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1、1 By: Serial #: Operations Manual Portico 517 500 Series DI / Pre / Comp RadioFans.CN 收音机爱 好者资料库 2 Portico 517: 500 Series DI / Pre / Compressor User Guide Thank you for your purchase of the 517: 500 Series DI / Pre / Compressor. Everyone at Rupert Neve De- signs hope you enjoy using this tool as mu
2、ch as we have enjoyed designing and building it. Please take note of the following list of safety concerns and power requirements before the use of this or any Portico Series product. Safety Its usual to provide a list of “dos and donts” under this heading but mostly these amount to common sense iss
3、ues. However here are some reminders: Dont operate your Portico module in or around water! Electronic equipment and liquids are not good friends. If any liquid is spilled such as soda, coffee, alcoholic or other drink, the sugars and acids will have a very detrimental effect. Sugar crystals act like
4、 little rectifiers and can produce noise (crackles, etc.). SWITCH OFF IMMEDIATELY because once current starts to flow, the mixture hardens, can get very hot (burnt toffee!) and cause permanent and costly damage. Please contact support as soon as possible at for resolution. Dont be tempted to operate
5、 a Portico module with the cover removed. The cover provides magnetic screening from hum and R.F. stray fields. Power Requirements Each Portico 517 is fitted for use with standard 500 Series Rack Mounts and requires 110-125 mAmps +/- 16V Portico 517: Block Diagram COMPRESSOR BLEND MIC PRE DI INPUT O
6、UTPUT STAGE PHASE ROTATE MIC PRE IN INSTR INPUT INSTR THRU-OUT PHASE 0-180 DEG HPF 0/180 0-30dB 0-66dB 6dB Steps 80Hz INTERNAL JUMPER SETTINGS PHANTOM INTNL JMPR GAIN/THRESH. FAST SLOW TIME CONST. OPTION A (FACTORY DEFAULT) FAST - 5ms/50ms OPTION B SLOW - 250ms/500ms COMPRESSOR TIME CONSTANT OPTION
7、A (FACTORY DEFAULT) OUT OPTION B IN - 80Hz HIGH PASS FILTER INTNL JMPR OUTPUT TRANSFORMER CW +48V RadioFans.CN 收音机爱 好者资料库 3 Rupert Neve Designs517 THRUINST VARI-PHASE 48v IN MIC GAIN BLEND SILK O/L ACTIVE IN GND LIFT 36 30 24 18 12 6 0dB 66 60 54 48 42 MINMAX COMPRESSOR INSTMIC 0dB -20+10 INST GAIN
8、0+30 +15 Gain +66dBin6dBincrements Compressor Singleknobopto-coupler compressorwith2:1ratio Blend Determinesbalance ofMicandDIinputs InstrumentGain From0to30dBofgain oninstrumentinput 48V 48VPhantomPowerprovided by500seriesrack Silk Silkaddsnostalgicwarmth andpresencetowhenengaged InstrumentInput Fr
9、ontpanelTRSInputand passivethroughforhi-zsources Portico 517: Front Panel 4 MICROPHONE PREAMPLIFIER DESIGN NOTES In former years, before the introduction of solid state amplifiers, transformers were necessary to step up to the very high input impedance of tubes, and to provide a balanced input for t
10、he microphone line. An input impedance of 1,000 or 1,200 ohms became established for microphones having a source impedance of 150 or 200 ohms, with connection being made on a twisted twin screened cable (This type of cable, while excellent for low impedance work, has high capacitance between its con
11、ductors and between each conductor and screen. Resultant high frequency losses are excessive with piezo pickups and may cause resonances with magnetic pickups.) Thus microphones were not heavily loaded. Condenser microphones worked off high voltage supplies (300V!) on the studio floor which polarize
12、d the diaphragms and powered a built-in pre-amplifier. More and more microphones were needed as “Pop” music gained ground and this led to the popular and efficient method of 48-volt “Phantom” powering that was built into the multi-channel recording Console in place of numerous bulky supplies litteri
13、ng the studio, a miniature pre-amplifier now being fitted inside the microphone casing. The 48-volt supply was fed to the microphone through balancing resistors so it was impossible for this voltage to actually reach the microphone, resulting in low polarizing volts and virtual starvation of the lit
14、tle pre-amp inside the microphone. Nevertheless amazingly good microphones were designed and made, becoming the familiar product we use today. If a low value resistive load is connected to the output of an amplifier, that amplifier has to produce power in order to maintain a voltage across that load
15、. Obviously if we want more voltage (output from the microphone) we need to provide a larger supply for the amplifier or settle for a lighter load. A microphone is a voltage generator, not a power amplifier. Most microphones give their most accurate performance when they are not loaded by the input
16、impedance of a traditional preamplifier. If the microphone uses an electronic circuit (transformerless) output, a low value of load impedance can possibly stress the little microphone pre- amplifier, causing slew rate and compression at high levels. On the other hand, a high value of load impedance
17、allows the microphone to “breathe” and give of its best, this being particularly advantageous with very high level percussive sounds. If the microphone has an inductive source (such as would be the case if it has a transformer output) a low value of load impedance causes the high frequencies to roll
18、 off due to leakage inductance in the transformer in addition to the above amplifier distortion (This can be an advantage with some microphones!). For this reason we have provided a high value of input impedance that will load microphones to the smallest possible extent and makes the best possible u
19、se of that limited “Phantom” 48-volts supply. DYNAMIC RANGE Traditionally, high quality microphones such as ribbons, had very low source impedances as low as 30 ohms at the output of a ribbon matching transformer. Moving coil microphones were higher but had not been standardized as they are today. C
20、ondenser microphones, before the days of semiconductors, used tube head amplifiers that were coupled to the outgoing line with a transformer. Microphone amplifiers, such as in a mixing console, also used tubes and these typically have a high input impedance. Microphones are Voltage generators, not P
21、ower generators. It is always desirable to deliver the maximum possible signal voltage into the amplifier. It was traditional to provide an amplifier input impedance of about 1,000 or 1,200 ohms; about 5 or 6 times the source impedance of the microphone. This provided relatively low loading on the m
22、icrophone whatever its type and went a long way to avoid voltage loss. 5 In the early 1960s when the “Pop” music scene was exploding and sound levels in the Studio became very high, there was concern that the head amplifiers in Condenser microphones would overload if the Console input impedance was
23、too low. In the early days of Consoles I was asked to provide higher input impedance than the normal 1,000 ohms. This of course, resulted in less “step-up” in the Console input transformer and there were then fears that we would lose out at the other end of the scale; Noise. The fact that microphone
24、s were less heavily loaded allowed an increased microphone signal. The reduced loading also resulted in less deviation of frequency response due to variation of microphone impedance and consequently less distortion at high levels. The Portico 517 microphone amplifier provides an input impedance of 1
25、0,000 ohms which means that variations in microphone source impedance with frequency, have only a very small effect on the sonic quality. This high input impedance has minimal effect on microphone output and loading with the result that microphone distortion is very low adding up to a noticeable imp
26、rovement in “transparency”. A NOTE ON DISTORTION The human hearing system is a remarkably complex mechanism and we seem to be learning more details about its workings all the time. For example, Oohashi demonstrated that arbitrarily filtering out ultrasonic information that is generally considered ab
27、ove our hearing range had a measurable effect on listeners electroencephalo-grams. Kunchur describes several demonstrations that have shown that our hearing is capable of approximately twice the timing resolution than a limit of 20 kHz might imply (F=1/T or T=1/F). His peer reviewed papers demonstra
28、ted that we can hear timing resolution at approximately with 5 microsecond resolution (20 kHz implies a 9 microsecond temporal resolution, while a CD at 44.1k sample rate has a best-case temporal resolution of 23 microseconds). It is also well understood that we can perceive steady tones even when b
29、uried under 20 to 30 dB of noise. And we know that most gain stages exhibit rising distortion at higher frequencies, including more IM distortion. One common IM test is to mix 19 kHz and 20 kHz sine waves, send them through a device and then measure how much 1 kHz is generated (20-19=1). All this hi
30、nts at the importance of maintaining a sufficient bandwidth with minimal phase shift, while at the same time minimizing high frequency artifacts and distortions. All of the above and our experience listening and designing suggest that there are many subtle aspects to hearing that are beyond the real
31、m of simple traditional measurement characterizations. The way in which an analog amplifier handles very small signals is as important as the way it behaves at high levels. For low distortion, an analog amplifier must have a linear transfer characteristic, in other words, the output signal must be a
32、n exact replica of the input signal, differing only in magnitude. The magnitude can be controlled by a gain control or fader (consisting of a high quality variable resistor that, by definition, has a linear transfer characteristic.) A dynamics controller - i.e. a compressor, limiter or expander - is
33、 a gain control that can adjust gain of the amplifier very rapidly in response to the fluctuating audio signal, ideally without introducing significant distortion, i.e. it must have a linear transfer characteristic. But, by definition, rapidly changing gain means that a signal “starting out” to be l
34、inear and, therefore without distortion, gets changed on the way to produce a different amplitude. Inevitably our data bank of “natural” sound is built up on the basis of our personal experience and this must surely emphasize the importance of listening to “natural” sound, and high quality musical i
35、nstruments within acoustic environments that is subjectively pleasing so as to develop keen awareness that will contribute to a reliable data bank. Humans who have not experienced enough “natural” 6 sound may well have a flawed data bank! Quality recording equipment should be capable of retaining “n
36、atural” sound and this is indeed the traditional measuring stick. And “creative” musical equipment should provide the tools to manipulate the sound to enhance the emotional appeal of the music without destroying it. Memory and knowledge of real acoustic and musical events may be the biggest tool and
37、 advantage any recording engineer may possess. One needs to be very careful when one hears traces of distortion prior to recording because some flavors of distortion that might seem acceptable (or even stylish) initially, may later prove to cause irreparable damage to parts of the sound (for example
38、, “warm lows” but “harsh sibilance”) or in louder or quieter sections of the recording. Experience shows that mic preamps and basic console routing paths should offer supreme fidelity otherwise the engineer has little control or choice of recorded “color” and little recourse to undo after the fact.
39、Devices or circuits that can easily be bypassed are usually better choices when “color” is a consideration and this particularly is an area where one might consider comparing several such devices. Beware that usually deviations from linearity carry at least as much long-term penalty as initial appea
40、l, and that one should always be listening critically when recording and generally “playing it safe” when introducing effects that cannot be removed. 1. Tsutomu Oohashi, Emi Nishina, Norie Kawai, Yoshitaka Fuwamoto, and Hishi Imai. National Institute of Multimedia Education, Tokyo. “High Frequency S
41、ound Above the Audible Range,Affects Brain Electric Activity and Sound Perception” Paper read at 91st. Convention of the A.E.S.October 1991. Section 7. (1), Conclusion. 2. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina. “Temporal resolution of hearing probed by bandwidt
42、h restriction”, M. N. Kunchur, Acta Acustica united with Acustica 94, 594603 (2008) (http:/www.physics. sc.edu/kunchur/Acoustics-papers.htm) 3. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.Probing the temporal resolution and bandwidth of human hearing , M. N. Kunchur,
43、 Proc. of Meetings on Acoustics (POMA) 2, 050006 (2008) 517 USAGE NOTES The 517s feature set allows it to be used in many different ways in the studio. Here are a couple creative things to try: For vocals, take two mics, your favorite condenser plugged into the Mic Input, and a SM57 or SM58 set up 6
44、 inches closer to the vocalist and plugged into another mic pre, then into the 517 Inst Input. Adjust Vari-Phase to taste, and maybe add some light compression from the 517 followed by your usual vocal compressor, which may behave even nicer because of that touch of “pre-compression” from the 517. T
45、he 517 can also be a very useful tool on multi-miced sources like drums. A snare drum mic for instance can be amplified, compressed and phase alligned to the rest of the kit (especially the overheads) when changing mic placement alone isnt satisfying. This technique can be extremely useful when reco
46、rding in a home studio environment, with fewer placement options available. Used with a synthesizer, the blend can be used to mix together or alternate between the tones from a room capture off an amp and the direct signal. As the blend is turned towards mic, the “room” signal becomes more prevalent
47、. When blend is closer to direct, the signal is drier. The variphase, silk and compressor controls may also be incorporated for additional effects. 7 ToRecorder orMixingBoard Amplified Instrument Use with Blended DI and Mic Signals Whenusedforinstruments,the517canbeusedtophasealign, combineandcompre
48、ssdirectandmicedinstrumentsignals.To achievethis,usetheDIfortheinstrumentsdirectsignalandthemic preampforthespeakercabinetsignal.Connecttheexternalampli- fiertothepassiveDIthruonthe517faceplate.Theblendcontrolis usedformixingdirectandamplifiedsignalstoachievethedesired tonalityofthetwosources,andthe
49、variphaseisusedtominimizeor extenuatephasecancellationsbetweenthetwosignals.Tocompress theblendedsignal,simplyengagethecompresorandadjustthe conpressorthresholddialasdesired.Thistechniquecouldalsobe usedtocreateasingle,mixedoutputofaguitarandvocals,orany otherpairingofmicrophoneandinstrumentsignals. Instr. In Mic In Amp Mic Rupert Neve Designs517 THRUINST VARI-PHASE 48v IN MIC GAIN BLEND SILK O/L ACTIVE IN GND LIFT 36 30 24 18 12 6 0dB 66 60 54 48 42 MINMAX COMPRESSOR INSTMIC 0dB -20+10 INST GAIN 0+30 +15 Line Out 8 517 FEATURES MICROPHONE INPUT The microphone input i
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