DOES YOUR POWER CORD COMPLY?

[Marc]

52 minutes ago, Sir Sanders Zingmore said:

The problem is that in order to get a cable approved, it needs to be tested. And we all know that once any piece of audiophile equipment is measured or tested with electronic instruments it cannot, by definition, sound any good. 

 

Quite a dilemma. 

 

No need to continue stirring the pot.

[Weka]

Quote

Just be careful of those ones. I've bought loads of them for making my own cables (for personal use), and there are a lot of non-AS standard chinese knock offs that are a perfect copy, sans approval number.

 

No problem, thanks Marc. The 10A and 15A ones I use have full SAA Certification and I have hard copies of the certs as verification.

 

Edited March 14, 2017 by Weka

[Weka]

1 hour ago, al said:

how can anything "re designed" or modified be compliant anymore. something designed and gets approves on basis of its design and how it meets the requirements. changing that design or modifying it I cant see how on any level could be said to still be in the approved category. good luck to you basically just because it still has the little compliance mark means nothing anymore...

Suggest you read through AS/NZS 3112 and AS/NZS 3123 (should be available at you local library) and you will see that there are exceptions and exemptions under specific applications were modifications can be made without taking an item out of certification.

 

And... the term redesigned was purely tongue-in-cheek in response to @powerav

 

[powerav]

32 minutes ago, Weka said:

Suggest you read through AS/NZS 3112 and AS/NZS 3123 (should be available at you local library) and you will see that there are exceptions and exemptions under specific applications were modifications can be made without taking an item out of certification.

Mate seriously no need to be smart, I know and you know that taking the orange screw ring off will make bugger all difference but you always have to cater for the lowest common denominator.  What if someone plugged that industrial outlet into a standard elcheapo powerboard and then tried to squeeze another outlet next to it not fully inserting it? 

[Guest gmdb]

Nice piece of work, Marc. Thanks.  Clears up a lot.

[Sub Sonic]

On 14/03/2017 at 6:50 PM, powerav said:

Just use 1.5mm max, why 2.5? no one compliance used for domestic use is drawing that much current. Ohms law.

 

People using these larger cross section cables aren't concerned about current carrying capacity, they're trying to minimise volt drop.

 

Regards,

 

SS

[sir sanders zingmore]

16 minutes ago, Sub Sonic said:

 

People using these larger cross section cables aren't concerned about current carrying capacity, they're trying to minimise volt drop.

 

Regards,

 

SS

 

How much is voltage gonna drop across a 2m cable?

In any event, most complaints I read about mains voltage is that it's too high. 

[powerav]

33 minutes ago, Sub Sonic said:

 

People using these larger cross section cables aren't concerned about current carrying capacity, they're trying to minimise volt drop.

 

Regards,

 

SS

What???? Over 1.5 metres, that is even more obsurd.

[Zaphod Beeblebrox]

1 hour ago, Sub Sonic said:

 

People using these larger cross section cables aren't concerned about current carrying capacity, they're trying to minimise volt drop.

 

Regards,

 

SS

 

Let's compare using the manufacturer's data:

 

http://www.prysmiancable.com.au/documents/2ce-flat-pvc.pdf

 

* 1.5mm^2 CSA - resistance Ohms/km = 13.6 = 0.0136 Ohms/Metre

* 2.5mm^2 CSA - resistance Ohms/km = 7.41 = 0.00741 Ohms/Metre

 

OK, let's put some current through these puppies. Let's say you want to run a reasonably power hungry amplifier. Idle power of 460 Watts. At 230VAC, that equals 2 Amps. 

 

Therefore, our Voltage drop across the cable will be: 2 X (0.0136 X 2) = 0.0544 Volts (54 millivolts) for the 1.5mm cable.

 

The 2.5mm cable will be 2 X (0.00741 X 2) = 0.02964 Volts. 29.64mV.

 

Let's translate that into measured performance in the amplifier. Assume the amp is rated at 200 Watts/channel. We will assume, therefore, that 60 Volt (+/-) rails are used to achieve this power. To obtain 60 Volts DC, we must supply the rectifiers with around 40 Volts RMS. An extra 24millivolts (the difference between 2.5mm CSA and 1.5mm CSA) will result in an extra 0.034 Volts on the rails. Or, an extra 7.22 X 10^-5 Watts. That is: 72 MICROWATTS. Not enough to run sensitive headphones. 

 

IOW: Insignificant. 

 

 

 

[Sub Sonic]

Please note I said "trying". It is the only reason to go larger in CSA if the current carrying capacity of thinner cables is adequate (which it would be). 

 

I do not use special power cables as the loss/variation at the mains end due to cable size is negligible.

Edited March 21, 2017 by Sub Sonic

[Weka]

4 hours ago, Zaphod Beeblebrox said:

 

Let's compare using the manufacturer's data:

 

http://www.prysmiancable.com.au/documents/2ce-flat-pvc.pdf

 

* 1.5mm^2 CSA - resistance Ohms/km = 13.6 = 0.0136 Ohms/Metre

* 2.5mm^2 CSA - resistance Ohms/km = 7.41 = 0.00741 Ohms/Metre

 

OK, let's put some current through these puppies. Let's say you want to run a reasonably power hungry amplifier. Idle power of 460 Watts. At 230VAC, that equals 2 Amps. 

 

Therefore, our Voltage drop across the cable will be: 2 X (0.0136 X 2) = 0.0544 Volts (54 millivolts) for the 1.5mm cable.

 

The 2.5mm cable will be 2 X (0.00741 X 2) = 0.02964 Volts. 29.64mV.

 

Let's translate that into measured performance in the amplifier. Assume the amp is rated at 200 Watts/channel. We will assume, therefore, that 60 Volt (+/-) rails are used to achieve this power. To obtain 60 Volts DC, we must supply the rectifiers with around 40 Volts RMS. An extra 24millivolts (the difference between 2.5mm CSA and 1.5mm CSA) will result in an extra 0.034 Volts on the rails. Or, an extra 7.22 X 10^-5 Watts. That is: 72 MICROWATTS. Not enough to run sensitive headphones. 

 

IOW: Insignificant. 

 

 

 

 

Yes that's all valid under RMS power conditions but what happens when the power supply of a large amp is demanding instantaneous high current from the mains supply to recharge the PSU capacitors under real life dynamic music amplification. My understanding is that the instantaneous peak current drawn can be in the order of 10 - 20 times the steady state current for a millisecond or so and if the mains can't deliver then neither can the power supply.

[Saxon Hall]

I would respectfully suggest that the "bling" factor would be a primary consideration when using chunky power cables.

Sent from my F1f using Tapatalk

[Zaphod Beeblebrox]

2 hours ago, Weka said:

 

Yes that's all valid under RMS power conditions but what happens when the power supply of a large amp is demanding instantaneous high current from the mains supply to recharge the PSU capacitors under real life dynamic music amplification. My understanding is that the instantaneous peak current drawn can be in the order of 10 - 20 times the steady state current for a millisecond or so and if the mains can't deliver then neither can the power supply.

 

Let's take the absolute maximum that can be consumed from an Australian power point - 10 Amps.

 

The Voltage drop across a 1 Metre, 1.5mm CSA cable will be: 0.272 Volts

The Voltage drop across a 1 Metre, 2.5mm CSA cable will be: 0.142 Volts

 

Therefore, the difference will be: 0.13 Volts. 130 millivolts.

 

However, that only tells a very small part of the story. The main filter capacitors in all amplifiers will smooth out the peak demands on the mains supply. IOW: Short term transients will be supplied from the storage capacitance. In the amplifier I use, the storage amounts to around 750 Watts for 1 second. Easily enough to circumvent any excess demands from mains power. In fact, the amplifier can be unplugged for many seconds, with no audible inpact on sound quality. Now, I realise that is an slightly unusual situation, but, in even quite humble amplifiers, there is adequate capacitance to deal with normal musical demands. Here's what I am getting at:

 

Let's take the hypothetical, 200 Watt amp previously mentioned. Since it can deliver 200 Watts maximum power, then it's typical peak to average demands (under high power operation), using normal rock music, suggests that it will be required to deliver AN ABSOLUTE MAXIMUM of 20 Watts of average power. That would be using music with a highly compressed peak to average ratio of 10dB. Most rock music exhibits a peak to average ratio of more like 20dB, thus giving an average power demand of 2 Watts. Classical music can easily exceed 30dB. The main filter capacitors can usually deal easily with peak demands of most types of music.

 

The maximum power demands for MOST amplifiers (very high power Class A designs, excepted) is vastly over-estimated by many listeners. An amplifier that idles (no music) at (say) 100 Watts, will typically rise to around 150 Watts under VERY high SPLs.  

[sir sanders zingmore]

59 minutes ago, Zaphod Beeblebrox said:

 

Let's take the absolute maximum that can be consumed from an Australian power point - 10 Amps.

 

The Voltage drop across a 1 Metre, 1.5mm CSA cable will be: 0.272 Volts

The Voltage drop across a 1 Metre, 2.5mm CSA cable will be: 0.142 Volts

 

Therefore, the difference will be: 0.13 Volts. 130 millivolts.

 

However, that only tells a very small part of the story. The main filter capacitors in all amplifiers will smooth out the peak demands on the mains supply. IOW: Short term transients will be supplied from the storage capacitance. In the amplifier I use, the storage amounts to around 750 Watts for 1 second. Easily enough to circumvent any excess demands from mains power. In fact, the amplifier can be unplugged for many seconds, with no audible inpact on sound quality. Now, I realise that is an slightly unusual situation, but, in even quite humble amplifiers, there is adequate capacitance to deal with normal musical demands. Here's what I am getting at:

 

Let's take the hypothetical, 200 Watt amp previously mentioned. Since it can deliver 200 Watts maximum power, then it's typical peak to average demands (under high power operation), using normal rock music, suggests that it will be required to deliver AN ABSOLUTE MAXIMUM of 20 Watts of average power. That would be using music with a highly compressed peak to average ratio of 10dB. Most rock music exhibits a peak to average ratio of more like 20dB, thus giving an average power demand of 2 Watts. Classical music can easily exceed 30dB. The main filter capacitors can usually deal easily with peak demands of most types of music.

 

The maximum power demands for MOST amplifiers (very high power Class A designs, excepted) is vastly over-estimated by many listeners. An amplifier that idles (no music) at (say) 100 Watts, will typically rise to around 150 Watts under VERY high SPLs.  

If we take an extreme example of a transient that needs say, 1,000 w (humour me) what would the impact be of the voltage drop between the two cables

 

[Addicted to music]

4 hours ago, Weka said:

 

Yes that's all valid under RMS power conditions but what happens when the power supply of a large amp is demanding instantaneous high current from the mains supply to recharge the PSU capacitors under real life dynamic music amplification. My understanding is that the instantaneous peak current drawn can be in the order of 10 - 20 times the steady state current for a millisecond or so and if the mains can't deliver then neither can the power supply.

 

The max current that ANY power amp can draw out of a typical 240v 10 amp supply is wjen the amplifier is first switched on, when the cap reserve in the power amp is totally drained of charge and not while it's playing peaked out music transient.

When amplifiers cap reserves are fully discharged and has been switched off for a lenght of time,  once switched on your mains power will see a short circuit momentarily because the caps are fully discharged, as the caps charge the mains gradually see an open open circuit drawing less current.  This process happens in milliseconds.  This is why so many GOOD decent designers will incorporate a soft start circuit, some involving placing a 10-20ohm resistance in series with the mains and PSU of the amp and a timing circuit is used to switchout the resistor and some will incorporate a SSR for soft start.  

If you think that music transient exceeds mains supply (240v, 10A; 2400W)  it would then tripped the 10amp circuit breaker in your switch board.

[skippy124]

2 hours ago, Sir Sanders Zingmore said:

If we take an extreme example of a transient that needs say, 1,000 w (humour me) what would the impact be of the voltage drop between the two cables

 

In Trevor's example that you quoted, at the start he took the example of the max rated current draw for a standard power point - 10 amps. That equates to 2400W, so for 1000W roughly 100mv drop if using a 1.5sqm cable 1 meter in length. The regulation of the transformer would have a much larger impact than the voltage loss across the mains cable for a 1000w transient output load spike

Edited March 21, 2017 by skippy124

[Zaphod Beeblebrox]

14 hours ago, Sir Sanders Zingmore said:

If we take an extreme example of a transient that needs say, 1,000 w (humour me) what would the impact be of the voltage drop between the two cables

 

 

I note that skippy has answered your question correctly. However, the issue not mentioned, is the impact of filter capacitance. The main filter capacitors in an amplifier are there to provide several functions, but one is to smooth out peak current demands. So, your 1,000 Watt transient demand will have different effects on different amplifiers. If we assume that virtually no filter capacitance exists in an amplifier, then the maximum difference between the two cables will be around 100mV. In reality, however, all amplifiers contain some filter capacitance, so the peak Voltage difference between the two cables will always be somewhat less than 100mV. How much less is quite difficult to calculate, but somewhat easier to measure.

 

Skippy was correct to mention power transformer regulation too. A really good power transformer exhibits a regulation figure of around 5%. This means that from zero power to full power, the output Voltage of the transformer will vary less than 5%. If we assume a figure of 2% at 1,000 Watts, then, with an output Voltage of 86 Volts RMS (the approximate figure required for a 200 Watt amplifier), the variation will be approximately 1.75 Volts RMS. Far, far in excess of 100mV. 

 

Good catch Skippy. 

Edited March 22, 2017 by Zaphod Beeblebrox

[raviasdffdsa]

DEAR MEMBER

 

To use 2.5 you have to tamper with the plug in some way to make it fit

thanks...

 

 

 

ravi

[powerav]

On 3/21/2017 at 9:40 PM, Addicted to music said:

it would then tripped the 10amp circuit breaker in your switch board

I hope you CB is rated above 10A in your power circuit, you'll be making constant trips to the switchboard.

[Weka]

On ?5?/?13?/?2017 at 7:54 PM, raviasdffdsa said:

DEAR MEMBER

 

To use 2.5 you have to tamper with the plug in some way to make it fit thanks...

 

ravi

 

Not necessarily... depends on what plug you use.

 

[Nigel]

My power cord completes me !

[A9X]

On 3/21/2017 at 5:19 PM, Weka said:

 

Yes that's all valid under RMS power conditions but what happens when the power supply of a large amp is demanding instantaneous high current from the mains supply to recharge the PSU capacitors under real life dynamic music amplification. My understanding is that the instantaneous peak current drawn can be in the order of 10 - 20 times the steady state current for a millisecond or so and if the mains can't deliver then neither can the power supply.

If an amp of 460W is actually delivering that as a peak, then on average it will be averaging about 5W. However, very, very few systems will ever be delivering 460W to a single channel even on the loudest peak so most of the time the voltage loss through the power cable will be even lower. The caps store many joules of energy and are being recharged at the rate of 100 times/sec and this is what actually powers the device.

So, Trev's example is still valid and adding a larger CSA cable in almost every circumstance is a waste of money.

[A9X]

On 3/21/2017 at 9:40 PM, Addicted to music said:

If you think that music transient exceeds mains supply (240v, 10A; 2400W)  it would then tripped the 10amp circuit breaker in your switch board.

No necessarily. Domestic breakers have 2 functions; and inverse time section and instantaneous. For a 10A rated breaker at somewhere around 7-8x rated it will trip instantaneously. Below this it will run on an inverse time curve. At rated (10A) it will run forever without tripping. At 2x it w ill take 40 secs, at 5x, about 4.5 secs to trip. At least on the attached curve. It's one I found googling, but they all have the same general characteristic and shape.

Edited July 27, 2017 by A9X

[Lance B]

One thing you're all forgetting when it comes to power cables and any voltage drop that may affect it etc is the source cable that runs from the meter box to the wall socket. Generally "only" 2.5mm, but the length from meter box to wall will usually be waaay longer than any flexible cord from component to said wall socket. The power feed cable in the roof/walls isn't made with any exotic materials and is sometimes a single solid conductor (older houses) and the newer power cables are stranded. Not only that, but it is also unshielded and can pick up noise from a variety of sources. So, one wonders about the affectiveness of these after market cables that are used from wall to appliance. If it has a reasonable cross sectional area for the appliance rating and tight fitting connection at both ends, then that should be more than adequate.

[A9X]

^^ You can use Trev's data above to calculate loop losses for any distance. 2.5mm^2 is 15.6mV/A.m so using the worst case that I can think of ever installing was about 30m, the drop is just over 9V if say running a 2400W/10A constant draw device like a heater. If you have higher power draws than this regularly you need to install a sub main with a larger CSA and run it to a point closer to the area of higher loads. You need to do this to comply with AS3000. However, mains draws are nowhere near as high as most audiophiles think and Trev's other info about power draws and avaerage power to speakers is spot on.

 

Noise is also not really an issue as at higher frequencies the primary of all transformers is fairly low inpedance because of the poor primary inductance and highish capacitance, so it shunts to neutral.

 

I agree entirely with your last sentence, and good connectors does not mean shelling out silly money on the aftermarket units (which may not be approved for use here). Standard units from known brands are more than enough.