Hello,
Today I did install this transformer between the power line and my digital gear ( aurender streamer and dddac dac).
This transformer gives isolation and because of the small airgap also stops dc current.
My supplier ( jac music Germany) did add another "" feature" namely balanced ac output. To do this there is a connection between the centre tap on the secondary side and the primary winding. In order to make it work the power plug on the primary side must be connected in the right way in the power outlet. To be sure a green and red neon light are used to make sure it is connected Properly!
I was expecting some improvement in Upper frequency region but it did get better "" full range "". Glare has gone, more spacious, even my favourite audio book sound more life like.
Power rating 300 va but lundahl says with good cooling it can be higher.
In the future I will add one or two more. I think the biggest improvement can be made by isolating the digital part from the other gear.
A second one for the previous amp.
A third one for the tube power amps.
300 va could be to small for solid state power amp.
Just give it a try.
Greetings eduard
Today I did install this transformer between the power line and my digital gear ( aurender streamer and dddac dac).
This transformer gives isolation and because of the small airgap also stops dc current.
My supplier ( jac music Germany) did add another "" feature" namely balanced ac output. To do this there is a connection between the centre tap on the secondary side and the primary winding. In order to make it work the power plug on the primary side must be connected in the right way in the power outlet. To be sure a green and red neon light are used to make sure it is connected Properly!
I was expecting some improvement in Upper frequency region but it did get better "" full range "". Glare has gone, more spacious, even my favourite audio book sound more life like.
Power rating 300 va but lundahl says with good cooling it can be higher.
In the future I will add one or two more. I think the biggest improvement can be made by isolating the digital part from the other gear.
A second one for the previous amp.
A third one for the tube power amps.
300 va could be to small for solid state power amp.
Just give it a try.
Greetings eduard
Attachments
Try this to reduce mains noise.... no thanks.
The test/tracer device used to trace twisted pairs in the likes of 24 or 96 pair cables. You clip on an audible frequency generator and you hear the warble long distance away from the generator... and hear telephone conversations for that matter without making any electrical connection with the probe.
These devices produce a loud supply frequency hum from the likes of wall lamp switches, power points, extension leads [and the mains connection leads shown here] and even shielded cable used for speaker wire [even with shield/drain connected to Earth/Ground]
So, use that and I bet the AC hum is still there both sides of this isolation transformer... and so the noise generation potential is still there.
Anyhow, ever seen how dirty the mains supply is? Isolation transformers won't help, line filter condition might.
You don't want to be down the road on the same low voltage supply as an industrial user with large 3phase variable speed AC or DC motor drives or next door to someone with cruddy old appliances!
- My money is better spent on real overvoltage surge protection [not the useless VDR fire in a power board behind your audio gear rack type thing] installed in the fuse box, mains line filters to deal with noisy neighbors... or a second dedicated for audio equipment only Earth stake and it's seriously large low impedance connection cable. I've installed this minimum standard industrial rated device in my small home unit here as priority need #1 - 1352250000VPU I 1+1 280V/12,5KA | Weidmller Product Catalogue
- Using the Earth for mains connection ID lamps is very dodgy practice. It's the same as using Earth as a Neutral conductor for 240V control circuits when the supply cable is only 3 phase + E. God help anyone if the Earth connection in plugs or at earth stake is accidentally disconnected. Fair chance that would trip an Earth leakage CB [RCD] in the meter box or at least add to any existing trickle current that would initiate a trip.
- The use of that Earth for indication has current flow into that conductor making it even 'dirtier'. if the Earth circuit has a relatively high impedance to true Earth potential at a properly installed stake.
- Connecting secondary common centre tap to Supply Neutral defeats 'isolation'. In my experience I have seen a potential difference of 15V AC between N and E due to crappy installation wiring systems and long cable runs from distribution boards.
- The construction method in AC leads is NOT twisted pair... the 2 wires in A+N+E have a helical twist purely for manufacturing reasons and not field noise attenuation.
- How does this prevent magnet field effect around the conductors in the cables?
The test/tracer device used to trace twisted pairs in the likes of 24 or 96 pair cables. You clip on an audible frequency generator and you hear the warble long distance away from the generator... and hear telephone conversations for that matter without making any electrical connection with the probe.
These devices produce a loud supply frequency hum from the likes of wall lamp switches, power points, extension leads [and the mains connection leads shown here] and even shielded cable used for speaker wire [even with shield/drain connected to Earth/Ground]
So, use that and I bet the AC hum is still there both sides of this isolation transformer... and so the noise generation potential is still there.
Anyhow, ever seen how dirty the mains supply is? Isolation transformers won't help, line filter condition might.
You don't want to be down the road on the same low voltage supply as an industrial user with large 3phase variable speed AC or DC motor drives or next door to someone with cruddy old appliances!
That case is enclosed isn't it? Like, you have a cover removed for photo and live terminals on the transformer are not IP-00 rated.
Must say, box cramped and fails safe clearance distance between solder terminations of transformer and any case [that appears to be missing] and probably the side with lamps mounted. Some form of insulation sheet is needed as a minimum build standard.... bigger box would be better.
LOL.... is the case Earthed? Maybe, seems to be a lot of Earth conductors terminated in those loathsome spring terminal blocks.
I sure hope you have Earth leakage RCD type mains breakers installed in that home to protect the life of all who may come into contact with that.
It don't look all that safe to me, as a licensed electrician, looking at those images.
> not isolated from the mains
Diagram shows CT to source "Neutral".
While there are lights, I sure do not like it for safety.
It also seems to inject all the crap on your Neutral lines INto your audio supply ground. (Neutral is current-carrying so has the same crap as the Hot.)
In my place it would also add 1V-4V of pure AC, due to a too-long feeder from the street and unbalanced household loads.
If lights are ignored (or there are multiple wiring errors), you have Hot on your audio "ground", VERY DANGEROUS.
Under US regulations, that secondary "could" be treated as a Separately Derived Supply. In that case it MUST be Earthed(Ground) for most ordinary uses; I can't think of ANY condition where it would be connected to white (Neutral).
Diagram shows CT to source "Neutral".
While there are lights, I sure do not like it for safety.
It also seems to inject all the crap on your Neutral lines INto your audio supply ground. (Neutral is current-carrying so has the same crap as the Hot.)
In my place it would also add 1V-4V of pure AC, due to a too-long feeder from the street and unbalanced household loads.
If lights are ignored (or there are multiple wiring errors), you have Hot on your audio "ground", VERY DANGEROUS.
Under US regulations, that secondary "could" be treated as a Separately Derived Supply. In that case it MUST be Earthed(Ground) for most ordinary uses; I can't think of ANY condition where it would be connected to white (Neutral).
Only 4V above PE on Neutral.... can go far higher and unpredictably so.
I've actually copped what felt like 50V from N in the past.....another story.
Here we use a MEN system of Neutral to Earth bonding.
Permitted exceptions are rare and generally associated with Low Voltage installations in a High Voltage shared environment. [Area pole mounted lighting in proximity to HV overhead rail lines at 1.1kV DC is an example]
I must say, the only use of 'Isolation Transformers', as say 240/240, I've seen haven't been Center tap BUT the intention has been to fully isolate for safety reasons i.e. not have A or N at PE level.
Never have I seen a secondary winding or part thereof connected to the supply [primary].
There seems to be a lot of misunderstanding what the purpose
of this application note (ll1662-application-230-to230v.pdf) is.
> ...not isolated from the mains - there is a hard connection!
> I would never deliberatedly connect a secondary connection to the mains!
The "secondary" is still an 230V mains outlet, this is
not a power supply transformer inside any equipment and
the thread title is misleading, as wired it´s of course
not an isolation transformer.
> have Hot on your audio "ground"
There is no "audio ground" (see above), and safety earth
(the middle prong of the IEC connectors) is connected
as it should be (the yellow-green dotted wire shown).
Of course the whole assembly should be in it´s own
metal case which is connected to safety earth, if this
is done I don´t see any safety issues with it.
Basically all you get is a plain 230V socket like a wall
socket, but DC removed and now balanced. If the latter
has any merit is a different story.
of this application note (ll1662-application-230-to230v.pdf) is.
> ...not isolated from the mains - there is a hard connection!
> I would never deliberatedly connect a secondary connection to the mains!
The "secondary" is still an 230V mains outlet, this is
not a power supply transformer inside any equipment and
the thread title is misleading, as wired it´s of course
not an isolation transformer.
> have Hot on your audio "ground"
There is no "audio ground" (see above), and safety earth
(the middle prong of the IEC connectors) is connected
as it should be (the yellow-green dotted wire shown).
Of course the whole assembly should be in it´s own
metal case which is connected to safety earth, if this
is done I don´t see any safety issues with it.
Basically all you get is a plain 230V socket like a wall
socket, but DC removed and now balanced. If the latter
has any merit is a different story.
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