isolation transformer

Hi, I would like to hear from fellow Audiogoners what they think whether or not the use of an isolation transformer for the front end gear (CD player/DAC/Phono) is worthwhile.
According to a well known Swiss manufacturer/distributor the use of an isolation transformer has profound effects on sonics (more detail, better bass, etc.). These effects are more pronounced when using silver wire for the transformer. Do you agree with these statements? What would be better: using a smaller transformer with silver wire (say 200VA) or a bigger one, using copper wire (1200VA)? Thx in advance for your response.
I tried a 2KVA Iso transformer in my system. No difference. In fact a power engineer friend commented if anything it would make it sound worse. The transformer is used to block
dc spikes, like lightening. If you must use it get one thats way big like the one I have - 2KVA (2000VA). In fact if you want I'll sell you mine. It still new and has an outlet on the secondary.
I have used a pair of Ensemble Isolink isolation trasformers for years on my digital rigs with great benefits- the only caveat being this: be careful daisy-chaining too many isolation transformers together. I actually found I liked the Isolinks better into a passive line conditioner/strip (actually, they worked great a few years ago with a Tice Signature IIIC) rather than the big BPT 2.5 transformer-based unit- YRMV. Also- I would be remis not to mention the Foundation Research LC-1 combo power cord/conditioner- works better on my dacs than any other particlur isolation device.
I use an Ensemble Duo Isolink for my digital front end with wonderful results(blacker background,more natural timbres,deeper bass,bigger deeper soundstage) and their are no negative aspects at all as far as I can tell. I have tried other power conditioners without getting the same results as the Duo Isolink transformer. I have also found that the Harmonix studio master power cords are the sounding on my digital front end.
These are not my words however it is very interesting reading. There has been much written about isolation transformers on Audiogon, seek your information.


There are a lot of different roads that lead to Rome and some may be better than others. Like anything else, it is a matter of personal preference, budget, etc...

As far as isolation transformers go, you want to look for the largest core that you can get. This will keep hysterisis distortion to a minimum due to reducing the potential for core saturation. This is true of either E-I type ( old school ) transformers or toroidals. Big core size translates to high weight, but that can be misleading. Some transformers use "end caps" or "shields" ( this is a good thing ) that also contribute to the total weight. As such, don't think that a higher weight figure makes a transformer "better" as one might have heavier end caps with a lighter core than a unit with very light end caps and a huge core. The only way to really see what is going on is to either remove the end caps and weigh the transformers and / or simply eyeball the size of the core itself.

Two other key factors are based on spec's. One is the amount of rejection or "level of isolation" that the transformer achieves from the input windings to the output windings. A good transformer is down below -120 dB's. It is not uncommon to see figures ranging from -120 to -150 on high quality isolation transformers. If you do some checking though, most anything with a spec like that will be an "old school" iron core transformer. There's a reason for this and i'll explain why and what the other pertinent spec is at the same time.

The reason that the iron core works better than a toroidal is that the iron core typically has a MUCH lower level of internal capacitance. A higher level of capacitance basically equates to more signal leakage / increased coupling between the primary and secondary windings of the transformer. Obviously, the more coupling between windings, the less isolation. As such, a "good" toriodal will typically display a rating of -80 to -85 dB's compared to the -120 dB or better rating of the iron core. In this case, the lower the number, the better.

As you can see, the "old school" iron core transformer is measurably better. What this translates into right off the bat is a much lower noise floor and "blacker background. Treble performance is also "typically" much cleaner with less glare, sibilance and smearing. As a side note, this is also true of transformers used within audio components themselves. Any "honest" audio manufacturer / designer will tell you the same thing. The reason that most companies use toroidals is that they cost a LOT less to buy / build, they weigh a LOT less and the manufacturer can get away with a lighter duty chassis, they have a LOT less potential for breaking loose and destroying the product from the inside out when shipping, the products are cheaper to ship due to the weight reduction in both the transformer and chassis, etc... The one "real" advantage that toroidals may have in terms of actual performance is that, depending on how they are wound, they offer the potential for less EMI or "magnetic spray" inside of the component. Since many manufacturers stick large toroidals very near signal circuitry, much of that benefit is drastically reduced.

Other than that, the other "specs" that you want to look at are power rating and the input and output voltages. Most isolation transformers that you would be interested in would be rated in KVA ( KiloVolt /Amps or "watts" ). To make things simple for you, a 1.8 KVA or 1800 watt isolation transformer would be rated for 15 amps at 120 volts. To figure out how many amps the transformer is good for, you take the KVA rating ( 1800 ) and divide it by the voltage that you'll be using it at ( 120 ). As such, 1800 divided by 120 = 15. If you were looking for a 20 amp transformer at 120 volts, you would need one rated for 2.4 - 2.5 KVA ( 2400 - 2500 watts ).

Now here's where it gets tricky. Much like audio gear, different manufacturers play games with spec's. It is quite possible for two isolation transformers rated for 2.5 KVA with similar levels of isolation to be capable of very different levels of low distortion operation. You see, one transformer may begin to saturate the core at 15 amps whereas the other one is good for a "real" 20 amps. That's why i said that you should look for "BIG" core size. If you aren't sure of whether or not the core of the transformer is big enough, figure that it is good for 60% of its' advertised rating and go from there. This will allow plenty of "headroom" in most circumstances and you should never have a problem. Most of the people that complain about "side effects" when using iso's were trying to pull too much power from them and that's why they ran into problems with them. Kind of like saying "i only need 10 watts to drive these speakers" and then buying an amp that is only good for 10 - 12 watts. Sure, it may play loud enough, but the amp is stressed due to running near capacity and so is the sound. Such is the same thing with a transformer i.e. so long as quality does not suffer, a greater quantity is always preferred.

As a side note, the cores on my 3.0 KVA transformers are larger than the ones i used to have, which were rated at 5.0 KVA each. While the 3 KVA's will not pass as much power individually, the power that they will pass has less potential for hysterisis distortion since it would be next to impossible to saturate the core, even at full load. Only problem with this scenario is that i had to go to more transformers to achieve the same total power rating.

As to whether or not you want to go this route is up to you. I have a lot of respect for what PS Audio has done with the PowerPlants, but this approach also has a LOT of drawbacks. It is VERY costly, very in-efficient, throws off a LOT of heat, etc...

Balanced power has some benefits to it too. I think that there was a recent review of a product of this nature in Stereophile.

Running 220 - 240 volts and then stepping it down to 110 - 120 at the equipment level is also worthwhile. If you can reconfigure your gear for direct 220 - 240 volt operation, that is even better.

Like i said, there are a LOT of different paths that one can take. Running dedicated lines does reduce the potential for noise within the house to find its' way into your system to some extent. It is an excellent starting point. Since the dedicated lines typically share the same AC main though, noise can still "communicate" between your house lines and the dedicated lines. On top of this, there is nothing between what is coming in through the AC lines and your dedicated lines. While you do have a lower resistance path through the dedicated lines, which results in more stable voltage and current delivery, you've also got the potential for "dedicated noise delivery" too. As such, you really have to do something to isolate noise from the outside lines feeding AC into the house and the lines feeding the rest of the house from "contaminating" your dedicated lines via crosstalk at the breaker box. How you choose to do that and what suits your budget is up to you. Most anything will be a step forward so long as the device that you use isn't easily saturated. If the device does saturate, it is introducing distortion into the line rather than cleaning it up. That's why i stressed maintaining a certain amount of "headroom" above and beyond what you would ever pull from the devices used for filtering and / or isolation.
Thx for all your reponses. What do you think of using silver wire for an isolation transformer? Does it make sense? Or is this just "nonsense"?
I have a T-4 (see picture in my system) that is wired with silver wire. There is (IMO) a 15% increase in sonics. A lot depends upon what wire is used, and where.
I use a xentek ultra isolation transformer daisy chained to a MIT dual iso bank in which my TT and pre are plugged into 1 bank and the digital to the other iso bank. I think Seans comments are right on for my experience. Do not plug your amps in as a well designed amp dosent need them and it will sound worse. Excellent for the times before midnight when the ac is typicaly very dirty. You can find them on ebay for a song and could be a great upgrade for you. Forget about the silver wire type, big, ultra iso with iron core not torroidal is best in my opinion. Be aware theat they have their own slight hum so careful placement is needed.
I am interested in trying an isolation transformer but I am concerned about mechanical noise. The equipment has to sit in the same room as where the listening takes place. Doesn't make sense to me to imnprove the quality of the sound in return for an annoying buzzing. I have had amps with huge transformers and no buzzing so maybe I am overly concerned. Can anyone identify make/model that did or didn't buzz?
I think all isolation transformers of this nature will produce some type of noise, usually between 60-100 dB. Is it not possible to have the isolation transformer located in a different room within the AC line? See my system set up and check out the picture of the power filtration to serve as a visual aid.
Lak, What I am thinking of is something like the T-4 you have on the main rack for the front end. As far as I know, the new one from Exact Power is the only thing comparable being made. I looked at having a pair of large isolation transfomers installed in the basement, but the layout posed some problems and I think I scared the electrician. He couldn't figure out why anyone would want to do that. Instead I put an Exact Power EP15A in which handles one of the two amps and all the front end gear. I am looking for a second one for the second amp. I think a multi-transformer unit like the T-4 could either be plugged into one of the EP-15A's or into its own dedicated line. But its got to be QUIET. With everything I have described here I don't think I have a need for the brutes in the basement.

Maybe a pair of PS Audio UPC-200 would suffice. Those would provide 4 zones of isolation.
I only use "Isolation Transformer" when working on high voltage equipment, like TV's and tube amps. I have never thought that a isolation transformer would serve in a manner stated above. I believed the function of an isolation transformer was to provide a saftey net of sorts, seperate you from the ac mains. I guess I learn every day. I will try my isolation tranny in my rig to see what happens.
Sorry to dissapoint,but I believe that T4's are extremely rare and hard to find.I would love one also.Member "Psycicanimal" has two of them,but told me they were impossible to find.He was lucky.
Excuse late response. Just been browing around an found this.

Beowulf, what you're looking for is a Q-rated transformer. GE made several such as my 5KVA 9T21B1004G2, which is silent. That is an industrial, general purpose and very heavy transformer that I found on Ebay. Signal also makes unboxed versions. Converting either to balanced AC is easy.
I use a 1 KVA and a 3.7 amp Topaz on my Digital gear with great results. But after checking out Lak's system I'll be dreaming of power tonight. really nice set up Lak very well done.
Thanks :-)!
Where did you get yout T4 man?NICEEEE!!!!!
The T-4 is really sweet. One has to hear and demo it to really appreciate it. Great for front end equipment.
I watched Ebay and other sources for about 1.5 years before I located this T-4. As it happens I had a “want to buy” ad on Audiogon for about three months and a member sold it to me.