The cheapish conditioners are just that, cheapish. Surge protection on these is generally a MOV (Metal Oxide Varistor) that will divert excess voltage to ground, but this is generally over 260V, more for when a neutral goes across another phase or a transformer fails. It won't protect against 240V +10%.
A double conversion UPS ,as Bob mentions earlier , is a cost effective way of cleaning up power( I use a redundant 80KVA double conversion UPS for all studio and technical power at our Radio Station), after you've had the sparky do the power points and sub board and even perhaps have the main board in the building checked out. Breakers and contacters all deteriorate over the years and increased contact resistance means voltage fluctuations depending on current drawn , like if you're in an older house and the Aircon / heating kicks in and the lights dim--- Voltage Sag. If you are a tenant in the building , you should be within your rights to have the building owner correct any wiring faults/ dodgy old power points etc, from at OH&S perspective. Another thing that occurs in NSW and probably in SA as well is the energy authority changes voltage taps on substation transformers for winter to cope with increased load from electric heating. This is probably due to change back soon. Also if the building has excess load on one particular phase this may be affecting voltage on the other phases and shifting the power factor (Current lagging voltage due to inductive load and may require power factor correction--common with lots of Fluro lights in offices)
an explanation of power factor is available here
http://www.allaboutcircuits.com/vol_2/chpt_11/3.html For more heavy duty power conditioning, e.g. a full studio or in my case a Transmitter site we use automatic 3 phase Auto-transformers ( Big things suspended in oil) Our transmitter in right next to the main distribution substation for the Homebush Olympic Precinct and subject to to some big fluctuations .
Newer versions of these are available from ABB
http://www.abb.com/product/seitp322/e039976253ee76f8c12576f600410658.aspx but they're not cheap, so ...
1) Get the sparky to check and/ or replace the crusty old powerpoints
2) Get the sparky to check the subboard and replace older breakers, check the neutral link and earthing
3) Get the sparky to check the phase load balance in the building
4) Look at your power bill, energy authorities often rate the power factor on the bill e.g. a power factor of 0.78 is poor and you will be paying more for your power. Simple power saving tip , have power factor correction applied.(If possible)
5)Look at obtaining a double conversion UPS for critical gear to run on. This can be installed on a seperate circuit in your studio , with bypass available.Use a different coloured powerpoint to identify clean / tech power e.g. Red.
6) Get Rob round to check it out (Maybe that should be point 1)
Well there's some more ideas. Good clean power and good earthing is critical to any audio facility and the investment will pay big dividends from the reduction in equipment failure,less noise problems and safety
