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API TranZformer GT Multi-Effects Pedal

Guitar Pedal and DI Box


Special 12-Month No-Interest Financing.

SKU: APIGTGuitarTranZformer Categories: , Brand:


The API TranZformer GT is a foot pedal optimized to give your guitar the distinctive API sound onstage or as a recording DI

Nothing makes a guitar sound like rock and roll like API EQ and compression, which the TranZformer GT gives guitarists in a foot-pedal format. A multi-functional pedal, the TranZformer GT combines an API 525 feedback-style compressor with a 3 band equalizer. The compressor is especially useful for evening out acoustic guitars and arppegiated electrics. The TranZformer GT’s EQ is equipped with the most often-used settings of the renowned API 550A equalizer. The three corner frequencies include 200Hz for adding body, power, and warmth; 1.5kHz for presence and transient articulation; and 5kHz for air, edge, brightness, and brilliance—and of course, API’s unmistakable sound.

API TranZformer GT in one take:

  • Traditional fully discrete API circuit design
  • Variable compressor with in/out switching
  • 3-Band +/-15dB equalizer with in/out switching
  • Input Gain control with +30dB gain
  • Balanced and unbalanced output phase reverse
  • Balanced output ground lift
  • Included 18-volt external power supply optimizes performance
  • Hardwire bypass switch
  • Universal +18VDC power supply
  • LED clip indicators input and output stage clipping
  • Five-year parts and labor warranty


 The signal path of the TranZformer GT from input is gain, compressor, EQ, and transformer output. Like the studio gear it derives its sound and functionality from, the TranZformer GT includes phase reversal switches on each output, ground lift, clip indicator, transformer output, and a hardwire bypass switch. The input gain level is +9dB to +30dB and interacts with the compressor, increasing compression as gain increases (much like some famous studio compressors).

The equalizer is a 3-band with ±15dB gain, with three corner frequencies set at 200Hz, 1.5kHz, and 5kHz for low, midrange and high. The low and midrange EQs are peaking, while the 5kHz is a shelving EQ. The TranZformer GT’s output is –inf (full off) to 0dB, which sets the output level for the unbalanced 1/4″ output, which feeds your guitar amp. The balanced output is fixed. The compressor has six switchable settings): 1 = subtle compression, 6 = maximum compression. Turning clockwise Increases gain reduction (lower threshold) while simultaneously raising output level to match.

Both the compressor and equalizer are able to be switched in and out independently. The TranZformer GT is built to API’s exacting standards and represents the uncompromising and innovative approach audio circuit design that brought API to the forefront of professional analog gear for nearly 50 years.


The controls of the TranZformer GT are in the style of API’s studio gear. They include:

  • Gain: Input level; +9dB to +30dB; More gain creates more compression
  • Comp (compression): Determines amount of compression (gain-reduction); Higher
  • numbers provide more compression (lower threshold)
  • Clip LED: Illuminates to indicate Input Gain or Output stage (pre Level) clipping
  • Tone
  • Output Level: -inf. to 0dB attenuator; 0db (no cut) is fully clockwise
  • Sets level for 1⁄4” unbalanced output only (balanced output level is fixed)


  • Comp (compressor): Engage/disengage compressor; lit LED when engaged
  • Tone (equalizer): Engage/disengage equalizer; lit LED when engaged
  • Bypass: Hardwired unbalanced bypass; lit LED when bypassed


  • Instrument Input: 1⁄4″ Hi-Z, unbalanced
  • Unbalanced output (to amp): 1⁄4″ Hi-Z (fed directly from input in bypass)
  • Balanced Output: 3-pin XLR male, Lo-Z line level (XLR is muted in bypass)
  • 18 Volt DC power input (on back) 500mA maximum
  • 1mm x 5.5mm barrel connector, tip negative

Output Controls:

  • Unbalanced output phase reverse (inverts unbalanced output polarity)
  • Balanced output phase revers (inverts balanced output polarity)
  • Output ground lift (eliminates hum from ground loops)

 With the API TranZformer GT multi-effects pedal, you don’t have to wait until you get to the studio to add API mojo to your guitar. For more information, call or chat online with your Westlake Pro Sales Consultant today.


API TranZformer GT specifications:

  • Input connection: 1/4″ Hi-Z unbalanced instrument input
  • Input Impedance: ~500kΩ
  • Maximum Hi-Z instrument input level before clipping: +13dBu
  • Output connections: 1/4″ Hi-Z unbalanced output w/ variable level control,
  • XLR Male balanced line output, fixed level (Balanced line output level is +6dB higher than Hi-Z output with Level control fully clockwise)
  • Output Impedance: Hi-Z output: 7.5k ohm
  • Balanced Line output: Less than 75 ohm
  • Gain Control: 9.2dB – 30dB, Variable, Hi-Z output
  • 2dB – 36dB, Variable, Balanced line output
  • Level Control: -inf. to 0dB, Variable, Hi-Z output only
  • Maximum output level before clipping: Hi-Z Output: +21dBu
  • Balanced Line Out: +27dBu
  • Frequency Response: +0, -0.5, 20-20kHz, both outputs, low-capacitance cable
  • Noise: -75dBu
  • THD+N: Less than 0.01%
  • Tone Control: 200Hz & 1500Hz Peaking, 5kHz Shelving, continuously-variable boost/cut, +/-16dB range
  • Compressor: Ratio: Varies from 2:1 to 20:1 depending on compressor control setting
  • Attack (fixed): Less than 5ms
  • Release (fixed): 100ms average (frequency-dependent for natural envelope tracking)
  • Power Supply: 18VAC @ 1A
  • Size: 8″ x 5-1/2″ x 4″
  • Size (Boxed for Shipping): 10″ x 8″ x 8″
  • Actual Weight: 4 lb.
  • Shipping Weight: 6lb.

Additional information

Weight 4 lbs
Dimensions 6 × 8 × 4 in
Manufacturer Part Number

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