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During the late 90’s and into 2000 and beyond, RTZ® manufactured upgrade reproduce and record electronics for Ampex machines. These cards were also used in the smaller AG440 machines and were a popular upgrade for two track machines.

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.

Today we offer complete transport controller systems and other electronic upgrades to keep these machines running decades into the future. RTZ upgrades have a proven record of performance and reliability in MM1200’s around the world!


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, however the original Ampex transport control card can still be used afterward if ever needed for some reason.

The DTC-1200 is designed around a Texas Instruments 32-Bit Tiva M4 ARM microcontroller especially designed for real-time motion control systems and applications. A scalable real-time operating system provides true preemptive multi-threading processing. This allows the DTC firmware to run many tasks for the servo control loop and system communications.

The Ampex reel motors require modifications to add quadrature encoders to both motors. We sell an encoder 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 loop controller. Please refer to the DTC-1200 Installation Guide for complete installation details and modifications required.


The motor drive amplifier is a critical component that contains drivers for both of the machines AC torque reel motors. MDA stability is critical to maintaining proper tensions on the tape machine. This board was designed to work with the DTC-1200 specifically, but it also works with the stock transport controller.

The RTZ motor drive amplifier adds significant design improvements over the original Ampex design to improve stability and tape tension control. Precision 1% resistors and high-quality caps are used throughout. We also added TVS surge suppressors and fuses for additional circuit protection. Torque calibration offset trimmers allow for precise reel motor torque balancing between the reel motors.

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 both reel motors. The DTC-1200 requires the new RTZ MDA card for proper operation.


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 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 software updates will greatly enhance the functionality of the STC-1200 and DRC-1200 features. The powerful 32-bit Tiva ARM processor has plenty of room for future enhancements.


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 communications bus provides robust industrial strength high speed communications over long cable runs with standard CAT5 twisted pair eight conductor cable.


The STC-1200 also supports our full featured TCP/IP network-based software remote. The STC and DRCWIN communicate via Ethernet on your local network. This allows DRCWIN to provide high speed streaming tape time and status info to the DRCWIN software application.

DRCWIN also offer additional support for auto-punch and auto-loop mode. We plan to offer the DCS-1200 digital channel switching hardware board in the future. The DCS-1200 will replace the original wired remote and allows DRCWIN to fully control all track assignment and control functions of the machine. Complete software control of the machine will soon be possible!

Download the Latest Version Here

DRCWIN v2.03 for Win10 x86 64-Bit

Currently the DRCWIN client software only runs on Windows 10 based computers. It runs as a high-performance light weight native mode C++ based application using DirectX 2D for all graphics on Windows 10. This gives the best performance possible and makes DRCWIN a very responsive application.


The DCS-1200 replaces the original Ampex wired remote and allows full software control of the machine via DRCWIN. The DCS board mounts in the transport only control box with wires and pins to the Winchester connector. This gives the DCS controller access to all the audio switching control signals formerly used by the original remote. The DCS is controlled by a single communications cable connected to COM2 on the STC-1200 timer/locator board.

The DCS holds up to three tri-state driver I/O daughter cards that each control eight channels per card. This allows the DCS to support eight, sixteen and twenty-four track machines. DRCWIN also provides enhanced standby monitor switching and allows individual track assignment of standby monitor switching. This function automatically switches any tracks, with MON assigned, to input mode anytime the machine enters stop mode. When the machine exits stop mode, the track returns to its normal assigned state (sync or repro). This feature can be enabled/disabled on a per track basis, or globally by enabling/disabling the global standby monitoring function.


The Super Switcher is an upgrade switcher card that replaces the stock switcher card. These are sold as bare kits consisting of unpopulated PCB’s and metal faceplates with silkscreened legends. The BOM provided contains a complete list of all parts that can be ordered online through Mouser or other part suppliers. A complete assembly guide is provided with instructions for building the cards. The Super Switcher is designed with modern make-before-break relays and includes additional enhancements.

The level calibration pots have been replaced with 20-turn trimmers that allow precise level calibrations that do not drift. A 1/8″ mini stereo jack was added to allow direct access to the balanced line-out signal for easy test equipment access and signal monitoring during alignment. A switchable meter buffer circuit allows buffering the VU meter signal or not. Low current LEDs indicate the channel status in three colors (amber=input, blue=sync & green=repro). A red LED indicates the record active status of the channel.

Download the Complete Kit Assembly Instructions and BOM Files

Super Switcher BOM and Assembly Package

Coto Relay Adapter


We now offer new regulator cards for your MM1200. The 4840337F card provides a 39V regulator and master bias oscillator. The 4840339E card provides a 27V regulator and a precision low noise 15V regulator. These cards are supplied fully built, pre-tested and ready to install in your machine. We highly recommend recapping all the large screw terminal and other tantalum capacitors in the power supply and testing before installing the new regulator cards.

The master bias oscillator on the 39V regulator card has a 12V linear regulator added that powers the master bias oscillator. This 12V regulator replaces the original crude zener regulator and provides clean well-regulated power to the master bias oscillator. This also reduces heat from the original zener regulator design. The bias coil transformer is a NOS part originally made by the J. W. Miller company to the original Ampex specifications.

The 27V/15V regulator card contains a new 15V regulator design using a linear regulator and series pass transistor design. This greatly improves the stability and regulation of the 15V power supply, which provides power to various critical sensitive analog sections on the DTC and capstan board. The 15V rail provides power to the tension sensor amplifier and capstan servo/filter analog sections. The original Ampex 15V regulator is a poor design and we highly recommend replacing this regulator board for use our DTC and our capstan servo board for optimum system performance.

Both regulator cards contain crowbar circuits that protect against over-current and over-voltage error conditions. The crowbar circuit will trigger and engage a silicon-controlled rectifier (SCR) that shunts (shorts) across the input of the regulator, this in turn causes the power supply fuse to blow. The load is a large low value resistor which can handle the load for the short duration until the fuse blows. The crowbar circuit will trigger in the event of an over current condition or over voltage condition and remains in shunt mode until the fuse blows or power is removed. Therefore, extreme care must be observed when installing the new regulator boards or making any adjustments to regulator voltage adjustment trimmers. Likewise, make sure the correct fuses are installed in the machine!

The crowbar circuit will trip, causing a power fuse to blow, if the voltage adjustment trimmer is adjusted above the specified voltage limit for that regulator. Therefore, it is extremely important to make sure the proper mains fuses are in your machine before proceeding with replacing the regulator cards or making any voltage adjustments. If the wrong AC mains fuse is installed in the machine and fails to blow when the crowbar trips, the large shunt resistor on the regulator board will likely go up in flames and burn a hole through the regulator board and possibly cause other damage as well. You should contact a qualified service technician for help if you are unsure about any of the procedures involved with the power supply upgrades, service or maintenance work.

4840337F Rev-A

39V Regulator and Master Bias Oscillator

4840337F Rev-A Schematic PDF

4840339E Rev-C

27V and 15V Regulator

4840339E Rev-C Schematic PDF



DTC-1200 Owner’s Manual DTC-1200 owner’s manual and user reference.
DTC-1200 Install Guide DTC-1200 Installation and upgrade guide.
DTC-1200 v2.36 Firmware Latest release firmware for use with STC v2.01 or greater.
DTC-1200 v2.35 Firmware Previous release firmware for use with STC v2.01 or greater.
DTC-1200 Rev-D Schematic Schematic for DTC-1200 revision D hardware.
DTC-1200 Rev-E Schematic Schematic for DTC-1200 revision E hardware.
Ampex Tension Kit Removal Describes removing the original Ampex tension kit.
STC-1200 Owner’s Manual STC-1200 owner’s manual and user reference.
STC-1200 v2.02 Firmware STC firmware for DRCWIN TCP/IP software remote support.Requires DRCWIN v2.xx or greater.
STC-1200 Rev-B Schematic Complete schematic for the STC-1200 Rev-B hardware.
STC-1200 Rev-C Schematic Complete schematic for the STC-1200 Rev-C hardware.
DRCWIN v2.03 for Win10 x86 64-Bit DRCWIN is a TCP/IP based software remote control for the STC-1200 board. This is the x86 64-bit build for Windows 10. DRCWIN uses high speed DirectX 2D for high performance graphics. Requires STC firmware v2.02 or greater.
MRAC Connector Pinout Document Winchester MRAC connector pinout document. This also includes the mappings to the DCS I/O board connectors.
Super Switcher BOM and Assembly Guide Switcher Card Rev-A assembly and BOM documentation.
Coto Relay Adapter Coto relay adapter PCB Gerber files and documentation.
Super Switcher Guide Super Switcher assembly aid guide diagram by Stephen Tevlin.
Capstan Servo Manual The complete capstan board owner’s manual.
Capstan Servo Schematic Schematic for the capstan servo card.
MDA Owner’s Manual The complete MDA Owner’s Manual.
MDA Schematic MDA Schematic for the Rev-B capstan servo card.
4840337F-Rev-A-Schematic 39V regulator and master bias oscillator board schematic.
4840339E Rev-C Schematic 27V/15V regulator board schematic.
MM1200 Manual Complete The MM1200 complete owners/service manual.
MM1200 Manual Schematics The MM1200 manual schematics only.
USB-To-RS232 Convertor A USB-to-RS232 convertor to connect STC/DTC command line interface using TeraTerm.
TeraTerm Terminal Emulator (Windows) TeraTerm is a free public domain TTY terminal emulator program for Windows. This is used to connect to the DTC and STC serial terminal interface.
SERIAL TTY Terminal Emulator (Mac) A TTY terminal emulator program for the Macintosh. This is used to connect to the DTC and STC serial terminal interface.
LMFLASH flash utility Firmware upgrade utility for flashing firmware to the DTC or STC via the RS-232 serial port.
UniFlash JTAG flash utility UniFlash requires a JTAG interface pod for flashing the Tiva microcontrollers firmware directly via a JTAG programmer. This is required to flash the BOOTLOADER firmware on the STC or DTC. In normal use this is not required but can be used to flash any code on the Tiva processors.


Ampex upgrade products are available via direct order prepaid only. Please contact us to confirm pricing and availability information. Generally, these items are not stocked and built to order only. Note that lead times from part suppliers can be significant and dictate final order delivery times.


Due to supply chain issues, we are unable to get the Texas Instruments Tiva ARM processors used in our Ampex controllers. Unfortunately, we have no way to buy these in quantities and supplies are limited to what TI makes available. They tell us the problem is “raw materials” and it will be late 2023 before more of the Tiva microcontroller parts become available.


STC-1200 $925.00 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 $1400.00 The DRC-1200 wired remote, display and locator interface requires the STC-1200 and DTC-1200 systems for use. These are built on order depending on lead times from part suppliers.
DTC-1200 $920.00 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 $420.00 DTC-1200 reel motor quadrature encoder kit for the supply and take-up reel torque motors. Includes encoder PCB’s, mounting bracket, cables and hardware.
MDA $420.50 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.
SWITCHER PCB & FACEPLATE $40.00 Audio switcher PCB and faceplate for building your own audio switcher cards. No parts are included, only the unpopulated PCB and faceplate. Refer to the audio switcher documentation and assembly guide for the BOM and assembly guide.
39V REG / BIAS CARD $412.00 39V regulator and bias card part number 4840337F.
27V/15V REG CARD $350.00 27V and 15V regulator card part number 4840339E.