On April 30, 2010 10:55:09 pm you wrote:
> Tim E. Real wrote:

>Wow, man! I just spent an hour playing with
> Guitarix Distortion (ladspa plugin) +
> caps C* Amp VTS (ladspa amp sim plugin)
> in MusE's plugin rack.

Silly me! I missed a piece of the puzzle. The C* Cabinet plugins.
I was supposed to put a cabinet after the amp.
Sounds even better now!
It now approaches the type of sound that the JCM900 vst gives.

> > Until now I have mostly been using SimulAnalog's famous JCM900 VST
> > dll plugin under dssi-vst. (I do wish they would open-source those
> > plugs!)
>
> Aha, it's for free :), http://www.simulanalog.org/GSuite.zip, until now
> I didn't use VSTs when recording with Linux, but the web says, this VST
> should be awesome,
> http://www.google.de/#hl=de&ei=vJLbS_jPJc6YOMjj9JIH&sa=X&oi=spell&resnum=0&
>ct=result&cd=1&ved=0CAUQBSgA&q=JCM+900+VST&spell=1&fp=af503062d682e13a
>

I have not tried their other plugins in the suite yet, but the following
statement probably applies to them as well:
That JCM900 vst is by far the most absolutely mind-blowingly realistic
recreation of a Marshall amp *ever*. Most people agree.
It is *THE* standard by which *all* other plugins are judged, commercial
or free!

Sadly, I just found out the hard way that it has a really nasty
denormalization problem. It's so bad I may not be able to use it any more.
People have tried fancy anti-denormalization plugins ahead of it, with no
luck, apparently.

MusE has a basic DC anti-denormalization feature, and it didn't help.

I completely agree with you: The JCM900 VST rocks! I've been using it a lot on Windows, now I'm on the Mac, so I haven't used it in a while. Too bad the source code for these plugins is not available. The papers on the website only explain the basic principles.

Anyway, I also ran into the denormalization problem quickly, so I just made a small VST that mixes some -100 dB white noise into the signal. Actually, I made the noise gain adjustable, because the added noise made my synth-guitars sound much more authentic. ;-)

Alternatively one could make it more convenient to use by creating a separate wrapper .dll that loads the JCM900 and just intercepts the process-calls, while passing any other call to the plugin.

Jan

Also Guitarix seems to have a slight issue too, but thankfully MusE's
basic anti-denormalization feature cured it.
(Many thanks to Robert for the painstaking work on that feature!)

Can I get some comments on an issue nagging me for years:
Maybe I never learned some golden rule about floating point,
please correct me if I'm ignorant of some crucial technique or fact
which would help: ...

I used to be fanatical about floating point (remember the co-processor days?)
But I've grown to dislike it.
Bankers won't use it for calculations.
(Have you ever been stung by extra or missing pennies using a 'NUMBER'
database field instead of a 'BCD' field? I have.)

So why do we use floating point for scientific and audio work?
Considering audio can have really small values, does it not lead to errors
upon summation of signals?
Why do we not use some sort of fixed-point computations?

I mean take this simple BASIC program:
LET A = 0
LOOP: PRINT A
A = A + 0.000001
GOTO LOOP

It produces the stupidest output with wandering errors after several
iterations. A two-dollar calculator wouldn't do that.
It plagued me when I worked with 3D drawing, too.
You move an object incrementally several times in some direction
but you can't get back to the original position by the reverse
process. That's called 'non-return-to-zero'.

> :).
>
> On the web page there are some PDFs.
>
> Perception and Congnition
>
> A perceptual approach on equalization
> <http://www.simulanalog.org/eq.pdf>
> A perceptual approach on clipping and saturation
> <http://www.simulanalog.org/clip.pdf> Volume cranked up in amp debate
> <http://www.trueaudio.com/at_eetjlm.htm> (by Brian Santo)
>
>
> Numerical methods and models
>
> State variable changes to avoid non-computational issues
> <http://www.simulanalog.org/statevariable.pdf>
> A complete model of a tube amplifier stage
> <http://www.simulanalog.org/tubestage.pdf>
> Analysis and high performance simulation of linear networks
> Polynomial interpolators for High-Quality Resampling (Olli
> Niemitalo) <http://www.student.oulu.fi/%7Eoniemita/DSP/deip.pdf>
>
> Programming Techniques
>
> Optimizing with SIMD instructions
> <http://www.simulanalog.org/optimization.htm>
> Compiler Benchmarks <http://www.simulanalog.org/compiler.htm>
>
> I have little use for it, because of a lack of knowledge, dunno, perhaps
> it's useful for some people from the list.

Yesterday I took some time to read some of those papers.
Fascinating stuff, especially when presented with an audio effects/amp
simulation goal in mind.

Tim.

>
> Thank you for the information Tim :),
>
> Ralf

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