Audio Research LS25
Price unknown (around 1998)
Commentary
A tube type line-level preamplifier developed as a new generation model following Reference1.
All eight inputs, including the processor and tape monitor, support balanced / unbalanced connections.
Two main out and REC out channels are also equipped with balanced output jacks.
The amplifier circuit uses a pure A-class balanced amplifier.
The output stage employs 3 types of infinicaps for the coupling, and the impedance is extremely reduced in a wide band, so the optimum matching condition can be obtained regardless of whether it is a tube power amplifier or a semiconductor power amplifier.
The function control uses a microprocessor, precision relay and full digital control by toggle switch operation.
An electronic switch or electronic volume is not used, and the signal system and control system are separated from the power supply and are designed without interference.
The LS25 is equipped with an independent gain setting for each input and a set value last memory function.
This function allows you to change the total gain of the amplifier in three 6 dB steps (6/12/18dB for balanced connections, 0/6/12dB for unbalanced connections). The individual gain memories are retained even when the power switch is turned off.
Digital control is also used for volume control, and it can be adjusted by 104 steps.
Equipped with an auto-mute circuit for approximately 40 seconds when power is turned on.
The balanced and unbalanced inputs can be selected at any time by operating the toggle switch.
A detachable power cable with an IEC connector is used.
Wireless remote control is included.
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Model Rating
| Type | Control amplifier |
| Frequency characteristic | 1 Hz to 100 kHz ± 5 dB |
| Total harmonic distortion factor | 0.01% or Less (2 V, Balanced Output) |
| Main out gain | Switchable for each input Balance : 6, 12, 18 dB Unbalanced : 0, 6, 12 dB |
| Rec Out Gain | 0dB |
| Input impedance | Balance : 120k Ω Unbalanced : 60k Ω |
| Input terminal | Route 8 : Tuner, Phono, CD, Video, Aux1/2, Monitor, Processor (XLR/RCA) |
| Output impedance | Balance : 650 Ω Unbalanced : 325 Ω |
| Minimum load | 20k Ω, 2,000 pf |
| Max Input | Balance : 28 vrms Unbalanced : 14 vrms |
| Rated output | 2 Vrms (200k Ω balanced load) (Maximum balanced output 40 Vrms, THD0.5% or less, 1 kHz) |
| Signal-to-noise ratio | 103 dB (IHF, volume min) |
| Vacuum tube used | 6922/E88CCx4 |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 45W maximum |
| External dimensions | Width 480x Height 134x Depth 336 mm (Including Handle) |
| Weight | 8.2 kg (Body) 12.7 kg (when packed) |
| Attachment | Wireless Remote Control |
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