Softube Tube-Tech CL 1B mk II compressor plug-in: features and spec-based rating

Softube’s Tube-Tech CL 1B mk II is a plug-in for vocals that recreates the optical compressor CL 1B from Tube-Tech of Denmark. It puts two versions, Mk I and Mk II, on one screen, and you switch between them with the Generation Switch.

A compressor holds down sounds that are too loud and evens out differences in volume. For vocals it keeps the level stable and easy to hear, and it can also add punch to a sound.

In this article we compare CL 1B mk II with 16 compressor 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 16 compressor plug-ins, CL 1B mk II 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 3.3.

Strengths

• Compression character (4 points): you can choose among several characters of compression to suit the material and your taste.

Things to keep in mind

• Speed (2 points): you have to set the values yourself.

Who it suits: people who want to even out vocals and bass in a warm, musical way.

Main features of CL 1B mk II

Switch between Mk I and Mk II with the Generation Switch

It includes an early version of the CL 1B (Mk I) and Mk II, whose sound was rebuilt from scratch, and you can quickly compare them with the Generation Switch. The manufacturer explains that it also updated the look and functions for today’s production.

Optical compression that grabs quickly and lets go slowly

The manufacturer explains that an optical compressor grabs the start of a sound quickly and takes time to return, so it holds down peaks naturally while smoothing the body of the sound softly. It says the unit suits vocals, bass, acoustic guitar and so on.

A Wet/Dry knob

There is a Wet/Dry control, which allows parallel compression by blending the compressed sound with the original sound. The product page introduces this function in a user comment.

Where it is useful

• Smoothing a vocal warmly to bring it forward
• Bringing bass together with the softness of an optical compressor
• Switching between Mk I and Mk II to choose the texture that suits the song

Rating by criterion

Compression character: 4 / 5

We check whether you can choose the character of the compression, from transparent and natural to colored and vintage-style.

You can use the optical CL 1B by switching between two versions, Mk I and Mk II. The manufacturer explains that Mk II is a version whose sound was rebuilt from scratch.

Speed: 2 / 5

We check whether it has features that get you to a good setting quickly, such as automatic settings and easy presets.

The controls are standard. There is no AI or automatic aid.

If “speed” matters most to you, smart:comp 3 (5 points) is a better fit.

Mix applications: 3 / 5

We check whether it supports mix applications such as reacting to another sound (sidechain) and mixing with the original sound (parallel).

The Wet/Dry control lets you do parallel processing by blending with the original sound (introduced on the product page).

How we score (Compressor plug-ins)

Criterion	Basis	5 pt	4 pt	3 pt	2 pt	1 pt
Compression character	Whether you can choose the character of the compression to suit the material and your taste	Many compression styles and coloration to choose from, plus fine controls such as look-ahead	Several styles plus either coloration or spectral processing	Either several styles or a recreation of vintage hardware	One type, but with coloration or compression-curve adjustment	One type
Speed	How quickly you can reach a good setting	AI analyzes the sound and suggests settings	Several automatic aids, such as auto gain and auto release	Few knobs; almost everything is set with one	Standard controls	—
Mix applications	Uses such as sidechain, parallel and M/S	External sidechain, sidechain EQ, and M/S or parallel are all included	External sidechain plus either parallel or M/S	One of external sidechain, M/S or parallel	—	Not mentioned on the official page

Each criterion is scored from 1 to 5 on how well the product serves one goal: evening out the volume of a vocal and blending it into the backing track. Scores follow the conditions in the table above, and the rank is based on an average in which "Compression character" 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.

CL 1B mk II system requirements and getting started

Operating system	Windows 10 and 11 (64-bit) / Mac (macOS Sonoma 14, Sequoia 15, Tahoe 26)
Plug-in formats	AU, VST, VST3, AAX
Other	A Softube account and an iLok account are required (a physical iLok is not needed). An internet connection is required
Trial	20-day free trial available
OBS (streaming)	Works as it is (VST2 is listed)

Checked on the manufacturer’s official pages on October 17, 2026.

Compared with other compressor plug-ins

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

Read next

• MJUC: features and rating (rank B)
• 1176 Classic Limiter Collection: features and rating (rank B)
• Pro-C 3: features and rating (rank S)
• smart:comp 3: features and rating (rank S)