traderbam said:
I guess he is weighting the relative importance of the harmonic N by the factor (N-1)!/2 . There has been some more discussion about similar weighting, but AFAIK it doesn't take into account any masking effects of the lower harmonics, only the (assumed) effect of the particular harmonic considered.
Jan Didden
traderbam said:
I think John can answer this best, he's been working on it as he said.
Jan Didden
It can, should and is much more accurate than this for IC design.
If you have a good simulator (not necessarily a classic PSPICE), simulation is the only way to get an IC designed without extra iterations (which is a bout the worst thing which can happen).
Even regarding setting up tolerances for production, the simulation can be trusted often much more than a small batch of real devices.
But this means that you need e.g. transistor models which are tightly in line with the actual process (adjusted to process parameters regularly) and that all the parasitics of the chip are tailored in.
I doubt that many IC designers would share their simulation models with all their secret ingredients with DIYers ...
But perhaps a little more realistic model !?? Anybody ??
The equation cited gives the relative importance of the harmonics as a general series. I would ignore 4th and 6th, but 7th is VERY important and 5th is also important.
You just take the ratios and you get BIG numbers with 7th harmonic.
A BIG hint: It is 6!/2 Please, any real engineer can work this out.
for those less skilled in math: It is 6x5x4x3 = ? Now, do your homework!
You just take the ratios and you get BIG numbers with 7th harmonic.
A BIG hint: It is 6!/2 Please, any real engineer can work this out.
for those less skilled in math: It is 6x5x4x3 = ? Now, do your homework!
Look Jon, it is all nonsense, yet necessary. Spice models, Gummel-Poon models, hybrid PI models, and Ebers-Moll models are useful, BUT reality is really something slightly different. This happens especially with distortion prediction. I have known this since 1973, when I had SPICE simulations run on my complementary differential fet input circuits. The rest here will come to learn and understand this. NOTHING beats actually accurately measuring what you are going to make.
john curl said:The equation cited gives the relative importance of the harmonics as a general series. I would ignore 4th and 6th, but 7th is VERY important and 5th is also important.
You just take the ratios and you get BIG numbers with 7th harmonic.
A BIG hint: It is 6!/2 Please, any real engineer can work this out.
for those less skilled in math: It is 6x5x4x3 = ? Now, do your homework!
John, we all know that, but that wasn't Brian's question. Relative to what?
Jan Didden
/OT for Scott:
AES Munich, next month:
T8 - Microphone History
Chair:
Jörg Wuttke, Schoeps, Technical Director Emeritus
Presenters:
Ulrich Apel, Microtech Gefell GmbH
Sean Davies, S.W. Davies
Stephan Peus, Neumann GmbH
Abstract:
This tutorial will be presented in 3 parts.
Stephan Peus' presentation, "35 Years of Microphone Development at Neumann—What Touched Us, What Moved Us," gives an insight to specific development topics and to some very special test procedures including: microphone’s transient response: insights beyond frequency response or polar pattern; RF susceptibility: already a topic before the era of mobile phones; capsule distortion measurement: difficult procedure giving a lot of interesting results; dynamic range and self noise level of studio microphones: a remarkable development within the 35 years in question.
Ulrich Apel will report on "The Importance of Vacuum for Condenser Microphones." He will speak on such topics as: the electron-tube was and is still an important step in the development of condenser microphones; the construction of special-made tubes for use in mics such as RE084k, Hiller MSC2, Telefunken AC701k, EF804, Valvo EF86, 6072, etc.; and special measuring capabilities to select tubes regarding noise, stability. and sound.
Sean Davies' presentation is "Microphone History: The Why, The How, and The Who." The developments in microphone technology are reviewed from the earliest telephone based type through the decades as far as the 1970s. The “Why” section looks at the reasons behind the different designs, e.g., directional characteristics, output signal levels, diffraction effects, frequency range. The “How” examines the solutions proposed for the “Why” section, and the “Who” identifies the landmark designs and the designers behind them.
Wouldn't you want to be there? (And yes John, you knew all of this 135 years ago. We know 😉 ).
Jan Didden
AES Munich, next month:
T8 - Microphone History
Chair:
Jörg Wuttke, Schoeps, Technical Director Emeritus
Presenters:
Ulrich Apel, Microtech Gefell GmbH
Sean Davies, S.W. Davies
Stephan Peus, Neumann GmbH
Abstract:
This tutorial will be presented in 3 parts.
Stephan Peus' presentation, "35 Years of Microphone Development at Neumann—What Touched Us, What Moved Us," gives an insight to specific development topics and to some very special test procedures including: microphone’s transient response: insights beyond frequency response or polar pattern; RF susceptibility: already a topic before the era of mobile phones; capsule distortion measurement: difficult procedure giving a lot of interesting results; dynamic range and self noise level of studio microphones: a remarkable development within the 35 years in question.
Ulrich Apel will report on "The Importance of Vacuum for Condenser Microphones." He will speak on such topics as: the electron-tube was and is still an important step in the development of condenser microphones; the construction of special-made tubes for use in mics such as RE084k, Hiller MSC2, Telefunken AC701k, EF804, Valvo EF86, 6072, etc.; and special measuring capabilities to select tubes regarding noise, stability. and sound.
Sean Davies' presentation is "Microphone History: The Why, The How, and The Who." The developments in microphone technology are reviewed from the earliest telephone based type through the decades as far as the 1970s. The “Why” section looks at the reasons behind the different designs, e.g., directional characteristics, output signal levels, diffraction effects, frequency range. The “How” examines the solutions proposed for the “Why” section, and the “Who” identifies the landmark designs and the designers behind them.
Wouldn't you want to be there? (And yes John, you knew all of this 135 years ago. We know 😉 ).
Jan Didden
Jon Lord said:
I sure that everybody has read it, but anyway good reading.
http://www.diyaudio.com/forums/showthread.php?postid=1770375#post1770375
Relative to 2nd harmonic that comes out as 1/2 in this equation or 3rd harmonic that comes out as 1 in this equation.
NO, I knew this 30 to 45 years ago. Tubes, I lived with, and appreciate, but I did not design professionally with them. I have TRIED to make solid state as good as tubes. It has been a difficult challenge. I am only somewhat successful. Yet, I keep trying.
Others here, might try to make DIGITAL more satisfying. It is not MY calling, but I respect anyone who makes a real effort to make it better.
Others here, might try to make DIGITAL more satisfying. It is not MY calling, but I respect anyone who makes a real effort to make it better.
Jon Lord said:
That's precisely the problem. If they publish models at the device level, they give away their secrets.
Regrettably, as far as distortion is concerned, this policy forced me to simulate amps based on discrete components.
john curl said:
Let me translate that for you.
Are you saying that if the 2nd and 3rd harmonic are equal in level, the 3rd sounds/is twice as bad?
Jan Didden
john curl said:
Do not give up. SE tubes are NEVER able to play great orchestra well. But customer's taste is often unrefined. Do not cringe to them.
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