Boy some experts are missing the boat here!!
The isoloation transformers purpose serves (2) main purposes.
Voltage correction/protection and isolation of common mode noise..
Balanced power does not equally best esp on some regen units. Some line level gear designs do not like balanced power on because of their filter and grounding schemes.
yes an Arc welder DOES>> induce noise back thru the line and can cause some horrid THD problems .. sames as inverter duty drives in manufacturng plants!! I know.. seen it on a scope with TVA engineer... seen it disappear when 300 HP drive motor in a plant 6 miles away was shut down.. No air born RFI there!!
I live on the main power grid half way between (2) industrial parks 5 miles apart. I could not listen to my gear if it were not for iso transformers.
I have 3 types..
5kva 240/240 balanced for some of my amps
2.5 Kva 240/120 balanced for my Crown K2
both with faraday shields EI type
1kva 240/120 medical iso unit for line level gear.
1kva 120/120 medical iso unit for digital gear
http://www.geocities.com/jonrisch/index.htm
There are ONLY 2 reason transformers make any sound difference..
removal of common mode line noise.. quiter background
or compressed dynamics.. current limiting!!
You need to measure them for the lowest resistance per KVA load.. that means bigger wire..less copper more iron..
less current limiting..
Rule of thumb..unless you spec build a transformer for certain peak current demands ( my 2.5 kva unit will do 60 amp peak)size your transformer 2x the needed current load to prevent current limiting and do not use them on amplifier circuits.
The isoloation transformers purpose serves (2) main purposes.
Voltage correction/protection and isolation of common mode noise..
Balanced power does not equally best esp on some regen units. Some line level gear designs do not like balanced power on because of their filter and grounding schemes.
yes an Arc welder DOES>> induce noise back thru the line and can cause some horrid THD problems .. sames as inverter duty drives in manufacturng plants!! I know.. seen it on a scope with TVA engineer... seen it disappear when 300 HP drive motor in a plant 6 miles away was shut down.. No air born RFI there!!
I live on the main power grid half way between (2) industrial parks 5 miles apart. I could not listen to my gear if it were not for iso transformers.
I have 3 types..
5kva 240/240 balanced for some of my amps
2.5 Kva 240/120 balanced for my Crown K2
both with faraday shields EI type
1kva 240/120 medical iso unit for line level gear.
1kva 120/120 medical iso unit for digital gear
http://www.geocities.com/jonrisch/index.htm
There are ONLY 2 reason transformers make any sound difference..
removal of common mode line noise.. quiter background
or compressed dynamics.. current limiting!!
You need to measure them for the lowest resistance per KVA load.. that means bigger wire..less copper more iron..
less current limiting..
Rule of thumb..unless you spec build a transformer for certain peak current demands ( my 2.5 kva unit will do 60 amp peak)size your transformer 2x the needed current load to prevent current limiting and do not use them on amplifier circuits.