New Version of EXE Amp Sim (Improved Distortion Modelling + 33 Cabs)

[DaveClark]

Hi all,

For the few of you out there using my amp sims, I have uploaded a new version 0.0.3.0 of the "Classic Thirty" amp sim in a zip file HERE. (Hopefully functional now - Thanks, Ivan.)

A short, blurry video is .

The new features are 1) Improved distorion modelling on a per-tube basis. 2) 24 new cab models, bringing the total number of cabs to 33.

The improved distortion modelling is based on grid-conduction modelling as described by Will Pirkle in his Addendum to Chapter 19 of the second edition of his book on effects modelling. Grid conduction is implemented as an asymmetric, dynamic compressor. The "bias point" movement can be exaggerated so that the tube can cut in and out or emphasized just enough to add some oomph to the attack of musical notes. There is also a control to vary the frequency of the DC (actually slow AC) bias shifting. Another source of inspiration was Garrin's excellent distortion modelling in Swanky Amp.

The additional cabs came from a collection of 300 experimental cab simulations which were created by various means, mostly from previous cab measurements and from solving the 3-D wave equation for a box. The cab measurements and bandpass filters were themselves filtered again to shape them into approximations of various types of cabinets, providing a greater variety of easily selected sounds.

Regards,
Dave Clark

[Ivan_C]

Hello! Just playing with it quickly, I think there are some issues on Windows. When I click on the power and cabinet sections, I don't see the associated panels...

And your link in the message is not working, I had to go to the website to download it

[DaveClark]

Hi Ivan,

Thanks for your post. Sorry about the link.

On the Windows issues: Are you clicking on the LED or on the actual button above the LED? The LEDs are for quickly turning things on and off whereas the buttons above them are for access to the associated panels. If you are indeed clicking on the buttons above, which host are you using? I just downloaded the distribution zip, unzipped, copied to Common Files, then tested using Cubase Elements 11. It worked as intended.

Thanks again.

Regards,
Dave Clark

[filo01]

Hi Dave,
I have tried I guess all your amp listed on VST4Free plus this one. Don't know why but I hear and feel (by my hands) a significant latency from all of them. Approximately about 10ms is added to overall roundtrip and it doesn't matter whether I'm using internal cab or not. I don't have this issue with other amp sims like e.g. Nalex, V.Taranov, MLLabs on the same machine (Win10, Focusrite Scarlett 2gen).

Do you have an explanation for that?

[acousticglue]

I experienced similar on the other models

[AC222]

Liking the new style of demos. A lot easier to follow when you can see the tweaking and hear the audio playback at the same time. Cheers.

[DaveClark]

Do you have an explanation for that?

Yes, I do have an explanation, but it's somewhat complicated in its full glory.

Back in 2016, when I first started developing this series of amp sims, I decided to use exclusively convolution for all of the simulations. One of the reasons for this was that IIR filters are limited in the order that can be implemented due to instability concerns, so you have to break up the circuit into several filters or create other approximations; FIRs are unconditionally stable (won't blow up) even for high orders. Some tonestacks are fourth-order filters, so this is a big problem for accurately simulating them. Other circuits are lower order, but I wanted freedom to create more complicated input circuits, interstage voltage dividers, etc.

Because the linear portions are separated by nonlinear portions (i.e. tubes), I had to have separate convolutions for each filter stage. If not for the nonlinear tube stages, the convolutions could all have been combined. For each convolution, I did not want to have zero delay because this would have made the CPU usage even greater than the large amount it was already.

Soooooo ... the result is a number of delays, one for each convolution stage, that add up to a delay that you can hear if you compare or see if you measure.

In one of the videos I mentioned that these amp sims were developed for mixing rather than for live playing --- although I do, of course, play through them all the time for testing and don't have any problems with delays. The delay is one of the reasons I said that.

Now the more recently (i.e. since 2016) Eco mode of operation does replace some of the circuits with IIR filters, so there should be less delay, but it's still not eliminated. I myself don't care for the Eco mode as it's quite limiting.

Regards,
Dave Clark

[filo01]

Ok, understand now - it is by design, not a some DAW or particular computer issue. Anyway, thanks for your post.

[acousticglue]

Yes any linear aspects like EQs don't play well 0 latency

[enroe]

I've tried the "Thirty One" now.

And yes: I am pleasantly surprised. The middle distortion for
crunchy sounds is very soft, dynamic and really tube-typical.
Hardly any of the amp simulators commonly used today can
do this so well. Great!

Not so strong are: a. Somewhat confusing operation (maybe
a small manual would help). And b. the CPU usage is quite high.

But that's not really a criticism because the sound is really
good. A real surprise!

[Scrubbing Monkeys]

I really like all of these. Great job and Thank You!!

[DaveClark]

Thanks for the latest feedback. For very low CPU usage and zero latency, please try out Tiny F:

http://www.execonsultingtx.com/wp-conte ... t3_x64.zip

I created this to help with my own projects. It takes the complete opposite approach of sound quality first and CPU/latency is whatever it is for the "Classic" series. For the "Tiny" series, it's CPU/latency first and sound quality whatever it turns out to be. It may still be satisfactory for use in situations where a lot of the stuff that guitarists worry about disappears into the mix. I use them now in my own work to dramatically reduce the CPU load for larger projects, using the "Classic" amp sims only when necessary.

The "Tiny" (so far just Tiny F) series are single-channel (Left or Right) and use filters instead of cabs. They have the same distortion modelling as "Classic." You can turn the cabs off and use your cab sims. No integrated FX. I did make a Tiny Distortion pedal:

http://www.execonsultingtx.com/wp-conte ... t3_x64.zip

and a Tiny Compressor pedal:

http://www.execonsultingtx.com/wp-conte ... t3_x64.zip

I'm currently experimenting with hand-crafted x64 assembly versions to create stereo and dual-amp sim versions of these plugins. The dual versions are difficult to program, but they have a really fat sound for so little CPU and latency, and no phase artifacts that I could hear.

Regards,
Dave Clark

[enroe]

Hello Dave!

Thank you for the stripped-down version Tiny F!

Your current work on a "dual version" sounds really fantastic,
because as guitarists we are all looking for "the fat guitar sound".
Every small step in this direction would be a big step forward.

I'll keep my fingers crossed for you, and yes - I'm very curious
to see what the results will look like.

[enroe]

... and I almost forgot:

If you are currently working on something, then der "Developer Challange
2021" could be something for you. Maybe?

Look here: https://www.kvraudio.com/kvr-developer-challenge/2021/