Author Topic: Why wounldn't big "modern" stereo amp have main's Earthing ?  (Read 457 times)

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Offline lordvader88

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I'm just wondering, it has a big linear trans, bolted to the case, made + 2001 by Kenwood, and I'm sure meets all safety requirements to be sold here, yet has no mains earthing ?
« Last Edit: June 26, 2019, 01:01:17 pm by lordvader88 »
 

Offline ebastler

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Re: Why wounldn't big "modern" stereo amp have main's Earthing ?
« Reply #1 on: June 26, 2019, 01:03:55 pm »
It must be double-insulated, or "class II", then. You should find the "two concentric squares" symbol on its type label:
https://en.wikipedia.org/wiki/Appliance_classes#Class_II
 

Offline madires

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Re: Why wounldn't big "modern" stereo amp have main's Earthing ?
« Reply #2 on: June 26, 2019, 01:41:15 pm »
Some amps with 2-prong plugs have a ground terminal for optional earthing. Since ground loops are a common problem with audio setups an enforced ground via the amp's mains plug might be not the best idea.
 
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Offline mariush

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Re: Why wounldn't big "modern" stereo amp have main's Earthing ?
« Reply #3 on: June 26, 2019, 01:47:52 pm »
There are ways to make transformers with enough insulation between primary and secondary that earthing is not required.
For example, there are R core transformers where each winding is in a separate spool, on opposite sides of the core material : http://jamestransformer.com/en/transformer/R_core_transformer.html
Or you can use double insulated wire, or plastic frames with plastic wall between the two windings...


 

Offline floobydust

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Re: Why wounldn't big "modern" stereo amp have main's Earthing ?
« Reply #4 on: June 27, 2019, 02:28:36 am »
Historically consumer audio gear is not grounded, instead double-isolated because of the ground-loops that occur.
Power amp, tape player, turntable, TV, DVD player etc. would be connected together and lots of mains hum results.
You would have to use balanced audio connections instead of single-ended RCA jacks, so added cost there they avoid.

Really old audio gear from the 1950's or so, there was no earth ground in North American outlets. So they manufacturers used the "death cap" to stop RF and noise from being a problem.
 


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