The Dastardly Duo: Hum And Buzz - Crown CE 4000 Reference Manual

Hum and Buzz Tips
1. It is imperative that all of your electrical equipment share the same
power ground reference.
2. Unless you are interfacing to a microphone, the shield of the cable
should only be connected at one end. (See Fig.4.3)
3. Do not pass signal ground between electrical components in a
grounded source system.
4. If you wish to avoid ground loops, it doesn't matter if you lift the input or output signal
ground for your system topology, just be consistent. Personally I prefer to lift the input
signal ground and it has always been successful...so far!
5. NEVER use a ground lift adapter to lift the power ground on a 3-wire AC cord; this is not
its intended purpose. It is better to have it SAFE than SILENT!! Look for the true source
of the noise.
6. Even when interfacing to an unbalanced load, it is preferable to use two-conductor
shielded cable.
7. Get rid of the lighting company!
The Dastardly Duo: Dr. Hum and Mr. Buzz
If you have noticeable hum or buzz in your system, you may
want to check your cable connections to see if the unwanted
noise is being introduced via a ground loop. To determine the
proper wiring, first check whether the output from your source
is unbalanced or balanced (if you don't know, refer to the unit's
back panel or instruction manual). If the source is balanced,
refer to Figure 4.3; if it is unbalanced refer to Figure 4.4. Next,
determine if the source's power cable is floating (ungrounded,
2-prong) or grounded (3-prong). Finally, if the source is unbal-
anced, check the type of wiring: twin-lead or single coax.
Page 30
CE 4000 The amp with an Attitude!
Reference Manual
CE 4000 The amp with an Attitude!
Check Figure 4.4 to see if your cable has been wired with the
proper shield and ground connection. If the cabling is incor-
rect, you may be able to avoid the ground loop (and associ-
ated hum) by plugging all of your equipment into the same AC
circuit (on the same breaker). If this is impractical, you will need
to fix the cable to match the appropriate illustration. Or you
may want to simply replace the offending cable with a com-
mercially manufactured cable of the appropriate type.
Reference Manual
Fig. 4.3
Balanced
Input Wiring
Page 31