This started bugging me. There are 5 wires in a tonearm cable, 2 per channel plus a shared L/R ground, right? But the ground doesn't always tie into anything, using the downstream ground post is optional.
So would you say the output is balanced (V+, 0, V-) or differential (V+, V-)? Or single ended (V+, 0) since the outputs into the phono stage are single ended RCAs?
So would you say the output is balanced (V+, 0, V-) or differential (V+, V-)? Or single ended (V+, 0) since the outputs into the phono stage are single ended RCAs?
The cartridge is a floating signal generator. The choice of ground reference determines the type of electronic interface. The ground reference can be one leg of the cartridge signal, in which case, the interface is single ended and there is one signal wire and one ground wire per channel.
We can also have two identical signal inputs in the electronics that share the same ground. Each input presents an impedance to ground. If the impedances are equal, the cartridge delivers half the voltage to each input, with each channel now having two signal wires, which swing in opposite directions with respect to ground. This is a balanced differential system. If the input impedances are not equal, the system is not balanced, but still differential, with unequal swings about ground.
In all cases, if the impedances of the inputs correctly match the cartridge, the total signal voltage is the same.
We can also have two identical signal inputs in the electronics that share the same ground. Each input presents an impedance to ground. If the impedances are equal, the cartridge delivers half the voltage to each input, with each channel now having two signal wires, which swing in opposite directions with respect to ground. This is a balanced differential system. If the input impedances are not equal, the system is not balanced, but still differential, with unequal swings about ground.
In all cases, if the impedances of the inputs correctly match the cartridge, the total signal voltage is the same.
The standard stereo phono cartridge is not a "balanced" source.
You have a "hot" and a "ground" for each channel = 4 wires.
The 5th wire is a chassis ground, seperate, in order to eliminate any ground loops/hum.
You have a "hot" and a "ground" for each channel = 4 wires.
The 5th wire is a chassis ground, seperate, in order to eliminate any ground loops/hum.
A magnetic stereo phono cartridge per se has no ground reference - it is simply two coils not connected to anything. The fact that cartridge pins are labelled +L,+R, GL and GR is simply due to the fact that most eqipment has single ended inputs were one of the coil outputs is grounded at the preamp - this was made a quasi standard from the very beginning of vinyl records. While most MC cartridges are build with the generator coils floating, they can be used with balanced or single ended inputs. MM cartriges most often are made ground referenced as one of the coil outputs is connected to the cartridge shield. In this case, only single ended operation is possible.
I've written about this particular subject quite a bit. Here's one example: A Super-Simple Budget Fully-Balanced Tonearm Cable https://www.lathetrolls.com/viewtopic.php?f=9&t=5876
As pointed out earlier there are two floating coils. On many MM carts there is a removable (and re-installable) clip from one of the "-" pins to the shell.
The generator, having two wires, is balanced, differential and floating. How it's terminated then determines whether its balanced or floating or not. It does not have to have a center-tap to be balanced or differential.
As pointed out earlier there are two floating coils. On many MM carts there is a removable (and re-installable) clip from one of the "-" pins to the shell.
The generator, having two wires, is balanced, differential and floating. How it's terminated then determines whether its balanced or floating or not. It does not have to have a center-tap to be balanced or differential.
Thanks!
Here's a post on modifying an SL-1200 for balanced wiring: https://proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=753&p=9245#p9245
You can see from the pic of the tone arm base that it's floating 5 wire until terminated by the RCA cables where it becomes unbalanced.
Here's a post on modifying an SL-1200 for balanced wiring: https://proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=753&p=9245#p9245
You can see from the pic of the tone arm base that it's floating 5 wire until terminated by the RCA cables where it becomes unbalanced.