On May 5, 2017 at 08:47, highfigh said...
Connecting the tonearm to the RCA ground isn't 'grounding' the turntable, it's making those two equipotential. Grounding is connecting the cartridge's negative wires to the electrical ground of the building.
You're doing what I sometimes do: you're letting words get in the way of finding a solution. You'
re defining grounding in an accurate but too narrow way. Ground and grounding mean different things in different situations.
This is from wikipedia. Notice the word
OR:
In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. Electrical circuits may be connected to ground (earth) for several reasons.
Okay, so ground may be exactly what you say it it, but it might be something else instead or something else also.
As preamble to a question, a statement at electronics.stackexchange.com says| Automotive electronics generally use the metal chassis as the negative ground connector for the DC circuits.
This is a perfectly reasonable way to describe a situation in car wiring. (Note that circuits using PNP transistors might use "ground" to refer to the positive terminal of the battery or power supply, which would probably be connected to the chassis enclosing the circuit.)
People correctly use the term "ground" in automotive electronics without meaning driving down the road while wired to a copper stake driven into the earth.In talking about turntables, "ground" is the reference point from which voltages are measured. This is usually the chassis of the preamp that the cartridge is connected to. Grounding is connecting together the chassis of the different components in a system.
In analog consumer audio, most such grounding is done by the shields of the RCA cables. We don't even think to mention ground or grounding until we have hum; at that point we say we have a ground loop. It's a fact that connecting a pair of RCA cables between two components creates a ground loop, but we're generally not even aware of that until there's hum. To be totally accurate in a manner similar to your grounding definition, we should say "What is commonly referred to as a ground loop is a ground loop that causes hum; many ground loops do not cause problems, so we are not even conscious that they exist." But that's not really a helpful definition.
If one were to connect up a turntable that had a ground wire by plugging the RCA cables into a preamp and connecting the ground wire to an earth ground, the amount of hum would be AMAZING! That's because what's meant is chassis ground, not earth ground. Chassis ground might be connected to earth ground for other reasons. For instance, if you have an AM antenna on an AVR, connecting the chassis to earth ground makes the antenna signal appear stronger.
I have mentioned using a small amplified speaker from Radio Shack- RS is dead,
RS is not necessarily dead.
but Parts Express should have something and a headphone amplifier is a good substitute but it should be battery-powered.
That's an excellent tool and will do EXACTLY what buzz's suggestion of a headphone will do: if hum is present at the output of the turntable all by itself, it will prove that the turntable itself is causing the hum. If there's no hum when using headphones or an amp like this, that means the problem is due to something about the interconnection of the turntable with other products. That's no proof, however, that messing with the connections of chassis or other internal parts, dare I say circuit grounds, of the turntable will solve the problem.
