Full Studio Compression Controls in Pedal Format
The CompIQ STELLA Pro MK2 is a feature-complete and powerful all-analog compressor/limiter pedal for use with guitar, bass, or any other instrument or audio source. It is also one of the very few that can be powered by an internal 9V battery or an external supply in the range of 9-18VDC. It is built around the flagship 4320 THAT Analog Engine® which incorporates a true RMS-level detector that accurately measures the input signal and processes it through an ultra-transparent-sounding Blackmer® VCA. Unlike peak detection, commonly used in other compressors, the RMS (root mean square) sensor calculates an average peak level of the signal, aligning more closely with how human hearing perceives differences in loudness.
To my mind the Stella is the very best Pro Studio Style Pedal Compressor you can currently get – there really is nothing else at this level / form factor and degree of surgical precision – really nothing out there is more comprehensive and finely controllable than the CompIQ Stella!
The pedal now offers two selectable compression modes. In Feed Forward mode, emphasis is on speed and accuracy, utilizing a pre-VCA copy of the input signal. This mode can provide subtle compression up to brick-wall limiting based on control settings. The “old-school” Feed-Back compression delivers a smooth response suitable to transparently even out playing dynamics. This mode uses a post-VCA copy of the audio signal for its dynamic processing. While Feed-Back mode excels at low-to-medium compression ratios, it may be less suitable for using compression as an effect or hard peak-limiting. Nevertheless, by adjusting the threshold, employing a hard knee, selecting a higher ratio, setting a fast timing, and even boosting the control signal in the side chain filter, the Stella can function as a genuine Feed-Back limiter. In any settings, both modes sound clean and natural, without pumping, breathing, distortion or other artifacts.
The Stella – the brand’s flagship compressor for bass and guitar – is the perfect embodiment of the company’s spirit. Apart from your regular controls like ratio, threshold, attack, release and gain make-up, the Stella also has toggle switches for the side-chain filter, Tilt EQ, and knee. While there’s a lot going on with this pedal – it has nine knobs, seven LEDs, and four switches – it’s a lot more intuitive than it seems. WE SAID Small, but packs all the features of a VCA compressor, and the same audio quality too.
The Compression Knee feature provides two options, each with its particular sonic signature. Hard Knee compression is quick and snappy, suitable for peak limiting or enhancing the compression feel. Soft Knee compression is gradual and gentle, creating a transparent effect even at high ratios.
The Stella MK2 features upgraded side-chain capabilities, including a variable Lo-cut/boost filter specifically designed for bass instruments (±12dB @ 90Hz, 12dB/octave). By cutting lows in the side-chain, compression in the lows at the output is reduced, restoring overall signal energy. Conversely, boosting lows in the side-chain increases compressor sensitivity, aiding with very low-level signals. Moreover, a matching variable Hi-cut/boost filter in the side-chain further refines this balance (±7dB @ 3kHz, 12dB/octave). The cutting side of the side-chain filter avoids overly compressing highs, preserving a natural brightness in the output. Conversely, boosting highs in the side-chain enhances compressor sensitivity to high frequencies, which helps with very bright sounding instruments. When both filters are set to cutting, the compressor becomes more sensitive to mid-frequencies within 1-2 kHz, resulting in increased compression in this range at the output. These enhancements effectively manage compression across lows, mids, and highs, delivering impactful dynamics without unwanted pumping and maintaining desired balance in the audio spectrum.
The X-EQ tilting equalization circuit, rooted in the Hi-Fi era of the 1970s, offers two pivot frequency options: High (at 1kHz) suitable for guitars, and Low (at 330Hz) which works better for bass. This post-compression gentle correction can compensate for differences between instruments or be employed to enhance the lows or highs of the instrument. Both settings can be used in either application, each bringing a different but useful and likable EQ result.
The STELLA Pro MK2 also includes two internal DIP switches for voicing selection, allowing for subtle shifts in the internal dynamic frequency processing that add nuanced coloring to the sound. The Spark setting enhances the highs with polished brilliance, while Tight slightly dips the low-mids for added depth. Punch, on the other hand, delivers a tube-like compression feel with rich lows and warm highs, perfectly complementing the DITOS transformer voicing. While “punch” often suggests action, in this context it specifically relates to tonal sound perception. If you’re aiming for action-punch, we recommend using the Punch voicing along with Short auto timing or manual timing that features longer Attack and shortest Release settings. Additionally, Hard Knee and Feed-Forward side-chain configuration are ideal (Feed-Back will also work for punchiness with short timings). During manufacturing, we may set the Spark or Punch options as default so you can start experimenting immediately. However, if you prefer to maintain the most transparent sound response that preserves the instrument’s natural character, you can simply turn off the voicing switches.
The Stella is a compressor that could prove itself vital as part of any guitarist or bassist’s pedalboard, offering fully-featured, studio-quality control over your dynamics in compact form. There’s not much else Becos could have squeezed on here, though it is worth noting that there is a larger dual-band/stacked compressor in the range, the Twain, if you wanted more.
The Dynamic Auto Timing circuit offers user-friendly operation with two selectable options: Fast and Slower. These settings adapt to different playing styles. For added versatility, manual control over Attack and Release timings is available, unlocking a range of other compression possibilities. For instance, setting the compressor for slow attack and fast release allows initial transients to pass through at a higher audio level (set by the Make-up Gain), creating a tight and percussive sound suitable for guitar “chicken picking” or bass “slapping.”
The Becos CompIQ Stella Pro MK2 with DITOS is not just another compressor pedal – it’s a professional tool that brings the finesse of high-end studio gear to your pedalboard. Its combination of pristine audio quality, deep control, and the added versatility of the DITOS makes it a must-consider for serious guitarists, bassists, and even recording engineers.
The Stella also features a Dry/Wet Mix, which allows for blending a desired amount of clean signal with the processed signal, resulting in a more natural compression effect. Such a mixing technique (a.k.a. New York style) is usually employed when hard compression is set out as an effect or when limiting must be made more subtle.
An 8-LED gain reduction meter allows for accurate monitoring of the compression applied to the input signal. This feature provides useful visual feedback on the degree of sound processing.
This incredibly full-featured compressor offers all the controls a rackmount unit offers, but in a pedal format.
The optional DITOS board featuring a transformer-coupled balanced output in 1/4″ TRS format is available for insertion in the space typically used for the 9V battery. It enables direct recording or sending the signal to a mixing console and can also function as an unbalanced floating output to connect to another pedal or amplifier, delivering the warmth of the output transformer. The main VCA output remains functional for routing the signal to another processing chain or tuner. An internal ground-lift jumper is available to resolve potential ground-loop noise issues; we recommend keeping the jumper in place unless internal circuit ground lift is necessary. When the VCA output is in true bypass, DITOS still receives input from it, acting as a consecutive device. This always-connected active load results in a slight signal level difference between Stella’s powered and non-powered VCA output in true bypass. When not powered, DITOS can’t output any signal. Please note, the DITOS board is no longer sold separately and is now only available as an option for a new CompIQ Stella.
I must say, wow! The transformer output is filled with natural warmth, with huge punchy lows and just all around brilliant tone. You definitely could just go instrument into Stella MK2 direct to console and find yourself really content with your tone. Everything about the Becos Stella oozes quality and fidelity. I’m not aware of any compressor on the market that packs this much punch in terms of functionality. I mean, this thing is really in a league of its own. Use it in the studio or on your pedal board. It really is quite amazing. From my perspective, for many use cases the Becos Stella MK2 is one of the best compressor pedals currently on the market.
Note! The DITOS marking is present on all enclosures, even if the DITOS option isn’t purchased, to streamline production. If you’d like to add DITOS later, the pedal must be sent to us, with prepaid installation and return shipping costs. Contact us for details on adding DITOS to your Stella.
DITOS sound demos
Sound demos on bass
Audio examples graciously provided by jazz artist Jean-François Untrau from France, showcasing the alternating effect of the compressor in bypass and active modes. For specific details on the utilized settings, please refer to the Settings Examples tab located above.
Pristine audio processing
The CompIQ series of compressors preserves the unique tonal characteristics of the input signal. They provide pristine audio compression and offer a high dynamic range, which enables clean, natural-sounding tones with minimal noise and no artifacts or distortions in any settings.
Key features
- Full analog circuit with true by-pass
- True RMS-level detector for accurate input signal measurement
- High-performance Blackmer® VCA compression engine
- Optional DITOS board for transformer-coupled balanced output (10KΩ impedance)
- Feed Forward/Feed-back compression modes
- Ratio 1:1 to infinite:1 (limiter)
- Threshold -45dBu to +10dBu
- Make-up Gain -6dB to +20dB
- Soft/Hard compression knee selection
- Manual timing: attack 0.12-12 ms/dB of gain reduction, release 1.2-120 ms/dB of gain reduction
- Fast/Slower dynamic auto attack and release timing with hold for peaks over the threshold
- X-EQ with selectable frequency pivot 330Hz for bass instrument or 1KHz for guitar or other applications
- Voicing: Flat, Spark, Tight, Punch (internal DIP-switch selectable)
- Lows/Highs variable side-chain filter with boost & cut around 90Hz and 3kHz
- Dry/Wet mix
- 8-LEDs gain reduction meter
- High-end quality Burr-Brown FET audio ICs, low tolerance metal-film resistors, Panasonic, Kemet, Cornell Dubilier plastic film audio capacitors, Gold-plated multi-layers PCB, Gold-plated micro-switches
- Genuine Hammond black-powdered aluminum enclosure
- Runs on standard 9V internal battery or 9-18 V DC external power supply (not included), center negative, 12mm long barrel plug
- 3-year warranty (direct to manufacturer, international, transferable)
- Hand-assembled in Vienna, Austria
Note! Optimal configuration of the CompIQ Stella for studio recording or live performances typically necessitates a solid understanding of audio compression.
Reviews
For more reviews, mentions, and information, please visit our Blog.
Posted: October 24, 2019
Becos CompIQ Stella Pro Compressor was nominated in the Guitar Magazine’s poll for The Best Effects Pedal of the Year 2019.
Cast your vote by 4 November 2019!
Posted: August 17, 2024
Use it in the studio or on your pedal board. It really is quite amazing. From my perspective, for many use cases the Becos Stella MK2 is one of the best compressor pedals currently on the market.
Posted: December 21, 2019
Every once in a while, a very pro user finds the time to write a complete review on a product of hours. This time, the Dark Wizard of the Knights Martial user on Basschat.co.uk forum took the task to make an in-depth review of the CompIQ STELLA Pro Compressor pedal.
Posted: October 26, 2019
“I’m not aware of any compressor on the market that packs this much punch in terms of functionality. I recommend this one.” – Chris Tromp, Compressor Pedal Reviews
Posted: June 17, 2022
Even if you apply a lot of compression, the amount of sound information does not decrease. It has a core body, so in that sense, it creates a high-quality impression. There is no noise and the build quality is high.
The measurements were taken using FRA4PicoScope 64-bit software with a PicoScope 2204A oscilloscope and its synchronized signal generator, a -20dBu (0.22Vp-p) input signal positioned at average instrument-level dynamics, and a 9VDC power supply. The CompIQ Stella Pro Compressor MK2 controls were set to balance input and output levels across the Dry and Wet lines. The output was connected to a high-impedance load during measurement.
The Stella Pro offers extensive control over frequency dynamics. The tilting EQ and Voicing settings shift specific frequencies, adding controlled coloration to the signal. By adjusting the side-chain frequency filters (cut or boost), users can intentionally alter the compression of affected frequencies at the output. While we don’t provide frequency response plots for every possible configuration, the Stella offers a wide range of adjustments. Each setting creates a unique response, making it adaptable to individual instruments and user preferences. The measurements use a 4:1 Ratio, threshold set for the indicated compression in dB, Hard Knee, Slower Auto Timing, and highlight Feed-Forward (FF) and Feed-Back (FB) side-chain topologies. Note that the input signal is not shown, as it would appear as a straight line at 0dB, similar to the bypassed signal in both powered and non-powered states.
Frequency response without compression and in true bypass
Below are the frequency response plots for the compressor output, covering both Wet and Dry lines with no compression applied. The bypassed signal is also shown for both powered and non-powered pedal states.
VCA output, 100% Wet line
VCA output, 100% Dry line
VCA output, True By-Pass (powered)
VCA output, True By-Pass (not powered)
Tilting X-EQ with two frequency pivot options
When the X-EQ knob is turned clockwise (CW), Highs are boosted and Lows are attenuated. Turning it counterclockwise (CCW) boosts the Lows and attenuates the Highs. Two tilting frequency point options are available: 330Hz for bass and 1kHz for guitar. With X-EQ knob at noon, there are no frequency changes. Small variations in the tilting point may result from Make-Up Gain settings and component tolerances (we use 1% tolerance thin-film resistors and 5% tolerance plastic film capacitors).
VCA output, 100% Wet, no compression, 330Hz Pivot (L), max tilting toward Lows
Lows are boosted while Highs are attenuated, 330Hz frequency pivot
VCA output, 100% Wet, no compression, 330Hz Pivot (L), max tilting toward Highs
Highs are boosted while Lows are attenuated, 330Hz frequency pivot
VCA output, 100% Wet, no compression, 1kHz Pivot (H), max tilting toward Lows
Lows are boosted while Highs are attenuated, 1kHz frequency pivot
VCA output, 100% Wet, no compression, 1kHz Pivot (H), max tilting toward Highs
Highs are boosted while Lows are attenuated, 1kHz frequency pivot
The “Normal” Side-Chain
The two plots below show the compressor’s output frequency response during compression with the Lows and Highs SCF knobs at noon in “Normal” mode. The side-chain signal mirrors the input without extra filtering. With output level matching the input, the CompIQ Mini maintains a nearly perfect flat frequency response from 30Hz to 30kHz, even under this high compression.
The slight subsonic adjustment at the start reflects the RMS sensor responding to the automatic low frequency sweep. The starting level is set by the Make-Up Gain for the chosen compression amount. Once compression settles in, the circuit’s frequency response at the output is linear. The plots show responses for both Feed-Forward and Feedback compression types.
VCA output, 4:1 Ratio, 12dB of Compression, 100% Wet, Feed Forward, with normal SCF
VCA output, 4:1 Ratio, 12dB of Compression, 100% Wet, Feed-Back, with normal SCF
Cutting and boosting Side-Chain Filters frequency
Cutting and boosting the Side-Chain Filters frequency allows users to manipulate the balance of specific frequencies within the side-chain, influencing how the compressor responds to those frequencies at the output.
When the Lows and Highs SCF knobs are turned fully clockwise (CW), the side-chain progressively attenuates lows and highs using first-order variable High-Pass Filters. This reduces the compressor’s sensitivity to these frequencies, resulting in less compression and making them louder at the output via Make-Up Gain, as shown in the plots. Turning the SCF knobs counterclockwise (CCW) boosts these frequencies in the side-chain, increasing compression and reducing their levels at the output. With the SCF knobs at noon, the filters leave the signal unchanged, which we refer to as “Normal” side-chain processing.
Although there are slight differences between Feed-Forward and Feed-Back compression modes, only Feed-Forward plots are shown here. Additionally, the side-chain plot is overlapped (in Green), illustrating how the output frequency response (in Blue) mirrors the filtering in the side-chain.
VCA output, 4:1 Ratio, 10dB of Compression, Feed Forward, with max cut on Lows SCF
VCA output, 4:1 Ratio, 20dB of Compression, Feed Forward, with max boost on Lows SCF
VCA output, 4:1 Ratio, 8dB of Compression, Feed Forward, with max cut on Highs SCF
VCA output, 4:1 Ratio, 16dB of Compression, Feed Forward, with max boost on Highs SCF
VCA output, 4:1 Ratio, Feed Forward, with max cut on Lows & Highs SCF’s
More compression is applied to the Mids.
VCA output, 4:1 Ratio, Feed Forward, with max boost on Lows & Highs SCF’s
More compression is applied to the Lows and Highs than to the Mids.
SCF measurements were taken after balancing input and output levels with the SCF in the neutral position for the initial measurement. The filters were then adjusted to their extremes (fully CW and CCW) to demonstrate their effects. In practical use, Make-Up Gain and other parameter adjustments are necessary to maintain a balanced input-output level, factoring in the SCF setup. Filtering combinations, including the tilting EQ and Voicing, create even more distinct compression tone-prints.
Before you start
The CompIQ Stella is a full-featured compressor in pedal format which allows complex processing while preserving the dynamics of your playing. A good understanding of compression is normally required to optimally set it up for live performance or studio recording.
We advise testing the CompIQ Stella with an instrument amplifier instead of using headphones. Start by playing with it alone then integrate your settings along with your other pedals.
Here is the Stella Manual for your reference. For more in-depth technical info on our VCA line of compressors please take a look at the CompIQ 101 section. If you have particular questions regarding how Stella works, or you would like to share your feedback please contact us.
Stella sound demos on bass
Each demo has an associated image with pedal’s knobs & switches position used when recorded. A higher resolution image is displayed when loading the track on Soundcloud — along with details regarding the instrument, strings used for that phrase, and playing technique. Start by playing any track in the playlist below and click View Track to load it on Soundcloud for details.
The audio phrase is played twice in each track. First, the dry sound with the pedal in bypass, followed by a take with pedal engaged.
Many thanks to jazz artist Jean-François Untrau (France) who recorded these demonstrations.
Stella + DITOS sound demos on guitar
Back to Product Page
Blog post: CompIQ Stella Settings Examples
CompIQ STELLA
CompIQ TWAIN
CompIQ MINI
CompIQ ONE
Ziffer Overdrive
Usually, when I use a compression pedal, it’s more like an effect because it sounds cooler playing slap, rather than the use it to even out peaks. But the Stella can be set radically: you can hit only the high peaks with some nuances, or you can make it sound tight.
All in, the Stella manages to cram a dizzying number of top-quality features into a standard pedal. At all times, the tone was clear, clean and detailed in the way that I've come to expect from high-end studio plugins. Bravo!
In short, it’s what I’ve always wanted of a compressor pedal. The Stella can sound wonderfully transparent, or full of character, and there’s oodles of control at your fingertips. Bass players should absolutely love this thing (though I suspect they may be even more enamored with the company’s new split-band compressor).
This pedal is designed to provide an array of features – with rack unit-levels of tweakability – in a pedalboard-friendly format. A highlight of the CompIQ Pro Stella Compressor is its analog tape saturation circuit.
For those who take their dynamics seriously, this fully featured stompbox offers a studio-grade VCA compressor that you can mount on your pedalboard. The Stella is a compressor that could prove itself vital as part of any guitarist or bassist's pedalboard, offering fully-featured, studio-quality control over your dynamics in compact form.
Knob-heavy pedal offers compression, limiting, tape saturation and more.
