Changing Turntable to Balanced Output

So, the Edison phonograph is not balanced? Heh heh, there is always so much to learn here.

  Differences between a balanced connection and a balanced circuit (not just an electrical adjustment, but in fact a truly balanced design) are important to remember. That can further muddy the waters by not just accepting that an input may not be true to its suggested nature.

@atmasphere 

The input used an input transformer as well. This allowed the tape machine to have microphones a good 150 feet from the machine with no degradation of the mic signal. 

Do you really believe this. My understanding is that any low signal level cable over 3 metres no matter how whoopdido is going to have high frequency roll off. And what about phase shifts and internal reflections within the cable itself.

I find it hard to believe there is no degradation.

Do you really believe this. My understanding is that any low signal level cable over 3 metres no matter how whoopdido is going to have high frequency roll off. And what about phase shifts and internal reflections within the cable itself.

I find it hard to believe there is no degradation.

@dover 

No- I don't 'believe' it- I know it. I've run similar lengths for microphone signals myself- with no rolloff. Its helpful to keep in mind that a properly set up balanced line system is also low impedance (600 Ohms is typical) and the low impedance aspect allows you to run longer connections.

@atmasphere 

I've run similar lengths for microphone signals myself- with no rolloff. Its helpful to keep in mind that a properly set up balanced line system is also low impedance (600 Ohms is typical) and the low impedance aspect allows you to run longer connections.

I get the low impedance argument, but I still can't believe there is no signal degradation with a pair of 150ft interconnects and no phase distortion across the frequency spectrum. I would agree that in a properly designed balanced system cables are less susceptible to noise intrusion and have less effect than in a single ended system.

Have you measured frequency response and phase accuracy ( across the full frequency range ) in these situations ??

Have you measured frequency response and phase accuracy ( across the full frequency range ) in these situations ??

Sure! I've been unable to measure any loss of bandwidth even with 100 foot cables. To be clear though that means only up to 100KHz. Most transformer systems that operate at line level will only be going about that high- our preamps go higher since they have a direct-coupled output and no need for a line transformer. Phase accuracy in a passive or zero feedback system is entirely dependent on bandwidth. 100KHz bandwidth means there won't be any phase shift below 10KHz.

You might want to consider than in almost any classical recording there is a good 100 feet of cable before the mic signal hits in the inputs of the recording system. Put another way, the bandwidth/phase issue was 'fixed' by balanced line operation back in the 1950s.