Unitiqute Mains Transformer Rattle
Posted by: David Weller on 27 June 2016
Has anyone had an issue with mains hum / buzz from Unitiqute. Hum / Buzz is only apparent at zero volume levels, disconnect speakers and hum still there. Appears to be a mechanical hum vibration from the unit
I think almost everyone with Naim gear that houses a toroidal transformer has this to some degree
My Unitiqute is deadquite. I've had many Naim amps over the years.
The only amp that suffered from transformer hum/buzz was (unfortunately) the Nait 5si. (tried 3 of 'em)
It's usually related to errors in the mains waveform in your property.
So how would one deal with noisey supply ?
It's not noise on the mains power supply (although you may have that problem as well), it's usually that the mains waveform is asymmetrical - the positive half of the waveform isn't the same as the negative half (this is often incorrectly referred to a DC offset on the mains).
There are a few approaches known to work:
The first is to see if the cause is internal, by unplugging (or turning off if they can't be unplugged) all suspect appliances(fridges freezers, heaters, hairdryers, showers, washing machines) from the mains and see if it goes away.
Two is to use a balanced isolation transformer wired centre tap to earth (CTE). This works best in combination with a dedicated radial circuit.
Third is an in-line DC blocking filter. Commercially in-line DC blocking filter are available from Isotek and Isol8 (and probably from others), but these do tend to be quite expensive.
Most "Mains conditioners" (and ALL the cheap ones) won't cure this problem.
If you are very confident at electrical & electronic DIY you can build one - but don't do this unless you're completely confident at building stuff for mains voltages (and check, check, check, and just to be sure check again).
Ok will try a different supply and if that doesn't cure will make up a simple centre taped isolation transformer. Looked at isol8 and isotek a bit pricey !
With an isolation transformer, be aware that the isolation transformer itself may hum - it's best to locate it in another room, well away from the audio equipment (for instance, get an electrician to install it next to the consumer unit).
I agree about Isotek and Isol8, which is why I built my own unit (N.B. DIY mains discussion is against forum AUP).