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Isolation transformer - benefits?

post #1 of 7
Thread Starter 

Came across a lot of compact isolation transformers, wondering if anyone else is using such a piece to deliver cleaner power to their equipment, possibly even with an audible difference.

These are medical grade (tighter specs)


In addition to protection it can offer, my scope shows that pretty much all noise on the line has been eliminated. Audibly, my USB DAC is marginally quieter at max volume with no input attached.


Any arguments against the use of these in audio applications?

Any other users with experience, using these?

post #2 of 7

The advantage of isolation is usually not "cleaner power", but rather eliminating ground loops, which are a frequent problem when connecting a grounded amplifier to a PC based setup (since the PC itself is also grounded). For a USB DAC, an isolator can be added between the USB port of the PC and the DAC, and such devices are available for a few tens of $.

post #3 of 7
I have used an Iso. Transformer for years now. It has lowered the noise floor of my DAC. I use it on my hard drives, computer and DAC. I keep my amps on the power receptacle.
post #4 of 7

indiscriminate application of mains power isolation to equipment designed for 3-wire safety end use can be dangerous - violates electrical, safety codes for home use


there is a section of the NEC for isolated power technical gnd for studio use


quality audio frequency line level isolation transformers are pricey at higher quality levels but not a safety hazard


http://www.jensen-transformers.com/apps_wp.html is a good resource

post #5 of 7
If each three pronged device is fused with 10 amp fuses on the secondary and the ground bus is directly connected to the ground pin to the receptacle, what is the issue? The house circuit is only protected by a 20 amp breaker so the devices are protected by local fuses, transformer fuses and then the breaker.
post #6 of 7

lifting/interrupting safety gnd is the problem - which some may do when adding a power line isolation transformer


you can have hum induced on the safety gnd wire run in the conduit from the other wiring

safety gnd runs to different outlets, possibly on different branch circuits, may show different gnd noise levels - and cause gnd loop currents between 3-wire gnded equipment plugged into the different outlets - so some may want to interrupt the safety gnd with the power line isolation transformer

post #7 of 7

I found a balanced AC supply has reduced real earth noise to any AC line to microvolts. My system has TV, tuner, computers, DACs, amplifiers all off the same balanced supply and I don't have any hum.

All mains cables are shielded, shields earthed at both ends. Interconnects are of the shelf silver types, usually with the screen connected at one end, sometimes both ends.

Should have invested in one years ago. They aren't cheap starting at around $2k for a 1kVA. Best results are if you have a standard line conditioner like a Furman, an isolation transformer, then the balanced transformer. The first two protect against dangerous conditions, the end cleans up the noise.


Everything is earthed, DAC, Amp, Tuner, TV, PC, the lot.

Edited by One and a half - 11/3/13 at 1:37am
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