The Portico 5012 is a dual channel mic pre featuring Neve’s custom input and output transformer designs. In addition to individually selectable phase, mute, phantom power and a fully sweepable high pass filter, the 5012 incorporates a “Silk” circuit which yields the rich warmth and presence of the renowned classic designs.
The microphone input is balanced but not floating, being a variant of an instrumentation amplifer using a “Transformer-Like-Amplifier” (T.L.A.) configuration with a toroidal Common Mode Rejection Low Pass Filter that excludes frequencies above 150 kHz. The T.L.A. is followed by an actual input transformer permitting a full +25 dBu input signal to be handled at unity gain without an input pad over the whole audio spectrum. This combines the advantages of both an “Electronically Balanced” and true transformer input. When the Phantom voltage is switched off, this input serves as a very high quality line input with an impedance of 10,000 ohms.
Low Noise, Low Distortion Operation
Much care was given in designing the 5012 to produce as little noise and non-harmonic distortion as possible. Carefully implemented signal paths and Class A operation are a large part of the 5012′s sweet, whisper quiet performance. For more information, go to Mr. Rupert Neve’s Design Notes
A complete discussion on transformers is out of place at this point but a technical discussion will be posted at a later date. Here it is helpful to review some of the essentials where it will be seen that a design needs to be viewed as a whole, not simply from the point of view of a single component.
The fine subtleties of circuit design relating to sonic performance are gradually becoming more clearly understood. For example, research has shown conclusively that frequencies above 20 kHz affect the way in which humans perceive sound quality. But, long before scientific evidence emerged a substantial body of musicians and engineers knew that equipment with apparently the same technical measurements could sound very different.
Incredibly small amounts of musically dissonant odd harmonics have a disastrous effect on the sound quality. Extraneous noise or interference that finds its way into a signal path seriously impairs performance of the whole chain.
Many control rooms make use of outboard gear that is not well protected from external signals. Poor grounding of such equipment can be a serious problem. “Electronically balanced” circuits much used in modern equipment, can give very good measurements on the test bench but they do not provide adequate rejection of the stray fields found in every working environment.
Input and output circuits must be freed from ground dependence so that only the “wanted” signal enters and leaves the processing path. Transformers are the ideal solution. The sweet and silky sound of my classic old favorite consoles was achieved with big transistors and large high quality transformers. Rupert Neve Designs Portico modules achieve similar quality today without the bulk or the cost.
In order that modules can work together as would be expected (i.e. in a proprietary console configuration) without producing hum, R.F. interference, or other interactions, the connecting interfaces, grounding, levels and impedances must receive careful attention. Each Portico module is a complete integral signal processor that delivers its specified performance independently. This is one of the reasons we use transformers.
Much could be written about this feature, suffice to say, that it gives a subtle option to enhance sound quality in the direction of vintage modules. The Silk button reduces negative feedback and adjusts the frequency spectrum to provide a very sweet and musical performance. We suggest you try it and make your own judgment.
-30 dBu to +22 dBu With reference to the output
Cuts of the output signal post metering and pre Buss Output. Be sure to mute the outputs before engaging phantom power.
High Pass Filter
The High pass filter is a valuable aid in any signal chain but particularly so in a microphone preamplifier. Signals between 20 and 250 Hz can be attenuated, leaving the range above this unaffected. This gets rid of building rumble, air handling motor hum etc.
Provides 48V phantom power to microphones
The To Buss output is unbalanced and has a high impedance output. It is intended for use with the Portico Buss Amp/Monitoring modules. A TRS patch cord is used to connect the 5012 Buss output to one of these bussing modules. The Monitor connection is derived pre mute on the 5012 and will produce a signal at the output of the buss modules that is equal in level to that at the 5012 output. The Monitor output cannot be used for any other purpose.
Flips the phase of an incoming source 180 degrees
Balanced, using “Transformer-Like-Amplifier” (T.L.A.) with toroidal Common Mode Rejection Low Pass Filter that excludes frequencies above 150 kHz.
The T.L.A. is followed by an actual input transformer permitting a full +26 dBu input signal to be handled at unity gain without an input pad over the whole audio spectrum.
Combines the advantages of both an “Electronically Balanced” and true Transformer input.
When the Phantom voltage is disabled, this input serves as a very high quality Line Input.
Input Impedance: 10,000 Ohms + or 20%
Measured at Main Output: Input terminated with 150 Ohms.
Measured over band limited 22Hz-22kHz, Unweighted: With Gain at Unity: Better than 100 dBu. With Gain at 66 dB: Better than 62 dBu
Equivalent Input Noise (E.I.N.): Better than 128 dBu
Main Output, no load:
@ 10 Hz: 0.2 dB
@ 160 kHz: 3 dB
@ 10 Hz: 0.2 dB
@ 160 kHz: 3 dB
High Pass Filter:
Swept Frequency continuously variable from 20 Hz to 250 Hz. Slope: 12 dB/Octave.
Gain: Switched Gain from Unity to +66dB in 6 dB steps.
Trim: Continuously adjustable potentiometer from 6dB to +6dB with reference to setting on the Gain Switch.
Maximum Output Level: Balanced and Floating Transformer Output from 20 Hz to 40 kHz: +25 dBu. (Clips at just over +26 dBu)
Mute: Mutes Main Output only. (i.e. Monitor remains Live)
Total Harmonic Distortion and Noise:
@ 1kHz, +20 dBu output level, no load: Better than 0.001%. (No high order Harmonics)
Silk Engaged: Approximately 0.2% Second Harmonic
Main Output: @ 20Hz, +20 dBu output level, no load: Better than 0.01%.
Buss Output: @ 1kHz, +20 dBu output level, no load, measured at the output: Better than 0.002%.
SILK: The 5012 uses mainly single-sided amplifier circuitry that excludes any possibility of crossover distortion. The “SILK” button reduces negative feedback and adjusts the frequency spectrum to provide a very sweet and musical performance.
Buss Output: The Buss Output is designed to feed other Portico Series modules with Buss Inputs.
Measured Channel to Channel: Better than 90 dB @ 15kHz.
Phantom Power: +48 Volts DC +/- 1%
Main Power Required: (From External Power Unit) Voltage Range, 9 to 18 Volts DC.
@ 9VDC = 1.3 A typical
@12VDC = 1A typical
@15VDC= 800 mA typical
@18VDC= 650 mA typical
Rear Panel Power Connector: 5.5mm X 2.1mm DC jack, Center Positive