John Curl's Blowtorch preamplifier part II - Page 2965 - diyAudio
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Old 20th November 2012, 09:58 PM   #29641
fas42 is offline fas42  Australia
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Originally Posted by RNMarsh View Post
The low cost sims dont take into account anything that isnt on the schematic.
Does that mean the expensive ones can read your mind, or have the "psychic" means to eyeball your prototype .. ?

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Old 20th November 2012, 10:01 PM   #29642
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Does that mean the expensive ones can read your mind, or have the "psychic" means to eyeball your prototype .. ?
Do you mean that Special SIM for cables and vacuum rectifiers that draws break-in curves?
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Old 20th November 2012, 10:24 PM   #29643
fas42 is offline fas42  Australia
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You do not understand the problem as I meant..probably poor explaining on my part... That is of course not an issue which will stand between us. If you wish to discuss it further, PM me. Or, we can do here for the benefit of others.
Yes, continue here. You said:

Quote:
Any modification of the ground loop path will modify the system. Flux loop trapping is the culprit here, not any material properties of the cables.
And the first part I agree with. Ground loop path variations will effect the system to some degree, and may subjectively alter the sound quality. I have gone through many iterations of dealing with such matters, can't say I always have a firm handle on what works and what doesn't, but understand the potential impact.

However, what I was responding to was your stating that the change wasn't due to material properties. I have done tweaking for many years where the electrical layout has not changed in the conventional sense, including loop pickup and have still seen the effects. In one sense anytime anything is moved, even at the most minute level, loop pickup will alter but the difference between a good vs. a less good arrangement is too dramatic for changes in flux to be the cause in what I've experienced.

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Old 20th November 2012, 10:26 PM   #29644
RNMarsh is offline RNMarsh  United States
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Does that mean the expensive ones can read your mind, or have the "psychic" means to eyeball your prototype .. ?

Frank
haha. Almost -- they can calculate the trace parameters and pcb material (or substrate) and include all the trace factors amoungst other things - like thermal gradients and emi and for RF - the S parameters and much more. Even suggest best routes for path lengths and Z and timing events, delays and on and on. Not LT free software being used here. Why Scott W. says his company has spent millions on their SIM's. Thus, can do a complete design and be sure it will work without issues and go right to fab.

Last edited by RNMarsh; 20th November 2012 at 10:28 PM.
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Old 20th November 2012, 10:28 PM   #29645
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Originally Posted by RNMarsh View Post
haha. Almost -- they can calculate the trace parameters and pcb material (or substrate) and include all the trace factors amoungst other things - like thermal gradients and emi and for RF - the S parameters and much more. Even suggest best routes for path lengths and Z and timing events, delays and on and on. Not LT free software being used here. Why Scotts says his company has spent millions on their SIM's. Thus, can do a complete design and be sure it will work without issues and go right to fab.
So all designers can be fired soon and replaced by SIM-operators? Sad...
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Old 20th November 2012, 10:59 PM   #29646
fas42 is offline fas42  Australia
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Originally Posted by RNMarsh View Post
haha. Almost -- they can calculate the trace parameters and pcb material (or substrate) and include all the trace factors amoungst other things - like thermal gradients and emi and for RF - the S parameters and much more. Even suggest best routes for path lengths and Z and timing events, delays and on and on. Not LT free software being used here. Why Scott W. says his company has spent millions on their SIM's. Thus, can do a complete design and be sure it will work without issues and go right to fab.
Impressive! But, do they use such for their evaluation boards? And, could a completely human designed and constructed PCB be effectively scanned and analysed? Or would the effort to input such make it not worthwhile?

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Old 20th November 2012, 11:15 PM   #29647
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Thus, can do a complete design and be sure it will work without issues and go right to fab.
Adding a virtual music source and a virtual listener, real music will be restored to humans, while SIMs programs will fight endless on DIY forums about electronic performances....
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Old 20th November 2012, 11:26 PM   #29648
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To be serious, while SIMs programs do not change anything to the process they fast and simplify, i wonder if the loss of contact with calculations during design, and real parts during prototype, as well as the oscilloscope witch is some king of prolongation of ourself, will not finish by cutting us away from a physical knowledge, something incarnated we acquire with time.

You know, the "Add-it, it sound better, remove-it, it sound better".

Thank-you for not observing that it is typically an old fart questioning.
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Last edited by Esperado; 20th November 2012 at 11:29 PM.
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Old 21st November 2012, 12:19 AM   #29649
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Originally Posted by Esperado View Post
To be serious, while SIMs programs do not change anything to the process they fast and simplify, i wonder if the loss of contact with calculations during design, and real parts during prototype, as well as the oscilloscope witch is some king of prolongation of ourself, will not finish by cutting us away from a physical knowledge, something incarnated we acquire with time.

You know, the "Add-it, it sound better, remove-it, it sound better".

Thank-you for not observing that it is typically an old fart questioning.
I am absolutely agree with you. It is easy to calibrate own perception and learn to think in terms of schematics, "feel" and "hear" distortions imagining waveforms, spectrums, when working with breadboards, tools, soldering iron. But how somebody would expect to design something really new using computer models only? It's like building a "poetry" by copying and pasting from schoolbooks and dictionaries. Dull and boring.
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Old 21st November 2012, 12:21 AM   #29650
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Very well, but some quibbles: minimum phase can apply to nonlinear systems as well. The only requirement is that the phase be the derivative of the amplitude response wrt to frequency. And single valued functions indeed contain no loops, but if (for example) you have a 2d function unwinding in a 3d space, you can inadvertently have multiple values which are not loops in the 2d representation. Rooms have 3 dimensions (assuming the room size is time invariant!), the signal applied to them has one dimension plus time. So, no minimum phase (there's delays from reflections) and multiply valued (amplitude varies over space as well as time).
Thank you SY for the answer (and I'll stick to linear systems).
So any acoustic resonances (room and speaker enclosure 3D space) are non equalizable.
Effects from structure vibrations (e.g. driver or enclosure, if not damped) are non equalizable.
Effects from cone break-up are non equalizable.
I wonder if there can exist an acoustic or mechanical resonance that is not plagued by your last sentense.

George
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