M2TECH MITCHELL User Manual

Stereo analog electronic crossover

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M2TECH

MITCHELL

STEREO ANALOG ELECTRONIC CROSSOVER

USER MANUAL

REV. P

– 12/2020

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Page 1 M2TECH MITCHELL STEREO ANALOG ELECTRONIC CROSSOVER USER MANUAL REV. P – 12/2020...
Page 3 For a proper operation of this unit, all connections to other equipment in the system must be done when all equipment are off. Failing to comply with this advice may lead to damage to the MITCHELL. The label above, printed on the product case, indicates that the product, when no more usable, can’t be...
Page 4 Mitchell provides a wealth of configuration options that make it possible to tailor it to the most demanding set-up. The all-analog operation avoids the sound quality detriment and artefacts that affect digital crossover.
Page 5: Table Of Contents
7.4. State Variables Filter (SVF)..................19 7.5. Gain block .......................20 7.4. Inversion blocks.......................20 7.5. Composing blocks to obtain a desired filter configuration ........20 8. Configuring the MITCHELL....................21 8.1. Set commands ......................22 8.1.1. Set Filter (SF) ..................22 8.1.2. Set Input (SI) ..................23 8.1.3.
Page 7: Unpacking And Placing The Unit
Should one or more item be missing, please contact your retail dealer. Remove the MITCHELL from the cardboard tray enclosure and place it onto a stable base, far from heat sources. Avoid full sunlight on the unit. Allow for ample room around the unit for venting.
Page 9: Front Panel
MITCHELL enter/exit standby together with other Rockstars units in the system. This feature must be enabled by the configuration app at set-up. 2) ON/OFF button. Allows to turn the MITCHELL on and off. Also, when the Mitchell is in standby, pressing this button will activate it.
Page 11: Back Panel
Barrel 5.5/2.1mm socket, negative on sleeve. 11) Trigger inputs. A 12V trigger signal may be sent to this input to switch MITCHELL on and off by the preamplifier or other trigger source. This input has a higher priority than the...
Page 13: Connecting And Powering The Unit
If the trigger feature is to be used, connect a mono cable with 3.5mm jack to the MITCHELL trigger inputs (Fig. 2, 11). Connect the stock wall adaptor to the MITCHELL power input socket (Fig. 2, 10) and to a wall outlet.
Page 15: Cleaning The Unit
– DECEMBER 2020 5. Cleaning the Unit The MITCHELL should be cleaned with a soft, slightly damp cloth. Do not use alcohol or any other types of cleaning fluids as they could damage the unit. Avoid fluids from dropping or leaking inside the unit. Fluids of any type poured into the unit will void your warranty.
Page 17: Theory Of Operation
MITCHELL and two stereo power amplifiers. A more expensive, more refined system with 5-way speakers will need two MITCHELL set in mono mode and at least 5 stereo power amplifiers (or up to 10 monoblock power amplifiers).
Page 18 The Mitchell elegantly solves this problems by providing six filter modules (three per channel in stereo or all six for one channel in mono) each one can be set as low-pass, band-pass or high-pass independently.
Page 19: All-Pass Filter
An all-pass filter is a filter which amplitude response is flat over the whole frequency range (0dB), while its phase changes linearly with frequency. In the MITCHELL, the phase goes from 0 degrees at very low frequencies to -180 degrees at very high frequencies. The frequency at which the phase is -90 degrees can be set by configuration.
Page 20: Gain Block
As speakers systems usually use drivers and/or power amplifiers with different sensitivity, the crossover must be able to compensate sensitivity differences. The MITCHELL allows each way gain to be set in a wide range (-111dB to +30dB) in 0.5dB steps.
Page 21: Configuring The Mitchell
– DECEMBER 2020 8. Configuring the MITCHELL The MITCHELL can be configured using a computer connected to it via USB using the stock cable and a simple terminal program. The USB makes for a virtual UART connection, therefore the MITCHELL is seen by the computer as a UART serial device.
Page 22: Set Commands
L means “1-pole Low-pass” (b). Example 1: #SF,A,L,L,045,1FF Selects the cut-off frequency of the 1-pole low-pass filter in the left channel of way A. as Q is not defined for a 1-pole filter, q may be any allowed value. Copyright © 2020, M2Tech Srl...
Page 23: Set Input (Si)
The command returns ERR because the ”q” parameter is missing. 8.1.2. Set Input (SI) Input selection. The MITCHELL has two inputs: one single-ended and one balanced. Way A is directly connected to the selected input, while ways B and C can be connected to the selected input or to the output of the previous way (see examples).
Page 24: Set Level (Sl)
#SI,B,P #SI,C,M Configures the MITCHELL to use the balanced input, feeding way B from way A output and way C from the balanced input (chosen by the first command of the sequence). By default, the crossover is configured to feed all three ways from the single-ended input.
Page 25: Set Mode (Sm)
The command returns ERR because the g parameter is our of range. 8.1.4. Set Mode (SM) The MITCHELL can be set for stereo operation (3 ways) or mono operation (6 ways) by this command. The command has one parameter: m indicates the chosen mode.
Page 26: Set Path (Sp)
L means “Left channel”. R means “Right channel”. Example 1: #SP,A,B,44A0 Set both channels of way A on the MITCHELL to operate as 6dB/Oct low-pass filter, non inverting. Example 2: #SP,B,L,9501 Set left channel of way B on the MITCHELL to operate as 30dB/Oct high-pass filter, non inverting.
Page 27: Set Remote (Sr)
It is possible to toggle standby from configuration any time, provided the trigger input is not used, otherwise an error message will be produced. The command has one parameter, which can be “1” (MITCHELL is active) or “0” (MITCHELL is in standby).
Page 28: Get Commands
Activates the MITCHELL. If the crossover is already active, the command has no effect. 8.2. Get commands 8.2.1. Get Configuration (GC) Returns the complete configuration of the MITCHELL in verbose mode so that it can be easily read by the user. Syntax:...
Page 29: Get Filter (Gf)
= [L,R] b = [1,2,A,H,L] A,B,C indicates the way the command is applied to (w). L means “Left channel” (c). R means “Right channel” 1 means “State Variable Filter 1”. 2 means “State Variable Filter 2”. Copyright © 2020, M2Tech Srl...
Page 30: Get Input (Gi)
The command has one parameter: w indicates the way which input must be returned. Syntax: #GI,w where: w = [A,B,C] A,B,C indicates the way the command is applied to. Example 1: #GI,A BALANCED Copyright © 2020, M2Tech Srl...
Page 31: Get Level (Gl)
= [L,R] A,B,C indicates the way the command is applied to. L means “Left”. R means “Right” Example 1: #GL,A,L 10,00 Example 2: #GL,A The command returns ERR because the “c” parameter is missing. Copyright © 2020, M2Tech Srl...
Page 32: Get Mode (Gm)
STEREO ANALOG ELECTRONIC CROSSOVER www.m2tech.biz REVISION P – DECEMBER 2020 8.2.5. Get Mode (GM) Returns the operation mode the MITCHELL is set to. Syntax: Example 1: STEREO 8.2.6. Get Path (GP) Returns the configuration of the selected way and channel as a 4-digit hex number.
Page 33: Get Status (Gs)
The commands are only listed below for reference. 8.3.1. Update Start (US) Initiates or re-initiates the update procedure for the MITCHELL firmware. Syntax: Copyright © 2020, M2Tech Srl...
Page 34: Update Data (Ud)
8.3.2. Update Data (UD) Sends a block of 16 data bytes to the MITCHELL, in the form of 16 x 2-digit hex numbers plus a checksum. The checksum value is the lower byte of the sum of all 16 payload bytes.
Page 35: Configuration Software
MITCHELL via the SF command, M2TECH has developed a free configuration software running under Windows, called “Mitchell Configurator”. The software allows for thoroughly configuring the MITCHELL, as well as for simulating the various filter modules frequency response graphs, uploading/downloading configurations and saving configuration parameters on files.
Page 37 M2Tech MITCHELL STEREO ANALOG ELECTRONIC CROSSOVER www.m2tech.biz REVISION P – DECEMBER 2020 Figure 5: Mitchell Configurator Filter Plots The use of the configuration software, albeit quite straightforward, is scope of a specific manual. Copyright © 2020, M2Tech Srl...
Page 38: Specifications
1V out, A-weighted, depending on configurations) THD+N:..........0.015% (1Wrms on 4 Ohms) Supply voltage: ......... 15V Power consumption: ......12VA Size:..........200x50x200mm (w x h x d) Weight..........2kg (device and ancillaries) 2.5kg (packed) Copyright © 2020, M2Tech Srl...
Page 40: Appendix A: List Of Available Configurations In The Configuration Software
Band-pass, 6-12dB/Oct, inverting: ..........A560 Band-pass, 6-18dB/Oct, non-inverting:........5460 Band-pass, 6-18dB/Oct, inverting: ..........9460 Band-pass, 6-24dB/Oct, non-inverting:........5540 Band-pass, 6-24dB/Oct, inverting: ..........9540 Band-pass, 6-30dB/Oct, non-inverting:........5440 Band-pass, 6-30dB/Oct, inverting: ..........9440 Band-pass, 12-6dB/Oct, non-inverting:........64C0 Band-pass, 12-6dB/Oct, inverting: ..........A4C0 Band-pass, 12-12dB/Oct, non-inverting: ........4400 Copyright © 2020, M2Tech Srl...
Page 41 Band-pass, 6-12dB/Oct + notch, non-inverting: ......5520 Band-pass, 6-12dB/Oct + notch, inverting: ........9520 Band-pass, 6-18dB/Oct + notch, non-inverting: ......5420 Band-pass, 6-18dB/Oct + notch, inverting: ........9420 Band-pass, 12-6dB/Oct + notch, non-inverting: ......6421 Band-pass, 12-6dB/Oct + notch, inverting: ........A421 Copyright © 2020, M2Tech Srl...
Page 42: With All-Pass
High-pass, 6dB/Oct, non-inverting: ..........4780 High-pass, 6dB/Oct, inverting: .............8780 High-pass, 12dB/Oct, non-inverting: ..........46C0 High-pass, 12dB/Oct, inverting: ...........86C0 High-pass, 18dB/Oct, non-inverting: ..........57C0 High-pass, 18dB/Oct, inverting: ...........98C0 High-pass, 24dB/Oct, non-inverting: ..........4601 High-pass, 24dB/Oct, inverting: ...........8601 High-pass, 30dB/Oct, non-inverting: ..........5701 Copyright © 2020, M2Tech Srl...
Page 43 Low-pass, 12dB/Oct + notch, inverting: 8620 Low-pass, 18dB/Oct + notch, non-inverting: 6620 Low-pass, 18dB/Oct + notch, inverting: A620 High-pass, 6dB/Oct + notch, non-inverting: 57E0 High-pass, 6dB/Oct + notch, inverting: 97E0 High-pass, 6dB/Oct + double notch, non-inverting: 5723 Copyright © 2020, M2Tech Srl...
Page 44 High-pass, 12dB/Oct + shelving + notch, non-inverting: ....7721 High-pass, 12dB/Oct + shelving + notch, inverting: .....B721 High-pass, 24dB/Oct + shelving, non-inverting: ......7701 High-pass, 24dB/Oct + shelving, inverting: ........B701 Band-pass, 12-12dB/Oct + shelving, non-inverting:.....7700 Band-pass, 12-12dB/Oct + shelving, inverting:......B700 Copyright © 2020, M2Tech Srl...