Professional Audio System Components
Technical Specifications
Audio: |
Power output |
4 W/15 Ω |
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5 W/8 Ω |
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2.5 W/4 Ω, continuous, sine wave |
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THD |
< 0.1% @ rated output, 30 Hz...16 kHz |
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Frequency response |
±0.5 dB, 30 Hz...16 kHz |
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Input impedance |
10 kΩ, balanced |
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Sensitivity |
–17...+16 dBu (0.11...4.9 Vrms) for rated output |
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Maximum input level |
+24 dBu (12.3 Vrms) clipping point |
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S/N |
100 dB, linear to 23 kHz at normal operating gain (input +6 dBu) |
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85 dB, at maximum gain |
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Supply: |
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±15 V DC (40 mA idling; 400 mA @ 5 W/8 Ω) |
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Output stage quiescent current |
23 mA |
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Dimensions: |
Euro-card |
100 × 160 mm, 7M units wide |
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Weight |
approx. 210 g |
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Ordering Information: |
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5 W amplifier with |
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transformerless input |
1.915.410.xx |
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input transformer |
1.915.411.xx |
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transformerless input and remote muting facility |
1.915.412.xx |
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input transformer and remote muting facility |
1.915.413.xx |
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transformerless input and remote gain control (VCA) |
1.915.414.xx |
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input transformer and remote gain control (VCA) |
1.915.415.xx |
E42 |
Date printed: 29.11.01 |
Professional Audio System Components
2.2.7 |
40 W Power Amplifier |
1.915.440/441 |
For applications where higher power level is needed, a 40 W amplifier has been realized on a Euro-card. Its width is 32 mm, which equals 7M widths approximately.
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Power is supplied from a separate 45 VDC source, as is contained in the |
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19” mounting frame 1.918.120.xx. Two amplifier cards will fit into that |
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frame, making it suitable for applications where stereophonic monitoring |
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is required. |
Special Features |
• Transformerless version with electronically balanced inputs standard |
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• Version with balanced and floating inputs available |
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• Output stage protected from overload by momentary power limiting |
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• Temperature sensing avoids thermal overload |
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• High-end frequency response limited to prevent transient intermodulation |
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distortion |
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• Low distortion performance, even at low power output |
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• Operation with output transformer possible |
Date printed: 29.11.01 |
E43 |
Professional Audio System Components
Technical Specifications
Audio: |
Power output |
40 W/4 Ω, continuous, sine-wave, |
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THD |
< 0.1 %, 30 Hz...15 kHz (up to rated output) |
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Output impedance |
0.1 Ω |
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Input impedance |
10 kΩ |
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Common mode rejection |
> 50 dB, 30 Hz...16 kHz (with input transformer) |
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Input sensitivity –12...+18 dBu (0.195...6.2 Vrms) for rated output (adjustable with jumper |
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in three 10 dB-increments, plus fine-trim range of 12 dB) |
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Frequency response |
+0.5/–1 dB, 30 Hz...15 kHz |
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S/N |
105 dB @ maximum gain |
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90 dB @ minimum gain |
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Supply: |
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45 VDC (70 mA idling, 1.5 A @ 40 W/4 Ω) |
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Dimensions: |
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Euro-card |
100 × 160 mm, 7M units wide |
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Ordering Information: |
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Euro-cards |
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40 W power amplifier with transformerless input |
1.915.440.xx |
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40 W power amplifier with input transformer |
1.915.441.xx |
19”/1U standard products |
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40 W power amplifier |
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Mono version, 19”/1U |
75.700.80311 |
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Stereo version, 19”/1U |
75.700.80322 |
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19”/1U mounting frame (without amplifier cards) |
1.918.120.xx |
E44 |
Date printed: 29.11.01 |
Professional Audio System Components
2.2.8 |
Monitor Switching Relays |
1.915.601/602 |
Two different monitor circuit switching cards are available. They are equipped with either five or eight relays for switching of a corresponding number of stereo sources to one or two stereo outputs in monitor circuits.
The relays are available with coil ratings of 6VDC or 24 VDC, depending on the user’s requirement. Click-suppressing diodes are wired across each relay coil. The relays are equipped with four double throw (change-over) contacts each.
Isolation of the monitor lines from external circuitry is achieved by 5.6 kΩ resistors in the “a” and “b” legs of each stereo line, thus a high impedance (bridging) load is presented to the outside source, even in deenergized (non-selected) status, when the respective pair of relay contacts shorts the lines after the respective isolation resistors. With a relay energized, the corresponding stereo pair is routed to a stereo bus available on four pins of the 32-contact edge connector (in case of the 5-input card 1.915.601.xx).
Date printed: 29.11.01 |
E45 |
Professional Audio System Components
Card 1.915.602.xx features a similar circuit configuration with eight relays, to switch one unbalanced and three balanced stereo inputs. Two stereo buses appear on eight pins of the edge-connector; in this way, the four inputs can be switched to either one or to both outputs, such as may be the case with separate monitor circuits in the control room and in the studio.
Dimensions: |
Euro-card |
100 × 160 mm, 4 M units wide |
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Weight |
approx. 250 g |
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Ordering Information: |
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Relay card, 5 IN/1 OUT |
1.915.601.xx |
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Relay card, 4 IN/2 OUT |
1.915.602.xx |
E46 |
Date printed: 29.11.01 |
Professional Audio System Components
2.2.9 |
Transistor-Driven Relays (7+2) |
1.915.603 |
This Euro-card is supplied with nine transistor-driven relays with singlepole, double-throw (SPDT) contacts. For two of the relays, both nor- mally-open and normally-closed contacts are routed to the edge connector; for the remaining seven it is jumper-selectable whether the normally-open or the normally-closed contact is used.
The relays are designed for operation on 6 VDC, and each relay coil is bridged with a click-suppressing diode. PNP transistors in series with the coils are blocking the current flow, because each transistor is normally biased off. By applying the output from the gate of an external control logic to the base of a transistor, it is switched into saturation, thereby energizing the respective relay. This arrangement of nine relays was designed for use in signaling systems within a studio installation; however, it may find its use for other applications as well.
MAKE OR BREAK CONTACTS |
CHANGE-OVER CONTACTS |
(7 ×) |
(2 ×) |
4k7 |
4k7 |
10k |
10k |
– 6 V |
– 6 V |
Polarity of the relay’s supply voltage must be observed when utilizing this circuit.
Date printed: 29.11.01 |
E47 |
Professional Audio System Components
Technical Specifications
Contact Ratings: |
Note: |
max. 1 A/30 VDC or 0.3 A/125 VAC |
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In this application 48 V must not be exceeded to avoid shock hazard. |
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Switching power |
60 VA (AC) |
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100 W (DC) |
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Dimensions: |
Euro-card |
100 × 160 mm, 4 M units wide |
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Ordering Information: |
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Transistor-driven relays |
1.915.603.xx |
E48 |
Date printed: 29.11.01 |
Professional Audio System Components
2.2.10 Dual Limiter |
1.915.700 |
In sound work there are numerous situations where the signal amplitude has to be limited to a pre-determined level in order to prevent overloading of succeeding equipment, such as light modulators in film work, or radio transmitters. With this limiter, excessive levels are automatically reduced to a preset level, and, since regulation is controlled by the program’s energy content, the performance of this limiter is free of any “pumping” effects. Gain reduction is achieved with a Studer Voltage Controlled Amplifier (VCA) which ensures low noise performance and negligible distortion.
Two identical, independent limiter circuits are contained on one Eurocard, plus additional, separate gain stages to drive peak program meters. The perfect tracking of the two VCAs makes this Dual Limiter suitable for stereo work as well, in which case a simple electrical connection is needed to link the units.
Note: Gain reduction meters (not supplied) can be connected to the LINK outputs as well, if required.
Date printed: 29.11.01 |
E49 |
Professional Audio System Components
Technical Specifications
Input: |
Impedance |
5.4 kΩ, balanced configuration |
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2.7 kΩ, unbalanced configuration |
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Overload point |
+20 dBu (7.75 Vrms) |
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Output: |
Impedance |
< 50 Ω, unbalanced |
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Frequency response |
+0/–0.5 dB, 30 Hz...15 kHz |
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+0/–3 dB, 2 Hz...200 kHz |
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Gain |
0 dB, limiter off |
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Output noise level |
–102 dBu, Limiter on |
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–106 dBu, Limiter off |
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Limiting ratio |
20:1 |
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Threshold |
–15 dBu...+3 dBu, adjustable |
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Limited output level |
–14 dBu...+4 dBu, depending on threshold setting |
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Attack time |
1 ms |
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Release time |
50 ms...5 s, program-dependent |
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PPM Section: Output impedance |
< 50 Ω, unbalanced |
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Maximum output level |
+20 dBu |
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Gain |
2.5 dB...27 dB, adjustable |
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Frequency response |
+0/–3 dB, 2 Hz...200 kHz |
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Supply: |
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±15 V (100 mA) |
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Dimensions: |
Euro-card |
100 × 160 mm, 7 M units wide |
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Ordering Information: |
Dual limiter |
1.915.700.xx |
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E50 |
Date printed: 29.11.01 |
Professional Audio System Components
2.2.11 Telephone Hybrid |
1.915.760/764 |
In order to record or transmit a conversation between the announcer in the studio and a person outside the studio being interviewed by telephone, the telephone line must be connected to the mixing console.
In such a case, the full conversation is transmitted, since both voice signals are carried on normal 2-wire telephone lines. However, also the voice of the announcer in the studio is then transmitted in telephone quality (300... 3400 Hz). By mixing the microphone signal of the announcer (in studio quality) to the conversation, the addition of the “good” and “poor” signals results in a distorted and untrue signal.
Principle of a telephone transmission via a mixing console
The telephone hybrid allows to greatly improve the quality of a telephone transmission by selectively suppressing the undesired “poor” announcer signal (side-tone attenuation). This side-tone attenuation is done in principle by a hybrid circuit which is a familiar feature in telephony.
Date printed: 29.11.01 |
E51 |
Professional Audio System Components
The Studer telephone hybrid permits high-quality transmission of telephone conversations with the announcer in the studio. Apart from connecting it to the telephone line, the hybrid works automatically.
Maximum side-tone attenuation of the studio voice signal in the receiver line is achieved by automatically constituting a dummy load for the telephone line. This adjustment is performed electronically, the real (resistive) and imaginary (capacitive) components of the telephone line impedance being matched as near as possible. This automatical matching process begins as soon as an announcer signal is present.
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Operation with a single Telephone Hybrid Board |
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The telephone set is used to establish a telephone connection (call). After |
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switching over to the mixing console, the holding current for the sub- |
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scriber’s relay is maintained by a resistor on the hybrid board. |
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Versions: |
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A variety of 19” Telephone Hybrid units with one or two channels is |
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available, consisting of the following versions: |
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• Standard version (ST) – 19”/1U Telephone Hybrid unit for direct connec- |
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tion to the telephone line and a relay to switch the telephone line from the |
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telephone set to the hybrid. |
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• Noise gate version (NG) – same as standard version, equipped with a |
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noise gate |
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• Current-adjustable version (CA) – same as standard version, but addition- |
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ally featuring adjustable holding current for the telephone line. |
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Ordering Information: |
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Euro-cards: |
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Telephone hybrid card |
1.915.760.xx |
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Telephone hybrid card with noise gate |
1.915.764.xx |
19” standard products: |
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Telephone hybrid 1CH-ST |
75.700.89118 |
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Telephone hybrid 2CH-ST |
75.700.89228 |
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Telephone hybrid 1CH-NG |
75.700.89114 |
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Telephone hybrid 2CH-NG |
75.700.89224 |
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Telephone hybrid 1CH-CA |
75.700.89116 |
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Telephone hybrid 2CH-CA |
75.700.89226 |
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Telephone hybrid 1CH-CA/NG |
75.700.89117 |
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Telephone hybrid 2CH-CA/NG |
75.700.89227 |
E52 |
Date printed: 29.11.01 |
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