Chameleon Labs 7603 Microphone Preamplifier and EQ

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Chameleon Labs upgraded their 7602 preamp/EQ's transformers and op-amps to create this 7603 model. Dial in your sound on this musical-sounding channel strip!

Proudly made in Seattle, Washington, USA, the 7603 is Chameleon's flagship pre-amplifier, representing a leap forward in analog design, performance, versatility and value. It is the true embodiment of Chameleon Labs' philosophy: analog for the digital age. Its fundamental design architecture retraces the path of revered, classic pre-amps of the past as well as Chameleon Labs' popular 7602.

Marcelo at Chameleon Labs gives you an in-depth look inside the 7603 preamp's design:

Engineers at Chameleon have worked tirelessly in developing pivotal components that take the next step forward in performance. These enhancements start with all-new proprietary microphone and line-level input transformers that feature custom-made nickel laminations and bobbin assemblies -- all designed in-house. By developing new engineering processes focused on the material science associated with lamination manufacturing, Chameleon was able to develop a lamination "recipe" that delivers optimized audio performance, providing the 7603 with high bandwidth and incredibly low distortion.

Design of Chameleon Labs' new transformers was based around the need to capture and preserve the delicate audio input signals' truest form, and so they are enclosed in high permeability MuMetal enclosures, designed to protect sensitive audio signals from radio frequencies, spurious and parasitic noises.

Once your audio exits the input transformer, Chameleon Labs' circuit boards are carefully crafted to ensure the highest read more possible signal integrity. As a starting point, Chameleon Labs developed a new discrete audio input gain stage based on their vision for a solid topology that provides extremely low noise, high dynamics and extreme bandwidth. All of the 7603's operational amplifiers used throughout the device are based on this topology.

The 7603 features EQ stages with four different available adjustments -- Variable High Pass, Low Frequency Shelving, Mid Frequency and High Frequency Shelving. Chameleon engineers made a conscious decision to stay with the same, desirable, inductor-based topology that made the 7602 so popular -- however, they implemented a new discrete Op Amp to drive signal through a new set of custom Chameleon designed and manufactured inductors, providing the musicality you'll love.


- Chameleon wound microphone and Line Input transformers and Chameleon output transformer, all with mu-metal housings
- High resolution, low noise discrete audio circuitry
- Hi-Z Direct Instrument Input (TRS)
- Discrete Class A Electronic Topology
- Three band, inductor based EQ
- 48V phantom power for mic input
- Selectable 300Ohm or 1200Ohm Mic Input Impedance
- Custom VU meter (input/output) with calibrated ballistics
- Relay based selection of Line / Mic & DI Inputs
- Overload input and output indicators
- Reverse Phase Switch
- Universal, on-board power supply
- Proudly made in the USA in Seattle, Washington
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- On Switch: Turn Pre Amp On - VU Meter Light
- 300Ohm / 1200Ohm Switch: Switch between 300Ohm and 1200Ohm input impedance for the mic input
- 48V Power Supply Switch: On/Off
- DI Switch: Direct Input with 100KOhm input sensitivity
- EQ Switch: Engages audio high pass filter and equalization circuits
- Polarity Switch: Reverses the polarity of the audio signal
- Mic/Line Sensitivity Switch: +20dB to +70dB of mic boost and -30dB to +20dB of line level adjustment.
- High Pass Filter: Provides a 15dB/octave high pass filter at 40Hz, 80Hz, 160Hz and 320Hz
- Low Frequency Equalization: Provides +/-15dB of Boost or Cut at 35Hz, 60Hz, 110Hz or 220Hz
- Mid Frequency Equalization: Provides +/-15dB of Boost or Cut at 360Hz, 700Hz, 1.6kHz, 3.2kHz, 4.8kHz or 7.2kHz
- High Frequency Equalization: Provides +/-15dB of Boost or Cut at 3.4kHz, 4.9kHz, 7kHz, 12kHz or 16kHz

- Inputs:
- Microphone (XLR): Transformer balanced input, RF isolated
- Line (XLR): Transformer balanced input, RF isolated
- Direct In (1/4" TRS): High impedance instrument input

- Input Impedance:
- Microphone: 300Ohm or 1200Ohm
- Line: 10kOhm line bridging from 600Ohm or lower source impedance
- Direct Input: 100kOhm

- Sensitivity:
- Microphone: From -70dBm to -20dBm in 5 dB steps for 0dBm output
- Line: From -30 dBm to +20 dBm in 5 dB steps for 0 dBm output
- Noise Specification: Better than -125dBm EIN between -80 and -40 dBm referenced to 600Ohm input impedance, SNR 116dB at maximum output
- Output Type: Transformer balanced and floating to drive 600 Ohm load
- Maximum Output: +28dBu into 600Ohm load impedance
- Frequency Response: 10Hz - 20kHz -0.5dB 10Hz - 50kHz -1dB

- Indicators:
- VU Meter Light: Power ON
- Red Input Gain: Input Overload
- Red Output Gain: Output Overload

- Power Supply:
- 100V - 240V (50/60Hz): Switch mode power supply, fully shielded 3 amp peak output capability, quiescent consumption 0.5 Watts

- Mechanical:
- 1RU Steel enclosure
- Aluminum front panel
- Laser etched graphics
- Milled aluminun knobs

For support or warranty questions, please contact the manufacturer:

Reviewers gave this product an overall rating of 5 out of 5 stars. (3 ratings)
Submitted December 10, 2020 by a customer from
"Chameleon Labs 7603"
Overall: 5 out of 5 stars
(see rating details)
Verified Customer zZounds has verified that this reviewer made a purchase from us.
This mic preamp sounds excellent - it has a very cool full tone for vocals. The eq is super smooth - I would definitely recommend this to anyone looking for a quality mic preamp. For the price, I think it's an excellent value.
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