What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Ampex ATR 100 Series

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 ATR-100 is a 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 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.

Incredible as it sounds,  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.

Distortion - Third harmonic distortion and intermodulation 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 1,0% at the same recorded flux level.

Signal-to-Noise - This specification depends, on tape speed and the particular technique of measurement used. Any way you measure it, ATR-100 Signal-to-Noise 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-100 response at 15 in/s over the commonly used range of 100 Hz to 15 kHz just ±3/4dB.
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.

Flutter - this specifications also depends on tape speed and measurement technique, but consider a worst case. At 30 in/s the 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 ATR-100 also allow it to use higher coercivity tape than any now available. When better tape is here the ATR-100 can take full advantage of it.

It even looks dofferent. Any 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 traditiona 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 ATR-100 handles any reel size from 2 inches to 14 inches in diameter.
The ATR-100 also treats your valuable tapes with a special brand of kindness. When you thred 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 ATR-100 also contributes to smooth tape handling, and also takes over in the event of a power failure to prevent tape damage. The ATR-100 always stops in a programmed manner, even without ower.
Ferrite heads, unrivaled fro performance and long life, are used in the 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 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 3-3/4, 7-1/2, 15 or 30 inches per second. You can order a 7-1/2 - 15 in/s version, for example and later set it up for any other speed pair, even 3-3/4 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 features of the 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 soon 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.
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 optiona remote control panel with a 25-foot cable contains all functions except Dump Edit and deactivable servos.
An extremely accurate integral tape timer is standard equipment on the 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 ATR-100, then you can add optional input-output modules for a full capability one, two or four-channel recorder (ATR-101, ATR-102, or ATR-104, respectively). Each I/O module include the normal balanced input and output circuitry and its own matering. You can even switch the metering between ASA balistics with VU indication, or EBU balistics with Peak indication.

Along with all its perormance benefits, the 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 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.
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. Spoot Mode alows 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 split tape, the 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 split tape in a controlled manner.

Tape Widths:  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 40track systems, 0,070 (1,8 mm) track width
Tape Speeds:  3,75 in/s (9,5 cm/s); 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]
Reel Size:  2-inch to 14-inch diameter (50 mm - 355 mm )
Reel Type:  NAB
Inputs (with Input/Output system - bridging  input standard)
Balanced, Floating
Input Impedance : 50 k Ω, Resistive ±5,0 %, 5 Hz - 20 kHz
Input level (Variable)
Minimum :  -5 dBm, to produce 1000 nWb/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)
-1 dBm to +20 dBm to produce 1000 nWb.m recorded  flux level
Outputs (with Input/Output system)
Balanced, Floating
Output Impedance :  les than 50 Ω, 5 Hz - 20 kHz
Maximum Output Level
With 600 Ω load :  +26 dBm
With 200 Ω load :  +25 dBm
Preset Output Level
Line output level is adjustable over a range of +12 dBm to -2 dBm
Meters are switchable, VU or peak
VU balistics conform to ASA standards
Peak balistics conform to EBU standards
Zero meter reading is continuously adjustable  over a range of +12 dBm to -2 dBm line level
Inputs (without Input/Output system)
Input Impedance:  10 k Ω min., 5 Hz - 20 kHz
Input Level :  -5 dBm, nominal, for system operating level
-5 dBm, input level provides 26 dB clip level margin at mid-freguency
Outputs (without Input/Output system)
Output Impedance:  40 Ω, 5 Hz - 20 kHz
Maximum load Impedance: 5 k Ω
Output level :  -5 dBm, nominal, for system operating level
-5 dBm output level provides 26 dB clip level margin
 at mid-frequency
Overal Frequency Response (within ±2 dB)
At 30 in/s :  35 Hz - 28 kHz
At 15 in/s :  20 Hz - 20 kHz
At 7,5 in/s :  30 Hz - 15 kHz
3,75 in/s :  30 Hz - 10 kHz
Signal-to-Noise Ratio (full tarack format, 30 Hz - 18 kHz unweighted)
At 30 in/s :  77 dB (AES equalization)
At 15 in/s :  73 dB (NAB equalization)
At 7,5 in/s :  75 dB (NAB equalization)
At 3,75 in/s :  66 dB (NAB equalization)
Signal-to-Noise Ratio (full tarack format, ANSI "A" weighted)
At 30 in/s :  81 dB (AES equalization)
At 15 in/s :  77 dB (NAB equalization)
At 7,5 in/s :  78 dB (NAB equalization)
At 3,75 in/s :  62 dB (NAB equalization)
Wow and Flutter (NAB, RMS unweighted):
At 30 in/s :  0,03%
At 15 in/s :  0,04%
At 7,5 in/s :  0,06%
At 3,75 in/s :  0,1%
Basic Machine (including transport, power supply, audio and servo electronics):
(W x H x D) 19" x 15,72" x 12" (48,26 x 39,93 x 30,48 cm)
Cabinet (1 or 2 channel :
(W x H x D) 21" x 19" x 32" (53,34 x 48,26 x 81,28 cm)
Cabinet (4 channel):
(W x H x D) 21" x 23" x 34" (53,34 x 58,42 x 86,36 cm)
Input/Output System :
(W x H x D) 19" x 3,5" x 10" (48,26 x 8,89 x 25,4 cm)
Complete System (including basic machine, 4-channel cabinet, Input/Output system and roll-around pedestal):
(W x H x D) 26" x 46,5" x 34" (66,04 x 118,11 x 86,36 cm)
Basic Machine :  125 lbs (56 kg)
Cabinet :  15 lbs (7 kg)
Input/Output System 2-Channel :  15 lbs (7 kg)
Pedestal :  50 lbs (23 kg)
Power Line Requirements:  90 - 115 / 110 - 135 / 180 - 230 / 220 - 270 V AC; 50/60 Hz
Power Consumption:  0,6 k VA maximum
Environmental Operating Specifications:
Temperature :  10° - 50° C (50° - 122° F)
Humidity :  20 - 95%, non-condensing

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