Chameleon Labs 7603 Microphone Preamplifier
The Chameleon Labs 7603 Microphone Preamplifier is Chameleon’s flagship pre-amplifier, representing a leap forward in analog design, performance, versatility and value. It is the true embodiment of our philosophy - Analog for the digital age.
Its fundamental design architecture retraces the path of revered, classic pre-amps of the past as well as the popular Chameleon Labs 7602. Chameleon Labs engineers have worked tirelessly in developing new, pivotal components that allow us to 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 the 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, the circuit boards are carefully crafted to ensure the highest possible signal integrity. As a starting point, Chameleon Labs developed a new discrete audio input gain stage based on our 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 Labs engineers made a conscious decision to stay with the same, desirable, inductor-based topology that made our 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 we all love to use.
The output stage of the 7603 is unique with respect to its design and performance. It can be described as a variable-gain circuit that simultaneously adjusts both the input and output levels in order to generate a lower noise floor and extraordinary audio performance.
The 7603 pre-amplifier provides a desirable set of user selectable functions designed to make the unit flexible and an integral part of the artistic process, incorporating a full portfolio of traditional features as well as some not commonly seen on other pre-amps. Microphone input impedance can be selected between 300 and 1200 ohms, providing a method by which a microphone can be more ideally matched to the input stage and making it easier to get the best from lower output microphones such as ribbon-based designs. Chameleon Labs added a low impedance Direct Input on the front panel for plugging in instruments such as guitars that can be run through the line input stage, and added a precision VU meter with custom ballistics for visual monitoring of either the input or output levels.
Chameleon Labs 7603 Microphone Preamplifier Features
- 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 300Ω or 1200Ω 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
Chameleon Labs 7603 Microphone Preamplifier Specifications
- User Controlled Functions
- On Switch: Turn Pre Amp On - VU Meter Light
- 300Ω / 1200Ω Switch: Switch between 300Ω and 1200Ω input impedance for the mic input
- 48V Power Supply Switch: On/Off
- DI Switch: Direct Input with 100KΩ 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
- 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: 300Ω or 1200Ω
- Line: 10kΩ line bridging from 600Ω or lower source impedance
- Direct Input: 100kΩ
- 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 600Ω input impedance, SNR 116dB at maximum output
- Output Type: Transformer balanced and floating to drive 600 Ω load
- Maximum Output: +28dBu into 600Ω load impedance
- Frequency Response: 10Hz - 20kHz -0.5dB 10Hz - 50kHz -1dB
- 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
Chameleon Labs 7603 Microphone Preamplifier Includes
- 7603 Microphone Preamplifier
- Manual & Literature
- IEC Power Cable
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I have owned and used many Chameleon Labs products over the years and have consistently found them to punch way above their price point. Having used this late model 7603 now for several months, I can say without equivocation that since Marcelo took over the company he has kept that original vision alive, and shifted it into turbo mode. He clearly cares deeply about his products and keeping quality as high as possible. This pre is a steal at it's price point - I can think of precious few alternatives that offer as much as the 7603, and fewer still that show the attention to detail and quality of this unit.
As you'd expect from any quality preamp of this type, the 7603 is a real all-rounder. I've recorded a variety of instruments through the 7603 - electric bass, vocals, drum overheads, snare, and kick, electric guitar. I can't say I have been disappointed with any sound captured through this pre. It imparts a flattering sheen possessing a clear and dynamic timbre that sounds "pre-cohered", as if the instrument has already been tweezed a bit, ready to mingle with others. I should also point out that the unit seemed almost unnervingly quiet, even with the gain cranked. The noise floor is astonishingly low. I was also glad to see that CL ditched the old style power supply for an internal one.
The EQ section, while not exactly surgical (it's not meant to be), can be great for adding a bit of corrective adjustment to problem areas. The bands are well chosen for a variety of instruments and situations. I found myself using the shelving eqs quite often. I did not notice any unexpected artifacts even when using rather heavy handed settings. The pre is at home with both dynamic and condenser mics, with the added bonus of a mic impedance selector, which is a really smart and professional touch.
I also appreciated the very easy to read graphs in the manual illustrating the freq response curves for the EQ section. When first setting up the preamp, I found myself wondering exactly how broad of a q the midband eq had, and was very impressed (and relieved) to see it spelled out clearly in the manual.
My few very small quibbles with the unit are all in relation to the VU meter. The meter is quite difficult to read, as it is very small. In most situations this is easily ignored, as it's not necessarily to be constantly checking the meter. Another small complaint is the choice of color for the backlight. The garish tungsteny blue hue is very unflattering, and the warm up time for the light is rather long. The first few times I powered the unit up, I found myself double checking that everything was plugged in properly, as it took the light a good while to turn on. Again, these issues can be overlooked in real world situations. The overload light next to the gain dial makes dialing in the gain a breeze. I rarely check VU except for fun.
The 7603 is a really fantastic unit. I wish I had a dozen. The subtle but helpful character it imparts to a wide variety of instruments make it a true workhorse preamp. I can't wait to hear their new 7721 VCA compressor and compare it to my old silver model. I can only imagine how much cleaner and more controlled the sound must be. Chameleon Labs have clearly put tons of thought into their products and I am very pleased at the direction they seem to be taking.
Overall I found the 7603 to add a unique color that sits nicely in-between my clean and colored pres. The low mid warmth from the 7603 was never muddy or overpowering and engaging the eq with knobs flat adds some nice subtle harmonics. I've never been a fan of sub $1,000 Neve clones because of their lack of clarity in the low mids and the top end sounding a little dark. The 7603 has low mid clarity with warmth and is open on the top end, making it easy to get great results on vocals. Especially when paired with a transformerless mic like a vanguard V4 or mojave MA-50, which can be heard in my YouTube review. Also love the fact that while this is a Neve 1073 clone, CL decided to make this NOT copy other clones with it's look and design, and hint of Neve in it's products name. Tired of all these same old clones copying the original look and features. CL took the 1073 concept and added it's own flavor of tone and features, making their own, and just not another clone.
Very nice device! Good Buisiness!
My current front end is an A-Designs Pacifica mic pre into an A-Designs Hammer Eq. Adding this compressor after the Eq took NOTHING away (that I can detect so far- after three continuous days of use) from the quality of the signal I had before I inserted the compressor. (I've tracked vocals, acoustic guitar, and used it on the two buss). It can be very transparent to very 'apparent' (some would call 'color'). It can be made to suck if you turn the compressor knob fully clockwise and peg the gain reduction to the 18db mark on the VU. However, I'll never work it that way and for the record, the much-loved Pacifica can be made to suck if you drive it into distortion.
I'm very happy so far. Frankly, I don't see how anyone can go wrong spending well less than $1K on a two channel compressor that actually compliments the quality of a high-end boutique chain of gear like A-Designs.