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Re: Tubes versus Modeling Caged Death Match

At 11:40 PM 4/27/2003, Mark Sottilaro wrote:
>I said this a while ago and a friend of mine started quoting it in her 
>signature file and I thought it might shed some light on this subject:
>"You can't simulate dressing like a clown. It's a do or not do thing.
>If you're wearing a clown suit, you're a clown."
>I hope this helps.

perfect Mark, thanks.

for a reference point, I spend a lot of time in my professional life 
simulating electronic circuits. In my case it is usually the output driver 
circuits on high-performance IC's driving PCB traces, assorted parasitic 
impedances, connectors, and the input receiver on another IC. This is 
reasonably comparable in complexity to simulating an audio amplifier. In 
work I simulate transistors, but tubes would be a similar chunk of math 
when you consider what the electrons are doing.

There are two approaches to this that I use. Either a fast "behavioral" 
simulation, that runs quickly but with less detail. (or perhaps good 
detail in the operating region I care about.) Or a detailed "transistor 
level" simulation that gives a much more accurate result across all 
operating regions but takes much longer (using a simulation engine called 
spice, for those who care).

I usually simulate about 3 cycles of a given waveform. On the PIII 850MHz 
machine on my desk the fast behavioral simulations take about 1 second. 
slow, detailed, spice simulations can take as much as an hour and a half, 
but they come out looking very much like the real thing. One of the guys 
working for me has a P4 1.9GHz, when he's not around I VNC into his pc to 
run spice. It speeds up by a factor of 5. Still, 15-20 minutes to get 3 
detailed waveform cycles is a long way from real time. My guess is your 
tube amp modeler isn't doing that kind of detail....


Kim Flint                     | Looper's Delight
kflint@loopers-delight.com    | http://www.loopers-delight.com