George Massenburg Labs GML 2020 High Resolution Discrete Input Channel The GML 2020 High Resolution Discrete Input Channel sets a new standard in signal processing. Combining the features of the GML flagship 8200 Parametric Equalizer, 8300 Transformerless Microphone Preamplifier, and 8900 Dynamic Gain Control with additional functions, this powerfully pristine single channel unit embodies the legendary detail and accuracy for which GML is renowned. Owner's Manual Version 1.
INTRODUCTION The GML 2020 High Resolution Discrete Input Channel sets a new standard in signal processing. It combines the features of the GML flagship 8200 Parametric Equalizer, 8300 Transformerless Microphone Preamplifier, and 8900 Dynamic Gain Control into a powerfully pristine single channel unit.
• Precise input signal LED meter; 5 color-coded steps • Interstage (EQ out, DYN out) Clip/OL LED • Illuminated push-button switches for "EQ In", "Dynamics In" and "Link" • Carbon-film precision potentiometers, manufactured to GML exacting standards • GML-specified custom robust rotary switches; precious metal contacts • Precious-metal interconnects • High-quality XLR interconnects, Au over Ag • Proprietary discrete VCA; excellent low-level resolution, low distortion, low noise • Highly accu
OPERATION The Model 2020 High Resolution Discrete Input Channel offers unprecedented flexibility and sonic accuracy when dealing with a variety of signal sources and conditions. Whether a very simple gain stage or a comprehensive processing path with filter, EQ, and compression is desired, the Model 2020 can accommodate, quickly adapting from one requirement to the next.
The input source for the Model 2020 is selected on the lower Routing switch, located near the lower left corner of the front panel. Only one source may be active through the channel at a time; however, signals may be present at the other inputs since the source select function does not ground unused inputs (see Specifications page of this manual for separation figures).
II. Filter Immediately following the input section of the Model 2020 is an extremely useful and transparent high-pass filter, which has three optional settings: 40Hz roll-off, flat response, or 100Hz roll-off. Designed for maximum clarity and musicality, this active second order Butterworth high-pass filter is implemented with premium-grade film capacitors, precision metal-film resistors, and a pristine GML 9202 discrete opamp.
IV. Parametric Equalizer The EQ section of the Model 2020 High Resolution Discrete Input Channel offers astonishing precision and sonic accuracy when sculpting the response of any source. Its operational characteristics, duplicated from the Model 8200 Parametric Equalizer, have been honed through many years of use in the most critical recording and mixing situations and have proven both reliable and amazingly accommodating.
V. Dynamics Note: A basic understanding of the fundamental terms and concepts regarding dynamic range devices in general is paramount to the following discussion and is presumed to exist for the user. In contrast to most conventional dynamic range devices, the Dynamics section of the Model 2020 is a complex dynamic range controller that incorporates several powerful features to provide unparalleled flexibility and musicality.
Peak Detector active Fast RMS Detector active Slow RMS Detector active P F S FRONT PANEL LEDS A Detector Compare circuit immediately follows the three detectors of the Dynamics section. The function served by the comparison circuit is to determine how the dynamic range will be affected in subsequent processing blocks. At this stage, the Crest Factor controls--both Fast and Peak--determine at what level the dynamic range will be altered for the corresponding control signals from the RMS Detectors.
0 -10 THRESHOLD -20 OUTPUT - dB THRESHOLD (Soft Knee) -20 -10 0 +10 +20 INPUT - dB The second mode of operation, Hard Knee, is less straightforward to explain. Under this condition, the Threshold control should be thought of as a compression gain control instead of merely a traditional threshold control, as in the 1176-style compressors. In this case, the effective threshold is predetermined, while the Threshold control acts as an input gain stage.
The importance of this control to the operation of the unit cannot be overstressed: it provides for two entirely different modes of operation. Soft Knee mode performs as described in the preceding sections with a preset non-user definable variable ratio, while Hard Knee mode allows the user to determine the desirable ratio from 1.5:1 to actual limiting (infinity to one) for a great deal of flexibility.
VI. Clip/OL In light of the internal routing complexities and the considerable amounts of gain available in both the EQ and Dynamics sections of the Model 2020 High Resolution Discrete Input Channel, the Clip/OL LED indicator provides an essential metering function. This peak detection meter monitors both the EQ and Dynamics outputs to warn of signal overload, regardless of the routing option selected on the Routing control.
MODEL 2020 FRONT PANEL DIAGRAM A. The Gain control switch sets the amount of gain or attenuation for the input section in precise 5dB steps from -10dB to +70dB. This is a GML-specified custom precious-metal contact rotary switch. B. The Phase switch determines the phase/polarity of the selected input signal, while its associated Green LED indicates the state of the Phase relay (Off for in-phase, On for out-of-phase). No audio signal is present at this switch. C.
MODEL 2020 BACK PANEL DIAGRAM A. The 7-pin D.C. Power Supply Input enables interconnection of the external supply required for the unit to operate (Model 9015). A 6-ft. 7-pin power supply cable ships standard with all new units. B. The Grounds terminal block gives a common point of continuity to the chassis ground (Chassis) and the electronics ground (Supply).
SPECIFICATIONS* INPUT Input Impedance Mic: 1 kΩ balanced Line: 20 kΩ balanced M/I: 1 MΩ unbalanced (tip "hot") 1 CMRR, 20 Hz to 20 kHz Mic: 93.8 dB Line: 92.3 dB CMRR, 100 Hz and 10 kHz Mic: 94 dB Line: 92 dB 2 Maximum input before clipping Mic/Line: +36.6 dBu M/I: +20.1 dBu THROUGHPUT INPUT SECTION MIC INPUT 3 -0.1 dB / +0.002 dB, <10 Hz to 40 kHz -0.01 dB / +0.002 dB, 15 Hz to 15 kHz 4 -3 dB at 280 kHz and <<10 Hz 5 <0.002% Harmonic distortion at +20 dBu, 20 Hz to 30 kHz 6 <0.
Specification Notes * All tests conducted at the GML laboratory using the Audio Precision System Two Cascade Dual Domain (AP S2C), or otherwise as noted. Unless specified differently, all tests include AP S2C residual measurement and were conducted under the following conditions: Rs=40Ω, RL=100kΩ, <10Hz to >500kHz analyzer bandwidth. GML reserves the right to make changes to these specifications as it deems necessary.
FORM FACTOR One channel, multi-input, gain, filter, parametric equalizer, and dynamic range controller Input Section 3 inputs: Mic, Line, M/I (Tip = Signal, Sleeve = Ground) Input Source control: Mic, Line, M/I Gain control: -10dB to +70dB, 5dB steps Input meter, 5 LED's: -30dB, -20dB, 0dB (green), +18dB (yellow), +24dB (red) Phase switch, toggle: In-phase (LED off), Phase reverse (LED on) Phantom switch, toggle: Phantom on (LED on), Phantom off (LED off) Filter -- Second-order Butterworth active high-pass
DESIGN On the surface it is not eminently evident just how much "new" design is represented in the Model 2020 High Resolution Discrete Input Channel. Indeed, the EQ and Dynamics sections have been barely modified from the reference-standard Model 8200 Parametric Equalizer and Model 8900 Dynamic Gain Control and even the Model 8300 Transformerless Microphone Preamplifier is largely copied herein.
Great care has also been taken--as in all aspects of the GML Model 2020--to select the highest quality components, from the potentiometers on the front panel to the smallest passive elements. This attention to detail partially elucidates the quality found in the High Resolution Discrete Input Channel. These component choices, coupled with superior design and a proclivity towards innovation, combine to make the Model 2020 the most powerful, flexible, and transparent single channel processor ever designed.
POWER SUPPLY Integral to the superb quality of all GML products is the external power supply. No piece of electronic equipment can operate as designed without an adequate power supply; however, most contemporary processors do not feature a supply which can provide clean, quiet power without unduly heating the device. The Model 9015 excels in this respect, providing clean, quiet power for the many complex and sensitive circuits of the Model 2020, while remaining cool and efficient.
TROUBLESHOOTING Note: This unit is a highly sensitive device that includes many complex circuits. THIS UNIT CONTAINS NO USER-SERVICEABLE PARTS. Warning: Risk of electric shock if top cover is removed. In the event of unit operational failure, contact the GML Repair Department. Refer to the "Contacts" page of this manual, or for more current contact information, check our web site.
CONTACTS General Information: GML, LLC. P.O. Box 1366 Franklin, TN 37065 615.790.1016 (ph) 615.794.4802 (fax) internet:: www.massenburg.com Repairs: GML, LLC. Attn: Repair Department Franklin, TN 37064 615.790.1016 (ph) 615.794.4802 (fax) Engineering: GML, LLC. Attn: Jeffrey Warren, Chief Engineer Franklin, TN 615.790.1016 (ph) 615.794.4802 (fax) email: jeffrey_d_warren@yahoo.com Pricing/Ordering: GML USA Sales Office: TransAmerica Audio Group 4760 Dewey Dr. Las Vegas, NV 89118 702.365.5155 (ph) 702.365.
NOTICE OF COPYRIGHT AND OWNERSHIP All designs, circuit board artwork, front panel artwork, text contained herein and therein, and all other intellectual material is the sole property of George Massenburg Labs, LLC (and/or GML, Inc.). Unauthorized use, distribution, reproduction, etc. is strictly prohibited. GML intellectual property is protected by U.S. and international copyright laws. Violators will be prosecuted to the fullest extent of all applicable laws.
ADDITIONAL GML PERIPHERALS Model 8200 Parametric Equalizer, Series II Model 8300 Transformerless Microphone Preamplifier Model 8355 Power Supply Model 8900 Dynamic Gain Control, Series III Model 9015 Power Supply Model 9500 Two Channel 5-Band Parametric Mastering Equalizer HRT 9100 Mixer HRT 9145 Multi-Output Power Supply Model 9550 Two Channel Digital Noise Filter Model 9560 Digital Noise Filter w/ Macintosh Controller For ordering information, contact: GML USA Sales Office: TransAmerica Audio Group 4760
MODEL 2020 HIGH RESOLUTION DISCRETE INPUT CHANNEL BLOCK DIAGRAM All Routing Options Gain LINK (5dB steps) +24dB (red LED) LINE 1 Input Meter +18dB (yellow LED) S4 Input 0dB (green LED) 0dB -20dB (green LED) 2 3 -10dB Pos. 1 -30dB (green LED) +70dB S1.A Pos. 1 MIC 1 2 3 OUTPUT Control Link In/Out Input Gain+Balancing S3.A HPF (2nd order Butterworth) EQUALIZER (4 bands, GML 8200) S1.B Pos. 1 S3.B S2 S3.D DYNAMICS Pos. 1 Pos. 1 Routing Routing Control Path Input Pos.
MODEL 2020 HIGH RESOLUTION DISCRETE INPUT CHANNEL BLOCK DIAGRAM Routing Option: EQ before DYN Gain (5dB steps) LINK +24dB (red LED) Input LINE 1 +18dB (yellow LED) S4 0dB (green LED) 0dB -20dB (green LED) 2 3 -10dB Pos. 1 +70dB Input Meter -30dB (green LED) S1.A Pos. 1 MIC 1 2 3 OUTPUT Control Link In/Out Input Gain+Balancing HPF EQUALIZER DYNAMICS (2nd order Butterworth) (4 bands, GML 8200) (1 channel, GML 8900) 2 1 3 Control Path Input S1.B Pos. 1 Routing S2 S3.
P/N 202-RS-001 INPUT FILTER EQUALIZATION CUT 40Hz Phantom 0dB BOOST 3 flat 6 100Hz 9 CUT 3 0dB BOOST 3 6 CUT 3 0dB DYNAMICS BOOST 3 6 6 CUT 3 0dB BOOST 3 6 6 -20 3 6 20 +18 + 0 25 30 35 45 50 55 60 15 10 5 0 65 70 5 10 -20 GAIN -30 DYN EQ SC IN No SC before 40 (dB) 9 12 15 Hz x 100 EQ to SC No SC EQ before SC IN DYN .5 1.5 .3 3 1 3 4 6 .4 8 .15 M/I SHELF ROUTING 1 .5 9 12 15 Q 1.5 kHz 2 3 1.5 2 1 kHz 2 3 2.5 1.5 6 .8 .4 4 8 .12 .