Audio Research SP-9mkII/LS-1
SP-9mkII : ¥ 410,000 (around 1990)
LS-1 : ¥ 330,000 (around 1990)
Commentary
Control amplifier that adopts a hybrid design of vacuum tube and solid state.
LS-1 is a model which omitted the phono stage from SP-9mkII.
The power supply and signal circuits have a simple design, and most of them are solid-state, centered on FET.
Vacuum tubes are used for circuit points related to musical emotion. The SP-9mkII uses one bi-triode 6DJ8 for the phono equalizer stage and one for the flat amplifier.
The SP-9mkII has a 46 dB phono circuit gain and a 20 dB flat amplifier gain, for a total 66 dB design. Therefore, not only MM type cartridges but also high-output MC type cartridges can be connected as they are.
It is also possible to change the load resistance by adding the supplied resistance element to the circuit.
In addition to phono inputs, four high level systems and two tape input / output systems are mounted.
Equipped with a 5-position mode switch.
It also has a muting switch and balance control that turn off the signal.
The power supply section uses a high-performance constant-voltage circuit as the B power supply instead of a conventional diode and capacitor, and a large-capacity toroidal transformer is used as the power transformer.
In order to focus on sound quality, all vacuum tubes and other parts are strictly selected.
For example, shielded wires are not used for signal lines from each input, but high-purity wires are used.
Black panel and knob are sold separately, and it is also possible to change to BlackCar color.
Model Rating
| Type | Control amplifier |
| Phono | Route 1 Gain : 46 dB Withstand input : 200 mv Load Resistance : 47k Ω (Can be changed by attached resistance element) |
| Line | Route 6 Input impedance : 50k Ω Gain : 20 dB |
| Output | Main out : 1 system, 500 Ω Record out : 2 systems, 850 Ω |
| Power consumption | 50W |
| External dimensions | Width 480x Height 134x Depth 260 mm |
| Weight | 5.9kg |