Guitar Compressor Pedal: Ratio, Attack and a Useful Comparison

Choose a passage before choosing a setting. You might want accented notes to stand out less, or you might want to preserve a sharp initial attack while controlling the note that follows. Write down that aim and use the same passage throughout the comparison.

For the downward compression discussed here, the processor reduces gain above its threshold. Fender explains threshold, ratio and timing as separate controls. A pedal with fewer knobs can combine those functions or set some internally. Its panel labels are not a complete circuit description.

Compression also cannot decide which note belongs in a musical accent. If the aim is cleaner timing or deliberate accents, include a dry practice pass. Use the lead and rhythm guide to define the musical role of the part.

The Empress MKII provides a concrete example: its Input control drives more or less compression, its Output control changes level without changing the amount of compression, and its Mix control blends the dry and compressed paths. Its attack time increases clockwise. Those are documented details of this pedal, not a direction rule for every compressor.

A knob labelled “Sustain” needs its own explanation. Do not assign it a universal threshold, ratio or release function from the name alone. Record the model and its control meanings before copying a suggested setting.

Assume a steady input 6 dB above a fixed threshold, an abrupt transition at that threshold, and no added output gain. Ignore attack and release and use only the compressed path. In that simplified model, output above threshold equals input above threshold divided by the ratio number.

These are exact decimal results for the stated assumptions. The ratio describes level changes measured in decibels; 4:1 does not mean that the listener hears one quarter of the original volume. The Empress manual uses the same above-threshold definition and offers 2:1, 4:1 and 10:1 choices.

Real note attacks are changing signals. A softer knee, timing behaviour and a dry blend can all make an actual passage differ from this static example. Use the table to understand the ratio label; it does not predict the complete pedal output or recommend a ratio for your playing.

Begin with a clean or lightly driven sound that you already know. Keep the guitar, pickup selection, amp gain and playing position fixed. Follow the pedal’s own setup instructions, then play a short passage containing a soft note, an accent and a held note. Leave a pause at the end.

Alternate bypass and effect. Use the documented output control while alternating the same passage in bypass and effect. Bring the levels close enough that switching does not create an obvious level jump before judging which response helps the passage. An approximate match is an owner comparison, not a calibrated loudness measurement. If the pedal automatically changes output gain, note that limitation.

Change one compression control at a time. Listen for the initial pick or finger attack and the following note separately. Then try release changes while repeating your actual rhythm. Describe what happened to that passage instead of calling a setting universally “transparent” or “punchy.”

If the pedal has gain-reduction metering, read it using its manual. A meter can help show that the detector is responding, but its display does not establish that the result suits the song. These steps are proposed; no comparison recording is supplied with this article.

Return the drive and other effects you normally use, keeping their settings documented. Compare the pedal’s contribution again: the result of a clean audition may not describe the complete chain. For the routing question, use the effects-order guide and check the input and output requirements of each device.

Include the silent pause in your listening record. If you hear more hiss or background sound, record the engaged controls and chain. An audible increase alone does not identify a faulty compressor; added output gain and the rest of the rig need to be considered. This article contains no noise measurements.

Do not change compressor level and overdrive gain together during a comparison. If you want to use the compressor as a boost into a drive stage, that is a separate musical aim. Check its transition deliberately after completing the similar-level comparison.

A useful result might be a small change, a setting reserved for one part, or choosing bypass. Keep the observations in words you can reproduce at the next rehearsal. Do not treat a clock-face setting copied from another pedal as equivalent timing or gain reduction.

If the passage loses an accent you wanted to keep, return to the last useful setting and repeat one change at a time. The purpose of this record is to connect a control adjustment with a playing decision. It does not certify a model’s performance.