Leslie Speakers
These are amplified speakers. You will need a preamp unit. Both of these Leslie speakers expect a 20W input from another small amplifier. Leslie sold a "Leslie pre-amp". These Leslies are an 8 Ohm speaker load. If you had a small amplifier (< 20W) you could disconnect the amplifier's 8 Ohm speaker and connect it to the input of the Leslie Speakers.
The Leslie 145 is a classic sound for guitars. The Leslie 820 has a lot more bass range than the 145. They have the same speaker. The extended bass range of the 820 is from the amplifier and not the speaker.
Leslie Speaker 145/147 (40W, all tube amp)
Leslie 145/147 Checking for Shorts Part 1: OverviewLeslie 145/147 Checking for Shorts Part 2: Capacitor CheckingLeslie 145/147 Amplifier Fuse LocationLeslie 147 Speaker MeasurementsLeslie 147 Plug: RF CapacitorsLeslie 145/147 Speakers and OperationLeslie 145/147 Crossover Circuit LocationLeslie 145/147 The OC3Leslie 145/147 Output TransformerLeslie 145/147 ChokeLeslie 147 Sound CheckLeslie 145/147 Diode CheckLeslie 145/147 Power Capacitor ReplacementLeslie 145/147 Checking for Shorts Part 2: Capacitor CheckingLeslie 145/147 "Motor Break"
Leslie Speaker 820 (60W, all solid state amp)
Leslie Model 820 Project IntroductionLeslie 820 FeaturesLeslie 820 Drum and Motor SpeedLeslie 820 Sound CheckLeslie 820 Control CableLeslie 820 Motor TestLeslie 820 Fuse HoldersLeslie 820 Solder and Fuse RepairLeslie 820 vs 147 Speaker MeasurementLeslie 820 with Bass Guitar