Vintage Analog Lives

The Ampex MM1200 Studio Recorder

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This page is dedicated to vintage Ampex MM1200 multi-track analog recorders and keeping these wonderful sounding machines alive! During the 70's and 80's, countless hits were recorded on these machines in many major studios. Many of your favorite songs from this period were likely recorded on these machines along with countless other classic hits.

During the late 90's and into 2000 and beyond, RTZ® manufactured upgrade reproduce and record electronics for these machines. The cards were also used in the smaller AG440 machines and were a popular upgrade for two track machines. The RTZ upgrade electronics significantly improved the audio quality of these machines and raised the bar on some of the best sounding analog tape recorders ever produced.

We produced and sold these cards in limited quantities during this period and these cards are still sought after for their outstanding audio peformance even today. Unfortunately, these cards are fairly rare and it's unlikely you'll run across many of these in the field. None the less, our upgrade electronics achieved significant praise in the short period these were produced.

We still maintain and use a 24-track MM1200 in our private personal studio. Our machine has received numerous upgrades and modifications over the years, and we still continue to upgrade this machine and design new electronics as a labor of love.


Digital Transport Controller

DTC-1200 Card

The DTC-1200 digital transport controller completely replaces the original Ampex transport controller and provides full servo loop control of the transport reel motors as well as real-time constant tension control. A few wiring modifications are required in the MM1200 control card bay to use this new controller, but the original Ampex transport control card can still be used afterward if ever needed for some reason.

Reel Motor Encoder

The DTC-1200 is designed around a Texas Instruments 32-Bit Tiva ARM M4 microcontroller especially designed for motion control systems and applications. TI-RTOS was selected as the real-time operating system. The real-time kernel is scalable and provides true preemptive multi-threading processing.

The Ampex reel motors require modifications to add quadrature encoders to both motors. We provide a kit with bolt on magnetic quadrature encoders that are easily installed with common hand tools. These new magnetic quadrature encoders provide high resolution tachometer and direction information to the DTC-1200 servo controller. See the DTC-1200 Installing Guide below for complete installation and required modifications.

DTC-1200 Owners Manual DTC-1200 owners manual and user reference. This describes using and configuring the DTC parameters in detail.
DTC-1200 Install Guide DTC-1200 Installation Guide. The machine requires modifications to use the DTC-1200. Please read this manual first for complete details.
DTC1200 v2.34 Firmware DTC-1200 firmware v2.34 This beta release includes new default values for 1" configuration profile. Also added new parameters for tension sensor ADC offset. See the README.TXT file for additional information.
DTC-1200 Schematic The complete schematic for the DTC-1200 revision D hardware. Please refer to the owners manual and installation guide for additional information.
Ampex Tension Kit Removal This document by Stephen Tevlin describes the process of removing the original Ampex tension kit from the MM1200. You will still need to perform the additional wiring modifications required for DTC usage as described in the DTC-1200 Installation Guide above.


Search/Timer/Comm Controller

STC-1200 Card

The STC-1200 replaces the original Ampex search-to-cue/timer-counter card and greatly expands the functionality of the machine completely via software. This card uses an even more powerful Tiva TM4C1294NCPD ARM M4 processor that supports a number of communication interfaces as well as providing tape counter and multi-point auto-locator services.

The STC-1200 provides complete communications interfaces for RS-232, RS-422, Ethernet and basic MIDI MMC.The Ethernet interface currently provides a web server interface for system monitoring and configuration. The SD card interface provides file storage capabilities. Future enhancements will allow system event logging and machine hours usage. A battery backed time-of-day clock is also provided.

The MIDI interface provide basic Midi Machine Control (MMC) functions for transport control. Future support for an optional time code daughter card is also planned. Future sofware updates will greatly enhance the functionality of the STC-1200 and DRC-1200 features. The powerful 32-bit Tiva ARM processors have plenty of room for future enhancements.

DTC-1200 Remote

DRC-1200 Remote

The optional DRC-1200 wired remote is designed to provide remote transport control and full featured multi-point auto locater services. The STC-1200 serves as the host for the DRC-1200 remote and the two systems communicate via a high-speed 1Mbs RS-422 serial link.

The DRC-1200 remote is basically a display terminal device with buttons and a jog wheel that communicates to the STC-1200 host. The balanced RS-422 communctions bus provides robust industrial strength high speed communications over long cable runs with standard CAT5 twisted pair eight conductor cable.

STC-1200 Owners Manual STC-1200 owners manual and user reference. This describes using and configuring the STC.
STC1200 v1.03 Firmware STC-1200 firmware v1.03 This is the initial firmware release. See the README.TXT file for additional information.
STC-1200 Schematic The complete schematic for the STC-1200 revision B hardware. Please refer to the owners manual and installation guide for additional information.


Motor Drive Amplifier

MDA Card

The motor drive ampliifier is a critical component that contains drivers for both of the machines AC torque reel motors. MDA stability is critical to maintaining proper tesions on the tape machine. The RTZ motor drive amplifier adds significant design improvements over the original Ampex design to improve stability and tape tension control.

A precision 24V regulator was added to stabilize power to the op-amps and provides the critical reference voltage used by the motor servo torque driver loop. The original Ampex card suffers from tension drift with any drift of the 27V power rail. The slightest bit of reference voltage drift creates significant tension drift with the old Ampex design. The new design solves this by adding a precision linear voltage regulator. Fuses were added after the TVS surge suppressor to limit in the event of excessive overcurrent or spikes. Offset adjustment trimmers allow precise balancing of torque between the two reel motors. The DTC-1200 requires the new RTZ MDA card for proper operation.

MDA Owners Manual The complete MDA Owners Manual.
MDA Schematic MDA Schematic for the Rev-B capstan servo card.


Pricing and Availability

Ampex upgrade products are not sold through dealers and are only available direct from RTZ. Please contact us directly to confirm pricing and availability information. Generally these items are not stocked and most of our Ampex upgrade products are built to order.


STC-1200 $825.00 STC-1200 search, timer and communications controller PCB card (Rev-B). Requires the DTC-1200 controller system. The DRC-1200 wired remote is optional and must be purchased separately.
DRC-1200 (CALL) The DRC-1200 wired remote, display and locator interface requires the STC-1200 and DTC-1200 systems for use. This is a special order item, please contact us via email for additional information.
DTC-1200 $820.00 DTC-1200 Digital transport controller PCB card (Rev-D). The DTC requires the DTC-QEI-KIT encoder kit and the RTZ MDA motor drive amplifier board.
DTC-QEI-KIT $320.00 DTC-1200 reel motor quadrature encoder kit for the supply and takeup reel torque motors. Includes encoder PCB's, mounting bracket, cables and hardware.
MDA $320.50 Motor drive amplifier PCB 4840393 board with adjustable torque offset trimmers for precise torque calibration. This MDA board is required for proper operation with the DTC-1200 servo loop controller.