Spice simulation

[Edmond Stuart]

Originally posted by GRollins
.......................
Yes, I water cool my amps. No, I'm not willing to go cryogenic on my phono stage just to lower the noise...
...wait a minute...
Just kidding. It'd be a pain in the butt.
Still, I'd like to pick their brains over a beer. Better yet, single malt Scotch or a good wine.

Grey

Hi Grey,

As far as I can remember, Marcel van de Gevel has built a 'cryogenic' phono stage and published it in EW, some 9 years ago. Of course he didn't use liquid He, rather a negative resistance. As he is a diyaudio member, you can easily find his e-mail address and ask him for more info.

Cheers,

[Edmond Stuart]

Originally posted by john curl
............Unfortunately, I have a MAC, not a PC, ..........

Originally posted by john curl
Bonsai, I have BSpice on the computer in front of me. I prefer MICROCAP which is Spiced based. ................

So you prefer an early MAC version of Micro-Cap. These stone age versions were released between 1981 and 1987. For today's standards rather obsolete I think.

Cheers,

PS: Micro-Cap 9 supports: the Philips Mextram bipolar model. This is a vertical NPN or PNP bipolar model that describes velocity saturation, base widening, Kirk effect, impact ionization, and self heating effects.

[GK]

Originally posted by estuart



So you prefer an early MAC version of Micro-Cap. These stone age versions were released between 1981 and 1987. For today's standards rather obsolete I think.

Cheers,

PS: Micro-Cap 9 supports: the Philips Mextram bipolar model. This is a vertical NPN or PNP bipolar model that describes velocity saturation, base widening, Kirk effect, impact ionization, and self heating effects.

I've got the old DOS PC version of Micro-Cap and I use it a lot. Only for passive stuff though. It's a little gem and is fantastic for quickly double checking pasive filter/matching networks for RF stuff. Draws really nice and clear full screen graphs, which puts some of the modern fancy packages to shame, in this regard.

Cheers,
Glen

[Edmond Stuart]

Originally posted by G.Kleinschmidt
I've got the old DOS PC version of Micro-Cap and I use it a lot. Only for passive stuff though. It's a little gem and is fantastic for quickly double checking pasive filter/matching networks for RF stuff. Draws really nice and clear full screen graphs, which puts some of the modern fancy packages to shame, in this regard.

Cheers,
Glen

Hi Glen,

I'm using version 8. Graphs are now almost full screen and still pretty nice. Why not using the free demo of version 9? Probably much easier than switching to DOS, unless your version runs in a DOS-box.

Cheers,

[ingrast]

I used Microcap for several years before finding LTSpice when joining DIY. Since I am not a sophisticated Spice user I cannot really make a comparative evaluation. Being simulators just that, I use to do a quick check for design ideas and explore alternatives before commiting to hardware.

OrCad comes to mind, and it was my staple schematics capture tool in the DOS days, played a little with the integrated capture-simulation-layout version later but found it not very friendly for casual use.

Rodolfo

[Bob Cordell]

Originally posted by GRollins



I once witnessed an argument between a friend of mine who was a chemist and another chemist. It was one of those red-in-the-face, spittle-flying arguments that went nowhere once the two sides defined their positions. One of my degrees is in geology and they pump you full of chemistry along the way. I could somewhat follow the lines of the argument, and from what I knew it seemed that my friend had the upper hand, in large part because he had more hands-on experience. The other fellow was arguing from a completely theoretical viewpoint, which was fine as far as it went, but he wasn't including some things that my friend said were relevant. (It's been twenty years or more--I don't remember the finer points of the argument--something about solute deposition from an aqueous solution. Temperature was involved. Something about iron ions. I don't remember the rest.)
As for what you've designed...unless it's high end audio, I don't care. John Curl has earned my respect in this manner. Ditto for Nelson Pass and Charles Hansen. Electronics is a vast field. To assume that ability--even perhaps expertise--in another portion of electronics does not ipso facto grant you expertise in audio. There are too many quirky, weird things in audio.
Peufeu's memory distortion concept is one example. Simple, elegant, and quite reasonable, even from a theoretical point of view; doesn't require much, if any, hand-waving to see how it could apply. But does it show up in simulations? That's another matter entirely. I have no doubt that code can be written and spliced into simulation programs to cover this idea, but it hasn't happened yet.
Sooner or later simulators will address the things that matter in audio, but at this time it's still in the future.
Arrogant? No, just truthful.
It's all in attention to details. To take the superficial view that all that matters is reliability when thermal criteria are on the table is not at all helpful.

Grey

Hi Grey,

You are so very right about experience, and how it matters in a discussion or argument. What I have often seen is that the two participants have experience, but they have DIFFERENT experience. Some on this thread have a lot of audio experience, both professional and on the side, but they don't have a lot of experience with SPICE. There are others who have the SPICE experience and have little practical experience. Herein often lies the rub. Of course, there are also those who have experience in both domains, and that is very helpful.

The key thing about SPICE is that it is an extremely valuable tool, but it certainly does not do everything. But because it does not do thermal analysis and some of the more subtle things that may come up in audio certainly does not mean that it is not highly useful in audio design.

Cheers,
Bob

[GRollins]

Bob,
Isaac Asimov (I believe) once wrote a story about a bunch of armchair scientists who theorized and argued and wrangled and contrived towering reputations based on an incestuous system wherein they analyzed each others' learned papers.
The whole wobbling edifice came crashing down when one maverick decided to go out in the field and do original research.
In essence, the story is a subtle re-telling of The Emperor's New Clothes.
From my point of view, The Emperor's New Clothes stops just as the plot begins to thicken. What happened to the child who pointed out that the Emperor actually had no clothes? Do you really believe the story had a happy ending? My personal experience from when I was young, coupled with later book learning, agree that adults do not look kindly on children (or adults, for that matter) who deconstruct their world views. Children rebound nicely from finding out the truth about Santa Claus. Adults get nasty.
I well understand the attraction of simulations. I used to use them, myself. Then, as now, people were claiming, "Oh, sure, simulations used to be flawed...but now we've got [insert flavor of the month] and we're golden." Then, as now, there were glaring gaps and inaccuracies. Yet every month or two the cry would go out, "If you haven't tried Version XX, all your criticisms are invalid, because now we've got [you guessed it...the new flavor of the month]."
Well, no, the criticisms aren't invalid and there are quite a few of them. I hope that someday the list gets whittled down to nothing, but I'm not going to wait. I've got far too many hastily scribbled notes I need to try out.
Your point about people who simulate, people who build, and people who do both is valid within limits. One thing that disturbs me is simulator/builders who count their experience simulating as though it were experience building. "Oooh, look at me! I spent one hour building and seven hours simulating this week, so I have eight hours of experience." The not-so-subtle implication is that he is better than the fellow who spent a mere five hours building.
To put this in perspective, ask yourself this question the next time you take a seat in an airplane: Would you rather have a pilot who has 1000 hours actual flying time and 4000 hours in a flight simulator or a pilot who has 5000 hours experience actually flying?
To me the choice is clear.

Grey

[GRollins]

Originally posted by estuart


Hi Grey,

As far as I can remember, Marcel van de Gevel has built a 'cryogenic' phono stage and published it in EW, some 9 years ago. Of course he didn't use liquid He, rather a negative resistance. As he is a diyaudio member, you can easily find his e-mail address and ask him for more info.

Cheers,

You're evil. The worst possible thing you can do when I come up with one of these goofy ideas is encourage me.
I haven't taken time to think this through in detail, but I was thinking something less drastic than liquid helium. Dry ice (frozen carbon dioxide) came to mind, but that would be a logistical nuisance, so I had gotten as far as tanks of gas. That's going to be a problem, too, at least around here. (I live out in the boondocks.)
Do you happen to know Marcel van de Gevel's user name here?

Grey

[Edmond Stuart]

Originally posted by GRollins
You're evil. The worst possible thing you can do when I come up with one of these goofy ideas is encourage me.
I haven't taken time to think this through in detail, but I was thinking something less drastic than liquid helium. Dry ice (frozen carbon dioxide) came to mind, but that would be a logistical nuisance, so I had gotten as far as tanks of gas. That's going to be a problem, too, at least around here. (I live out in the boondocks.)
Do you happen to know Marcel van de Gevel's user name here?
Grey

Hi Grey,

You're really lazy, aren't you. Never mind, his nick is MarcelvdG, or look at:
http://www.diyaudio.com/forums/membe...fo&userid=5881

Regarding simulator version xx.01 vs xx.02 etc., you probably missed my point. If we are dicussing the merits and flaws of simulators, it's not unreasonable to suppose that we mean today's simulators. So, if someone is complaining about missing features of a 25 years old version or so, that is totally irrelevant IMHO.



Cheers,

[rdf]

Could much of the difference in value perception relate to topology? Though nowhere near as experienced with Spice as most here I do use it regularly for sanity checks on simple tube circuits. In that application, generally low or no feedback, the topology can't compensate for inaccuracies in device models and 'calc errors' come shining through. The modeled distortion spectra ususally bears little resemblance to measurements, not urprising since the same device from different manufacturers rarely measure the same either. I would imagine though a high GNFB topology would swamp minor deviations from reality in device models. In that application Spice would be a much more powerful tool.