The GoldMike is another jewel in the SPL Tube series. Like all SPL tube processors, the GoldMike combines the unique sonic qualities of tube technology with state-of-the-art manufacturing, meticulous component selection and high-tech conception.

This latest product, a dual-channel tube microphone preamplifier with superb sonic qualities, is particularly suited for recording vocals and acoustic instruments. You will be surprised by not only its precision but also the natural impact of different vocal timbres - the silky warmth of a pristine tube sound is needed by more than just acoustic guitars!

You don't have to listen to those dead and sterile HD recordings. GoldMike's whisper quiet performance makes it ideal for digital recording. Even the most demanding recording subjects, such as a choir, are easily handled. The Class A tube amp, designed as two independent mono blocks, guarantees absolute channel separation. Your stereo recordings in particular will benefit from a wider stereo depth.

GoldMike's technical standards are predicated on an uncompromising effort to combine the sonic advantages of tubes with the experience of more than 12 years of research in semi-conductor amplification design.

The GoldMike allows for up to 72 dB of gain - a value tube-only designed preamps can't match. The SPL tube/IC construction, on the other hand, superbly combines today's standards with such trademark tube characteristics: improved spatial depth, rich detailed imaging, warm and smooth sonics. Moreover, the GoldMike delivers high common-mode-rejection and ultra linear amplification in addition to the high gain capabilities.

Features
Unique "FLAIR" circuitry enhances the presence and intelligibility of any signal. Vocals, for example, seem to move closer. Pristine, non-colored "softening"of very harsh and aggressive sounds.

50Hz high-pass filter, phase reverse switch, 30 dB pad, switchable 48-volt phantom power with independently filtered power supply, high-quality ALPS potentiometers, click-free switches, five LEDs per channel, two backlit VU meters, Warm-up LED indicates tube status during warm up, Star ground wiring scheme for best sound performance, extra wide PCB ground connections guarantee stable voltage distribution, Power supply with state-of-the-art filtering schemes and solid power reserves (6000 µF in the main supply and 400 µF in the tube supply), XLR inputs, XLR and 1/4" outputs (can be used individually or simultaneously).

Advantages of the SPL dual-stage preamplifier
The GoldMike's engine is the newly designed SPL dual-stage preamplifier. During the first stage of amplification the signal is amplified by a semi-conductor circuit while the second stage applies tube electronics. We achieve a high common-mode-rejection by using laser trimmed components. Likewise, minimal noise and distortion figures distinguish our high-quality preamp. Analog Device's semi-conductor (SSM2017) is very unreceptive to HF and hum interference, and is perfectly integrated by the PCB layout; wide PCB conductors guarantee a stable power supply even when extreme level changes demand an immediate current supply. The star ground wiring scheme ensures a quiet electronic performance. The dimensions of the PCB conductors, and their respective layout (wide or narrow), were especially designed for the integration of tubes and ICs in the preamplification circuitry. The MIC GAIN potentiometer adjusts the semi-conductor stage, allowing amplification up to 2200 times the original signal. The following secondary tube stage adds a constant 6 dB of gain; therefore, the same amount of tube character is added regardless of amplification. The MIC GAIN should be adjusted for a "0" VU meter reading. At this level the best signal-to-noise performance is achieved and the tube will perform in its ideal sonic range. (Please note that the VU readings are not peak PPM but average levels. In other words, watch out for the meter hitting the red.)

In summary, our dual-stage design maximises the amplification power and signal-to-noise performance of the SPL semi-conductor at the first stage and then maximises the warmth and liveliness of a meticulously selected and tested ECC 83 tube at the second stage. This makes the GoldMike an ideal partner for high-end HD recording. The unit's dynamic range of 111 dBu even outperforms some 24-bit recording gear.

Advantages of the dual mono design
GoldMike's two mono amplifier blocks are designed with a central power supply that utilises a star ground wiring scheme. Chief advantages of this particular layout are the excellent channel separation and, respectively, the low crosstalk figures.

In your daily work you will find many practical applications for these advantages. You may use the GoldMike's channels for a snare and a vocal (arguably the most important elements in a mix) simultaneously. Stereo recordings, benefiting in particular from the low crosstalk figures, will have wider stereo depth and precise spatial definition. Another advantage of the central power supply with a star ground wiring scheme is that the two individual circuitries, operating discretely, can deliver identical sonic performances per channel. The current demands of one channel (i.e., snare) are not compromised by the current demands of the other channel (i.e., vocal). All power supplying conductors, layed out identically and symmetrically, provide both channels with the necessary current.

FLAIR circuitry
The Flair circuitry was developed by SPL labs. Enhancing the presence of vocals and acoustic instruments, Flair makes these elements cut better through a mix. Also known as the "Soundprettifier", it has proved to be superior in double-blind tests. Once a signal completes the semi-conductor amplification stage, it is then split and fed into the tube stage and the FLAIR electronics.

The Flair circuit is built from a unique valve/inductor/capacitor hybrid. It operates in a bandpassed frequency range from 1.5 kHz to 20 kHz. The center frequency is set at 6 kHz with a boost of 2.5 dB. Frequency response, harmonic contents and time of impact are manipulated as well. The Flair circuit's output is mixed directly in the tube with the source signal. The circuit's character can be best described as a "closed shelving bandpass"; nevertheless, a shifted timebase (phase) is responsible for boosting the harmonic content. The close correlation, however, between frequency- and amplitude-timebase to the dynamics of the input signal remains intact.

When working on a hard disc recording system, you will greatly appreciate the appeal of the Flair circuitry and the topnotch sounding signal it delivers. It can spare you hours of twiddling with a compromised recording.

Warm Up Circuit
The Warm Up circuit measures the tube's anode plate and heater voltages. After approximately eight seconds the anode voltage of 250 Volts is reached; the heater voltage takes only four seconds. Once the ideal working status is achieved, the output signal is enabled. As the Warm Up LED is lit, no output is present.

Specifications

Measurements
* Frequency Response: 10 Hz - 100 kHz, +/- 0.5 dB
* Common-Mode-Rejection at -20 dBu: 1 kHz: -80 dBu; 10 kHz: -73 dBu
* Harmonic Distortion Input level: THD 0.175% at 30 dB Gain
* Signal-to -Noise Ratio: -85.6 dBu (A-weighted) at 30 dB Gain
* Dynamic Range: 111 dBu
* Noise Figure: 3.8
* E.I.N. (Equivalent Input Noise): 135.4 dBu

Inputs
* Microphone/Instrument Preamplifier, electronically balanced (differential), transformerless
* Input Impedance: 1.8 kOhm
* Max. Input Level : +25.72 dBu

Outputs
* XLR-Output: Microphone/Instrument Preamplifier, electronically balanced (differential), transformerless
* Nominal Output Level XLR: +6 dB
* Max. Output Level XLR: +25.4 dB
* Nominal Output Level 1/4": 0 dB
* Max. Output Level 1/4": +19.4 dB
* Output Impedance (XLR/Jack): < 600 Ohm

Dimensions
* Standard EIA 19"/1HE chassis: 19" x 3.47" x 6.18" (482 x 88 x 157mm)
* Weight: 6.7 lbs. (3.05 kg)

Rear Panel Controls and Connectors
* Balanced Inputs and Outputs (XLR/+6 dB)
* Unbalanced Outputs (1/4" / 0 dB)
* Voltage Selector 115 V/60 Hz or 220 V/50
* 3-Prong Standard-IEC-AC Receptacle
* GND-LIFT-Switch