Walrus Audio Mira Compressor

Full Feature List

• Studio-grade Optical Compressor
• Controls: Threshold, Ratio, Make-up, Level, Attack, Release, Blend, Side-Chain High-Pass Filter, Bypass
• Warm, analog optical compression with loads of sustain
• Extensive controls normally only found on studio units
• Threshold sets volume-point at which the compressor starts to engage
• Adjustable Ratio from 1:1 to 20:1
• Make-up control to maintain unity level after signal has been compressed
• Level knobs sets overall output
• Smooth attack and release
• Blend control to mix dry and affected signal
• Switchable 120 Hz High Pass filter in side-chain
• Great for Bass Guitar due to HPF- and Blend-feature
• Runs internally at ±15VDC for higher headroom
• Gain reduction LED illuminates when compression is applied
• Top mounted Input & Output
• True Bypass design
• 9-volt DC, Center Negative, 200mA minimum
• Power Supply not included
• Smoky grey die-cast enclosure with Cream, Orange, Red, and Dark Blue ink
• Made in the USA

Look! Come and see the Mira's capabilities. In the Spanish language, Mira is a command that translates to look, see, and call attention to. With the Mira Optical Compressor, you’re creating and shaping a studio-grade timbre that demands to be seen, heard, and above all, felt. The Mira delivers warm, analog optical compression with mountains of sustain and a smooth attack and release that can be blended in to taste. Dynamically engage the senses with the Mira.

The Mira is a true bypass optical compressor offering studio-grade sound sculpting and sustain packed with controls you’d normally only find on studio units. Use the Blend knob to mix in your compressed sound with your clean tone to maintain note clarity while offering increased sustain. Mira also offers in-depth control over Attack, Release, Ratio, and a Make-Up knob to help maintain unity levels after your signal has been compressed. For higher headroom, Mira runs internally at ±15VDC.

Adding to the bonus features, Walrus decided to also provide apush-button High Pass Filter in the side-chain (the part of the circuit that controls the optical element in the compressor). This is great for preventing bass frequencies 120Hz or below from engaging the compressor as much as higher frequencies. The keenresult of this keeps the compressor from overworking on lower notes and is great for bass guitar or keeping low-frequency dynamics dramatic for guitar players.

Look to the Mira as your new always-on pedal. Even at low settings, not only will you hear rich, full clarity in your notes, but you’ll feel the difference in its response too.

Blend – The Blend knob controls the amount of compressed signal mixed in with the dry signal at the output. With this control at minimum, all compressed signal is removed from the output leaving just the dry signal. With this control at maximum, all dry signal is removed from the output leaving just the compressed signal. Mixing in some dry signal with the compressed can maintain note clarity while offering increased sustain.

Make-Up – The Make-Up knob sets the amount of gain applied to your signal after it has been compressed. This allows you to “make-up” any lost volume due to the action of the compressor to maintain unity level of the compressed signal.

Threshold – The Threshold knob allows you to set the volume point at which the compressor
starts to engage. Counter-clockwise is a lower threshold; clockwise is a higher threshold.
Lower the Threshold for stronger compression and raise it for less compression.

Ratio – The Ratio knob sets the ratio of the compressor or how much volume reduction occurs after signal crosses the threshold. The higher the ratio, the more the signal gets compressed once it crosses the threshold. The range is about 1:1 - 20:1. A ratio of 1:1 (one to one) is the lowest and it represents no attenuation. A ratio of 2:1 indicates that a signal exceeding the threshold by 2dB will be attenuated by 1dB, or a signal exceeding the threshold by 8dB will be attenuated by 4dB, etc. Use this control to fine tune how the compressor responds to signal once it crosses the set threshold.

Attack – The Attack control allows you to tune the initial response, or the engagement of the compressor once the signal crosses the threshold. Counter clockwise will give you faster attack times; clockwise will give you slower attack times. Use faster attack times if you really want to grab the attack of your guitar and get it under control. Use slower attack times if you want the attack of your notes to shine through before the compressor engages.

Release – The Release control allows you to tune the release response (“release time”) of the compressor once the signal goes below the threshold. This is where you can really control the sustain of your signal. Lower settings will give you a faster release, while higher settings will give you a slower release. Use slower release times if you want more sustain and faster release times if you want less sustain.

*Note - Use the attack and release together to help control transients, and dial in sustain to “glue” things together.

HPF – When engaged, the HPF switch introduces a High Pass Filter in the side-chain (the part of the circuit that controls the optical element in the compressor). Use this when you want to prevent bass frequencies (120Hz or below) from engaging the compressor as much as the higher frequencies. This will keep the compressor from overworking on lower notes, which tend to have more amplitude and can cause the compressor to not respond to your playing as well. This filter is finely tuned and will be most noticeable when playing instruments with greater lower frequency content like bass guitar and keeping low-frequency dynamics dramatic for guitar players. Leave the switch out for normal operation, in to engage the HPF.

Gain Reduction LED – Illuminated when gain reduction is happening and compression is
being applied. It gets brighter the more the gain is reduced.