Mains conditioner - home made as good as Isotek Aquarius

[theabbot]

Is there anyway of testing your mains to see if you have a noise problem before buying anything?

Thanks














is there

[Pharos]

Look at the waveform on a scope.

[Light Dependant Resistor]

Look at the waveform on a scope.

Hope you inferred reading low voltage secondary voltages, as scopes are way too sensitive to use
on mains primary readings. Low voltage secondaries to approx 20v AC can be read
but not much more. Using a conventional scope has limitations with voltage.

Cheers / Chris

[blackstar]

You can use a 10:1 probe and adjust the settings to suit. I've read mains on an oscilloscope many times in the past.

[anthonyTD]

Correct!
However, when you attenuate the voltage, you also attenuate the noise, making it harder to detect!

You can use a 10:1 probe and adjust the settings to suit. I've read mains on an oscilloscope many times in the past.

[Marco]

Yes - I didn't describe my point very well as I was rather time pressured. What I meant is that the system sounded the same whether the SM power amp was wired into the dedicated ring the rest of the gear used or plugged into the normal house ring. Of course this doesn't particularly prove anything. The particular amp I'm referring to is intended to be used in the pro arena and likely with a whole bank of identical units (one for each pair of drive units); it will certainly be complying with all the relevant international RFI standards. Finally, as Marco implies, although I did compare I didn't really go searching for issues and was quite happy to let this particular sleeping dog lie after a relatively cursory investigation.

Yup... All you can do with these things is 'suck it and see', as you'll never achieve the same results in every system, or property where tests are tried, simply because both mains quality itself and sensitivity of the equipment to it varies, thus what happens in the final analysis is dependent on a number of factors.

However, experience tells me that when noise/interference are effectively addressed by the judicious use of filters, mains regenerators, separate spurs, etc, particularly when as a result mains impedance is reduced to a notable degree, the effect of that is *always* very clearly audible

Incidentally, one of the most effective ways I've found of reducing noise on the mains, which usurps that of anything discussed here, and which is rarely mentioned, is installing a dedicated earth solely for your hi-fi system, via the use of multiple copper rods [plunged into a damp area of your garden], which is tagged onto a separate mains spur (with consumer unit).

The installation of said dedicated earth almost completely isolates your system from noise/interference present on the standard house ring-main and earth, in a way that simply isn't possible with a separate spur alone, and subsequently allows your system to perform to its maximum capability. In my view, if it's practical to achieve in the property where you live, this should be done before the purchase of any expensive active mains treatments, as it could negate any need for their use at all.

Marco.

[Light Dependant Resistor]

You can use a 10:1 probe and adjust the settings to suit. I've read mains on an oscilloscope many times in the past.

NO this is not to be done,

1. Because the oscilloscope ground probe is at safety earth potential - inviting active mains
to be shorted, or neutral to be shorted to safety earth !.
To qualify this a bit more https://www.youtube.com/watch?v=SUVpRVI06cc move cursor to 8.03

2. Scope Probes are not designed for high voltages, although they appear insulated they do not meet
insulation criteria for high voltage measurements.

To do such a measurement you would traditionally use a isolation transformer at much lower potential
so always viewing from the secondary side of that transformer to see the primary waveform.

Or use an industry approved isolation device designed for such measurement to then interface
with an oscilloscope,

Cheers / Chris

[anthonyTD]

Chris,
With all due respect, I am pretty sure that the safety aspect was not at question here, Milo [Blackstar] was merely explaining that the mains can be read on a scope, using attenuation!

NO this is not to be done,

1. Because the oscilloscope ground probe is at safety earth potential - inviting active mains
to be shorted, or neutral to be shorted to safety earth !.
To qualify this a bit more https://www.youtube.com/watch?v=SUVpRVI06cc move cursor to 8.03

2. Scope Probes are not designed for high voltages, although they appear insulated they do not meet
insulation criteria for high voltage measurements.

To do such a measurement you would traditionally use a isolation transformer at much lower potential
so always viewing from the secondary side of that transformer to see the primary waveform.

Or use an industry approved isolation device designed for such measurement to then interface
with an oscilloscope,

Cheers / Chris

[blackstar]

Battery powered scopes are ideal for this, but I disagree about the probes not being up to it. I have had to probe mains on many occasions in the past, and I used an old battleship of a scope and its probe (I think it was called Powerscope - its been that long); I assure you that it was designed to scope big voltages.

With regard to attenuation of noise with a 10:1 probe, you just need to examine the waveform more carefully. I will say that I was never examining waveforms for the noise they were carrying in the past, so my experience may vary from yours.

[Light Dependant Resistor]

Hi Anthony
No it cannot be done safely without an isolation device because of the design of scopes
BNC which is wired to safety earth, this then extends out to the probe flying lead

Scope probes have the probe ground at safety earth potential. Grab a multimeter
and confirm close to zero ohms.

Now picture the scope ground lead connecting to active mains - you then get the
scope probe ground diverting active straight to safety earth.

So always measure using a isolation transformer or approved device
to interface with a scope.