User manual SPL GOLDMIKEMKII

Manual PHANTOM 48 V Off PAD dB VU CAL dB LIMITER dB PHANTOM 48 V PAD dB VU CAL dB LIMITER dB -20 Off 48 V Clip Limit AD OVL -10 0 Dual Channel Microphone, Line & Instrument Preamplifier PHASE Rev. Nor. HI PASS Hz So un d 20 %0 Perf orman ce 35 18 Off 12 -20 Off 48 V Clip Limit AD OVL -10 0 La b FLAIR High Off Med 3 10 10 7 5 30 50 70 100 TUBE AMP dB 50 Off VU 18 6 12 Gold Mike Mark 2 Off PHASE Rev. Nor. HI PASS Hz So un d 20 %0 Perf orman ce 35 18 Off 12 La b FLAIR High Off Med 3 10 10 7 5 30 50 70 100 TUBE AMP dB 50 Off VU 18 6 12 Discrete Class A Preamplifier Stage Gain 24 27 29 22 21 20 19 18 17 16 15 14 dB 32 35 38 41 44 49 54 60 66 SOURCE Instr. Line Mic 1 INSTR. INSERT On Off Output -10 -9 -8 -6 -12 -5 -14 -2.5 -16 0 -18 2 -20 3.5 -22 -24 5 5.5 -25 -26 6 dB Gain 24 27 29 22 21 20 19 18 17 16 15 14 dB 32 35 38 41 44 49 54 60 66 SOURCE Instr. Line Mic 2 INSTR. INSERT On Off Output -10 -9 -8 -6 -12 -5 -14 -2.5 -16 0 -18 2 -20 3.5 -22 -24 5 5.5 -25 -26 6 dB Power Model 2485 GoldMike Mk 2 Model 2485 Dual-channel microphone and instrument preamplifier Manual GoldMike MK2 Version 2.0 ­ 11/2004 Designer: Ruben Tilgner Model 2485 This user's guide contains a description of the product. It in no way represents a guarantee of particular characteristics or results of use. The information in this document has been carefully compiled and verified and, unless otherwise stated or agreed upon, correctly describes the product at the time of packaging with this document. Sound Performance Lab (SPL) continuously strives to improve its products and reserves the right to modify the product described in this manual at any time without prior notice. This document is the property of SPL and may not be copied or reproduced in any manner, in part or fully, without prior authorization by SPL. SPL electronics GmbH Sohlweg 55, 41372 Niederkruechten Germany Tel. +49 (0)2163 983 40 Fax +49 (0)2163 983 420 Email: info@soundperformancelab.com www.soundperformancelab.com SPL USA: www.spl-usa.com/info@spl-usa.com © 2004 SPL electronics GmbH. All rights reserved. Names of other companies and their products are trademarks of their respective owners. 2 GoldMike MK2 Contents Introduction ................................................................... Before You Begin ............................................................ Rear Panel/Connections ................................................. Wiring ......................................................................... General advices ........................................................... Mic Input 1/2, Line In 1/2, Inserts 1/2 ........................... Outputs 1/2, GND Lift .................................................. Front Panel/Connections ............................................... Instr. Input 1/2 ............................................................. Control Elements ............................................................ Power, Gain, About Gain Adjustments .......................... Output, Phantom ........................................................ Phase, Pad, Hi Pass .................................................... Flair, Tube Amp, About Tube Amping ............................ Limiter ........................................................................ VU-Cal, Source, Display, VU-Meter ............................... 48 V LED, Clip LED, Limit LED, AD OVL LED .................... 4 5 6 6 7 8 9 9 9 10 10 11 12 13 15 16 17 Technology .................................................................... 18 Solid State and Tube Stages, Output Stages ................ 18 Instrument Input, Relays, Foil Condensers ................... 19 Power Supply ................................................................. 20 Options (A/D Converter and Lundahl Transformers) ........ 21 Specifications/Dimensions & Weight ............................ 23 Warranty ......................................................................... 24 Notes ............................................................................. 25 GoldMike MK2 3 Introduction The GoldMikeMK2 is the result of all our experience and knowledge from its successful predecessor and represents an improved, more flexible and, more modern version. We have added technologies that have already proven to provide superior tonal results in other SPL products. For example, the instrument input is designed around a class A impedance converter which premiered in the SPL GainStation. A significant contribution to the success of the predecessor was the hybrid preamplifier concept. It combines transistor and tube preamplifier stages and specifically utilizes their technological and sonic advantages: The efficiency and low noise of a discrete transistor stage is enriched with musical coloration of a tube stage. The transistor stage is composed of single transistors in a class A design. The circuitry is fully discrete, and each transistor is completely optimized for its specific task. You will not find any IC's in this preamplifier stage because they cannot be optimized for this specific application to the degree we at SPL aim for. This all new discrete class A transistor stage is a genuine innovation in the entire preamplifier market at this price level. The degree of tube pre-amplification is no longer the fixed +6 dB value of its predecessor. The GoldMikeMK2 sports the selection of three different tube pre-amplifications: +6 dB remains the standard complemented by +12 dB and +18 dB. This allows creative variety with the tube saturation and limiting effects. We have also added an extra setting to the popular Flair circuitry to give more flexibility to the presence improvement. Because the GoldMikeMK2 is a dual channel preamplifier, its channel separation is of fundamental importance for the stereo image. Therefore the print-board layout is symmetrically mirrored around the power supply in the center from channel 1 to channel 2. This results in an identical signal flow to supporting a naturally balanced stereo image. Additionally the print-board provides extra-large ground areas maximizing the shielding against crosstalk and interference. 4 GoldMike MK2 Before You Begin IMPORTANT: Before you operate your GoldMike MK2, first check carefully whether the local voltage setting corresponds to the switch setting on the rear panel! VOLTAGE 220 ­ 240 V~50 Hz 110 ­ 120 V~60 Hz If not, and the voltage is in one way or another, incorrect, you will either experience an immediate fuse burn through (if the setting is lower than the supplied power) or, if the power is 110-120 V at a 220-240 V input switch setting, the GoldMike MK2 will simply not function correctly. Moreover, make sure you remove the power plug from your GoldMike MK2 before changing this switch setting! Always turn volume down or mute your speakers when connecting or repatching audio cables to avoid damage to your speakers and ears. It makes good sense to think about where you place your MTC before connecting it. It should be positioned so that you can easily reach it, but there are other considerations. Try not to place it near heat sources or in direct sunlight, and avoid exposure to excessive vibrations, dust, heat, cold or moisture. It should also be kept away from transformers, motors, power amplifiers and digital processors. In addition, please: · Do not open the case. You may risk very dangerous electric shock and damage to your equipment. · Leave repairs and maintenance to a qualified service technician. Should foreign objects fall inside the case, contact your authorized dealer or support person. · To avoid electric shock or fire hazards, do not expose your unit to rain or moisture. · In case of lightning, unplug the unit. Always unplug the cable by pulling on the plug only; never pull on the cable. · Never force a switch or knob. · Use a soft, lint-free cloth to clean the case, if necessary together with an acid-free cleaning oil. Avoid cleaning agents as they may damage the unit. VOLTAGE GoldMike MK2 5 Optional A/D converter, model 2376 S/P-DIF signal for external synchronization S/P-DIF signal to DAW, HD recorder etc. TRS Jacks: Balanced +4dB Use Mono Jacks for Unbal. Operation Use Mono Jacks for Unbal. Operation XLR &TRS Jack: Balanced +4dB 220 ­ 240 V~50 Hz 110 ­ 120 V~60 Hz TO REDUCE RISK OF FIRE OR ELECTRIC SHOCK DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. DISCONNECT MAINS BEFORE REMOVING COVER. THIS EQUIPMENT MUST BE EARTHED. WARNING XLR &TRS Jack: Balanced +4dB TRS Jacks: Balanced +4dB Use Mono Jacks for Unbal. Operation Mono Jack: Unbal. 0dB Use Mono Jacks for Unbal. Operation Mono Jack: Unbal. 0dB SEND RETURN RETURN SEND C AU T I O N RISK OF ELECTRIC SHOCK DO NOT OPEN Rear Panel/Connections MIC INPUT 2 AVIS: RISQUE DE CHOC ÉLECTRIQUE - NE PAS OUVRIR LINE IN 2 INSERT 2 OUTPUTS 2 VOLTAGE GND LIFT OUTPUTS 1 INSERT 1 LINE IN 1 MIC INPUT 1 Effects (EQs etc.) Converter, recorder, console Line signals* Microphone PUSH 2 1 3 Pin wiring of XLR mic inputs 1 3 2 Pin wiring of XLR outputs 1=Ground, 2=hot(+), 3=cold(-) Pin wiring of TRS connectors Tip=hot(+), Ring=cold(-), Sleeve=Ground 1=Ground, 2=hot(+), 3=cold(-) Wiring GoldMike MK2 * For signals with impedances lower than 1kOhms, i. e. D/A converters, synths, samplers. Instruments with impedances above 1kOhms are to be connected to the instrument input on the front (see input descriptions on pages 8 and 9). MIC INPUT 1 LINE IN 1 INSERT 1 OUTPUTS 1 GND LIFT VOLTAGE OUTPUTS 2 INSERT 2 LINE IN 2 MIC INPUT 2 6 24/96 AD SAMPLE RATE Converter SPL electronics GmbH Niederkrüchten, Germany SYNC INPUT DIGITAL OUTPUTS SYNC LOCK XLR Wiring: Pin 1 = GND, Pin 2 = (+), Pin3 = (­) www.soundperformancelab.com G o ld M i ke 2 4 860 0 00 220 ­ 240 V~50 Hz: 315 mA slow 110 ­ 120 V~60 Hz: 630 mA slow Model 2376 TRS Jack Wiring: Tip = (+), Ring = (­), Sleeve = GND SPDIF OUTPUT OPTICAL OUTPUT Made in Taiwan MADE IN GERMANY SERIAL NUMBER FUSE RATING Sound Performance Lab 44,1 48 x2 SPDIF INPUT Mono Jack Wiring: Tip = (+), Sleeve = GND General Advices Rear Panel/Connections Again, while the GoldMike MK2's housing is EMV-proof and protects against HF-interference, placement of the unit is very important since it amplifies microphone signals as well as other unwanted signals. Before connecting the GoldMike MK2 or any other equipment turn off all power. VOLTAGE 220 ­ 240 V~50 Hz 110 ­ 120 V~60 Hz IMPORTANT: Adjust the voltage setting on the back so that it corresponds with the power conditions. The following graph shows the correct wiring for connecting unbalanced signals to the balanced XLR connectors: VOLTAGE Output balanced unbalanced 1 3 2 1 3 2 1=GND 2=cold (+) 3=hot (-) The Line Input connector is designed for unbalanced signals only. The TRS output connectors (see "Outputs" on page 9) can be operated both with balanced and unbalanced wiring. Simply use a mono 1/4" plug for unbalanced operation. GoldMike MK2 7 Rear Panel/Connections Mic Input 1/2 Dynamic, condenser or tube microphones can be connected to the Mic inputs. The 48 V switch provides the phantom power necessary for some microphones (see also ,,Control Elements/ Phantom" on page 11). Alternatively the GoldMike MK2 can be equipped with optionally available transformer inputs from Lundahl (see "Lundahl Transformers" on page 22). MIC INPUT 1 MIC INPUT 1 LINE IN 1 TRS Jacks: Balanced +4dB Use Mono Jacks for Unbal. Operation Mono Jack: Unbal. 0 dB Line In 1/2 The unbalanced Line Inputs are dedicated to high-impedance, high-level signals such as A/D converters, synthesizers or samplers with an impedance of less than 1 kOhm. Signals with an impedance of above 1 kOhm, e. g. instruments like E bass, acoustic guitars with pickups or Fender Rhodes must be connected to the Instrument Input on the front panel. The max. input level of the Line Inputs is +23 dB. IMPORTANT: The Line Input is deactivated as long as an instrument is plugged into Instrument Input jack on the front. We recommend connecting the Line Input to a patchbay if sources need to be changed regularly. RETURN INSERT 1 INSERT 1 LINE IN 1 SEND Inserts 1/2 The balanced TRS Insert connectors (Send and Return) are used to integrate further units (EQs, Compressors, Limiters, Effects ...) into the signal path of the GoldMike MK2. The Send connector is placed behind the tube stage and can also be used as direct out (without output level control). The Return connector is located in front of Limiter and Output control which allows to control the output level, e. g. for precise drive level of following A/D converters. 8 GoldMike MK2 Rear Panel/Connections XLR &TRS Jack: Balanced +4 dB Use Mono Jacks for Unbal. Operation The preamplifier signals are fed to these electronically balanced outputs. Alternatively the GoldMike MK2 can be equipped with optionally available transformer outputs from Lundahl (see "Lundahl Transformers" on page 22). Since the XLR and 1/4 inch TRS connectors are wired in parallel, an unbalanced connection at one connector will cause unbalanced operation in its parallel connector, e.g. if a mono 1/4 inch plug is inserted into the 1/4 inch jack, the corresponding XLR socket will also operate unbalanced. OUTPUTS 1 The GND Lift switch separates internal ground from chassis ground. The switch can be activated to eliminate ground loop humming which may occur if the GoldMike MK2 is connected to units with a different ground potential. The switch should normally be in the GND position to maintain the shielding effect of the metal housing for internal GoldMike MK2 electronics. GND LIFT Front Panel/Connections Instr. Input 1/2 The Instrument input jack is placed on the front panel for easy access. It should be used to connect instruments like E-bass, electric guitars, acoustic guitars with pick-ups etc. The Instrument input features a 1 MOhm (one mega Ohm) input impedance. IMPORTANT: As long as an instrument is plugged into front Instrument input, the rear panel Line Input is deactivated. INSTR. GoldMike MK2 9 GND LIFT GND Lift OUTPUTS 1 Outputs 1/2 Control Elements Power Power You guessed that: with the Power switch the GoldMike MK2 is activated, verified by the illuminating switch. Please read "Before You Begin" on page 5 before throwing in for the first time. Gain 24 27 29 22 21 20 19 18 17 16 15 14 dB 32 35 38 41 44 49 54 60 66 Gain The Gain control determines the pre-amplification of the microphone signal. The pre-amplification values cover a range from +14dB up to + 67dB. IMPORTANT: If Lundahl input transformers are fitted the scale values are to be increased by up to +14dB (depending upon microphone in use). About Gain Adjustments Amplifying a signal to line level should principally be done solely with the Gain control. The Output level control is used to adjust the proper drive level for subsequent equipment. The VU Cal switch should be set to 0dB (Note: The VU displays the pre-amplification, not the output level). Now turn up the Gain control until the VU shows values between 0dB and +3dB. There is still enough headroom to prevent clipping at varying input levels. Note that the VUs show average levels instead of peak levels (which can be up to 10 dB higher). Thus, in recording high-level signals such as snare and kick etc. it may be necessary to engage the Pad switch. You can drive the Gain harder if you know that unexpected input level changes are unlikely to occur. Watch if the Clip-LED indicates clipping in the preamplifier stages and set the VU Cal to -10dB to adjust the VU meter range accordingly. IMPORTANT: The Clip-LED should never illuminate during a recording session to avoid distorted results. 10 GoldMike MK2 Control Elements Output This potentiometer adjusts the output level for devices following in the chain or to the converter. The Output Level control allows an additional +6dB of amplification or -26dB of reduction. Output level values set with the output level control are not indicated by the VU meters, which indicate pre-amplification levels before this final stage. Output -10 -9 -8 -6 -12 -5 -14 -2.5 -16 0 -18 2 -20 3.5 -22 -24 5 5.5 -25 -26 6 dB Phantom The GoldMike MK2 provides 48 Volt phantom power for microphones requiring external current (generally condenser microphones). Such microphones are dependent upon a clean, consistent and noise-free power supply for optimal operation and audio quality. The GoldMike MK2 continuously delivers precisely 48 V and a maximum of 14 mA, which will power all microphones. PHANTOM 48V Off VERY IMPORTANT: All microphones with balanced, groundfree outputs, including tube microphones, can be used with the phantom power activated. Phantom power should only be activated when using microphones that require it. Unbalanced microphones may only be used with phantom power deactivated. Please be sure to deactivate phantom power with all other microphones. PLEASE ALWAYS FOLLOW THESE INSTRUCTIONS TO ACTIVATE AND DEACTIVATE PHANTOM POWER: First connect the microphone to the GoldMike MK2, then activate phantom power. When finished, first deactivate phantom power and wait at least until the 48V LED has gone out completely before disconnecting the microphone! This ensures residual current will be discharged. Furthermore, when changing microphones, you should wait until the 48V LED is completely dark before re-patching. THE GOLDMIKE MK2'S INPUT STAGES CAN BE DAMAGED IF YOU IGNORE THESE PROCEDURES! GoldMike MK2 11 Control Elements PHASE Rev. Nor. Phase The phase reverse function reverses the polarity of the microphone signal, inverting the phase (by 180°) to correct phaseinverted signals caused by multiple signal sources. A voiceover artist, for example, hears himself during recording through the headphones and simultaneously through the bones in his head. Phase inversion will cause an unnatural sound, and even minimal variations in distance to the microphone will cause drastic variations in the sound. Phase inversion is also commonly encountered when using multiple microphones on a single sound source. We recommend checking for correct polarity before each recording. PAD dB Pad The Pad switch attenuates the input by -20dB. High-level input signals can be attenuated in order to prevent overdriving the preamplifier. The GoldMikeMK2 has a minimum pre-amplification of +14dB. But with miked signals such as drums and brass or high level line input signals, this may already be too much. Engaging Pad attenuates the minimum pre-amplification (Gain control fully counter clockwise) to -6dB, thus providing a useful Gain control range for loud input signals. -20 Off HI PASS Hz 50 Off Hi Pass This switch activates the integrated high-pass filter, which operates at a 50 Hz center frequency and 12dB/octave (often called a ,,rumble filter"). The filter is entirely passive, avoiding additional active circuitry that could potentially degrade the signal, and cuts 6dB pre- and 6dB post-solid-state stage pre-amplification to prevent the amplification of unwanted low-frequency signal components. 12 GoldMike MK2 Control Elements Flair As with its predecessor, the model 9844 GoldMike, the GoldMike MK2 features our sound-optimizing Flair circuitry. This circuitry takes advantage of a combined coil and tube filtering to enhance signal presence. In comparison to simple EQ manipulation, this intensified presence sounds very natural and unobtrusive, and is particularly suited for optimizing the overtones in voice and acoustic instruments. Through Flair, a recorded signal gains richness in detail, presence, intelligibility (for voice) and in an increased ability to cut through in a mix. In such mixes, a Flair-processed signal stands out without resort to conventional processing often unsuited to the task, saving both time and a need for artificial processing. Flair works through an emphasis in the 1.5-20 kHz range centered around 6 kHz. The GoldMike MK2 provides for two different settings, with a "High" setting of +2.5 dB and a "Med." with +1.5 dB emphasis. An Off setting allows you to deactivate the Flair circuit entirely. FLAIR High Off Med Tube Amp The Tube Amp switch varies the degree of tube pre-amplification added to the discrete class A pre-amplification, which itself is set with the Gain control. The switch allows for three settings: +6dB (standard) +12dB and +18dB. In each setting, the output of the tube is automatically reduced in proportion to the increased input, thus eliminating affects to the overall output level - there is no need to recalibrate. This allows for instant comparison between varying Tube Amp values and their sonic effects. (see ,,About Gain Adjustments" on page 10). TUBE AMP dB 18 6 12 GoldMike MK2 13 Control Elements Using the Tube Amp switch Engaging the Tube Amp switch tends to have a significant impact on the overall sound, as it directly changes the sonic character of the tube. The higher the Tube Amp value, the more you will have tube saturation and harmonic distortion, in addition to limiting effects. These effects can be used creatively to shape a sound. Subtle overdrive of the tube creates moderate saturation effects and relatively little harmonic distortion--the limiting effects are already present. If this behavior is desired, try a +12 dB setting with the Gain control also set to moderate pre-amplification. For a more dramatic tube sound the Tube Amp switch should be set to +18 dB. This results in a very audible saturation and harmonic distortion. The intensity can then be fine-tuned with the Gain control: The more gain, the more "phatt". Tube limiting controls peaks in a musically advantageous fashion and can be used to complement the Limiter. The tube limiting is not as accurate and sonically neutral as the PeakLimiter because harmonic distortion is added to the signal. To fully protect connected converters you should keep the PeakLimiter active and monitor the action of the VU meter, the Clipand Limiter-LED. 14 GoldMike MK2 Control Elements Limiter The GoldMike MK2 offers a peak limiter that operates before the output level control. This ensures that the limited signal can be controlled as perfectly as possible for the internal--or an external--converter. The peak limiter operates with special diodes that convert signal peaks into a pleasant-sounding saturation. Depending on the signal, this allows for an effective and subtle level limiting. Diode-based limiting works very quickly (much faster than common VCA- or FET-based limiters), reliably limits even microsecond-long transients, and is very effective for drums and percussion. The peak limiter also enables maximum loudness. Its degree of activity is displayed via the Limit LED. The peak limiter is ideally suited to limit signals with a high degree of transients such as snare, kick, brass and other percussion instruments. Sine-wave like signals such as vocals, flute and layer sounds can also be protected, but the degree of increased loudness is limited. Overdriving the peak limiter will be audible as distortion, an effect quite similar to overdriving the preamplifier. In order to avoid irritations please monitor the Clip-LED. If the Clip-LED is not illuminating, the distortion is coming from the peak limiter. In that case reduce the Threshold value. There are two threshold values to choose from: +12 dB and +18 dB. Limiting is less when selecting the +18dB threshold and intensified when choosing +12 dB. If the Limit LED illuminates constantly, you should select the +18 dB setting or reduce the Gain control setting (also see "Limit-LED" on page 17). After setting the Limiter you can adjust the output level signal for equipment coming next in your chain. If you have opted for the internal A/D converter, you should keep an eye on the A/D Ovl LED. When this LED illuminates, the internal A/D converter is clipping. Reduce the output level until the A/D Ovl LED goes out. If external converters are used, check their clipping LEDs when setting the output level. This placement of the limiter before the output level control helps exploit the headroom of A/D converters to the maximum while at the same time offering a signal peak safety margin. LIMITER dB 18 Off 12 GoldMike MK2 15 Control Elements VU CAL dB VU-Cal The display range of the VU meter can be shifted using the -10dB VU Cal switch position. If the VU Cal switch is set to its 0 dB position and the output level control is also set to 0dB with the limiter switched off, the output level will effectively be 0 dBu.With the VU Cal set to -10 dB the 0 dB mark on the VU meter will represent a +10 dBu output level. This way you can display audio level higher than +6 dB (up to +16 dB) on the VU meter. -10 0 SOURCE Instr. Line Mic Source This switch allows you to select between the Mic and Line/ Instrument inputs. All inputs can remain connected at all times, regardless of which input is selected. You can choose the Line input as source as long as the Instrument Input is not being used. If you engage this switch first after powering up the unit, there can be a noticeable pop due to the discharge of residual current. This is normal and no cause for concern. Clip 48 V Limit AD OVL Central Display The display consists of all status LEDs and the VU meter so that all important information can be viewed without distraction. So und 20 %0 Pe rforman ce 35 Lab 3 10 10 7 5 30 50 70 100 VU 1 Display/VU Meter The VU meter shows the internal gain level (not the output level). Its scale ranges from -20 dB to +6 dB. If needed, the sensitivity can be reduced by 10 dB, which extends the scale to +16 dB (see "VU Cal" above). Please refer as well to the information "About Gain Adjustments" on page 10. 16 GoldMike MK2 Control Elements Display/48 V LED The 48V-LED indicates that the phantom power supply is activated. The 48V-LED will slowly dim before going out to indicate that it takes some time for residual current to discharge. VERY IMPORTANT: The connection between microphone and GoldMikeMK2 should not be disengaged before the LED is completely dark! To avoid damages, please note also the phantom power supply usage information on page 11. Display/Clip LED The Clip LED shows internal clipping of the GoldMike MK2. To avoid distorted results the Clip-LED should never illuminate during a recording session (also refer to "About Gain Adjustments" on page 10). Display/Limit LED The Limit LED shows the activity of the Peak Limiters. The Limiter threshold can be set to 12 or 18 dBu, and for optimal operation, should only illuminate in very short intervals. If the LED is illuminating too often even at the 18 dB position, you must reduce the Gain value (and possibly afterwards, further adjust the output level) to achieve unobtrusive results--unless, of course, you really want this effect (also see the chapter ,,Limiter" on page 15). Display/AD OVL LED This LED is only active when the optional AD converter module is installed. It displays clipping in the internal AD converter and illuminates at approximately 0.5 dB before 0 dBfs. This LED should never illuminate when using the internal or an external converter. If it does, the output level must be reduced accordingly. For further information on the converter module see page 22, "Optional Digital Output: 24/96 AD converter, model 2376". With external converters in use, please always check their internal clipping displays. GoldMike MK2 17 Technology Solid State And Tube Stages The solid stage preamp section is based on a fully discrete, balanced instrument amplifier and operates 12 single transistors in class A mode. A sophisticated circuitry ensures a nearly constant frequency response at any gain level. With an impressive slew rate of more than 200V/µs the solid stage is capable to amplify highest frequencies and fastest transients with almost no distortion, which is crucially important to achieve a realistic sound experience. Coupling condensers were used as sparingly as possible to avoid their inherent disadvantages such as diffuse sound, slurring and loss of dynamics. These are replaced by servo circuits, which eliminate DC artifacts. An op-amp subsequently converts the instrument amplifier's output signal into an unbalanced one, which is then fed to the tube. Here an additional +6 dB tube amplification is added, switchable to +12 and +18 dB with the Tube Amp function. The tube type--a Sovtek® 12 AX7 LPS--was also selected after extensive measurements and listening tests. This tube type outclasses the standard 12 AX 7 by far and delivers an open, transparent sound, excellent noise values and is especially reliable. An impedance converter adapts the tube's high-impedance signal to the following stages. Output Stage The output stage can drive very long connections (depending on cable capacities, up to several hundred yards). The max. output level is at +26 dBu, allowing plenty of headroom to drive subsequent converters. 18 GoldMike MK2 Technology Class A Instrument Input The Instrument Input is a fully discrete impedance converter that also operates in class A mode. It is based on a low-noise field effect transistor that, due to its extremely high input impedance, is especially well suited to this task. Relay Switching In order to ensure the shortest possible signal paths, nearly all switching functions are handled by optimally positioned, encapsulated relays with gold-plated contacts (the switches themselves only trigger the relays). Since resistors also greatly affect audio quality, the entire audio signal path utilizes painstakingly selected resistors with 0.1 % tolerance. Foil Condensers The op-amp circuits use premium FKP foil condensers, which sound much more open than ceramic types and provide more natural dynamic response. GoldMike MK2 19 Power Supply In the case of the power supply, no expense was spared. After all, the power supply is one of the primary factors in the audio quality and overall sound of any device. Just like the best coffee beans in the world will not produce a good cup of coffee with poor water, the best circuits can't produce a great sound with unreliable, inconsistent current. The transformer delivers three different voltages, each of which is separately screened and regulated: 250-V anode current for the tube, 48V for phantom power and 2 x 15V for the audio signal path. Critical currents are stabilized via a 100-nF MKP foil condenser, to ensure sufficient current for even the shortest impulses. The transformer is encompassed by double shielding to keep magnetic stray fields to an absolute minimum. An AC power cord is included for connection to the standard 3-prong IEC connector. The transformer, power cord and IEC connector are VDE, UL and CSA approved. The AC fuse is rated at 315 mA for 220/240 V and 630 mA for 110/120 V. 20 GoldMike MK2