Tripp Lite IS250 Review (Isolation Transformer)

[garbz]

Product deserves criticism since it heavily advertises isolation when in reality it doesn't provide anything like that with respect to safety ground.

Except it does, just not in the context you're thinking. I know you understand this but may just be missing the obvious purpose of this isolation so let's just talk through all possible electrocution scenarios.

Earthed equipment:
Live connects to Neutral -> Massive overcurrent main breaker trips.
Live connects to earth / chassis -> Massive overcurrent, but RCD trips first as it is faster acting than the main breaker.
Neutral connects to earth -> Usually a tiny current flows due to inductive pickup, RCD trips.

Now a person shorting live to neutral is dead.
A person shorting live to earth is saved by an RCD but critically still got electrocuted according to any workplace standards.
A person shorting neutral to earth is safe anyway but still has minor current floating through their body.

Earthed equipment plugged into this transformer:
Live connects to Neutral -> Massive overcurrent fuse on the isolator blows. LIMITED DOWNSTREAM CURRENT to the main breaker. Power stays on.
Live connects to earth / chassis -> Nothing happens. System now has a reference to earth.
Neutral connects to earth / chassis -> Nothing happens. System now has a reference to earth.

Now more importantly you as an engineer can now *safely* earth lift your equipment under test without risk of electric shock. You can now do differential measurements through your oscilloscope without the magic smoke coming out or electrocuting yourself when touching probes.
The purpose of an isolation transformer is so that it's user (electrician, engineer or service tech) can touch any one part of the circuit at whatever voltage and not get harmed.

None of this has anything to do with audio of course and it's still good to see these measurements so people don't buy them for that purpose, but they still very much provide isolation for their intended application. We do however need to stop idiots buying these for their audio gear not knowing what they are actually for.

 

[Ingenieur]

Nice review

One thought
The increase at ~1800 might be motor noise. 1800 is a common motor speed or 30 rps
30 rps x 60 Hz ~ 1800 Hz disturbance.

It's odd it would increase it that high considering the linear attenuation after that.
Something added power or disturbance to the system. I doubt a xfmr could do that?

 

[PeteL]

Everyone that needs one of these devices, knows what it does. They aren't going to NOT buy it because an audio forum tells them it's rubish for audio products. No sh*t it is, because they already know what it's supposed to be used for.
There is no damage done here

Yes and no, people in need for this product know what they want it to be doing, reviews should tell us how well it does this. Especially science based ones. We have a manufacturer a few post up that is not known for Voodoo witchcraft that is telling us it can help with audible ground loops. That is not "rubbish" to me. Now about damage, yes it may be minimal but bottom line Brand reputation matter. And it matters if a considerable community of audiophiles that are said to trust science all sing along the Snake oil song.

Being about science should also be about learning, isn'it better than just blindly conclude that it serves no purpose, even if this actual purpose don't apply? it may apply one day.

There is more to audio in general than just my Dac-Amp and Bargain Headphone that sound great once EQed.

Bottom line Compagnies like Tripp Lite and Furmann have been making no-nonsense Power distribution, conditioning and protection products for decades, have been used reliably by millions of professionals and do the job at hands, generally. It don't mean that they can't do wrong but I get the feeling that anything that has a 3 prong plug on it gets dragged in the mud. Not so much strictly the review itself, but the snowball it creates.

I think that we should be thinking further, look at audio science with its exceptions, its perturbations, its problems, because that's why products like that matter. If we like the science and not just like to follow blindly an agenda of "Let's fight against the fools".

 

[DWI]

I had a look at the review index for power products and cables and out of dozens only two items got a positive review, both were $20 and one was Belden 2-core cable. As a user of Belden cable, I can confirm it conducts electricity so I give it a thumbs up. So it seems that other than for the most basic power products, Amir doesn’t like any of them. So this product was always going to be a negative. Either he’s biased against such products or is not testing them properly for their intended function.

There is really no point measuring something because someone misinterpreted the Amazon description or some lunatic on the internet thinks it cures all audio problems. There are no doubt people on the internet who think the best acoustic damping is if you spread peanut butter on the walls of your living room. That should not need Amir to test peanut butter with his Klippel. A test of peanut butter in the context of audio performance is a waste of perfectly good peanut butter.

A good audio product is a power block that stops noise contamination and voltage swings between devices. This device reportedly does this with AV equipment. I have never heard of these being used for audio anyway. I have two such isolation products, one is the ifi Powerstation. I don’t know how you would check for cross-contamination, but it would be nice to see a positive comment once in a while.

 

[sam_adams]

Why. I don’t see a problem using a double insulated devices with 2-pin input with this transformer as it is.
Would reduce common mode noise and leakage to this devices.


i think i have
Uses didos in the ground part like many commercial devices do for example the hum ex

Ground loop hum eliminator

Ground loop hum eliminator

www.aggh.net

View attachment 198548

Also cheater plug is way saver and better if used with an isolation transformer
if this is code compliant depends on your local code...

But EBtech is selling the product in the USA so i assume its legal...?
View attachment 198549



Thanks for making it clear in the video what the scope of the test is by saying your testing not if it can fix hum or buzz. but only some esoteric Audiofool claims.

I can deal with this and totally agree it can’t magically improve on something that has no flaws to begin with.

This is an image of the device mentioned above that someone 'de-potted':

(Red arrow - resistor, Green arrow - arming LED, Blue arrow - arming LED resistor)

The schematic above is incorrect as there is no capacitor paralleling the diodes, but a 1/2W or 1W resistor. (It can't be discerned from the image and there is no mention of the value or power rating of the resistor.) There is no fuse. There is an LED with a resistor across the incoming 120VAC input connector to tell you that the device is armed and ready to go up in smoke.

Anyone who thinks about using one of these needs to ask themselves the question; "What part will fail first if there is a 100A, 2.5s Line-to-chassis short before the breaker trips?" Also, ask yourself; "What damage will occur if there is a 1000A, 10ms Line-to-chassis short before the breaker trips?" Then ask yourself; "What will happen to me—when the internal parts fail and the breaker doesn't trip—if I touch the energized chassis of the device that's plugged into this thing?"

 

[amirm]

So this product was always going to be a negative. Either he’s biased against such products or is not testing them properly for their intended function.

That's all the options you could come up with? It can't be that the devices can't or won't improve your audio performance based on simple knowledge of engineering of audio design? Talk about asking permission to put your head in the sand.....

 

[amirm]

Anyone who thinks about using one of these needs to ask themselves the question; "What part will fail first if there is a 150A, 2.5s Line-to-chassis short before the breaker trips?" Also, ask yourself; "What damage will occur if there is a 1000A, 10ms Line-to-chassis short before the breaker trips?" Then ask yourself; "What will happen to me—when the internal parts fail and the breaker doesn't trip—if I touch the energized chassis of the device that's plugged into this thing?"

Simple answer is that people don't "think." And assume accidents can't possibly happen.

Before I started to test this transformer, I was getting an AC cable ready to connect to my audio analyzer. I grab the female end of the power cable, connect my adapter that goes from it, to metal balanced banana jacks. I let go of the end after doing that and sparks start to fly! I look and the cable was plugged in and fully energized!! The banana jacks were metal as I mentioned and every time they touched, they would light up like a small bulb!

We have wood floor and there were plenty of flammable cables and such around the sparks. I did not dare touching the end of course and struggled to get them to not short while holding the middle of the cable. Then everything got quiet with the circuit breaker popping in my power strip. Had it not done that, I could have set the whole house on fire.

The power strip ironically was Tripp Lite. An industrial one that is built like a tank. It is its safety provision of including that breaker that saved me.

 

[sam_adams]

From Bill Whitlock:

 

[amirm]

From Bill Whitlock:

View attachment 198588

Should have known Bill would have something definitive to say about this! Thanks for posting it. The mains noise I saw matches the reasoning he is mentioning.

 

[sam_adams]

Before I started to test this transformer, I was getting an AC cable ready to connect to my audio analyzer. I grab the female end of the power cable, connect my adapter that goes from it, to metal balanced banana jacks. I let go of the end after doing that and sparks start to fly! I look and the cable was plugged in and fully energized!! The banana jacks were metal as I mentioned and every time they touched, they would light up like a small bulb!

"Suicide Cord" is my favorite test cable! Separates the men from the boys.

 

[sam_adams]

Simple answer is that people don't "think." And assume accidents can't possibly happen.

Dunning-Kruger Effect in action.

 

[sam_adams]

Basic explanation of a "separately-derived system".

 

[theREALdotnet]

From Bill Whitlock:

In the picture it says “safety ground can’t legally be interrupted, so ground loops will remain”. If that is the case in the US it would explain the way the TrippLite device is constructed. It is not the case in other countries, though, and actual isolation transformers are available there.

 

[sam_adams]

In the picture it says “safety ground can’t legally be interrupted, so ground loops will remain”. If that is the case in the US it would explain the way the TrippLite device is constructed. It is not the case in other countries, though, and actual isolation transformers are available there.

Whitlock does not address what the electrical code in the EU, UK or other countries are regarding devices of this type. An experiment for the brave—or possibly foolish—individual would be to modify one of these devices with a GFCI outlet on the output side of the transformer to see what, if any, effects it would have with the ground lifted.

I do not advocate for someone with limited experience in high-voltage AC circuits to try this. I would not even advocate that an experienced individual should try this. To do so could risk your life and property.

 

[theREALdotnet]

I would not advocate doing anything that’s illegal in your country. If that happens to be the case you’ll just have to learn to live without the benefits of isolation transformers . This shouldn’t be too hard, I find that not using ground/shield as a signal lead (i.e. using balanced interconnects) prevents most of the issues from occurring in the first place.

 

[sam_adams]

I would not advocate doing anything that’s illegal in your country.

Well, it's not like you'd be tearing the label off the mattress that says; "Do NOT remove."

 

[theREALdotnet]

Well, it's not like you'd be tearing the label off the mattress that says; "Do NOT remove."

And underneath that label it says “I see you have a problem with authority. Would you care to sign this petition against…”

 

[solderdude]

I was looking at the Trip Lite specifications and could not find the stated primary to secondary capacitance. This is certainly important for performing and isolating high dv/dt bench experiments, not so much for audio. As Amir stated, it will isolate common mode noise, is not necessarily true. Common mode will couple to the secondary through this capacitance. It depends on signal rise/fall times, amplitude and capacitance.

There is a Faraday shield between the primary and secondary winding and prevents capacitive coupling between the windings as both couple to safety ground. This shield is connected to safety ground (the green wire from the transformer).
For 'normal' transformers and toroids you would be correct. Capacitive coupling between windings.
This is why in audio we sometimes see R-cores touted as 'better' because the 2 bobbins are next to each other.

 

[solderdude]

FWIW we have successfully used these to reduce ground loops and hum in several areas that were problematic, and they've worked admirably for this. I don't think I ever saw anyone promoting this as producing generalized audio benefits...

Sometimes, certainly when switch mode power supplies are used, a ground loop may not be caused by different voltages between safety ground but is caused by 'leakage' though the mains power supply. For RF there is an almost direct coupling even (through a rectifier though)
This can occur with SMPS that, in order to comply to FCC rules, use a Y-cap between input and DC output.

Or between output and Neutral.

That current is very low of course (you may feel a slight tingle) but can be high enough to create a voltage drop across the screen of an RCA cable.
An isolation transformer with safety ground can still solve the problem with such a loop (think computer power supplies).

 

[rebbiputzmaker]

Simple answer is that people don't "think." And assume accidents can't possibly happen.

Before I started to test this transformer, I was getting an AC cable ready to connect to my audio analyzer. I grab the female end of the power cable, connect my adapter that goes from it, to metal balanced banana jacks. I let go of the end after doing that and sparks start to fly! I look and the cable was plugged in and fully energized!! The banana jacks were metal as I mentioned and every time they touched, they would light up like a small bulb!

We have wood floor and there were plenty of flammable cables and such around the sparks. I did not dare touching the end of course and struggled to get them to not short while holding the middle of the cable. Then everything got quiet with the circuit breaker popping in my power strip. Had it not done that, I could have set the whole house on fire.

The power strip ironically was Tripp Lite. An industrial one that is built like a tank. It is its safety provision of including that breaker that saved me.

I’m not making light of your accident but what did you really have that was so flammable did you have accelerants anywhere? Most hard household items are not that flammable Things like cloth sheets, window curtains etc are flammable. I’m glad nothing bad happened but honestly I think it be pretty hard to start a fire with a electrical cord at least it would have to stay shorted, get very hot and then it would actually have to have some type of material, cloth, window curtains or accelerants in contact with it for a period of time to smolder then start to burn.

Lionel Hampton the jazz musician many years ago had a fire in his apartment when the wind from an open window blew a curtain into a halogen torch lamp and that started a fire which burnt out his high-rise apartment in Manhattan.