Vintage Digital & Analogue Studio Effects

Audio Recorders

Ampex ATR-100 Series Professional Audio Recorder

In the world of two track analogue mastering audio recorders, the Ampex ATR-100 Series recorders are regarded as the finest reel to reel audio mastering recorders ever made. The fact that they are still in use today, more than forty years later is surely testament to that.

Introduction to the Ampex ATR-100 Series Professional Audio Recorder

In the three decades since Ampex introduced the first commercially feasible audio tape recorder in the U.S., many newer and improved recorders have come along. None of them, however, represented as great a step forward as this newest Ampex triumph, the ATR-100 Series. The Ampex ATR-100 is a different kind of professional audio recorder, and here “different” means vastly better performance by any measurement. Look at the specifications. Some of them are as much as an order of magnitude better than any other recorder now available.

Look at the all-new transport featuring a superb, fully servoed tape handling system and unique capstan drive with no pinch roller. Look at the new matrix-type control panel, designed to be used as efficiently as a hand-held calculator. Look at the editing capabilities, unrivaled by any audio recorder.  Look at its adaptability to any world recording standards and techniques. Look at its maintainability, requiring only a handful of tools. Close inspection of the Ampex ATR-100 and a demonstration of its capabilities prove beyond doubt that this is a truly different kind – a better kind – of audio recorder.


Incredible as it sounds, the Ampex ATR-100 performance specifications are as much as an order of magnitude better than any presently achievable on any other audio recorder. A bold claim. especially in view of the conservative approach that Ampex traditionally takes toward quoted specifications.

Third harmonic distortion and inter-modulation distortion are both at least an order of magnitude better. Third harmonic distortion is less than 0.3% at a recorded flux level of 370 nWb/m (0VU). Intermodulation distortion is less than 0.1% at the same recorded flux level.

This specification depends, of course, on tape speed and the particular technique of measurement used. Any way you measure it, Ampex ATR-100 S/N is significantly better than any other audio recorder. For example, it is in excess of 80 dB at 30 in/s, ANSI ‘A” weighted.

Frequency Response
Ferrite heads and fluxgate head design deliver unbelievable response. Again, specs depend on tape speed and the range of frequencies measured, but look at ATR-IOO response at 15 in/s over the commonly used range of 100 Hz to 15 kHz just dB! You can actually see the superiority of the ATR-100’s semi-automatic phase equalization by observing on a scope how remarkably well it makes square waves. This outstanding phase response is achieved by a unique record circuit.

This specification also depends on tape speed and measurement technique, but consider a worst case. At 30 in/s the Ampex ATR-100 achieves full flutter spec in 0.5 second.

Speed/Timing Accuracy
The triple-servo transport and unique capstan combine to deliver superb speed accuracy. Speed variation from the beginning to the end of a full 2400-foot reel is just .02% maximum. These specifications are only a few examples of the unprecedented performance of the Ampex ATR-100. The capabilities of the Ampex ATR-100 also allow it to use higher coercivity tape than any now available. When better tape is here, the Ampex ATR-100 can take full advantage of it.

It even looks different. Any Ampex ATR-100 Series recorder is built around the basic machine, consisting of the transport with audio and transport electronics. There is an unbalanced input-output circuit with no meters and no operator adjustments, and in some places and some applications, that’s enough. Yet all the advantages are here.

There is nothing traditional about the transport except Ampex quality. A super-rigid aluminum transport casting supports the fully servoed tape handling system. Both reel motors are servoed, as is the capstan, which has no pinch roller. You’re assured of precise speed accuracy with constant tape tension at all times. With no tension adjustment, the Ampex ATR-100 handles any reel size from 2 inches to 14 inches in diameter.

The Ampex ATR-100 also treats your valuable tapes with a special brand of kindness. When you thread up a tape and engage the servos, constant tension takes over to insure that you never stretch a tape. You have positive, gentle control of tape motion in either direction at any speed, with complete confidence.

Dynamic braking on the Ampex ATR-100 also contributes to smooth tape handling, and also takes over in the event of a power failure to prevent tape damage. The Ampex ATR-100 always stops in a programmed manner, even without power.

Ferrite heads, unrivaled for performance and long life, are used in the Ampex ATR-100. Ceramic tape guides help provide precise tracking accuracy with gentle tape guidance. For additional protection, there is also a unique head gate that can be raised and lowered.

Four standard record/playback speeds are available on all Ampex ATR-100 Series recorders, any two of which can be selected – or changed – by the user. The speeds do not even have to be adjacent. Choose any pair from 3%, 71/2, 15 or 30 inches per second. You can order a 71/2/15 in/s version, for example and later set it up for any other speed pair, even 3% and 30 in/s if you wish.

A speed selector knob for all four speeds is located on top of the head assembly cover. If a speed is selected other than the pair for which the machine is set up, the machine won’t start, and a lamp near the selector knob illuminates as a reminder.

Control Panel No other feature of the Ampex ATR-100 is more visually and functionally up-to-the-minute than the new matrix -type control panel with LED indicators. With channel selectors and mode controls so conveniently arranged, any operator will find himself working more smoothly and efficiently than ever. What’s more, the control panel can be mounted on either the right or the left side of the transport. (Left-handed tape machine operators of the world, your day has come!)

All transport controls have international symbols. There is no restriction on sequencing; you can go from any transport mode to any other without going through Stop, and without waiting for the machine to slow down or speed up.

An optional remote control panel with a 25-fcx)t cable contains all functions except Dump Edit and deactivate servos. An extremely accurate integral tape timer is standard equipment on the Ampex ATR-100. Its bright display reads in hours, minutes, and seconds, or you can set it up to display minutes, seconds, and tenths if you wish.

If your application requires more than just the basic Ampex ATR-100, then you can add optional input-output modules for a full capability one, two or four-channel recorder. (Ampex ATR-100, ATR-102, or ATR-104, respectively.)

Each 1/0 module includes the normal balanced input and output circuitry and its own metering. You can even switch the metering between ASA ballistics with VU indication, or EBU ballistics with Peak indication.

Transport and 1/0 modules are mounted in the attractive new optional cabinet, which can be placed on a bench or on the companion roll-around pedestal. Mounted on the pedestal, the recorder can be adjusted to any angle to suit the operator’s preference.

Along with all its performance benefits, the Ampex ATR-100 offers a number of features that make editing faster and easier. First of all, the Ampex PURC (Pick Up Record Capability) is standard on all Ampex ATR-100 Series recorders. PURC gives you perfectly timed edits by eliminating the overlap at the beginning and the hole at the end of an edit.

Ampex ATR-100 machines can wind tape at speeds that you have to see to believe. You can wind a full 2400 foot reel to another reel in just 60 seconds. Spool Mode allows you to spool tape off for storage at 60 or 180 in/s in either direction.

Once you reach an edit point, using the integral tape timer as an aid, you can position the tape precisely by turning the knob on top of the capstan, using just one hand. You don’t have to rock the reels by hand.

To spill tape, the Ampex ATR-100 can be placed in Dump Edit mode. In this mode, the takeup tension arm is employed as a pinch roller, allowing the operator to spill tape in a controlled manner.

A Cosmopolitan Audio Tape Recorder
The basic Ampex ATR-100 is truly a recorder for anywhere in the world. Without modification or special accessories, it is adaptable to any locale. A universal power supply allows it to operate from any line power source from 90 to 270 VAC, 50 or 60 Hz. Jumper settings for voltage, equalization, tape speeds, and operating levels permit the machine to be set up for any conditions preferred by users in every part of the world.

Thanks to the design concept employed in the Ampex ATR-100, it is one of the most easily maintainable audio recorders ever offered. All audio and transport electronics are easily accessible on plug-in cards employing back plane type circuitry. I/O modules are easily removable.

A minimum number of tools is all that is required for disassembly of the Ampex ATR-100. A couple of Allen wrenches are sufficient for most of the work you may ever want to do, including removal of the head assembly. The entire head assembly is precision machined to insure consistent tracking accuracy regardless of how many times head assemblies are changed. There’s a limited azimuth adjustment, but you’ll seldom if ever need it.

For added convenience, an Ampex ATR-100 mounted in the optional cabinet and pedestal can be turned completely upside down for servicing. You don’t have to remove the transport from the cabinet, or take it off the pedestal.

A ‘Transparent’ Recorder
Ideally, a mixdown machine should be as ‘transparent’ as possible to avoid degradation of the recorded signal. Considering its outstanding performance capabilities, the Ampex ATR-100 is as close to the ideal all-around recorder as you could find for any application; recording, mixdown, broadcast, post production or whatever. Once you’ve seen an Ampex ATR-100 in action, you’ll never be satisfied with anything else.

Basic Ampex ATR-100
Transport Audio & transport electronics (Basic machine can be configured as fixed rack mount or slide-type rack mount.)

Options & Accessories

  • Input/Output Modules (I, 2, or 4, as required)
  • Cabinet (One cabinet fits all configurations)
  • Pedestal (Attaches to cabinet)
  • Portable Case
  • Remote Control (With 25-foot cable)
  • VS-IO Variable Speed Oscillator (Allows variable capstan speed control to 250% of nominal)



    • 1/4 inch (6.3 mm) for full track and 2 track 2 channel systems, 0.075 inch (1.9 mm) track width
    • 1/2 inch (12.6 mm) for 4-track systems, 0.070 (I .8 mm) track width
    • 3.75 in’s (9.5 cmls). 7.5 in’s (19.05 cm/s),
    • 15 in’s (38.1 cm/s), 30 in/s (76.2 cm/s)
    • (any two speeds may be selected)
    • 2-inch to 14-inch diameter (50 mm to 355 mm)
  • REEL TYPE NAB, ElA (cine’)
  • INPUTS (with Input/Output system—bridging input standard)
    • Balanced, Floating
    • Input Impedance—50kΩ, Resistive 25.0%. 5Hz—20kHz
    • Input Level (variable):
      • Minimum: -5 dBm, to produce 1000nWb/m recorded flux level
      • Maximum: +40 dBm
    • Input clip level, including record amplifier at mid-freq. 26 dB above system operating level
    • Input level (preset)
      • -1dBm to +20dBm to produce 1000nWb/m recorded flux level.
  • OUTPUTS (with Input/Output system)
    • Balanced, Floating
    • Output impedance: <50Ω 5Hz—20kHz
    • Maximum output level:
      • with 6000 load—+28dBm
      • with 2000 load—+25dBm
    • Preset output level:
    • Line output level is adjustable over a range of + 12dBm to —2dBm
    • Metering:
      • Meters are switchable, VU or peak
      • VIJ ballistics conform to ASA standards
      • Peak ballistics conform to EBU standards
      • Zero meter reading is continuously adjustable over a range of
      • + 12dBm to —2dBm line level
  • INPUTS (without Input/Output system)
    • Unbalanced
    • Input min., 5Hz—20kHz
    • Input level
      • -5dBm, nominal, for system operating level
      • -5dBm input level provides 26 dB clip level margin at mid-freq.
  • OUTPUTS (without Input/Output system)
    • Unbalanced
    • Output impedance 40Ω 5Hz – 20kHz
    • Minimum load impedance -5kΩ
    • Output level
      • -5dBm. nominal. for system operating level
      • -5dBm output level provides 26dB clip level margin at mid-freq.
  • Frequency Response: 30ips; 35Hz – 28kHz

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