balanced vs. unbalanced...

[just me now]

oops -- meant to type 511 horn/802G/515B

sorry...

[just me now]

OK -- so I have been playing around recently between running my Altec A7s (511/802G/511B) and 19s with a balanced vs. unbalanced source recently...

Although it is a little harder to get everything hooked up without noise, it is possible...

neglecting any GL or hum that may be encountered while running unbalanced, what are your experiences with this change...

I'll reserve my comments for a bit later.

Thanks,
Louped

[joyspring]

neglecting any GL or hum that may be encountered while running unbalanced, what are your experiences with this change...

<font size="2" face="Verdana, Helvetica, sans-serif">In an ideal world where both unbalanced and balanced equipment are interfaced properly within specific physical limits, there is NO difference in audio quality between the two.

Balanced and unbalanced lines serve two different requirements, each with its own set of compromises:

Balanced is required when high Common Mode Rejection Ratio (CMRR) is sought, particularly in very long (physical) connections and especially when signals are low (i.e. - microphones).

However, balanced operation requires either: (i) additional circuitry (balanced line driver/receiver) or (ii) transformers. The former may add noise and may (in poor circuits) not be symmetrical, compromising CMRR. The latter (transformers) are excellent for isolation and CMRR but are typically avoided (like the plague) in modern, low-noise circuits because of LF phase anomalies, sensitivity to input/output impedance and expense.

Unbalanced operation does not require additional circuity (apart from proper buffering) for balanced line drivers, differential inputs, etc. and can be quieter. However, cable lengths must be short to avoid induced common-mode noise.

Ground loops and hum are entirely independent of balanced or unbalanced operation and may occur in each. It is simpler to mitigate ground loops in balanced operation as disconnecting the ground (`drain' or `shield') at one end may in many instances solve the problem; in unbalanced operation, the ground also carries signal so doing this will not work.

Ensuring all equipment is at the same potential is important for both balanced and unbalanced operation though it is critical for the latter.

Balanced and unbalanced operation is also completely independent of operating or reference levels though balanced line-level equipment is often `+4 dBv' (1.23 V) or `+4 dBm' (1 mW into 600 ohms) and unbalanced `consumer' equipment is often `-10 dBV' (0.3 V). This is a consideration for proper gain-staging and minimising noise.

Lastly, if one end of the interconnect is unbalanced, then the connection is unbalanced.

And to conclude, apart from noise (either common-mode or originating from additional balancing circuitry) there is absolutely NO difference in sound quality between balanced and unbalanced operation.

BobR