Modeling Classic Preamps and Output Circuits

[WilliamAshley2019]

So I started playing around with LiveSpice / LiveSpice VST for modeling specific analog circuits but not just for guitar pedals - instead I have started trying to copy some classic circuits - although somewhat basic at this point like the Neve 1073 output circuit, havn't quite got potentiometer and variable resistors working for gain control but probably just bad modeling on my part. Anyway THE QUESTION IS: How do I add LTSpice / Spice modules for components that are not included in Live Spice. For instance if I want to add Carnhill (originally Marinair) VTB9045 transformer for Neve models I might need to design the component and I might need to actually add components -- and their modules -- I have added components from LTSpice to LiveSpice and they appeared to work but I am sort of expecting for some of the rarer components I will need to add the .module stuff and I am not sure where I would do that in LiveSpice as they seem to have the XML for components but I havn't found the .module lists that are referneced as HTML files in the Livespice XML like BING CHAT brings up some information on modeling that follows, how would I add this to add an emulated VTB9045 transformer to my LiveSpice modules/components? Is this possible? I know I am taking the program further than pedal emuation but I think this VST is so cool for fl studio as it allows way more effects modules to be modeled than just for pedals imo. The Carnhill VTB9045 is a microphone input transformer known for its use in professional audio equipment, such as the classic Neve 1073 microphone preamplifier module1.

For simulating the Carnhill VTB9045 in LTspice, you would typically need a SPICE model of the transformer. Unfortunately, detailed SPICE models for specific audio transformers like the VTB9045 are not commonly available due to the proprietary nature of their design. However, you can approximate the behavior of the transformer using a generic transformer model and adjusting the parameters to match the specifications of the VTB9045 as closely as possible.

Here’s a basic example of how you might represent a transformer in LTspice using generic parameters:

.subckt VTB9045 pri sec
Lp 1 2 100m
Ls 3 4 100m
K12 Lp Ls 1
Rp 1 2 1k
Rs 3 4 200
.ends VTB9045

In this example:

Lp and Ls represent the primary and secondary inductance.
K12 is the coupling coefficient between the primary and secondary windings.
Rp and Rs are the resistances of the primary and secondary windings.
You would need to adjust the inductance (Lp and Ls), resistance (Rp and Rs), and coupling coefficient (K12) values to reflect the characteristics of the VTB9045. Keep in mind that this is a simplified model and may not capture all the nuances of the transformer’s behavior, especially non-linearities and core saturation effects.

For more accurate simulation, you might consider reaching out to Carnhill or looking for community-shared models from audio DIY forums where enthusiasts may have created more detailed simulations of such transformers1.

[WilliamAshley2019]

Sort of in mind here I am wondering if there are any conversion tools - something that would be great if there was some roughing file loader that would convert either netlist asc etc.. type files and roughly populate the components and connections. Reason being there is so much content out there for other spice models - often that are more complex, the thought crossed my mind to make a converter or batch converter, sort of working on it now, but I don't expect this to be done anytime soon. Is anyone already working on a way to load netlist / asc files rather than just schx? Can anyone point me in the right direction where the SCHX file format specifications are in the code, I am sort of plodding around the codebase trying to find the location that the SCHX format is described and coded. To me the SCHX and netlist seems very similar just likely slight coding differences, not 100% sure, one seems to be xml formated wile the other appears a little more like plaintext. It doesn't seem like it would be super complex to batch convert or convert a file even if it isn't perfect it should save a lot of time in hand drawing a circuit from scratch. Anytools out there in line of this? Also for adding components currently just dropping the cmp files into the lib folder for livespice but LTSpice for instances seems to have a much nicer component picking mechanism. Again it might be useful to be able to add components from a picker this may help with load times if there is an active and favorited components list and some type of refresh so you can have the favorites always load while if a new component is loaded you can simply refresh LiveSpice and if you want to keep it in the working library then you just star or favorite it. As I am experimenting with a large variety of circuits it has become useful to download additional components but a lot of the components are specific to a specific circuit. In saving time it would be a major time saver for me to be able to import things like netlists and asc files to start a circuit out.

[WilliamAshley2019]

Note I came across this github page Note there is some similar projects such as
https://github.com/f18m/netlist-viewer that may be helpful in providing some of the basis to this. that seems to take netlists and turns them into diagrams.. .basically doing what I was thinking as far as importing the netlist as much as possible as a schematic. This same process might be used for filtering and getting as much information as possible on other spice files that arn't not identical to .schx format, but would atleast help in getting part of the circuit down.