User manual SPL GAINSTATION

User's Guide Gain Station Power SOURCE Mic Hi Z -30 0 dB 9 18 Clip HI PASS 50 Hz Off AD OVL 48V Limit PHASE Rev. Nor. IMPED. PHANTOM LIMITER 10k 1.2k 200 On Off Peak Off +Fet C 19 21 18 16 15 14 13 12 11 10 O NG LEA 22 24AIN dB 12 16 26 9 29 32 7.5 35 6 38 4 41 2.5 46 1 54 b 63 tO e+ Tu e F ff BE GAIN TU 18 2021 U -10 -9 -8 -6 E -12 -5 -14 22 -2.5 -16 23 24 -18 0 24.5 -20 2 3.5 25 -22 25.5 5 -24 25.8 5.5 -25 -26 26 6 TPUT LEV L dB dB Mic: +7dB w/transformer Class A 60-Volt Amplifiers Discrete High-Gain Preamplifier / Model 2272 GainStation 1 Models 2272, 2273 Single channel microphone and instrument preamplifier User's Guide GainStation 1 Version 1.0 ­ 6/2003 Designer: Ruben Tilgner Models 2272, 2273 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 © 2003 SPL electronics GmbH. All rights reserved. Names of other companies and their products are trademarks of their respective owners. 2 GainStation 1 Contents Introduction .................................................................. Before you begin .......................................................... 4 7 Rear panel/connections ................................................ 8 Wiring ....................................................................... 8 General advices ......................................................... 9 Connectors and switches ........................................... 10 Optional AD Converter ............................................... 11 Converter-related connectors .................................... 12 Control elements .......................................................... Clean Gain, Tube Gain, Output Level .......................... Source, Hi Pass, Phase .............................................. Imped. , Phantom .................................................... Limiter ....................................................................... POWER-LED, LED Level Display, AD OVL ..................... 14 14 15 16 17 18 Operation ..................................................................... 19 Setting levels on the GainStation 1 ............................. 19 Limiter ....................................................................... 20 Application examples ................................................... Vocals/speech ......................................................... Acoustic instruments/orchestra ................................ Acoustic guitar with pickup ....................................... Guitar amps ............................................................. Electric Bass ............................................................ Keyboards/samplers/drum machines ........................ Tube distortions with GainStation 1 ........................... Drums/Snare-Drum .................................................. Kick-Drum ................................................................ Toms ........................................................................ Overhead ................................................................. Technology 22 23 23 23 23 24 24 24 25 25 25 25 ................................................................... 26 ................................................ 30 Technical Specifications Dimensions/weight ....................................................... 31 ...... 31 Optionen/Information on Lundahl input transformers Warranty Notes ...................................................................... 32 ........................................................................... 33 GainStation 1 3 Introduction Input makes all the difference. Modern audio production relies increasingly on digital systems for recording and mixing processes (DAW`s, digital consoles etc.). The advantages of digital audio are manifold and include affordable storage, comfortable editing, recall capabilities and automation. On the downside, digital systems still do not offer the same audio qualities and sound characteristics of high-end analog equipment. Especially digital equalizers and other aspects of the mixing domain cannot compete with the open, transparent sound of the best analog gear. So today more than ever, your input signal has to sound as good as possible--the quality of your original tracks will largely define the end result. Lifeless or dynamically lacking signals are often over-processed with EQ, compression and other effects in an attempt to compensate--often an extremely tedious process in the digital domain that doesn`t always produce the desired results. Attacking this problem on the preamplification front, with the goal of noticeably improving a signal and sending it along its path with a healthy foundation, requires a great deal of thought and engineering effort. To this end, the GainStation 1 employs technologies that not only satisfy test equipment, but also--and most importantly--the user. Components and circuits were carefully chosen and designed on the basis of extensive measurements and listening tests. In short, developing the GainStation 1 was a major undertaking that required immense amounts of time and experience. Another important goal in designing the GainStation 1 was that the case itself should optimally adapt itself to modern production environments. It was to be as compact as possible, allowing easy transport and ergonomic placement in virtually any situation. A free-standing case which does not need to be rackmounted has several advantages: not only are the inputs and outputs always easily accessible, but the unit can also easily be placed on top of an amp, outboard rack or even some keyboards, on your desk next to your laptop, or in direct proximity to a microphone to allow for maximum operational comfort and minimum cable lengths. 4 GainStation 1 Introduction To accommodate portability, the optionally available SPL GainBag ensures safe transport of the GainStation 1 and offers additional storage for cables and an average-sized microphone. For more permanent installations, up to four GainStation 1`s can be rack-mounted in one optionally available 3-unit rack space mounting frame. Main technical features of the GainStation 1 · Custom-designed and built, fully discrete, class A op-amps (no off-the-shelf stuff here). The GainStation`s op-amps feature 60-Volt operating voltage--twice as high as most common op-amps--for an incredible dynamic range. · An extremely high amplifier slew rate of 200 V/microsecond, ensuring clean transmission of high-frequency signal portions and rapid transients with virtually no cut-off. · An almost entirely DC-coupled signal path, making signaldegenerating condensers unnecessary. · An optimized layout guarantees the shortest possible signal paths, while generously proportioned grounding surfaces ensure low impedance and maximum shielding. · All switching functions are handled by encapsulated relays with gold-plated contacts. · All resistors are within 0.1% tolerance and were selected after extensive listening tests. · A no-compromise power supply with extensive additional shielding and seven separately wound and regulated voltages. The power supply is of primary importance to audio quality; its importance should not be underestimated. · A tube stage utilizing premium MKP foil condensers and a select 12 AX7 LPS tube for clear, dynamic audio. GainStation 1 5 Introduction This cutting-edge technology ensures that signals recorded with the GainStation 1 have more presence and substance and will easily cut through a mix even at lower levels. Extremely low-frequency signals are tight and transparent with clear intonation. Percussive transients are interpreted more precisely, which leads to a clearer rhythmic content and in turn a more solid rhythmic performance and perception. A bassist using the GainStation 1 as a preamp will immediately notice that he hears and feels what he is playing much better, which leads to improved playing and a better recording. The track will have more punch and dynamics, greatly improved presence and almost palpable detail. In short, the instrument sounds incredibly authentic and alive. Beta-tests with the GainStation 1 showed that all instrumentalists enjoyed playing more and in many cases were truly amazed at what their trusty instrument was capable of. Given this improvement in the input signal, one is much less inclined to equalize and compress--in many cases you will probably find that you can do without additional processing, which not only saves an enormous amount of time and processor power, but also has an extremely positive effect on the final result. The GainStation 1 itself offers effective sound-shaping capabilities at recording, most notably via the tube stage, which can be completely bypassed or continuously added to the preamp circuit, allowing everything from extremely subtle ,,warmth" to a very noticeable tube saturation effect. The integrated limiter can be used to protect an internal or external AD converter from clipping, or for example to add punch to drum tracks, which in turn reduces or in many cases even eliminates the need for subsequent compression. Put simply, the more tracks are recorded with the GainStation 1, the more solid and transparent--and easier to mix--the entire recording will be. 6 GainStation 1 Before you begin It makes good sense to think about where you place your GainStation 1 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 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. Avoid cleaning agents as they may damage the unit. GainStation 1 7 Rear panel/connections Wiring S/P-DIF signal to DAW, HD recorder etc. S/P-DIF signal for external synchronization POWER ON VOLTAGE/FUSE MAINS INPUT 230 V ­ 50 Hz/315 mA WARNING: TO REDUCE RISK OF FIRE OR ELECTRIC 115 V ­ 60 Hz/630 mA SHOCK DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE OFF CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN AVIS: RISQUE DE CHOC ÉLECTRIQUE - NE PAS OUVRIR 24/96 AD DIG. OUT SYNC INPUT SAMPLE RATE OPTICAL SPDIF LOCK SPDIF x2 PUSH 44.1 48 XLR Wiring: 1 = GND/ 2 = (+)/ 3 = (­) Jack: Tip = (+)/Ring = (­)/ Sle. = GND AD IN 2 AD IN 1 MUTE 2nd signal input of the optional A/D converter ANA. OUT 2 HI-Z/ LINE INPUT ANA. OUT 1 MIC INPUT Microphone Made in Germany Instruments, Line signals Converter, (HD) recorder or mixing console Pin wiring of TRS connectors Tip = hot (+), Ring = cold (-), Sleeve = GND PUSH 2 3 1 Pin wiring of the XLR microphone input 1 = GND, 2 = hot (+), 3 = cold (-) 1 3 2 Pin wiring of the XLR analog output 1 = GND, 2 = hot (+), 3 = cold (-) 8 GainStation 1 General advices Rear panel/connections Again, while the GainStation 1`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 GainStation 1 or any other equipment turn off all power. 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/FUSE 230 V ­ 50 Hz/315 mA 115 V ­ 60 Hz/630 mA Output balanced unbalanced 1 3 2 1 3 2 1=GND 2=cold (+) 3=hot (-) The HI-Z/Line Input connector is designed for unbalanced signals only. The TRS output connector (see ,,Analog Outputs", page 10) can be operated both with balanced and unbalanced wiring. Simply use a mono 1/4" plug for unbalanced operation. GainStation 1 9 Rear panel/connections MIC INPUT Dynamic, condenser or tube microphones can be connected to the MIC input. The 48 V switch provides the phantom power necessary for some microphones (see also ,,Control elements/ Phantom" on page 16). The MIC input can also be used as a balanced connection for professional audio equipment with a maximum output level of +20 dBu. IMPORTANT NOTE: Always switch the phantom power (48 V) off before connecting anything other than phantom-powered condenser microphones. HI-Z/LINE INPUT The instrument input HI-Z/Line Input is for electric guitars and basses or other high-impedance, line-level signals such as keyboards, samplers, drum machines etc. with unbalanced outputs. If a balanced connector (TRS) is inserted, the ring of the plug is automatically connected to the ground to ensure proper unbalanced operation. ANALOG OUTPUTS 1/2 The preamplified output signal is fed to the balanced Analog Outputs. Since the XLR and 1/4" TRS connectors are wired in parallel, an unbalanced connection at one connector will cause the other connector to operate unbalanced, e.g. if a mono 1/4" plug is inserted into the 1/4" jack, the corresponding XLR socket will also operate unbalanced. IMPORTANT NOTE: The output connectors can deliver an output level of up to +34 dBu. Please ensure that all other equipment can handle these levels to prevent possible damage. 10 GainStation 1 Rear panel/connections POWER The POWER switch turns the GainStation 1 on (indicated by the blue POWER LED on the front panel) or off. OFF POWER ON 24/96 AD Converter (optional) 24/96 AD DIG. OUT SYNC INPUT SAMPLE RATE OPTICAL SPDIF LOCK SPDIF x2 44.1 48 The optional 24/96 Converter module (model 2376) provides a digital output for the GS1 in the form of an S/P-DIF output with RCA and optical connectors (in parallel). The converter transmits 24-bit signals. The module is based on a 24-bit converter by AKM® with a variable sample rate of up to 96 kHz. All common sample rates can be selected (see below). Highly accurate quartz oscillators ensure a clean, low-jitter master clock. SAMPLE RATE The 24/96 AD converter module allows you to select between the four most common sample rates: 44.1, 48, 88.2 and 96 kHz. Using the 44.1/48 button, select one of the two basic sample rates (out: 44.1 kHz; in: 48 kHz). The x2 button doubles these sample rates to select 88.2 or 96 kHz respectively. GainStation 1 11 Rear panel/connections AD IN 2 AD IN 1 MUTE AD IN 2 If the optional 24/96 AD converter module is installed, this input can be used to convert an external analog signal. To avoid clipping, the input level should not exceed +12 dBu (+12 dBu corresponds to full digital gain of 0 dBfs). Excessive input levels are indicated by the AD OVL LED. If no connection is made here, the output signal of the GS1 is routed to both channels of the converter. TIP: AD IN 2 can also be used as an insert for external pre-conversion processing. Connect the analog outputs of the GainStation 1 to the external processor`s inputs and the processor`s outputs to AD IN 2 on the Gain Station 1. One channel of the converter output will contain the dry or unprocessed signal, while the other channel will contain the processed signal. AD IN 2 AD IN 1 MUTE AD IN 1 MUTE Channel 1 of the converter is internally connected to the analog output, so that the AD OVL LED is always active. If the converter is not being used, this connection can be bypassed via the AD IN 1 MUTE switch so that the LED does not continuously blink or illuminate. TIP: If no converter is installed, this switch should always be activated. DIG. OUT 24/96 AD DIG. OUT OPTICAL SPDIF The converted S/P-DIF signal is routed in parallel to the RCA and optical outputs. The signal is in professional format with no sample rate data in the status block. 12 GainStation 1 Rear panel/connections SYNC INPUT The SYNC input allows you to feed an external signal into the converter to control the sample rate. Connect an S/P-DIF output from your master source (e.g. sound card) to the SYNC input. The AD converter will automatically convert to the same sample rate that is received. The 2376 is not equipped to accept Word Clock for synchronization. The yellow SYNC LOCK LED illuminates when a valid sync signal is present at the SYNC input, and the converter is automatically synchronized to the external sample rate. The internal oscillators are automatically disabled when an external clock signal is present to prevent interference. If the sync signal is no longer present (e.g. in the case of a dropout), the converter automatically reverts to the sample rate selected via the buttons. SYNC INPUT LOCK SPDIF GainStation 1 13 Control elements C 19 21 18 16 15 14 13 12 11 10 NG LEA 22 24AIN 26 29 32 35 38 41 46 54 63 CLEAN GAIN This potentiometer controls the amount of preamplification provided by the class A solid-state stage. A range of up to +63 dB is provided. For more information, please see ,,Setting levels on the GainStation 1" on page 19. dB Mic: +7dB w/transformer IMPORTANT NOTE: If a Lundahl input transformer is installed, add 7 dB to the printed values. BE GAIN TU 16 18 2021 12 9 7.5 TUBE GAIN 24.5 6 4 2.5 22 23 24 25 25.5 25.8 1 Tu e F b tO e+ ff 26 dB This potentiometer controls the amount of preamplification provided by the tube stage. This stage follows the clean (solidstate) stage, so that the gain values of the two stages are additive. Setting Clean Gain at 20 dB and Tube Gain at 15 dB results in 35 dB of total preamplification. Turning the Tube Gain control fully counter-clockwise causes the tube stage to be deactivated and bypassed via a relay. TIP: For optimal signal-noise ratios at high preamplification values, the majority of preamplification should be achieved via the solid-state stage, adding just enough of the tube stage for the desired sound. Due to the nature of tubes and tube circuitry, the tube stage is somewhat noisier than the solid-state stage. O PUT LEV UT -10 -9 -8 -6 E -12 -5 OUTPUT LEVEL 0 2 3.5 L -14 -16 -18 -20 -22 -24 -25 -26 -2.5 5 5.5 6 dB This potentiometer adapts the output level to devices following in the chain or to the converter. At 0 dB the output level is equal to the internal level indicated by the LED display. The OUTPUT LEVEL control allows an additional 6 dB of amplification or 26 dB of reduction.The output level control is post-limiter to allow maximum levels to the internal or external converter. IMPORTANT NOTE: If the internal level is noticeably above +18 dB (the orange +18 dB LED is brightly illuminated) and the output level is set to +6 dB, the output level at the analog outputs can be up to +34 dBu. Please ensure that all other equipment can handle these levels to prevent possible damage. 14 GainStation 1 Control elements SOURCE This switch allows you to select between the MIC and HI-Z/LINE inputs. Both inputs can remain connected at all times, regardless of which input is selected. When first thrown after powering up the unit, this switch can cause a noticeable pop due to the discharge of residual current. This is normal and no cause for concern. SOURCE Mic Hi Z HI PASS This switch activates the integrated high-pass filter, which operates at a 50-Hz center frequency and 12 dB/octave (often called a ,,rumble filter"). The filter is entirely passive, avoiding additional active circuitry that could potentially degrade the signal, and cuts 6 dB pre- and 6 dB post-solid-state preamplification to prevent the amplification of unwanted low-frequency signal portions. HI PASS 50 Hz Off PHASE The phase reverse function reverses the polarity of the microphone signal, ,,turning" the phase by 180° to correct phaseinverted signals caused by multiple signal sources. A voice-over 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. The GainStation 1`s phase reverse switching is achieved passively via a relay, pre-preamplification, to avoid additional active circuitry. PHASE Rev. Nor. GainStation 1 15 Control elements IMPED. 10k 1.2k 200 IMPED. This 3-way switch allows you to select between three input impedances for the MIC input. The effect varies depending on the microphone used. With dynamic microphones, a lower impedance setting will also reduce the input level--this effect is less pronounced with good condenser microphones. We recommend the 10 k () setting for most applications, although some microphones may benefit from a different setting. PHANTOM On Off PHANTOM The GainStation 1 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 GainStation 1 continuously delivers precisely 48 V and a maximum of 14 mA, which will power all microphones. IMPORTANT NOTE: All microphones with balanced, ground-free outputs, including tube microphones, can be used with the phantom power activated. First connect the microphone to the GainStation 1, then activate the phantom power. When finished, first deactivate the phantom power and wait at least 30 seconds before disconnecting the microphone to allow residual current to discharge. Phantom power should only be activated when using microphones that require it. Please be sure to deactivate phantom power with all other microphones. Unbalanced microphones may only be used with phantom power deactivated. 48 V The 48V LED illuminates to indicate activated phantom power. When deactivating phantom power, it can take several seconds for the LED to go out, since the 48-V current dissipates rather slowly. When changing microphones, you should wait until the LED is completely dark before re-patching. 16 GainStation 1 Control elements LIMITER The GainStation 1 offers two types of output level limiting: PEAK and FET. The limiter is pre-output level control, so that the limited signal can be optimally adapted to the internal or external converter. The peak limiter operates with special diodes that convert signal peaks into a type of saturation. Depending on the signal, this allows levels to be effectively and subtly limited. This type of limiting works very quickly, reliably limiting even microsecondlong transients, and is very effective for drums and percussion. The peak limiter also enables maximum loudness. Operation is displayed via the Limit LED. The FET limiter is additionally available when the tube stage is activated. The FET circuit operates with a Field Effect Transistor (FET), which is connected to the tube and enables--always in conjunction with the peak limiter--a reduction of signal amplitude. Thus this limiter works in a similar fashion to a compressor, which makes it very effective for signals that undergo unforeseeable level changes (i.e. vocals, speech, guitar, bass, piano etc.) and where minimum loss in signal quality is desired. The peak limiter is always active post-FET limiter to ensure reliable protection. The Limit LED also displays the operation of the FET limiter (always somewhat more calmly than with peak limiting). IMPORTANT NOTE: If the tube stage is deactivated while FET limiting is active, the LED will continue to display in FET limiting mode. For more information on using the limiters please see page 20, "Limiter". LIMITER Peak Off +Fet Limit GainStation 1 17 Control elements Power POWER-LED This LED indicates that the GainStation 1 is connected to the proper AC current and switched on. If the tube stage is active when the unit is switched on, it can take several seconds before a signal can be heard--this time is necessary for the tube to reach operating temperature. -30 0dB 9 18 Clip LED Level Display The level display shows the peak level before output level control. A special circuit allows the LED`s to vary in brightness to display in-between values. The -30 LED illuminates weakly at -30 dB and reaches full brightness at 0 dB. The 0 dB LED illuminates weakly at 0 dB and reaches full brightness at +9 dB and so on. The CLIP LED operates post-CLEAN GAIN stage and displays clipping at this point in the signal path. It will not react to tube saturation in the tube stage, since this can be a desired effect. AD OVL AD OVL This LED 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. If the converter is not being used or not installed, the AD IN 1 MUTE switch should be activated, so that the output signal is no longer routed to the converter and the AD OVL circuit. Signals connected to AD IN 2 are also displayed by the AD OVL LED and cannot be switched off (they can only be disconnected). 18 GainStation 1 Operation In spite of its quality and flexibility, the GainStation 1`s transparent user interface allows quick, intuitive operation. The unit is suited for a wide variety of applications. The following sections will provide an overview of the most important operational concepts and several application examples. Setting levels on the GainStation 1 Start with the limiter switched off. With a representative signal present at either the MIC or HI-Z input, set the desired combination of Clean and Tube Gain so that the 9 dB LED illuminates brightly. When this LED illuminates weakly, you have 9 dB of gain. When brightly lit, you have 15-17 dB, which still leaves you with a good 9 dB of headroom (in the range displayed by the orange 18 dB LED) before clipping. The orange LED illuminates dimly at 18 dB and brightly at around 26 dB. The red Clip LED should never illuminate--this indicates clipping in the clean stage, which generally should be avoided, as it will lead to distortion of the solid-state circuitry. (You may find this desirable in some rare cases--we had lots of fun creating heavily distorted guitar sounds...) The Clip LED does not display high amplification levels in the tube stage that could lead to distortion. The GainStation 1 intentionally allows tube saturation, since tube distortion--contrary to transistor distortion--is often a desirable effect. Once you have adjusted the gain levels as described above, use the Output Level control to set the optimal output level for subsequent devices in the chain. IMPORTANT NOTE: The Output Level control should not be set above 0 dB when working with high internal levels of more than 18 dBu. Otherwise, extremely high output voltages of up to 34 dBu (approximately 38 Veff) can occur, which can damage other equipment. Please refer to the documentation of your other equipment regarding maximum input levels. GainStation 1 19 Operation Combining different amounts of clean and tube gain will create various effects. The GainStation 1 operates virtually distortionfree with the tube stage bypassed. The sound is clean and transparent with extreme detail and very low noise. The clean stage is ideal for most acoustic instruments, as well as jazz or classical recordings. If you activate the tube stage and increase the gain setting slowly, you will notice that once you reach a certain level, harmonic distortion enters the signal. The sound becomes punchier and ,,fatter", and attains more loudness. At this setting the tube stage is still relatively noise-free, and ideal for adding a bit of presence and liveliness to signals that may otherwise sound dull or lifeless. This setting works very well with stringed instruments like acoustic guitars, electric and acoustic basses and violins, since it highlights the harmonics of the strings. Naturally, these effects become more pronounced as the amount of Tube Gain is increased. The tube can be driven to full saturation to produce pronounced distortion, which can be very effective with synthesizers, samplers and drum machines that lack punch. Signals recorded in this fashion will generally cut through a mix with no trouble at all. Limiter To achieve the desired results with the integrated limiter, it is important to understand its operation. The threshold value is fixed at 20 dBu. The clean and/or tube gain settings determine the amount of limiting, so that these settings more or less work like a threshold control. When the limiter is activated, it levels everything above 20 dBu. The orange 18 dB LED, which displays this level range, varies in brightness depending on limiting. The actual amount of limiting is displayed by the Limit LED, which becomes brighter as more level reduction is applied. 20 GainStation 1