Balanced Power Supply - FAQs

Question 1)  What is the noise level?

Answer: The transformers used in our balanced power supplies are designed to be very quiet using a high quality military grade electrical steel impregnated with varnish.  (There is a trade-off between efficiency & mechanical noise), we do not have actual noise figures as these are dependent on several factors including: mains voltage (220V to 253V in the UK), mains purity & possible distortion caused by equipment connected to the unit.



Question 2) As part of the same spur/ ring main, can technical balanced power be combined with unbalanced mains to be used for desktop lighting - in other words one wall socket will feed the CBS2000 and the other will power lamps.

Answer: Although the units are ok for use with incandescent lamps, there may be problems with other forms of lighting.
Balanced PSU’s should not be fed from spurs supplying lighting controllers.



Question 3)  Can the unit feed one or more rack mount power conditioning units such as those by Furman. The Furman units have spike suppression systems and RFI/EMI filtering built in. Would the spike suppressor and filtering on the CBS2000 interfere in any way with the Furmans, or visa versa.

Answer: There is no benefit in placing a conditioner after the balancing unit. Doing this could actually degrade the performance. If you wish to use a power conditioner, it's best to put it before the balanced supply.



Question 4) Does the unit offer voltage regulation as part of the balancing process. Voltage level in the proposed location may rise up to 250V. Please indicate if this might be in any way a problem for the unit.

Answer: The balanced PSU’s do not regulate the output voltage – output voltage is proportional to the mains voltage



Question 5) Can a balanced power unit feed a UPS to be used for computers and related hardware (disk drives etc.) or should the UPS be powered directly off the mains.

Answer: If just for ordinary computer use, it's best not to connect a UPS to the output of a balanced supply as this could introduce unwanted noise into the system due to the switching PSU in the UPS. In the case of a computer which is part of the audio/video system, it's probably best to use a completely seperate balancing transformer to isolate the UPS from the rest of the equipment.



Question 6) Can a multiple socket extension lead be used from one of the outputs of a balanced power supply?

Answer: Any additional connections can introduce unwanted small impedances into the power source. Having said that, with a good quality power distribution board (and plugs), the effect should be negligible.



Question 7) Are the power supplies compatible with equipment that are fitted with single pole power switch.

Answer: Equipment to be used with a balanced power supply should employ double-pole switches to ensure that the equipment is fully isolated when the power is in the off position. Most good quality audio and video equipment uses double-pole switches.



Question 8)   How quiet is a balanced power supply.

Answer:   We consider that these Power Supplies are very quiet.
However a few customers have reported that when switched on a small audible click is heard followed by a low hum which subsides after a few seconds becoming almost silent.

In a few cases customers report that some transformer noise is still audible. This is most likely to be caused either by a higher than normal input voltage or some distortion of the mains sine wave leading to a slight DC offset.



Question 9)  What is the difference between your ‘Standard Balanced Power Supply’ and the ‘Conditioning  Balanced Power Supply’?

Answer:  Our Standard  Balanced Power Supply takes the incoming mains supply and, using a toroidal power transformer with a centre-tapped output, balances the mains voltage about the ground voltage (0V).

The Conditioning Balanced Power Supply has the addition of a three-stage EMI suppression filter between the line input and the transformer designed to suppress either common and differential mode noise or interference. Both types of supply have an inter-winding electrostatic screen which helps to stop high frequency interference from reaching the output and thus getting into the attached equipment. The mains filter reduces high frequency noise from the mains supply:

Balanced Power Supply Typical Attenuation



Question 10) I'm getting a physical buzz from my balanced power supply at certain times of the day. Can I do anything to stop it?

Answer: There are two main causes of the physical buzz or growl that can emanate from a toroidal transformer. The noise is caused by the transformer approaching saturation of the core either as a result of distortion of the mains waveform, causing a DC offset, or the application of a higer voltage than that for which the transformer has been designed, or a combination of both. In either case, if your Airlink balancing transformer is one of the models with optional higher voltage primary taps, you could try moving to a higher tap. This has the effect of reducing the flux density in the transformer slightly which may be sufficient to combat the effects of the distortion or overvoltage. Doing this will, however, slightly reduce the output voltage of the unit. This shouldn't adversely affect the performance of the attached equipment.