Discussion of AC mains isolation transformers

[asdf1000]

Well, I was going to ring Eaton Australia & see if they stocked or could get one here - no idea of cost. Their website is hopelessly opaque / all over the place! But iso transformer is on product lists at 240V.

 

I already went to Eaton Aus and asked the question. They said no, it's a US only product, not sold here. Eaton US said yes but to ask Eaton Australia. Round and round we went.

 

So are you going to get a Topaz then? The shipping is as much as the units themselves.

[jamesg11]

I already went to Eaton Aus and asked the question. They said no, it's a US only product, not sold here. Eaton US said yes but to ask Eaton Australia. Round and round we went.

 

So are you going to get a Topaz then? The shipping is as much as the units themselves.

Well, you're several steps ahead of me - thanks for the info. Makes it all very difficult then!

[sandyk]

Well, you're several steps ahead of me - thanks for the info. Makes it all very difficult then!

 

Do you Aussie guys REALLY need Isolation transformers ? I don't know anybody in Sydney who has felt the need to use one, and this is with a couple of systems worth around Au$100K, and one > Au$50K as well.

They could of course have improved mains supply problem rejection capabilities though.

We have the advantage over the USA of double the mains voltage and half the current needed. The doubling of the current seems likely to cause more mains supply degradation ?

[Superdad]

We have the advantage over the USA of double the mains voltage and half the current needed. The doubling of the current seems likely to cause more mains supply degradation ?

 

Yes, but at least we can touch our mains without being nearly killed!

[sandyk]

Yes, but at least we can touch our mains without being nearly killed!

 

 

 

Don't get so complacent !

Sure, the risk is lower, but it's still there , especially with older guys.

You probably have a further advantage when using heavy duty mains isolation transformers where the secondary is floating ?

[JohnSwenson]

Hello,

 

I am considering what John suggested i just don't know if these choices would serve the purpose and if, which can be the best choice:

 

It will be: Wall - Transformer - Strip - all system including Microrendu with LPS-1, Preamp, 200w Amp, DAC, MacMini, OPPO player and perhaps TV

 

Choices that i am believing are the ones John mentioned:

 

UPS & Uninterruptible Power Supplies | Eaton Power-Suppress 100 1kVA 120/240V In 120/240V Power Conditioner

 

TOPAZ 91001-12 Isolating Transformer 120V | eBay

 

Regards

 

Mike

 

These are essentially the same thing, but I am worried about the Topaz one since it has a Schuko plug, which is usually used in 230V areas. The tag on the transformer says 120V input, so something doesn't add up. If the transformer itself really is wired for 120V to 120V then you could just put a standard US plug on the cord, but if it actually has been modified to be 240 to 120 then it is a little more difficult to deal with.

 

John S.

[jamesg11]

/& the other doesn't have a plug ...?

[jamesg11]

Do you Aussie guys REALLY need Isolation transformers ? I don't know anybody in Sydney who has felt the need to use one, and this is with a couple of systems worth around Au$100K, and one > Au$50K as well.

They could of course have improved mains supply problem rejection capabilities though.

We have the advantage over the USA of double the mains voltage and half the current needed. The doubling of the current seems likely to cause more mains supply degradation ?

So, you're saying this is not the holy g after all?

[sandyk]

So, you're saying this is not the holy g after all?

 

An isolation transformer has the capability to markedly reduce mains related issues, but knowing whether your particular location will get a further worthwhile improvement for the additional cost is not predictable, at least for typical suburban areas .Large apartment complexes with lifts etc., or in an industrial area may be a different matter though.

 

It would be great if you were able to first try an isolation transformer before forking out the money.

Neither is it normally advisable to use an isolation transformer with higher powered amplifiers than perhaps 100W per channel.

[asdf1000]

An isolation transformer has the capability to markedly reduce mains related issues, but knowing whether your particular location will get a further worthwhile improvement for the additional cost is not predictable, at least for typical suburban areas .Large apartment complexes with lifts etc., or in an industrial area may be a different matter though.

 

It would be great if you were able to first try an isolation transformer before forking out the money.

Neither is it normally advisable to use an isolation transformer with higher powered amplifiers than perhaps 100W per channel.

 

 

I currently have a pair of 1600W subwoofers and a 350W per channel integrated amp (amp's power consumption up to 1100W max) , all plugged into a PS Audio Dectet power board/ power conditioner.

 

If it's not been a problem with this powerboard, could my setup have a problem with an iso transformer (which has a 10A circuit breaker installed of course)? If so, how so? Appreciate the advice

 

Cheers

[sandyk]

I currently have a pair of 1600W subwoofers and a 350W per channel integrated amp (amp's power consumption up to 1100W max) , all plugged into a PS Audio Dectet power board/ power conditioner.

 

If it's not been a problem with this powerboard, could my setup have a problem with an iso transformer (which has a 10A circuit breaker installed of course)? If so, how so? Appreciate the advice

 

Cheers

 

Are your 1,600W Subwoofers powered from a different outlet ?

Perhaps John Swenson or Alex C are better equipped to give you a definitive answer WRT the required size of isolation transformers, although I don't believe you can automatically transfer the USA experience to our own 240V (nominal) 50HZ supply.

The highest powered amplifier I have ever used was a DIY 240W/Ch. amplifier, and it could momentarily dim a nearby table lamp when starting up.

[asdf1000]

Are your 1,600W Subwoofers powered from a different outlet ?

Perhaps John Swenson or Alex C are better equipped to give you a definitive answer WRT the required size of isolation transformers, although I don't believe you can automatically transfer the USA experience to our own 240V (nominal) 50HZ supply.

The highest powered amplifier I have ever used was a DIY 240W/Ch. amplifier, and it could momentarily dim a nearby table lamp when starting up.

 

My GoldenEar Triton Ones, each with inbult 1600W subs, and my integrated amp are all currently plugged into the same PS audio Dectet powerboard, on the same one outlet. So I have 1600W x 2 + 700W x 1 plugged into the powerboard (in excess of 2400W) and have never had an issue, so I'm guessing my power consumption has to be less than the 2400W limit of the power board.

 

I think 2.5kVA equals 2kW ? So a 2.5kVA iso transformer could potentially not provide enough juice for my setup. Depending on the amp's drawn I'm guessing?

 

Thanks again in advance

 

PS: i really WISH I was consuming enough power to dim the lighting on start up :-)

[sandyk]

PS: i really WISH I was consuming enough power to dim the lighting on start up :-)

 

Many DIY amplifiers have larger input filter capacitor values than many commercial products, which can cause large start up currents. Some higher powered amplifiers even have start up current limiters ,which use a timing circuit to short circuit a series low value resistor in the active mains lead a predetermined time after switch on, using relay contacts.

[Superdad]

Due to the nature of the forum system, this intro post will appear below all the earlier-dated ones I just moved out of the UltraCap LPS-1 Troubleshooting thread.

 

--AJC

[Speedskater]

I hadn't noticed any of this in the old thread.

So random thoughts on Isolation Transformers.

a] There are larger permanently installed Iso Trans that power the entire audio system and there are small portable Iso Trans that power a few components. These are two very different tasks. We must keep thoughts about them separate.

b] Like John S, I too have a 5kVA Topaz transformer. It's near the audio equipment, but in the basement so a small amount of buzz isn't a problem.

c] The biggest virtue of a large Iso Trans is that it can be wired as a Separately Derived System near the audio equipment. It doesn't even need to have a lot of isolation! It's the Separately Derived System part that's important.

d] Instructions for installing a Separately Derived System can be found on page of this Middle Atlantic paper.

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment - White Paper"

Integrating Electronic Equipment and Power into Rack Enclosures

Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems

White Papers

[sandyk]

My GoldenEar Triton Ones, each with inbult 1600W subs, and my integrated amp are all currently plugged into the same PS audio Dectet powerboard, on the same one outlet. So I have 1600W x 2 + 700W x 1 plugged into the powerboard (in excess of 2400W) and have never had an issue, so I'm guessing my power consumption has to be less than the 2400W limit of the power board.

I presume that your 1600W subs are Class D and perhaps SMPS powered as well ?

If so, I am wondering whether your integrated amplifier would perform better if powered via an Isolation transformer .

Perhaps John or Alex C who have vastly more experience in this area could chime in ?

 

Alex

[asdf1000]

I presume that your 1600W subs are Class D and perhaps SMPS powered as well ?

If so, I am wondering whether your integrated amplifier would perform better if powered via an Isolation transformer .

Perhaps John or Alex C who have vastly more experience in this area could chime in ?

 

Alex

Yep the subs are Class D and so is the integrated amp.

 

I don't know much about their built in power supplies though.

 

Sent from my Blackberry DTEK50 using Tapatalk

[asdf1000]

Can an iso trans be plugged into a powerboard to power a single device, like my integrated amp (with it's built in DAC)? I know John said it's best to having everything plugged into the powerboard with the powerboard plugged into the iso trans and iso trans into the wall.

 

I couldn't find a 3kVA ++ iso trans (240V) though so went for a 2.5kVA. Which will support up to 8 amps? I THINK I should be ok but don't have the exact power consumption figures for my system and my usage.

 

But if I can use it for my Amp/Dac that would be good but it would need to be plugged into a powerboard

 

Sent from my Blackberry DTEK50 using Tapatalk

[ericuco]

Perhaps John or someone can comment on general sizing guidelines for an isolation transformer.

 

From what I am reading the difference between Watts and VA is the power factor (PF) which goes from 0 (zero) to 1. Should we just assume a PF of 1 so that the two values are the same?

 

Also, the power rating of my amps (Hypex N400 class D), like most amps, vary with respect to load (ohms). Any advice on what to use with respect to sizing an isolation transformer. I know (well I think I know) that the actual draw of most amps is usually just a few watts for normal listening and that speaker loads vary. Does any of this play into sizing an isolation transformer, given that amps will be the biggest draw?

 

Thanks for any and all assistance. This subject has me intrigued but I am well out of my element here, sorry if any of what I have said above is off base. I just don't want to spend $$ and get a unit that is well under or over spec'd.

[Speedskater]

In situations like this we can treat Watts & Volt/Amps as about the same (even though they are not really).

But power transformers are rated for resistive loads like heating units or old fashioned light bulbs. For big amplifiers leave a large safety factor. Use 60% or 50% of the rating.

[ericuco]

For big amplifiers leave a large safety factor. Use 60% or 50% of the rating.

 

Thanks for the reply.

 

That is one point of confusion for me. My amps are rated at 400 watts at 4 ohms but then double (half) depending on 2 ohms (8 ohms) loads. What should I use for your recommended 50 - 60% calculation?

[One and a half]

Thanks for the reply.

 

That is one point of confusion for me. My amps are rated at 400 watts at 4 ohms but then double (half) depending on 2 ohms (8 ohms) loads. What should I use for your recommended 50 - 60% calculation?

 

In this case, use the rating as stamped on the nameplate usually at the rear panel.

[jamesg11]

Thanks for the reply.

 

That is one point of confusion for me. My amps are rated at 400 watts at 4 ohms but then double (half) depending on 2 ohms (8 ohms) loads. What should I use for your recommended 50 - 60% calculation?

Then, 1.6kW for the power amp alone, + ... ?

[One and a half]

This post didn't come over.

 

The leakage currents on 120V systems is half those of 230V systems a bonus for audio equipment.

[jabbr]

The isolation transformer I'm using is a Topaz model, it is a very special transformer. It has extremely low inter-winding capacitance (.005pf according to the manufacturer). Most transformers have two mechanisms that transfer AC from one side to the other: magnetic and capacitive. The magnetic part is low frequency (it is what the 50/60Hz mains signal uses) and the capacitive is high frequency. The combination means that a "normal" transformer lets a lot of high frequency crud through.

 

With its extremely low capacitiance the Topaz doesn't pass the high frequency crud on the AV main, just the base line frequency and a couple harmonics. Thus it is a very effective noise filter.

 

In addition it is a very good surge suppressor as well. Most of the energy in high power surges is contained in high frequency components, which get suppressed by the low capacitance, thus it is quite an effective surge suppressor without needing any other special circuits to achieve this.

 

This isolation transformer keeps noise and surges from the rest of your house and neighborhood out of your audio system and fully preserves your safety ground.

 

Yes you are correct about the application, the Topaz plugs into the wall, the power strip plugs into it.

 

My recommendation is to use a simple power strip with NO filtering or surge suppression, the Topaz does it much better than what will come in almost any power strip. I plug EVERYTHING into thepower strip. This dramatically cuts down on the impedance between boxes, significantly lowering noise generated by leakage loops.

 

Some people will say "but then the noise injected back into the AC mains can go right into other boxes". Yes it can. BUT recent experiments have been pointing to the leakage loops being a significantly greater detriment to ultimate good sound than the injected noise. Of course different systems are different and this may not be true in all systems, but it is looking like this is a good place to start for many systems.

 

John S.

 

+1 These are great -- I have several of the .005 pF ones. They can be found for very reasonable prices -- downright cheap if you are willing to rewrire the plugs etc.