires from the speaker out to a NEMA 5-15P and adapters to convert NEMA 5-15R at the other, the idea being you’d use a heavy duty extension cord.
I have visions of some guy connecting his power amp or speakers the AC mains...with interesting consequences.
When I was in my early teens, so nearly 55 years ago, some friends had a band and used those for the PA system speakers, with precisely the consequences you envision.? I? was there when it happened.? It was loud.? The magic smoke came out of the speakers.
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Re: Two interesting projects
Hi, ? There was a video that was published four days ago by an Group of Audio Engineers (SMWTMS). It has some information in it that is interesting about Power Amplifier Bias settings, Distortion Measurements and opinions on hear-ability of different types of in-phase harmonics and out-of-phase harmonics Distortion (at the end of the video). ? They used an HP 339A Distortion Analyzer and a cascaded HP 3582A FFT Analyzer to make measurements. ? The title of the video is: Distortion at Low Levels in Power Amplifiers? Might be of interest to this topic. ? ? ? ? Ross ? ? ?
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From: [email protected] < [email protected]> On Behalf Of tgerbic Sent: Thursday, November 24, 2022 4:12 PM To: [email protected]Subject: Re: [Test Equipment Design & Construction] Two interesting projects ? While the terms total harmonic distortion or just harmonic distortion pop up pretty regularly. I seldom hear intermodulation distortion discussed or tested with audio or HF amplifiers.? It too is an interesting area to test. I was reading articles about IM distortion a few years ago and ran across this youtube demonstration of IM distortion. While shown with a huge amount of distortion added to the sound, it really drives home what IM is and how it affects a signal passing through a circuit with distortions or imbalances. Seeing it on a spectrum analyzer or scope screen does not provide the same impact.
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Re: Two interesting projects
Speaking of speakers, I looked into why Bose speakers were so popular over the years.? They are nothing great when it comes to music reproduction. So why have they always sold well? Turns out the appeal is that many people have an expectation of what the music should sound like, which generally has a bit more base and treble than normal and Bose speakers color the sound in these areas, I think by design.? So when most people hear music through them it sounds like they expect it or want it to sound.?
All this audio stuff is subjective and that is why most people don't get the search for music reproduction perfection. Perfectly reproduced sound may not be that appealing.
And, as many have pointed out, humans may be able to tell if a note is off my a hertz (some of us singers and musicians can often tell with a little more precision), but most cannot or don't notice a small amount of distortion. So how low of a distortion is practical in the design of an amplifier?? If an engineer needs to amplify a signal, usually an instrumentation amplifier is used, not a stereo amp so ultimate perfection does not have to be a goal.
The thing about power cords has always just been marketed to the non-technical, and I cannot blame some manufacturers/dealers. It is extra profit in a tight marketplace and some will fall for the pitch.? Same with speaker cables. It is not that hard to demonstrate the physics and electrical characteristics of speaker cables, but in the end 99.9% of people in blind tests cannot tell the difference between cables. It is mostly a problem with the speakers attached, hiding any benefit that might be there. This have been demonstrated since the 70s, but the debate just won't stop.
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Re: PCB making software, What do you use?
I used? Protel Easytrax with a DOS emulator for many years but now I've moved to Sprint PCB. It's not free but not too expensive either and produces Gerber files that can be sent to a PCB fabrication service. It has a comprehensive library and you can also make custom templates for new devices etc.
All new software requires a learning curve of some sort and Sprint wasn't too hard to get into. There's also a user group on groups.io but traffic is very low.
Morris
|
Re: Two interesting projects
While the terms total harmonic distortion or just harmonic distortion pop up pretty regularly. I seldom hear intermodulation distortion discussed or tested with audio or HF amplifiers.? It too is an interesting area to test. I was reading articles about IM distortion a few years ago and ran across this youtube demonstration of IM distortion. While shown with a huge amount of distortion added to the sound, it really drives home what IM is and how it affects a signal passing through a circuit with distortions or imbalances. Seeing it on a spectrum analyzer or scope screen does not provide the same impact.
|
Re: Two interesting projects
When I was stationed in Alaska in the '70s, the highly over specced stereo equipment from Japan was hitting the market. People made fun of my Harmon Karon 45 watt receiver, while boasting of their four or five hundred watt Sansusi or Pioneer equipment. One morning I was sick of the noise, so I turned my system up to near maximum. Our Captain heard it through the concrete floor of our barracks, and made everyone turn their stereos off. Never piss off an engineer who works with audio and video for a living.
A few years later, I installed a PA system for high school football games, at a rural school It was heas almost five miles awa, with just a 60W amplifier.
On Thu, Nov 24, 2022 at 10:34 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote:
As for battles in the audio world, look up speaker cables. There is more smoke, mirror, and snake oil then any political campaign in history.
I don’t know about other countries, but here in the UK it is used to be quite common to talk of “dumb blondes” For some reason blonde women are considered particularly dumb. The term is not used so much now.
I used to work with a blonde girl who wanted to buy a Hi-Fi system. Since it was very near to where we worked, she went to Tottenham Court Road in London to buy the system. The road had a particularly large number of shops selling Hi-Fi systems.?
The sales guys in the stores see her as a dumb blonde. They came out with a lot of convincing technical mumbo jumbo. What they didn’t realise is that the blonde girl had a Ph.D in physics, and wasn’t as dumb as they expected.?? Their huge power ratings in watts, as well as advice on uni directional speaker cables just amused her.?
Dave?
Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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Re: Two interesting projects
As for battles in the audio world, look up speaker cables. There is more smoke, mirror, and snake oil then any political campaign in history.
I don’t know about other countries, but here in the UK it is used to be quite common to talk of “dumb blondes” For some reason blonde women are considered particularly dumb. The term is not used so much now.
I used to work with a blonde girl who wanted to buy a Hi-Fi system. Since it was very near to where we worked, she went to Tottenham Court Road in London to buy the system. The road had a particularly large number of shops selling Hi-Fi systems.?
The sales guys in the stores see her as a dumb blonde. They came out with a lot of convincing technical mumbo jumbo. What they didn’t realise is that the blonde girl had a Ph.D in physics, and wasn’t as dumb as they expected.?? Their huge power ratings in watts, as well as advice on uni directional speaker cables just amused her.?
Dave? -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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? Elektrotanya has the manuals: ? ? ? ? ? ? This is an older Q-meter M5 of FERISOL ? ? ? ? ? Also, the following sites contain the manual: ? ? ? ? ? ?
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This might be of interest to the group. ? ? ? ? ? ? Is Ferisol M803 ~ HP160 ??? ? Excerpt: D’ailleurs ce Qmetre Ferisol a été copié et automatisé dans les années 75 ans par Hewlett Packard. Moreover this Qmetre Ferisol has been copied and automated in the 75s by Hewlett Packard. ? ? ? Manual with circuit diagram, info about the thermocouple and a light design solution, etc. ? Jigs for measuring losses ? ? Ref coils for M803: ? Jeu de bobines étalonnées?FERISOL Jeu N°960 14 bobines de 0,1?H à 20,64mH Q de 170 à 322 Livré sur son plateau de laboratoire Ferisol M621B?? 25,5 cm x 39 cm 
Poids de l'ensemble 4,5 Kgg 
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?
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Re: Two interesting projects
Hello Jeff,
?
Say we take the generally agreed value of A = 440 Hz as an
example.
Thanks to J S Bach, equally-tempered notes are 12th root
of 2 apart, ie, 1.059463…. This is the frequency ratio between half-tones, also
known as semi-tones.
The 2nd harmonic of A 440 is 880 Hz,
and the 4th harmonic is 1760 Hz. The 2nd and 4th
harmonics will be perfectly in tune with equally-tempered notes.
The 3rd harmonic of 440 Hz is 1320 Hz.
The 7th half-tone above A 880, in the equally-tempered scale is E, 1318.51
Hz. This is 1.49 Hz flat compared with the 3rd harmonic of 440 Hz
(1320 Hz). A good musician might hear that the 3rd harmonic is flat.
The 5th harmonic of 440 Hz is 2200 Hz.
The 4th equally-tempered half-tone above A 1760 Hz is C#, 2217.46 Hz.
So, the 5th harmonic of A 440, at 2200 Hz, is 17.46 Hz flat compared
with the equally-tempered note. It is about 1/7th of a half-tone
flat. Any good musician would hear that the 5th harmonic is flat.
The 6th harmonic of 440 Hz is 2640 Hz.
The 7th equally-tempered half-tone above A 1760 is E, 2637.02 Hz. So
the 6th harmonic is nearly 3 Hz sharp. The un-musical among us might
accept that; a good musician should pick it.
The 7th harmonic of 440 Hz is 3080 Hz.
The 10th equally-tempered half-tone above A 1760 Hz is G, 3135.96 Hz;
this note is 55.96 Hz sharp, while the 9th half-tone, F#, 2959.95
Hz, is 120 Hz flat. So the 7th harmonic is about 1/3 of a half-tone
above F# and 2/3 of a half-tone below G. This harmonic is referred to by jazz
players as a ‘blue note’, and is mucho desafinado. It is easily achieved
on such stringed instruments as unfretted guitar, violin, viola, cello and
bass, and on such blown instruments as trumpet, trombone, French horn, and Sousaphone.
It is very difficult to achieve on fixed-tuned instruments such as piano,
glockenspiel, harp, clarinet, bassoon, oboe and saxophone.
?
In summary, all harmonics to the power of 2 (2, 4, 8, 16 …) will
be in tune compared with equally-tempered notes. All other harmonics will be
sharp or flat.
?
When I tune my piano, I listen for a beat for about 13 seconds;
in other words, I’m listening for pitch variations of the order of 1/13th
of 1 Hz. A professional piano tuner, if asked to do ‘fine tuning’ will take
twice as long waiting for a beat.
?
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On Nov 23, 2022, at 15:58, Jeff
Green <Jeff.L.Green1970@...> wrote:
?
I forget which, I’ll
have to ask my daughter, she is a classically trained pianist.
Going from a faulty
memory, the 5th harmonic of an even tempered note is either sharp or
flat and considered “disharmonious.” I remember the word when our daughter was
studying theory because I thought it such an odd word.
?
<snip>
?
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Re: Two interesting projects
Jeff,
Loved it, I love to hear the sales types at the box stores rant on about the need for monster cables etc.
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On Nov 23, 2022, at 15:58, Jeff Green <Jeff.L.Green1970@...> wrote:
? I forget which, I’ll have to ask my daughter, she is a classically trained pianist.
Going from a faulty memory, the 5th harmonic of an even tempered note is either sharp or flat and considered “disharmonious.” I remember the word when our daughter was studying theory because I thought it such an odd word.
?
As for battles in the audio world, look up speaker cables. There is more smoke, mirror, and snake oil then any political campaign in history.
There are people selling special ceramic devices to lift the speaker cables off the floor.
Others sell cryogenically treated copper, some oxygen free (which means it has more iron) and some with other exotic treatments.
?
My favorite is a CD break in disk…
?
A friend showed me a crazy ad for adapters to convert the wires from the speaker out to a NEMA 5-15P and adapters to convert NEMA 5-15R at the other, the idea being you’d use a heavy duty extension cord.
?
For our members who aren’t in the USA or Canada, a NEMA 5-15 is the standard 3 pin AC power connector, R being receptacle, P being plug.
?
I showed the ad to the master electrician who is doing some work for us and he started cursing like a sailor on a 3 day bender.
?
[No I will not provide a link. Let those who wish to injure themselves do their own search.]
?
These adapters violate the National Electric Code; the NEC is now codified as law in every state in the USA.
?
I have visions of some guy connecting his power amp or speakers the AC mains...with interesting consequences.
?
Another snake oil sale pitch is special purpose power cables. The AC mains passes through so many miles of transmission line, transformers, etc, that magical thinking a 6 foot special power cord will be of any help is silly.
?
Since most of us have solid copper wire running from the load center (electrician speak for fuse or breaker panel/box) to the power outlet, I’m puzzled why anyone would expect a magic power cord to help.
?
Some of these magic cables a are 10AWG, very large, high current capacity, but most residential circuits are wired for 120V 15A with a few 120V 20A.
Some have all sorts of fancy weaving.
AWG 14 meets NEC requirements for 20A.
I’m not sure any standard AC outlet would accept 10AWG on the power side.
?
I routinely peruse some of the ‘audiophile’ pages for giggles. It is nice to see people who know less them me.
?
And these pdfs are mandatory reading for anyone who needs a giggle.
Hand soldered?
Sure it works nicely, Class A and all but really? There are easier, way less expensive ways to achieve the same performance.
I’ve started a “Now that is foolish” subdirectory just to store some of the nonsense.
[joking!] And you slackers trying to built the perfect Q-meter must bow to true fanaticism.
I am no expert, but, the head of the instrumentation and measurement lab told me that low THD almost always means low IMD and high THD almost always means high IMD.
I’m still trying to wrap my head around TIM.
?
An EE friend used a circuit based on these two pages...
?
?
....to demonstrate just how horrible the audio power IC is in the Kenwood R-2000.
?
I’d have thought after a radio signal has been refracted by the ionosphere it would be messed up enough a little more distortion wouldn’t matter. I was wrong. I guess every bit of distortion degrades intelligibility.
?
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Re: Two interesting projects
Jeff,
?
Loved it, I love to hear the sales types at the box stores rant on about the need for monster cables etc.
?
Steve, KC4SW
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Brian
Jim Allyn - N7JA
Michael A. Terrell
Dr. David Kirkby, Kirkby Microwave Ltd