Gforce Software Halogen FM: a new FM Synthesizer plugin that requires zero programming and knowledge of operator relationships: review + sound demo
Starting with a classic FM Synthesizer isn’t advisable. This type of synthesis is one of the most complex to initiate. This isn’t necessarily due to the synthesis itself, but rather to how FM synthesis is made accessible to the user. Many hardware synths from the past weren’t exemplary in this regard.
For several years, numerous attempts have been made to make FM synthesis more accessible and inspiring, while also removing it from the “I have no idea what I’m doing” category when you start working with it. My favorite example is the Korg Opsix synth, which achieved this first. Many others followed suit, including those in the software industry.
Now, the British developer company Gforce Software is following this path with the Halogen FM Synthesizer. Here is my full review.
Gforce Software Halogen FM
Halogen FM is a new polyphonic FM Synthesizer and Gforce Software’s first original synth plugin without a direct model. Indeed, it’s not a 1:1 emulation of a vintage synth, such as the Yamaha DX-7 or TX-81Z.
Installation was a breeze. Download the software, install it on macOS and Windows, and register it with a simple serial number. Once installed, a standalone version and the plugin are available in VST, VST3, AU, and AAX formats. It would be nice to have CLAP in the future.
For the fully scalable GUI, you can choose between the more striking white or the simpler, more elegant black finish. I chose black. The interface looks nice and reminds me a bit of Dawesome plugins. Color coding simplifies the view of the sections, and the FM synthesis is beautifully visualized in the center, reminiscent of the discontinued Wave Causal Nylon Synthesizer from 2019.
The Gforce software developers have devised a unique concept to make FM synthesis accessible to everyone, including beginners in synthesis. Instead of the usual 4 or 6 operator configurations, Halogen FM features only two more souped-up operators.
Additionally, there are classic modulators for each operator, an intriguing macro section, and a global reverb—a minimalist approach to FM synthesis, which is nonetheless interesting.
Zero Programming Operator Fun
The special feature of the Halogen FM is the Halogen Spark Core, a generative sound source with which you can generate new sounds with zero programming knowledge. Many elements of the Synthesiser engine have small stars that trigger the generative process.
In theory, press the Spark button to instantly generate a new, inspiring sound. In testing, it worked perfectly. However, I’m somewhat divided about the results, as is often the case with generative or random approaches. Some sounds are instantly fun, while others are just random noise and farts.
This way, you’ll have to tweak the generated sounds to your liking after the process. To be fair, Halogen FM doesn’t use any trained AI with countless different sounds. It employs more traditional parameter randomization with modern enhancements.
The Halogen Spark Core function for the entire sound and the individual sections (operators, modulations, etc.) works as intended. However, I would have liked to be able to control the intensity of this generative process.
More precisely, so that I can decide whether the process should impact the starting patch slightly or send it on a complete sonic rollercoaster ride, the latter is the case in the current version. A dedicated, advanced section for the Spark engine, where you can dial in the amount of sound variation, would be a welcome addition.
Macros
In addition to the generative approach, there is a second method for creating new sounds that requires zero FM programming knowledge. This is made possible by the six pre-mapped macro controls. Choose a preset and mangle it with the various macros. It’s impressive how flexible and how much impact they have on the sounds.
Mix sets the mix levels between operator 1 (green) and operator 2. The timbre macro manipulates the tonal characteristics of the patch. Tweak it to the left for softer, mellow sounds, and to the right for brighter, harmonically richer, and more aggressive tones.
Then, you have two envelope macros that control the overall length of the envelopes. Turn them to the right for evolving, long pads, and to the left for plucked, percussive sounds. The MOD macro sets the LFO and provides more controlled modulation on the left, while offering wilder, unpredictable results on the right.
And the last macro is the FX, in this case, a reverb. To the left, there are more subtle reverbs, while to the far right, the sound is immersed in an ambient cloud.
As a bonus, five macro controls also have spark buttons that can be used to generate new sounds. The biggest impact and the most significant sound changes are made by the spark button under the timbre knob, which randomizes the tonal character of your sound. Here, too, an option to adjust the intensity of this process would be useful.
FM Programming Is Possible
For those who want deeper control and geek out, Halogen FM also offers complete access to each operator’s parameters, allowing you to fine-tune or experiment with the engine.
Feature-wise, the operators are identical, but they have a slight sonic difference that gives you different sounds. This is quickly noticed in programming. Each operator has a handful of parameters and, of course, a spark button. It starts with the usual ratio and frequency settings.
Also onboard is a ring modulator that can be set to a fixed frequency, allowing it to run at a constant frequency. One level below, there are three shaping parameters: bright sets the amount of the feedback in the modulation oscillator. In testing, it added a nice high-frequency content to the sounds.
Next to this is the distortion knob that applies distortion to the sound. Turn this knob up to achieve a noisier and dirtier character. Great for experimental, industrial sound patches. The timbre knob sets the amplitude of the modulation oscillator, which also determines the modulation index.
If you use the Timbre Knob too intensively, you can achieve very harsh and nasty sounds. The built-in limiter helps maintain a good level of harshness without introducing unwanted aliasing. Ok, ok, aliasing can also be nice in FM, so it’s good that it can be switched on. Below, you can pan the operator in the stereofield and adjust the overall level.
Don’t forget the small parameter for Operator 2 that introduces X-mod, i.e., cross-modulation for more complex sounds with a twist of a knob.
Classic Modulation
On the modulation side, each operator has two classic ADSR envelopes: one for the modulation and one for the amplitude. A nice add-on is the repeat function, which triggers the envelope multiple times.
Pressing the Plus button takes you to the additional functions. This includes a multi-wave LFO with adjustable rate, noise, S&H, smoothing, and fade-in function. The noise function is enjoyable as it takes your modulation into very dirty, broken territories. Also inspiring is the intro function that delays the impact of the modulation.
There’s no advanced modulation matrix available. Instead, each modulatable parameter offers small dots that perform the mod matrix duties. Here, you can set the value the modulator should send to the parameter. The color coding makes this very accessible.
In addition to envelopes and LFOs, the engine also offers mappable keytrack, velocity, and aftertouch to various parameters, opening the gate for expressive playing. A bit of shame is that the modulation is fixed and not freely assignable like in modern synths. This means you can only modulate the predefined parameters.
For example, the bright and distort parameters cannot be modulated with the LFO or aftertouch. I also find the selection of modulators somewhat limited. Another LFO or some random modulator would have been interesting.
Once you reach frequency modulation heaven, you can refine your patches with an atmospheric-flavored reverb. Size, density, filter, modulation (depth and rate), and mix parameters provide you with plenty of options to create the perfect reverberation.
The reverb algorithm in the Halogen FM is on par with other Gforce software plugins and is impressive. It can sound subtle, classic, or super atmospheric. Other effects, such as a pitch shifter or delay, would have also been nice for sound design fun.
Also in this section is glide, an overall pitch envelope, and a global tune slider. An arpeggiator or sequencer is not onboard.
Sound Browser
Our zero programming FM path leads us further into the sound browser. Those who prefer professional sounds to the Spark Engine’s random generation will find what they’re looking for here.
Gforce Software supplies Halogen FM with over 320 sounds from well-known sound designers, providing a comprehensive overview of the sound collages the plugin can create. These range from monophonic aggressive basses, crazy drones, and FX to polyphonic vocal-like pads and metallic textures.
The included sounds are of high quality and inspiring. Compared to other Gforce Software plugins, they are less varied, as the engine is simpler and less complex.
Even though two operators sound like very little, I was surprised by how many different characteristics you can get out of the engine. But while playing, I often wondered how far the engine could be pushed.
With 320 sounds, you’ve already covered a lot of the Halogen FM spectrum. How much more is possible, apart from, of course, all the random noisescapes, farts, glitches, etc. that the Spark engine serves, must be seen. Third-party sound designers will use this.
Gforce Software Halogen FM Sound Demo
A no-talking overview of the engine and some presets can be found in my sound demo.
Gforce Software Halogen FM Review Conclusion
Gforce Software is going down a new path for the first time. A positive point for this. They certainly haven’t reinvented FM synthesis with Halogen FM. However, they’ve attempted to make the often overly complex synthesis type more accessible and musical. In my opinion, they succeeded.
Fewer operators, less complexity, yes, but they’ve implemented it in such a way that you get a wide range of sounds from only two. This is also because they are more like complex oscillators than classic DX-7 operators.
The Halogen FM also has some weaknesses. Firstly, I would have preferred a more playful spark engine, mainly with precise dosing of the impact. Secondly, a somewhat more flexible modulation system and additional effects would also be nice to have.
All in all, GForce Software’s new Halogen FM is an inspiring Synthesizer plugin for those who haven’t jumped into the mysterious FM world. It awakens curiosity about FM sounds and lets you take the first steps. A bit like painting by numbers does for kids. This is HFM for FM newbies.
It demonstrates the sounds that are possible and provides the user with a range of straightforward tools to help them progress. Everything complex, such as operator structures and algorithms, remains untouched. The simplicity is the key feature here.
For all others, including hardcore FM programmers, there are synths like the Korg Opsix, u-he Bazille, and Tracktion F.’em, among others.
Gforce Software Halogen FM is available now for an introductory price of £33 + VAT instead of £66 + VAT until the end of July 2025. It runs as a VST, VST3, AU, and AAX plugin on macOS (native Apple Silicon + Intel) and Windows.
More information here: GForce Software
Available at my partner
I tried the demo, and it seems that the ring modulator is actually just an operator fine-tune setting. The architecture is very reminiscent of the KORG DS-8. I find that Six Sines sounds much better and is free!
Six Sines is a great freeware synth but more complicated as its a DX-7-style synth
The narrative that FM synthesis is hard is incredibly dated. Ableton’s operator is 20+ years old… we should all collectively stop acting like to learn FM you need to know how to program a DX7.
give Ableton Operator without presets to a newcomer in FM Synthesis, I´m pretty sure he/she will not instantly make a track.
From a musician perspective who has synthesis knowledge for many years, it´s sure that we can say: oh it´s easy and not hard. Put you in the situation of a starting musician who maybe has no idea of operators, algorithms, feedback, etc but want these iconic FM sounds.
Programming your own sounds won’t happen instantly. When it gets too nerdy, many young people stop and use presets or a classic subtractive synth.
Halogen FM lowers the entry level to FM synthesis and reduces many of the barriers, allowing newcomers to discover FM synthesis. It’s great to have FM beasts in the DAW like opsix, etc. They’re only useful if you know how to control and program them otherwise they are preset machines. Halogen FM is good entry point but not a replacement or so for the FM flagships as written in the review.
Hi Tom, I appreciate your reply and I understand your views. I think a lot of what you say is applicable to every form of synthesis when we speak of newcomers.
My point however is that, imo, easy FM is a marketing gimmick riding on the old complexities of programming a DX7. FM has not been hard to learn for almost two decades thanks to improvements in user interfaces and free knowledge. Is it harder to grasp than subtractive? Sure, but not to the point where it is hard to learn of mythical.. Once you know how an operator works you pretty much know everything you need to know…
I find comments such as “Programming your own sounds won’t happen instantly. When it gets too nerdy, many young people stop and use presets or a classic subtractive synth.” more reflective of your own experience with FM than fact. Making a nice bass is with two operators is just as easy and fast as on a subtractive synth.
But hey, lets not debate cause it’s pointless. I enjoy G-Force VST’s a lot and it’s good to see them moving into a new direction.
Completely agree. This “FM is hard” was a DX7 thing, while modern approaches make it not more difficult than other forms of synthesis. Try a Digitone or an opsix and tell me that even just somewhat noodling with the knobs doesn’t give you usable sounds and makes it easy to adjust to taste after a bit of practise. If you want ‘hard” go for wavesequencing on a wavestate (and even this is not quantum physics hard).
An understanding of FM may have become more accessible, but the learning curve will always be higher than subtractive. I understand FM from a technical standpoint.. Cherry Audio’s sines had a great manual on the subject, and I’ve read some other stuff to wrap my head around it. But I can’t make good sounds, lol. Some kind of FM cookbook would probably be a big help, because I don’t have the hours required to become comfortable with it. Especially something like a six or eight operator…
i think it is hard due to grasping the concept of oscillator affecting other oscillator affecting third oscillator just requires too much brainpower – and sometimes it cant be even overcome
so the complexity lays in the concept more than user interface
While there definitely might be some slight marketing gimmickry in the advertisements for this synth, it’s not necessarily untrue. To understand FM synthesis to a level that John Chowninng (its creator) understood it would be quite difficult. Or even, to amass the level of FM synthesis knowledge and expertise Brian Eno did on programming DX7 would also be really hard, indeed. And perhaps, just to use some of the post DX7 instruments (virtual or physical), it may be not be that difficult, but it’s still not negligible. It’s sort of a Dunning-Kruger effect at work; if you’ve programmed in C# and wrote complex SQL queries for 20 years, you may be inclined to say that learning C# and SQL isn’t rally that hard. But I digress, and really just want to point out that one doesn’t have to subscribe to either-or thinking to really enjoy this synth. I use FL Studio, and there’s nothing to stop me from using this and Sytrus (a really powerful, but complex FM synth) and Arturia’s DX 7 V at the same time. I can use Patcher and just layer all three and make one patch out of it. Or better yet, I can use an analog pad from a Juno-60 vst and then add a bit of FM texture from Sytrus and DX 7 V, and if it feels lacking, I could use Halogen to add some accents to it, as it seems to have an excellent workflow, and could be quickly utilized when those intuitive flashes of creativity suddenly show up at the door.
I’m far from a beginner at FM, but I love it and appreciate all kinds of variations on it.
Halogen is a bit reminiscent of the Korg DS-8, without actually being close to an emulation of it. The apparent simplicity hides some depth. I have quite a collection of FM plugins as well as an FM-oriented Eurorack setup and I still feel like Halogen offers a unique approach.
(I’d kind of prefer more flexible modulation assignment, and perhaps even a comb filter/resonator to take advantage of that tasty noise it can generate… but that’s a job for other plugins / Bitwig Grid / VCV Rack…)