Mercury MSC-76 Mono Tube Channel Strip M76m + EQp1
M76m Studio Microphone Amplifier with EQ-P1 Studio Program Equalizer
New from the Mercury Custom Shop is Mercury’s twist on the professional studio channel, the Mercury Studio Channel 76. The MSC-76 is two independent channels of a Mercury M76m Studio Microphone Amplifier and a Mercury EQ-P1 Program Equalizer. Both amplifiers (the microphone amplifier and EQ’s gain make up amplifier) are fully transformer balanced, with the option to use them together or independently with separate XLR inputs and outputs on the rear of chassis. The MSC-76 is simply two great Mercury products in one 3U chassis.
Looking at other choices of “combo boxes,” especially ones with compressors along with pre-amps and EQs, choosing to cut corners to either be able to save costs, which usually means less transformers, and or to save space to be able to fit all the components in the products chassis, we wanted to do something much different. Unlike many “channel strips” or “combo boxes” in the marketplace, no corners were cut in the Mercury Studio Channel 76 (or our other Studio Channel – the Mercury Studio Channel 72).
With the philosophy that each part of your signal chain is important, after selecting a microphone for a specific source, the foundation starts with your microphone amplifier. We designed our Mercury Studio Channels to be an obvious choice to follow any microphone in your signal chain by matching up our tube Mercury Studio Microphone Amplifiers with our tube Studio Program Equalizers. We did not consider a compressor or limiter to be part of the product from the very beginning, thinking just like a microphone, the compressor is going to vary much more often depending on application or source you are recording concentrated on the heart of the signal chain. This would allow you to use it with any microphone you have in your mic locker and any compressor in your rack, making a Mercury Studio Channel an obvious choice for engineers and producers who are looking for tone, warmth and musicality.
The MSC-76 Mic Amp
The Mercury M76m Studio Microphone Amplifier is a recreation of the original German designed Telefunken/Siemens amplifier module used in many European broadcast and recording desks in the 1960s. However, the V76 modules are known as an outboard rack mounted mic pre-amp and are highly sought after by studios and engineers all over the world.
Drawing on years of experience, repairing, rebuilding, and most importantly listening to the Telefunken/Siemens V76 modules it was our first priority to build a modern Studio Microphone Amplifier that sounds identical to the original. Mercury Recording Equipment Co. kept the integrity of the original circuit, the M76m has the same open, warm tonality created with the transformer balanced, dual stage, high gain amplifier, and uses four transformers and four tube per channel. Mercury has built what is quite possibly the ultimate combination of vintage sound and modern features to be the benchmark in a modern tube microphone amplifier.
Tubes: The Mercury M76m amplifier in the Mercury Studio Channel 76 uses three EF806s tubes and one E83F tube.
The MSC-76 Mic Amp Features & Controls
The Mercury M76m has Gain Control of 0 to +60dB in 6dB increments, that works in conjunction with the Level control and Output Attenuation. TheLevel Control, which will work as a fader, increasing (clockwise) and decreasing (counter clockwise) the amount of gain from the first stage to the second stage of the amplifier. This also allows you the ability to add musical “fuzz” by turning down your level (control) and adding more (coarse) gain. The Output Attenuation Control (-0 to -10dB) has been added for even more control, including the ability shape tones in several different ways, if desired. Unlike the original, we have added an Impedance Select Switch for both high and low impedance devices, as well as all the staple features one expects from a modern piece of equipment were added. Phantom Power (on/off) , Phase (Polarity) Reversal, and our amazing sounding FDI (FET Direct Input) Circuit.
The Mercury FDI (FET Direct Input) is a proprietary J-Fet circuit, based on a class-A tube topology. The Mercury FDI is designed to reproduce every nuance of a direct recording, while the circuit lets the tube or solid-state character of the amplifier determine the overall tone. The instrument DI signal is sent through the entire microphone preamp circuitry, including Mercury’s custom, massive input transformers, so that the individual character of each preamp comes through.
The MSC-76 EQ
The Mercury EQ-P1 is based on the vintage ‘Pultec EQP1a’ circuit, which uses a passive EQ circuit with a fully balanced (push-pull) gain make up amplifier. This new Mercury production utilizes only the highest quality passive components, while remaining true to the original, and like all Mercury products, has transformer balanced input and outputs.
Besides a much more powerful and stable power supply and running DC on the heaters, rather than AC, the only other modernization is one of Mercury EQP2’s most popular features: the Mercury I.S.T. Switch.
The Mercury I.S.T. Switch offers the choice to switch the Interstage Transformer in or out of the circuit. Giving engineers a choice with a flick of a switch between the standard Mercury warm, musical, “vintage” tone with the I.S.T. Switch not engaged (out) or a much more open and airy version of the same full, warm tone with the switch engaged (in). In the original Pultec EQP the Interstage transformer was always in the signal path. With the I.S.T. Switch engaged and the interstage transformer not in the circuit, there is slight widening of the sound and slightly more open top end. Many of today’s engineers value this feature on the Mercury EQ-P1 and now the Mercury EQP2 Studio Program Equalizers to have choice between two great, but different sounds without changing their frequencies or setting and hearing the change instantly. Note: With the I.S.T. Switch engaged or not, the input and output transformers are always in the circuit.
Tubes: The Mercury EQ-P1 amplifier in the Mercury Studio Channel 76 uses one 12AX7 tube and one 12AU7 tube.
- Low Frequency Select (CPS; Cycles per second): 20, 30, 60, 100, 200 Hz
- Low Frequency Boost Control: Shelf Boost, 0dB to +13dB
- Low Frequency Attenuate Control: Shelf Atten. 0dB to -17dB
- High Frequency Bandwidth Control: Sharp to Broad
- High Frequency Select (KCS): 2, 3, 4, 5, 6, 8, 10, 12, 16k
- High Frequency Boost Control: Shelf Boost, 0dB to +18dB
- High Frequency Shelf Attenuate Select: 5, 10, & 20k
- High Frequency Attenuate Control: Shelf Attenuate, 0dB to +16dB
The Mercury EQ-H1 and EQ-P1 are based on the original Pultec equalizers which were tools developed to deal with the limitations of recorded music. Limitations that most often manifest themselves in the highest and lowest frequencies of the program material. The family of Pultec EQs were originally designed to bring back the life and musicality lost in the recording. Whether by accident or genius, nothing has been able to do it better. The interaction of the passive boosting and attenuating shelving EQs (not relying on negative feed back), as well as the transformers, tubes and other amplification circuitry all add to the incredibly musical character of the product. Working engineers try other types of equalizers, but always end up coming back to the Pultec style as the equalizer of choice for those final touches while tracking or mixing and even mastering.
With it’s stellar sound, faithfulness to the original V76, unique tonal flexibility, and helpful array of modern conveniences, the M76m could very well be the ultimate ‘vintage-style’ mic preamp available today.
Pete Weiss, TapeOp Magazine