Isolation Transformers

I've been considering isolating my digital gear from the rest of my system. I've read some good information in the archives and want to know if anyne has direct experience with the MGE or Tripp-Lite units. Tripp-Lite offers a hospital grade and a base model, both appear to be hardwired. Not sure what the differences are other than cost. MDE has a hardwired and cordless model. I like the idea of using my own power cord, but not sure this would make a big difference. I'm leaning towards a 1KVA version. Any advice would be appreciated.

BTW - I don't and cannot have dedicated lines. I'm using a North Star transport and Monarchy M24 DAC at the moment.
Tripplites are good rugged units, but not for audio. Too much noise and current limiting. Since you cant do dedicated lines (are you in an apartment or condo? Sometimes you can find an unused circuit, or one that has only one device on it) I'd advise you to buy an Exactpower EP-15A regenerator unit:

It has 8 outlets, 4 of which have digital filters to keep your digital gear from putting "hash" back into your power lines. It also "creates" perfect AC power even better than some dedicated circuits can.

Later on, if you want the ultimate, you can buy an SP-15A balanced power unit which you can plug into the EP-15A and use to provide quiet balanced power to all your front end stuff.

An isolation x-fmr wil only isolate your gear from noise on the power company side of the x-fmr, but not from each other on the "gear" side of the x-fmr.
In my experience some isolation trannies are more suitable for audio application than others. You can hear tonal differences as well between those trannies. I think it has to do with the characteristics of the (iron) core of the isolation trannie in conjunction with the unit's power supply that has been attached to the isolation trannie. For example: Tamura and Tango isolation trannies sound different (to my ears more musical, better) than some other trannies with comparable power that originally were not designed for audio. What do you think?

I've gone back and forth on the power regenration thing for a while now. I am familiar with ExactPower and think highly of the products they offer. My problem is my RSA Haley works quite well and I'm not inclined to mess with that. I have considered balanced power for the front end and the SP-15a would be a consideration.

As for tonal differences in isolation transformers, I'm not even at that crossroad let alone down the road. I'd have a lot more research and some auditioning to do. I can see the logic in the theory though. I would think that iron trannies versus toroids could conceivably offer sonic differences. I'm also told Q-type transformers are much better as well. So again, lots to consider. I guess I still have my work cut out for me.
Clio, I don't think I'm expressing myself properly. First I have to say that for me, the world is divided into those who can implement dedicated circuits, and those who can't.
Your statement about not being able to provide dedicated circuits is, to me at least, the key issue; and the reason I recommend a power regenerator unit.

Yes, I suppose you could get someone with an oscilloscope to look at what's coming out of your wall, and who knows, you might be the lucky utility customer who is getting constant 120V with a perfect 60 Hz sine waveform and full current at all times, but let's face it, that's not likely. And even dedicated circuits can't improve on what's provided by your power company. All they can do assure you that you're getting whatever is coming from the pole; and without noise from intervening devices within your house -- so dedicated circuits are only a "solution" if you have good electrical service to begin with (which thankfully is true probably 90% of the time in this country.)

Audio gear will perform best if it has "ideal" AC power available, and that's what regenerators do. They RE-generate the "house" power into "ideal" power, with negligable losses these days, due to the real-time analysis provided by modern computer processing techniques. This kind of economical "regeneration" was not even possible a few years ago. Normally, any filtration (conditioning) they might also provide is done before the regeneration takes place so it can't affect sonics. Ditto for surge protection circuits, if they are even provided (most manufacturers realize surge protection is a myth, and don't do it -- not to reduce the cost, but because "token" surge protection degrades sonics.)

So bottom line, here's my position on all this:

1.) If one can do dedicated circuits, then 90% of the time that'll give 90% of possible power improvement benefits. If one then wants to add some "finishing touches" with an isolation transformer and/or a balanced power unit for sources, great, but definitely much smaller bangs for your bucks.

2.) If you must use an existing house circuit, be savvy about which one you choose. If you have a choice, pick a 20A over a 15A, and pick one that just has a few low power, low noise devices on it (like incandescent table lamps.) And then plug in a regenerator to take the place of a dedicated circuit. If, (as with dedicated circuits) you want to add other power devices to the regenerator, that's up to you.

That's my thinking on the matter ;--)

Has anyone ever seen any data that shows that the power supply filtering in a component is not adequate for the typical household AC?

Also, how exactly does dedicated lines help? Aren't all the circuits tied together at the AC service panel?


Thanks for the advice. As always you are very helpful. I do use the 20a circuit for my gear, just not dedicated. There are a total of 7 duplex outlets on that circuit, but to my knowledge, no light switches to my knowledge. I just have audio gear plugged into one of those duplexes via the RSA. The others are not in use.

If I can get a trial on the EP I may give it a whirl. I'll have to look around and see.
Bob, yes they're all tied together at the panel, but a dedicated line means there is nothing else on that circuit but your audio, so there's no other equipment on that line between your audio gear and the power pole (except for that circuit's breaker and the main electrical cut-off switch) and so nothing (in your house at least) to introduce noise into, or reduce current in, the line used by your audio.

Clio, one thing that you could do to get the most out of your non-dedicated circuit is (first cut the power at the breaker) and rewire all the outlets on that circuit, making sure you use the screw terminals (not the push connections) and making sure all the wire and teminals are clean (you can use Caig De-Oxit) Generally, the electricians daisy-chain the outlets, so if your audio system isn't using the first outlet after the circuit breaker, then there are a lot of connections between it and the panel.
Nsgarch, sorry, but I'm still missing something. I'll start a new thread.
Nsgarch - no can do since I rent and the system is not using the first outlet after the breaker. In essence I'm probably back to looking at balanced power and power regeneration options. I was hoping to save a few bucks but it doesn't appear I can.
Bob, I'm sorry, i was responding to your question about dedicated circuits. As for equipment with built-in filters (and even built-in surge protection) I'm afraid the answer is a qualified "no". And here's the reason: If it's to be done in a way that doesn't degrade sonics (like happens with cheap, separate, surge protector and/or noise filter units) it's going to cost the manufacturer a lot -- in some cases more than the component itself if the component is in the $1000 - $2000 range. Sure, stuff like a Mark Levinson 33 or 33H amp has its own built-in non-sonically-invasive regenerator power supply but those pieces are so expensive to start with that the additional cost represents (I would guess) only 10% of their purchase price, so it kind of makes sense for them to build it in and do it the way they think it should be done, and not require their customers to have to make those additional decisions/purchases.

For less expensive equipment, what the manufacturer could provide within their pricing target really would do more harm than good. So it makes more sense for the customer to buy a $2000 regenerator/conditioner/balanced power unit which can then supply really properly produced power to a number of components.

Hope that throws some light on the subject.

Nsgarch, actually I wasn't implying anything unusual or additional to the standard filter capacitors and regulators within a component's power supply. We tend to assume that whatever noise is on the AC line finally reaches the amplification stages and, of course, manufacturers of all sorts of power conditioners promote that idea. I was wondering if there is any real published evidence that it's a problem.
Basic question: Why isn't the noise on the primary side of the isolation transformer induced onto the secondary? Is it not an AC voltage?
Bob, my experience w/ isolation transformers is limited to a brief flirtation about 30 years ago. I'm not sure why people use them. And what you say makes sense at least for most frequencies (although I don't think they pass RF) I think they do offer the ultimate in surge/lightening protection at the possible expense of frying the primary side of the transformer!

As for AC line noise, I can't point you to specific documentation but you shouldn't have much trouble finding it on Google, as it certainly exists. Personally, I'm not terribly concerned with that issue either, as I am with ample, accurate power, and here's why: Most noise in a system comes from what the components and ICs pick up in transmitting and/or processing the audio signals and not from the AC line noise. As you say, decent power supply design should take care of most of that, particularly in power amps. As for source stuff which is processing weak signals, yes noisy AC can be a bigger problem, especially for preamps and more so for tube preamps (and then of course there's the RF your digital stuff (can) put back into the line. But my solution to that is to avoid the problem altogether (if one has a problem) by using noise-cancelling balanced power for the front end components.

Jim Aud (of Purist Audio Design) pretty much convinced me that the first thing to cover is the issue of (AC) energy transfer from the reservoir of electrical potential in your wall, to the component. Which is why that last 5 feet of power cord is so important (I know a lot of folks have a hard time wrapping their heads around this ;--) Using minimum 10AWG PCs for amps, power regenerators, and for some weird reason, DACs, seems to me makes the next biggest difference, after dedicated circuits.
Nsgarch, since my post about dedicated circuits didn't get done, I'll ask here again.

Since all the circuits from the same service panel are in parallel and tied together at the service panel, by what mechanism are they isolated from each other so that noice created by a device on one circuit does not contaminate the other circuits?

My analogy is this. My neighbor cranks up his arc welder and my TV shows the effect. All the neighbors sharing the same power transformer are parallel circuits and tied together at the power transformer. Isn't this the same situation, but on a larger scale? What am I missing?
Without knowing anything about your digital set up one can only generalize; and' I would like to point out I am not in the industry and have no affiliations but I am very fussy after 39 years of record collecting and do enjoy a very revealing and musical system based on reference level Spectral, Goldmund and MIT products. You might want to investigate Equitech's factory blems sale. They have had & will again be selling some model "Q" balanced 'transformers in a box' at a huge discount from the cost of a retail 1.5 or 2Q. One will provide you "dramatic" power line conditioning and isolation for ~$400 and the benefit in sound quality would provide a great foundation for you to more easily & accurately evaluate the benefit of further conditioning items in the future. I bought one and found it to be a stunning value and wouldn't be w/o balanced power ever again. Best of luck. Pete
Bob, each separate (branch) circuit in your house is referenced back to the (transformer on the) pole. The (available) energy at the pole is so enormous compared to that carried by each branch leaving your panel that it's virtually impossible for one branch of a house to "inject noise" onto another branch which is also returning its current to the pole. That's why you don't/can't hear it. This is not strictly true, for example in the case of large apt/condo complexes where you have many, many panels working off of the same transformer, in which case the AC at the transformer itself can be pretty polluted -- but in a typical residential neighborhood, there are no more than a few panels (houses) on each transformer. In fact, when I was a homeowner here in Tucson, lightening severely damaged our (1/2 dozen houses) pole transformer, but it was still working (kind of) and noisy as hell before it finally gave up the ghost and got replaced!

As for your arc welding neighbor, he could cause a slight voltage drop in your local grid if the power transformer capacity has become marginal after a few people in the neighborhood have replaced their panels over the years with higher capacity ones, until the utility company finally has to put in a bigger transformer (or the existing one blows!) But the noise and interference from the welder isn't in the electric grid, it's being broadcast over the air as radio frequency interference from the arc -- causing snow on your TV (and possibly noise in your phono or on your FM tuner.)

Large iron core isolation transformers are very effective in protecting sensitive equipment from AC voltage transients, spikes, and electrical noise appearing on commercial power lines.

Iso transformers are designed to be exactly opposite to audio transformers. While an audio transformer needs to pass all audio frequency power uniformly, an iso transformer is designed to transfer power only at or near 60Hz. Frequencies below that are attenuated by operating the iso at relatively high flux densities, and frequencies above that are reduced by introducing as much leakage inductance as possible, consistent with good power transfer to the output side.

Power line noise exists in two forms: "common mode", which appears between both sides of the power line (hot and common) and ground, and "transverse mode", which appears from line to line. With good design, and the intelligent use of shielding and grounding, an iso can reduce both by as much as 120dB, and this specification is usually stated by the manufacturer, and sometimes stamped on the faceplate.

If the power line ground is shared on both the input and output sides, excessive ground line noise from other circuits can be transfered. In that case, it is advantageous to run a separate clean ground to the transformer frame and output side.

I am using a 4kva Topaz iso on 4 dedicated circuits, one each for CD, phono, pre and amp, and have realized a noticable overall improvement. I am also using a second 125va iso on the CD to keep its noise from getting back into the other dedicated lines.
Thanks, Nsgarch and Zargon. I appreciate your contributions.
I recently bought a Furman Elite 15 and was extremely pleased with the difference it made, especially with my video components. The Furman Elite 15 cost around $300.
When you implement a isolation transformer that is not purpose made for Audio, you might want to consider using an isolation platform or tweak, such as Aurios Pros. In addition, I always install an after market duplex receptacle(s), such as a Porter Ports and new wire to the receptacle(s). I always get the electrician to install a 240V line with a 30 amp breaker too. This really helps a stock unit do its job.
Boy some experts are missing the boat here!!

The isoloation transformers purpose serves (2) main purposes.

Voltage correction/protection and isolation of common mode noise..

Balanced power does not equally best esp on some regen units. Some line level gear designs do not like balanced power on because of their filter and grounding schemes.

yes an Arc welder DOES>> induce noise back thru the line and can cause some horrid THD problems .. sames as inverter duty drives in manufacturng plants!! I know.. seen it on a scope with TVA engineer... seen it disappear when 300 HP drive motor in a plant 6 miles away was shut down.. No air born RFI there!!

I live on the main power grid half way between (2) industrial parks 5 miles apart. I could not listen to my gear if it were not for iso transformers.

I have 3 types..
5kva 240/240 balanced for some of my amps
2.5 Kva 240/120 balanced for my Crown K2
both with faraday shields EI type

1kva 240/120 medical iso unit for line level gear.
1kva 120/120 medical iso unit for digital gear

There are ONLY 2 reason transformers make any sound difference..

removal of common mode line noise.. quiter background

or compressed dynamics.. current limiting!!

You need to measure them for the lowest resistance per KVA load.. that means bigger wire..less copper more iron..
less current limiting..

Rule of thumb..unless you spec build a transformer for certain peak current demands ( my 2.5 kva unit will do 60 amp peak)size your transformer 2x the needed current load to prevent current limiting and do not use them on amplifier circuits.
Did you end up getting an isolation transformer? I discussed using a medical grade isolation transformer on another thread.
Sabai, I did try a Topaz unit and also tried the Exact Power unit recommended by Nagarch. I actually preferred the Exact Power. The isolation transformer actually was prone to mechanical noise. At the time I was living in a triplex in CA and the power fluctuated quite a bit from 110V to 118V. When my neighbor used her hair drier or turned on her AC unit the effects the transformer made lots of noise. Probably something getting injected back into the power line causing it.

These days I use products from Alan Maher Designs. I have been quite happy with them.
I am surprised to hear the neighbors affect your transformer. I have no such problems. My transformer emits a constant hum but the music drowns it out. The level of hum never changes. I bought it on Ebay. It is a high quality made-in-Germany non-balanced medical grade isolation transformer. I was hesitant to buy it because it is heavy and the shipping costs are expensive -- I live overseas. The moment I connected it I knew it was one of the most significant things I have ever done to improve the sound in my system -- a quantum leap.

Which Alan Maher products are you using?
Sabai, I was pretty surprised as well. The Topaz units come highly regarded and yes mine was heavy as well. I think they are fine units and my business partner and I have discussed building our own since he winds transformers. So I might give it another go.

For about 6 years now I have been using the Alan Maher PE's and CBF's. The PE's are plugged into various wall outlets and the CBF's are installed in my circuit breaker box. I also have one of his power strips with PE technology. The PE's provide power factor correction and line conditioning.
The Topaz are highly rated. This is a mystery to me. I have some of Alan Maher's CBFs in my system. I have not seen the PEs before. I'll look them up. I use a lot of Jack Bybee's products.
Sabai, I have a set of speaker cables that incorporate Bybee technology. If you are a fan of Bybee's the Alan Maher PE's would be of interest to you or perhaps some of Alan's newer quantum designs.

The Topaz was indeed a mystery but resurrecting this thread has convinced me to revisit an isolation transformer. Thanks for that.
How do you get a hold of Alan. Thank you.
You're welcome. I took a long hard look at the Topaz when I was shopping for an isolation transformer. The Topaz was actually on the top of my quality list along with other balanced transformers but the price and the weight (extra shipping costs to get it to me overseas) had me stop short. I was trying to figure out if an unbalanced, lighter and cheaper unit would do the trick. I gambled and won -- big time.

Thanks for your offer but I don't think I need any more Bybee products at the moment. I have 3 of the Bybee Ultra power cords and 9 of the Bybee AC Purifiers. But please let me know the details -- in case. You can message me if you wish.

And please let me know which Maher quantum products you are referring to.
That is a good question. He used to have a Facebook page but it appears now a website is up again:
Thanks Clio09
I have to say after looking at Alan's website and noticing his Facebook page seems to have all content removed I am wondering if he is still offering any new products. My last dealings with him were 5 years ago and I have been really happy with the original set of PEs and CBFs that I have not had a need to address or purchase anything else from him. So unfortunately I am not sure I can be of much further help. Maybe someone else can chime in.
I took a look and saw there was no content on the Alan Maher site. We'll have to wait and see if he comes up with some products. I read that he dropped out for a while -- rumors. What are the PEs? I have never seen them.
Here are some pictures I found Googling them. You just plug them into outlets around your home. My method was to use onion every independent circuit in the home. In some cases I used two in parallel or series on the same circuit. You had various son tuning the circuit doing this. Over time the original PE design evolved but I still use the originals.

I know Alan used to work for a few different rock bands and last I knew he was living in Germany where his wife is stationed. Not sure what is up with him these days.
Thanks for this link. I have never seen the PE before. I would be interested in learning how they are working for you.

I have an Essential Audio Noise Eater, a couple of Kemp products, 4 Schumann resonance devices, a Quantum Symphony Pro and upwards of 20 Bybee products. The latter are the most effective, by far.

Have you heard the Nordost Quantum Qx4? From what I have read they do a very good job but all the reviewers talk about using multiple units in their auditioning sessions. I have never read a review when only one was used. At $2000 a pop this makes for a VERY expensive tweak.
Sabai, the PEs have been working great for me. They provide more than adequate noise reduction and they allow for flexible tuning. Depending on if I use them in parallel or series configuration I can dial in the sound as desired. Sort of like adjustable bias or tube rolling in some respects.

I have the Quantum power strip which offers a smaller dose of what your Quantum Symphony provides. I was very surprised at how well this product worked with video. I believe the developer of these products sold the IP to Nordost which in turn has raised the price of entry for audiophiles to acquire this technology.
Thank you for the details. Since I have no experience with the PEs this information enables me to get an idea of how they function in your system. I have never seen the PEs come up for sale on the aftermarket.

I am aware that Nordost bought the IP from Symphony and repackaged the technology at a much higher price point. I don't know how many cells the Symphony and Symphony Pro contain but the QX2 contains two and the QX4 contains four. I have no idea if Nordost modified the Symphony products for better performance or if the QX2 and QX4 contain essentially the same components as the Symphony products.
Sabai, found an old review I posted on Audio Asylum:

There is on on Audio Circle as well that I will look for. Hope this helps.
Thank you very much. I'll take a look.
Just don't dare send the item back for a refund... he can be unstable.