From mgarvi–(at)–anix.com Sat Jan 25 12:53:24 CST 1997
Article: 35788 of alt.guitar.amps
From: mgarvi–(at)–anix.com (Mark Garvin)
Subject: Re: Simulation software
Date: 25 Jan 1997 02:24:45 -0500
Organization: PANIX Public Access Internet and Unix, NYC
References: <19970118131201.IAA0071--(at)--adder01.news.aol.com> <5bv678$r1--(at)--anix2.panix.com> <32E5A052.3F--(at)--ellsouth.net>
>Mark Garvin wrote:
[re simulation software]
>> 2: Web search for ‘spice’ or ‘pspice’ for starting points.
In <32E5A052.3F--(at)--ellsouth.net> Randall Aiken
>Just go to http://www.MicroSim.com. Call them for their free CD that
>has the eval copy of PSpice. Well worth the money. It does limited
>size circuit simulations. Plenty good enough for tone circuits or gain
>build a few to get the feel of what sounds _look_ like. They are great
>for both AC frequency response simulations and transient simulations.
>You can see the behavior of your circuit ideas without having to build
>them. It pays for itself in the savings you get when you realize that
>you just mistakenly designed an excellent oscillating
>transformer-burning tube-eater instead of a guitar amplifier.
It has tube models?! I’ll have to check it out.
Regarding correlating response curves with sound, Dave Cigna’s
Fender/Marshall/Vox tone circuit response program is worth a look.
It’s on his web page (Sorry, I don’t have the URL memorized).
Response curves alone can shed a lot of light on an amp’s sound.
I finally took the time to write C++ programs to model a couple
of my own tone circuits…it got too tough to keep running the
numbers thru a calculator, and I wanted to see realtime response
as I changed the controls and component values on screen. Spice
programs are usually not nearly fast enough to do that.
One of the things that becomes very apparent when watching the graphs
is the tremendous variation in the treble control, and the relatively
little variation in bass in most standard guitar tone circuits (like
Fender). This is due to the low notch frequency (300hz) of the
time-honored Fender tone circuit, and I believe it to be one of the
very key elements to the Fender sound. Raising the notch to more
standard ‘hifi’ frequencies yields more bass response, but removes the
characteristic Fender ‘twang’ that comes almost entirely from the