Picked OPAx134 op amps because they have a good rep. Couldn't get them to work with KiCad/NGSpice. That's a morning I won't get back. Apparently you need NGSPcice 35 which is due for release RSN.
While poking around I read the OPAx134 doesn't like being a unity gain buffer. Since that's what I need for much of the circuit, BAD CHOICE.
Looking for recommendations for an Op Amp that, in order of priority:
- Has a great subjective sound
- Has models that work well with NGSpice
- Works well with unity gain
- Is easily available in Europe
That's the big ones. Small ones that would be handy but are not deal breakers:
- Is available in 1, 2, 4 versions
- Has the same pinouts as OPAx134
- Works well objectively, for bragging rights
Suggestions welcome. I hope the requirements are too specific for general Op Amp wars!
While poking around I read the OPAx134 doesn't like being a unity gain buffer. Since that's what I need for much of the circuit, BAD CHOICE.
Looking for recommendations for an Op Amp that, in order of priority:
- Has a great subjective sound
- Has models that work well with NGSpice
- Works well with unity gain
- Is easily available in Europe
That's the big ones. Small ones that would be handy but are not deal breakers:
- Is available in 1, 2, 4 versions
- Has the same pinouts as OPAx134
- Works well objectively, for bragging rights
Suggestions welcome. I hope the requirements are too specific for general Op Amp wars!
the OPA134/2134 works perfectly fine as a unity gain buffer.
Why not just learn how to use LTSpice instead ? It's pretty much proven and works just fine with the OPA134 model in my experience
Why not just learn how to use LTSpice instead ? It's pretty much proven and works just fine with the OPA134 model in my experience
Not very many diyAudio folks know which opamps "have simulation models that work well with NGSpice". Mostly TINA, LTSPICE, and Micro-Cap users around here. Sorry!
KiCad seems good, and NGSpice is built into it.
The latest unreleased but downloadable version of NGSpice works with the OPA134 files, and indeed all the the others it didn't like. Although I seem to be getting surprising results, but that's another story...
The latest unreleased but downloadable version of NGSpice works with the OPA134 files, and indeed all the the others it didn't like. Although I seem to be getting surprising results, but that's another story...
I personally don't rate KiCAD at all, being free is not an acceptable excuse for having a dreadful user interface.
Again, LTSPICE is tried and tested by many in the industry, and actively developed. I'd trust it over any newly developed open source stuff.
Again, LTSPICE is tried and tested by many in the industry, and actively developed. I'd trust it over any newly developed open source stuff.
Of course, I'm not IN the industry - hence the DIY bit! I'm quite impressed with KiCad, but then I have no basis for comparison, my profession is computer networks not audio. And with that hat on, I tend to find open source rather more trustworthy.
Just run LTSPICE, TINA or MicroCap in a VM if you don't trust closed-source software...?
There are good reasons why these simulators (especially LTSPICE) are so popular.
There are good reasons why these simulators (especially LTSPICE) are so popular.
Yes, but being free software means you have the right to improve it - as I understand it it is getting better over time as the userbase extends. Being cross-platform does have repercussions for creating a slick UI though - different OSes have different facilities and guidelines, it has to work on basic hardware (any random laptop, not just a CAD station).
One major problem with proprietry software is the fast rate that it crumbles to dust - very few commercial packages available now will be around in even 25 years time, but KiCad will you can bet.
I've successfully completed lots of projects using KiCad for PCB layout and LTSPICE for circuit simulation, including three that are for sale today in the diyAudio Store. I don't know whether either of them is the best-in-its-category or the worst; but I do know they both work just fine for me.
One nice feature of KiCad is the ability to lay out multilayer boards of unlimited size, without paying an extra license fee for "advanced capability". So I build 4 layer boards whenever I think they are warranted.
One nice feature of KiCad is the ability to lay out multilayer boards of unlimited size, without paying an extra license fee for "advanced capability". So I build 4 layer boards whenever I think they are warranted.
I've got KiCad and NGSpice working properly now, with various models I couldn't use before, by using a beta.
However, I'm not sure the results are actually right. I don't really know what I'm doing with electronics so when stuff didn't behave in simulations as I thought it should I went and fiddled around doing basic stuff, and things that out to work don't and then I managed to get an output from an op amp with no input.
So I've just downloaded LTSpice to see if it's me or NGSpice that can't do basic things with opamps.
However, I'm not sure the results are actually right. I don't really know what I'm doing with electronics so when stuff didn't behave in simulations as I thought it should I went and fiddled around doing basic stuff, and things that out to work don't and then I managed to get an output from an op amp with no input.
So I've just downloaded LTSpice to see if it's me or NGSpice that can't do basic things with opamps.
Neither am I. I was (until mental health forced me to quit) a software engineer and sysadmin.
Cross platform UI is not a huge deal, there are plenty of good systems to deal with that, such a Qt - which EAGLE uses.
One problem with open source software is that they often do not care about backward compatibility, and change things on a whim. It's a constant moving goalpost which is a frequent cause of issues. I say that from experience having developed across all of the desktop platforms (including Linux).