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 Elliott Sound Products Project 30 

High Quality Audio Mixer

© September 1999, Rod Elliott (ESP)


This project is probably the most ambitious so far, and can be expected to be very expensive.  On the positive side, it is also capable of excellent performance, and can be tailored to suit your exact specifications.  There are several different input modules in the series, the first being the microphone and line input.

The project is presented in parts, and Part 1 shows the mic/line module and has some background information on noise measurements and the general philosophy behind the project.


Since the project is presented in stages, this is an index for the various modules, and as the system is developed will also be the place to look for updates and other information.

Index Stage 1 Stage 2 Stage 3 Stage 4

Stage 1 Microphone / Line input module - Includes optional 48V phantom feed, and shows three different input stage configurations.  You can choose from transformer input, or two different electronically balanced circuits.  Also shows the tone control circuits, peak level indicator and all channel to group/master switching, faders and pan pots. 07 Jan 2001
Stage 2 Basic Mixing Modules - These are used for mixing the stereo sends from each of the Mic/Line modules, either as sub-mixers or the main mixer (the same unit is used for each).  Also included are the Auxiliary Mix Module and balanced line driver circuits, and the first stage of the power supplies.23 Oct 1999
Stage 3 Power Stages - This section shows the power supply regulators - both +/-15V main supplies and 48V phantom supply, and the headphone power amps.26 Nov 1999
Stage 4 Bits and Pieces - This describes the pre-fade listen and other headphone mixing and switching, as well as the talkback mic amp, phono and auxiliary input modules.

The additional modules, metering and a complete system layout will be added to the list as they are developed.

NOTE:  There has been a surprising amount of interest in this project, with a common requirement being a smaller version (an almost equally common request has been for a bigger version, too).  Scaling the project up is not really a problem, but it is difficult to know what you can leave out to make a small mixer of 6 channels or less.


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Copyright Notice. This article, including but not limited to all text and diagrams, is the intellectual property of Rod Elliott, and is © 1999.  Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro- mechanical, is strictly prohibited under International Copyright laws.  The author (Rod Elliott) grants the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference while constructing the project.  Commercial use is prohibited without express written authorisation from Rod Elliott.
Project created 22 Sept 1999 - Part 1 added at the same time.  Part 2 added 23 Oct 1999.  Part 3 added 26 Nov 1999