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Pearl Phono/ Power On
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Power is on and this is playing music. You can see the two blue LEDs indicating each channel is operational.
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Pearl Phono Top/Rear View
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This is the rear top view. An alligator clip is visible. This connects the tonearm ground wire to various points in the circuit, I was looking for the best possible grouding connection.
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Pearl Phono Top/Front View
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This is the front top view of the unit during testing. I am fooling around with the grounding.
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Pearl Phono Grounding
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Here is the final view with the star grounding. OK, we have enough trouble in DIY figuring out where to connect all the input/output/ circ grounds and here with a phono preamp you also have a "third" ground- a ground wire coming out of the turntable tonearm. Where is that supposed to connect to? So what I did was give myself two options, which turned out to be about the same in practice. First, I put an islolated elbow on the chassis shown in the next picture. Tonearm ground connects to the elbow which then connects via a wire to either the circuit ground (red connection) or to the chassis ground (blue connection). One of the channel boards has a ground which I used as the 'star' ground that feeds all the other grounds. This also connects to the chassis via a 25 ohm/ 3 watt resistor to isolate the circuit ground from the case, and the case is connected to the AC inlet ground prong for anti-shock protection. So I can connect the tonearm ground to either the case ground (blue connection on the elbow) or circuit ground (red connection on the elbow). In practice I could not hear the difference, hum is very low either way and I cannot tell which connection is better.
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Pearl Phono Back Panel Grounding
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Back panel. The elbow is insulated from the chassis with a rubber gromet. The eblow is threaded so that an allen head screw can clamp a turntable ground wire onto the elbow. Also on the elbow is a connection to EITHER star ground or chassis ground. Not much difference in practice but I would think that the connection to star ground is better. Come to think about it, this looks kind of rough, perhaps I could install a switch to make it look more professional and easier to use. I would not have to swap the wires manually but could flip the switch to select which connection to use? Hmmm....
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