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API Select TranZformer CMP Pedal

API’s legendary VCA-type compressor circuit integrated into a versatile and compact guitar effects pedal
MFR# TranZformer CMP

Product Description

The API Select TranZformer CMP Compressor Pedal incorporates API’s legendary VCA-type compressor circuit within a versatile and compact guitar effects pedal. Made to easily fit on your pedal board and engineered to run off any standard 9V power supply, the CMP pedal gives users a classic studio-quality compressor right at their feet. 

API has outfitted the CMP with adjustable attack and release times, buffered bypass in/out footswitch, wet/dry blend control, transformer output, selectable “feedback” and “feedforward” compressor styles, and the brand’s signature sound. 

There are two forms of compression on the API TranZformer CMP, the "old" and the "new." The “old” style uses the feedback type of compression typically found on the classic early 1970s 525, while the “new” style commonly uses a feed-forward type comparable to many popular modern compressors.


The API TranZformer CMP can easily equip your pedal board with the same pro audio studio-quality dynamic processing that effortlessly launched a thousand hit records. This API guitar effects pedal offers that signature API sound, courtesy of the 2510 op-amp, a 527 VCA-style compressor circuit, and a muscular-sounding transformer output. In addition, this stompbox was primarily engineered for high-performance recording studio operation with a standard 9-volt power supply. The API TranZformer CMP offers both a feed-forward and feed-back compression for an added level of sonic versatility, along with an adjustable attack and release times with an ultra-useful dry/wet knob. The TranZformer CMP Pedal boasts a high-quality buffered bypass by switching to ensure an ideal signal, even if your recording studio rig includes arena-sized cable runs. Finally, an easy-to-see LED indicator rounds out the API Select TranZformer CMP's outstanding features.


The TranZformer CMP Pedal allows studio-precise dynamics processing at any level of your audio journey. This compressor pedal's Input knob yields up to +9dB to +30dB of gain, and we know more gain equals more compression. The CMP’s Sustain knob determines the quantity of gain reduction, where higher levels lower the threshold for maximum compression. The Output knob helps deliver -inf. to 0dB of level control, where fully clockwise exhibits 0dB (zero level cut). Users also get Fast/Slow Attack and Release switches that can offer 1ms/10ms for attack and 300ms/1s for release. Pro musicians have found the Blend control to be part of the TranZformer CMP's most useful features, enabling users to dial in hyper-transparent compression in any audio application.

Requires separate power supply. 9 - 18V DC negative center, 2.1 x 5.5mm barrel connector. Do not use more than 18V DC.


  • Proprietary API 2510 OpAmp
  • Signature API output transformer
  • Adjustable attack and release times
  • Wet/dry blend control
  • Selectable feedback/feedforward compressor styles
  • Buffered bypass

Product Specifications

Condition New
Input Connectors 1/4-inch TS
Output Connectors 1/4-inch TS
Power Supply Required (not included)

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