Rotel RSS-900 Speaker Selector, 2004-2006, made in Taiwan

 

Link: rotel  | Owner's Manual

Rotel's RSS-900 answers the dilemma faced by many audiophiles seeking a combination of multi-speaker convenience in addition to accurate and transparent signal transfer from an amplifier to a single pair of high resolution speakers. Five pair of speaker outputs benefit from Rotel's unique Impedance and Anti-capacitance Compensation to preserve sound quality while protecting your power amplifier from the potentially difficult conditions that can otherwise arise when driving multiple pairs of loudspeakers. The sixth output pair ("Direct"), designed for the main system speakers, has minimal effect on the critical amplifier-loudspeaker interface. The RSS-900 provides yet another example that Rotel's Balanced Design concept brings you convenience without sonic penalty.

Mackie Big Knob revision C01 Studio Command System [monitor switching and level control box letting], 2005, made in China

Link: Manual PDF | soundonsound

Specifications

Frequency Response
Line-level Inputs and Outputs:
- +0, –1 dB, 10 Hz to 50 kHz
- +0, –3 dB, 5 Hz to 100 kHz
RIAA Equalization Deviation (Phono Input): ± 0.5 dB from 20 Hz to 20 kHz

Distortion (THD & IMD)
Line-level Inputs to Line-level Outputs (unity gain): > 0.015%, 20 Hz to 20 kHz @ +4 dBu
RIAA Input, Nominal Gain: > 0.015%, 20 Hz to 20 kHz @ +4 dBu

Noise Floor
(20 kHz Bandwidth, +4 dB level setting, 150Ω source)

Unity Gain, with DAW, 2-Track A, and 2-Track B Assigned: –86 dBu maximum (all outputs)
Monitor A, B, and C Outputs, Studio Output, DAW, 2-Track A, and 2-Track B Outputs: –90 dBu typical
Phono Input (nominal 41.8 dB gain @ 1 kHz, inputs shorted): –71 dBu maximum (all outputs)
Equivalent Input Noise (E.I.N.): 0.89 μV / –119 dBu maximum

Telefunken U250/20 Switching desk | Audio Selector, 1970, made in Germany

Link: radiomuseum | radiomuseum [model U250/8]

Country: Germany
Manufacturer / Brand: Telefunken Deutschland (TFK), (Gesellschaft für drahtlose Telegraphie Telefunken mbH
Year: 1970 ??

Category: Miscellaneous (Other, Various) - see notes
schematic requested
Wave bands - without
Details
Power type and voltage Alternating Current supply (AC)
Loudspeaker - For headphones or amp.
Power out
Model: U250/20 - Telefunken Deutschland TFK,
Material Metal case
Shape Tablemodel with Push Buttons.
Dimensions (WHD) 780 x 0 x 0 mm / 30.7 x 0 x 0 inch
Notes

- Telefunken U250/20 ist ein Umschaltpult für Audio-Vorführung (Rundfunk-Fachhandel, HiFi-Studio)

- Für 5 Stereo NF Quellen, 20 Verstärker, 20 Lautsprecher.
Net weight (2.2 lb = 1 kg) 13 kg / 28 lb 10.1 oz (28.634 lb)

Mackie Big Knob Studio Command System [monitor switching & level control box letting], 2005, made in China

Link: Manual PDF | soundonsound

Specifications

Frequency Response
Line-level Inputs and Outputs:
- +0, –1 dB, 10 Hz to 50 kHz
- +0, –3 dB, 5 Hz to 100 kHz
RIAA Equalization Deviation (Phono Input): ± 0.5 dB from 20 Hz to 20 kHz

Distortion (THD & IMD)
Line-level Inputs to Line-level Outputs (unity gain): > 0.015%, 20 Hz to 20 kHz @ +4 dBu
RIAA Input, Nominal Gain: > 0.015%, 20 Hz to 20 kHz @ +4 dBu

Noise Floor
(20 kHz Bandwidth, +4 dB level setting, 150Ω source)

Unity Gain, with DAW, 2-Track A, and 2-Track B Assigned: –86 dBu maximum (all outputs)
Monitor A, B, and C Outputs, Studio Output, DAW, 2-Track A, and 2-Track B Outputs: –90 dBu typical
Phono Input (nominal 41.8 dB gain @ 1 kHz, inputs shorted): –71 dBu maximum (all outputs)
Equivalent Input Noise (E.I.N.): 0.89 μV / –119 dBu maximum

Dynamic Range
Line Inputs: 112 dB minimum
Phono Input: 93 dB minimum

W.B. electronica Mini Comparator Type 434 Speaker/Amplifier Switch, made in Amsterdam

Link: radiomuseum | radiomuseum | gracesguide

Country:  Great Britain (UK)

Manufacturer / Brand:  Whiteley Electrical Radio, Boneham & Co. Ltd. (WB, Stentorian); Mansfield

alternative name Whiteley Electrical Radio Co. Ltd.; Mansfield
Dimensions (WHD) 308 x 80 x 170 mm

а при чем тут amsterdam на лицевой панели-то

SpeaKa (B-Tech) SPC-3 (BT-13PT) Speaker Switch

The Speaka BT-13PT, 4-way loudspeaker selector switch allows you to select any one of 4 sets of speakers, or all at once.

• For 4 pairs of loudspeakers
• Clamp terminals take cables up to max 2.5mm²
• 200W switchable
• Open circuit resistance 220Ω

Inputs x 1
Input interfaces x 4
Output interfaces Pin connector
Color Silver
Net depth 110 mm
Net width 170 mm
Net height 45 mm
Power supply No power
Switch function Manual