Foreword - Isolation Transformer (IT)
We have received an email from a reader asking about mains filtering. I owned a unit of the Topaz Ultra Isolation Transformer and I could not stop praising for the benefits it brought to my audio system. I can whole heartedly recommend this for those troubled with dirty mains. Go to Ken’s audio system
We are aware that our mains power supply comes with all sorts of noises, generated by the electrical devices connected to the shared mains we have, from our own house, from other people’s house, and even from our audio equipment themselves!
That’s why sometimes we can see noises on our TV screen when we have the air-conditioner, computer, or water heater operating at the same time. So, in order to get the best performance out of your electrical devices, we need to feed them with clean mains.
So, what can we do about this electrical noise pollution? There are plenty of solutions: EMI/RFI filter, voltage regulator, power regenerator, isolation transformer and etc!
Isolation transformer – device that is used to transfer electrical power from an AC source to another target device while isolating the target device from the source. It has many uses, and one of the main functions for audio is noise or interference suppression or isolation.
The ideal case would be to have your audio equipment an IT each! 1 for the CD player, 1 for the amplifier, 1 for the DAC, and so forth! Although a single IT works, but having separate works even better!
As we all know, in common, digital electronics generates a lot of noises due to the switching method. We would want to isolate that from the sensitive analogue electronics like the LP/Vinyl player and such.
Above picture illustrates it very well.
- Red – mains noise
- Blue – analog source generated noise
- Purple – digital source generated noise
The mains is polluted with the mains noise (from external source), and the noise from the audio equipment, the digital and analog source. The more electrical device (pollutants) we add to our mains, the more noise it carries.
- Digital source sees FULL LEVEL of noise from the mains and analog source!
- Analog source sees FULL LEVEL of noise from the mains and digital source!
Without any means of filtering or isolation, the mains will be a big noise cooking pot!
With single ITs added into the equation, things look much better now!
- Digital source sees ATTENUATED noise from mains but full noise pollution from analog source since they're connected to the same IT outlet.
- Analog source sees ATTENUATED noise from mains and full noise pollution from digital source since they're connected to the same IT outlet.
Mains noise pollution is minimized but digital and analog noise source still inter-pollute each other at full force due to the same outlet used.
With dual ITs added into the equation, things look ABSOLUTELY better now!
- Digital source sees ATTENUATED noise from mains and analog source.
- Analog source sees ATTENUATED noise from mains and digital source.
Noise generated from the digital and analog sources are contained and prevented to pollute the mains and each other.
Tests and measurements
You can use the PS Audio Noise Harvester, Audioprism Noise Sniffer, oscilloscope, spectrum analyzer, or even your own ears to do the measurement.
I’ve an annoying buzz riding on my power line and it is gone after I installed an IT! Apart from the noise elimination, it actually improves the sound as well. Background becomes darker and imaging gets better. Vocals stand out and have a more solid body to it.
The IT is going to stay in my audio system as a permanent resident!
At a later stage in time, I installed another IT to separate the USB to SPDIF converter with the tube amplifier & DAC. Things become even better! Sibilance and high frequency glare got lesser! The system is more analog sounding than ever.
The 2 ITs are going to stay!
What’s next? Installation of the 3rd isolation transformer – 1 for the amplifier, 1 for the DAC, and 1 for the USB to SPDIF converter!
Since the DAC and USD to SPDIF converter use less power, I can get a smaller VA isolation for the job. A 1KVA isolation transformer is just overkill for them.
Have one isolation transformer each for all your electrical devices and be prepared to be blown away!
For DIY extremist
Isolate your DC filament supply if you have them in your DIY tube amplifier! No, wait, have EACH of your DC filament supply isolated! Do not share the B+ power transformer with the DC filament power transformer. The solid state rectifier is a major source of noise pollution! If you’ve mono-block amplifier, isolate your mono-blocks separately!
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