Black Box Analog Design HG-2 saturation plug-in: features and spec-based rating

Plugin Alliance’s HG-2 is a saturation (a faint distortion, as if passed through analog gear) from Black Box Analog Design (Plugin Alliance), modeled on four tube stages and transformers. It can be used on the mix bus and on single tracks.

A saturation plug-in adds a faint distortion, as if the sound had passed through analog gear, to add thickness and warmth.

In this article we compare HG-2 with 12 saturation plug-ins and rate how well it serves its purpose on three criteria. The basis is official manufacturer information.

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Summary

Among the 12 saturation plug-ins, HG-2 is rank B. The ranks run S, A, B and C, and B is third from the top. Averaging the scores for each criterion (out of 5, with the one criterion that matters most for the purpose counted double) gives 2.8.

Strengths

• Mix and tone control (4 points): you can adjust in detail how much is mixed with the original sound, and the tone.

Things to keep in mind

• Per-band processing (1 points): it has no function for changing the distortion by pitch range.

Who it suits: people who want to add rich tube harmonics to a mix or a vocal to make the sound thicker.

Main features of HG-2

Combine four tube stages

HG-2 adds harmonics (tones at whole-number multiples of the pitch of the original sound) by combining four tube stages in series and in parallel. You can set the gain of the pentode and triode (two kinds of tube) separately, and input and output transformers sit before and after them. Think of it as blending the flavor of several kinds of tubes with knobs.

Shape the texture with Density and Calibration

Density is a knob that drives the two tubes harder while keeping the same balance, and you use it when you want to add thickness. Calibration is a menu that imitates the adjustment of the internal trim of the real unit, and it changes the character of the highs to Dark, Normal or Bright.

Air adds high-end sparkle, and Mix blends the original

Air is a knob that adds a silky sparkle above 10 kHz, and it can be used on vocals, strings, piano and the whole mix. Lowering Mix brings back the original sound, so you can add the softness of tubes while keeping the detail and attack of the original.

Parallel saturation

There is also a parallel saturation circuit in which you pick one of two kinds of 12AX7 tube and choose the frequency band of the harmonics to add. The manufacturer explains that one of the two is more aggressive in its sound than the other.

Video: “Black Box Analog Design HG-2 – Walkthrough | Plugin Alliance” (official Plugin Alliance YouTube channel; narration in English) Watch on YouTube

Where it is useful

• Adding sparkle to the highs of a cover vocal with Air
• Making a drum bus sound thick, like tubes
• Lowering Mix to add a thin layer of tube color to the whole mix

Rating by criterion

Range of texture: 3 / 5

We check the range of distortion types you can choose, from subtle warmth to strong distortion.

Four tube stages are combined in series and in parallel, and the parallel saturation lets you choose from two kinds of 12AX7 tube.

Per-band processing: 1 / 5

We check whether the distortion can differ for low and high pitches.

There is no multiband (processing split by range of pitch) processing.

If “per-band processing” matters most to you, Saturn 2 (5 points) is a better fit.

Mix and tone control: 4 / 5

We check whether you can adjust how much is mixed with the original sound, and the tone.

It has a mix that blends in the original sound, Air, which adds sparkle above 10 kHz, and Calibration, which changes the character of the highs to Dark, Normal or Bright.

How we score (Saturation plug-ins)

Criterion	Basis	5 pt	4 pt	3 pt	2 pt	1 pt
Range of texture	The range of distortion types you can choose, from subtle to strong	Choose from 20 or more kinds of distortion	Choose from 5 or more kinds of distortion	2 to 4 kinds	1 kind	—
Per-band processing	Whether the distortion can differ for lows and highs	Multiband processing of up to 6 bands	2 to 3 bands	—	—	No per-band processing
Mix and tone control	Control of how much is mixed with the original sound, and of the tone	Mix, tone, dynamics and more can be adjusted for each band	Both mix and tone are available	One of the two	—	Not mentioned on the official page

Each criterion is scored from 1 to 5 on how well the product serves one goal: adding thickness and presence to vocals and backing tracks. Scores follow the conditions in the table above, and the rank is based on an average in which "Range of texture" counts double. The basis is official manufacturer information. Sound quality and CPU load are not measured, so they are not scored; reviews from trade magazines are introduced in the articles for reference. Price is not part of the score. Features that cannot be confirmed from the manufacturer's or a retailer's description are scored as if absent. The "OBS (streaming)" column in the table shows whether the official page lists the VST2 format that the streaming software OBS Studio can use (○). OBS does not support the VST3 format. It is not part of the score.

HG-2 system requirements and getting started

Operating system	Windows 10 and 11 / Mac (macOS 13 to 26, Apple silicon and Intel)
Plug-in formats	VST2, VST3, AU, AAX Native, AAX DSP
Trial	14-day trial available
OBS (streaming)	Works as it is (VST2 is listed)

Checked on the manufacturer’s official pages on October 17, 2026. How to use plug-ins in the OBS streaming software is explained in How to use VST3 plug-ins in OBS.

Compared with other saturation plug-ins

Click a heading to sort. On a phone, the table scrolls sideways.

Read next

• Decapitator: features and rating (rank B)
• SDRR: features and rating (rank B)
• Saturn 2: features and rating (rank S)
• MSaturator: features and rating (rank C)