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I have a Tripp-Lite LC1200 that I acquired free of cost. It features xformer-based conditioning and voltage regulation, providing up to 10 amps to a load via two 2-gang outlets.
From what I have gathered, transformer isolation is more expensive with less current capability than that of transformer conditioning.
The LC1200 I have has a xformer hum that is inducing a vibration into the cords I had plugged into it. The assumption is that the vibration, xformer hum, or both, is/are detrimental to a high-end audio system. I have since plugged the cords directly into the wall, and to be honest, I have not noticed a difference. Even when the mini-frig full of beer on the same circuit kicks on.
My question is, is transformer isolation subject to transformer hum, accessory cord vibration and possible subsequent detriment to the sound of the system? If not, why not?
Throughout my 11 years in the hobby, I have yet to hear a "beyond a shadow of a doubt" difference when trying different things with ac power. I haven't spent much time on it, either. But swapping between different homebrew pc recipes is indistinguishable to me. It's not that I wouldn't like to hear a difference, I just haven't. Maybe I'm lucky that I do not find it a worthwhile pursuit?
But I would like to keep my system separated from the mini-frig and the rest of the items on the shared circuit, if for no other reason than for good measure and peace of mind. Is transformer isolation a worthy pursuit considering the cost? I have a Cary 303/300 cdp fed directly into a McIntosh 200wpc ss amp, so I would need a somewhat beefy isolation unit.
And I did not post this question to start a lengthy discussion about ac power, it's path to high-end components, and/or it's affect on sound. Admittedly I have not spent a lot of time auditioning high-end cords or exotic outlets/wallplates. I have made some homebrew pc's of differing designs (braid vs twisted pair with grounded foil/braid shield) and swapped them out on occasion without hearing anything distinguishable. Based on that fact, I lean more towards ic's between preamp and amp. That is where I hear the biggest difference. TIA...
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If you are looking for an isolation transformer, this might be of interest.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220712491412&ssPageName=STRK:MESELX:IT#ht_1224wt_1141
IME, perhaps more to the point is the Tripp Lite LC1200 line conditioner is not a suitable audiophile power line conditioner other than for a computer audio application; it functions well for use with my iMac (and computer peripherals) including beneficial digital audio filtering -- it sounds pretty dreadful for use with analog devices, though (IMHO). just my 2 centsBTW, I found the Tripp Lite LC1200 line conditioner to be very sensitive to proper vibration control. Simply replacing the stock feet with a quadpod set of Herbie's Audio Lab Baby Booties footers, then placing it on a 3/4-inch thick MDF floor-positioned platform with carpet-piercing spikes improved its sonic performance in a very remarkable manner as implemented for the computer audio server application...
Edits: 12/18/10
I knew it wasn't an "audiophile grade" component, but I figured since it was free and available I might as well use it in the new room. But when I realized it was humming and causing mechanical vibration in the 2 cords plugged into it I decided to go directly to the wall.
I have a gooseneck lamp on a dimmer that I use after sundown. That lamp's brightness dips when the 'frig turns on. The LC1200 would sometimes click at that time. A check of the front led's indicated it was performing some voltage regulation. But even when plugged directly into the wall, I hear nothing at the point when the 'frig kicks on, and do not notice any change in the presentation of the music.
I have a PS Audio outlet that I plan on installing in the electrical box when I locate it in the garage of disarray. I think I will stick with that for the time being while I continue experimenting with speaker placement and ic's. I have been switching back and forth between RCA and XLR ic's while also exploring the upsampling capabilities of the Cary cdp and the 2 input sensitivity settings on the Mac amp.
In the old house, my rig was in a bigger room (16 x 22) which allowed me to sit further back from the speakers. I am now sitting closer in a smaller room (about 17 x 19). I am hearing more low-level detail in this new room. If I were ever going to hear any differences in AC supply (pc's, conditioners, wall accessories, etc), this is the arrangement that will allow me to do so.
If you have a computer audio rig or perhaps try it on a TV video display, I would suggest placing it there and obtain an audiophile quality PLC for your main audio system. There are plenty fine ones available at various price points...
Cheers, Duster
You probably don't need the over/under voltage correction features, which are the main point of this device. It does have surge suppression and EMI/RFI noise filtering, which would help if your system had problems with these, but simple power strips can also have these things.
To see if your refrigerator causes problems, simple listen to some good, detailed recordings several times, until you are familiar with their sound, then unplug the refrigerator and listen again. Improvement will be obvious if there is any. If not, don't bother with an isolation transformer.
The purpose of isolation transformers is to remove any offset between neutral and ground potentials (which can be found in large industrial and office buildings). Sometimes they help with audio systems by absorbing RF noise. However, if there is not much RF noise, or your equipment is not sensitive to it, you would not notice any audio benefit.
As bartc pointed out, there are possible issues with DC on the AC causing mechanical hum. They also add series impedance and can degrade the dynamics with some power amps. These problems may outweigh any feeling of security such a device might give you.
I have been sticking with a couple of reference cd's since moving into the new house. There are low-level details, spatial cues and soundstage placements that I have been paying close attention to.
Perhaps the power supplies in the Cary cdp and McIntosh amp are immune to any "dirty" AC that might exist?
As I stated in another reply, I used to draw the line at AC power supply due to having a dedicated run from the breaker box. And I try not to fall for everything available to us lunatics as I did when I was a rookie. But I do not want to totally discount anything that might provide better sound now that I am in a more intimate setting.
The quick way to tell if you have audio system sensitivity to RF noise sources within your house is to compare the sound against the situation with every circuit except the audio system's turned off at the breaker panel. All non-audio appliances that share the audio system's circuit should be unplugged as well.
Audio system components themselves can generate electrical noise, so passing this test does not mean there would not be benefit in isolating the components from each other. It also does not test for external sources (appliances in neighbor houses, cell phone towers, etc.).
However, if you identify local noise sources, you can install EMI/RFI filters on the AC supply to the offending appliances.
In my situation, the satellite TV converter/DVR is the largest noise source, closely followed by the power supply in a Vizio TV. A combination microwave/convection oven is also a major source. All of these are on different circuits and in different rooms from the audio system. The Vizio TV not only pollutes the AC, it broadcasts noise and I have to unplug it for serious listening.
Saturation type transformer can be noisy.
For isolation, you needs to use a properly designed one with perhaps 50-70 dB of isolation and these are expensive.
I don't know what you mean by transformer conditioning, unless you are talking about using inline chokes.
"Reliable transformer-based voltage correction circuits maintain 120V nominal output..." followed by: "Network-grade AC surge and EMI/RFI noise suppression."
I assumed the transformer was doing it all. There is no clear explanation as to what is performing line conditioning.
If you don't hear any problems when your 'fridge starts, stops or runs don't worry about it. I did have problems with mine making the occasional horrible glitch at turn-on so I had to add a filter out of concern for my speakers. Since then it's starting relay failed completely and has been replaced so I might be able to get by without it but the root cause is the house wiring. The circuit that feeds the stereo runs cheek to jowl with the one running the refrigerator but a relatively cheap Isobar filter cleaned up the resultant HF coupling.
I too have found that interconnects make the most difference in my systems, guess it depends on where their weaknesses lie with respect to your environment.
Regards Rick
That's interesting. In my system power cords had a much bigger impact, followed by speaker cables, and finally interconnects. I experimented with power cords and speaker cables to get the big picture right, and then tried different interconnects to do the fine tuning. I wonder why our experiences differ.
"I wonder why our experiences differ. "
Off-hand I'd suppose that it's because we have different gear and different environments. Maybe even different priorities concerning sonic trade-offs.
The key thing in my book is figuring out what it takes to make your system work good enough for your tastes that you love it. I hate to admit it but I can remember a vacation long ago where I was eager to get home, not to see the pets, relatives, hearth or home; but I was missing my stereo...
And that was with stock interconnects...
You know, I wonder why cables weren't regarded as especially critical in the last century but in this one are regarded as crucial elements worthy of spending big bucks on. Was I deluded then or now? Or have we done something to our gear to make it generally more cranky? Or have we developed more exquisite tastes?
One thing I know for sure is my hearing isn't as good now as it was then so maybe the difference is in the aging of the audiophile population.
Regards, Rick
Its NOT a transformer based conditioner, its an autoformer based voltage regulator. While it will preform gross voltage regulation, and possibly some form of noise filtering, it cannot provide the galvanic isolation of a real transformer. Galvanic isolation is the principal mechanism of power filtering from transformers. An autoformer lacking a separate primary and secondary windings cannot implement a grounded shield between them to capacitievly shunt noise to ground. Google is your friend.
"I have made some homebrew pc's of differing designs (braid vs twisted pair with grounded foil/braid shield) and swapped them out on occasion without hearing anything distinguishable. Based on that fact, I lean more towards ic's between preamp and amp. That is where I hear the biggest difference."
Then consider yourself lucky as you don't need to spend money on power cords. Then again, while my efforts at building a jet plane have been unsuccessful, I do believe others have had more luck.....
I see you are a soon-to-be power cord manufacturer. Can you share with us what will make your product stand out from the crowd? Not trying to start an argument, just genuinely curious as to what would drive one to enter into the crowded high-end pc arena.
Not soon to be, but self sustaining for the last 2 years, albeit with really poor marketing and a useless website. My background is in power conditioning and it was the counterintuitive realization that regardless of the power conditioning efficacy, the cord connecting the conditioner to the wall (as well as cords from the conditioner to components) still has a major influence that prompted the masochistic efforts.
As to what makes my products stand out, this is not the proper venue, and can only suggest you look at the various reviews on Audiophilia, Positive Feedback, and soon, others. YMMV
Or hummmmm. Trannies have a tendency to hum. Lots of explanations, but there you have it. If it isn't loud, like a ground loop can be, then you'll just tune it out eventually, after you do what you can to mechanically damp it.
As to what you're calling isolation, well, not sure what you want. But here's a stab at it.
I found that I had a DC loud hum whenever my wife turned on her hairdryer in another room even on another circuit. It came from my sub. (I had other sub hum problems that weren't ground loops, but that's not relevant here.) At another inmates suggestion I built one of the simple DC blocker circuits, many of which are posted here, built it into a power strip and plugged my sub into that.
Result was no discernable limit to dynamics, but complete blocking of the DC buzz from my wife's hairdryer.
This kind of DC blocking might be what you're seeking. I'm told that it might limit dynamics on analog amps, however, so it isn't a cure all.
As to other AC tweaks, there are many posted here that you can DIY (or buy if your pocket is big enough). They DO work in my system and in any others that I've worked with at friends, both audiophile and not.
Of course, if you can't hear the difference, why pay for it? Try it from a commercial source that permits full refund returns. What do you have to lose?
I have isolated and balanced power via the Jon Risch design. The isolation transformer is a Signal Transformer DU-5 (5kva). Will a DC blocker ahead of the DU-5 be beneficial? If so do the values/capacities of the diodes and capacitors need to be increased?
Isolation transformers mechanically isolate the load from the line. Just wondering if they, too, are susceptible to hum, and is that hum capable of causing vibration in a cord plugged into said unit. If so, is it worth worrying about.
Like I said, to "isolate" my system from the other gadgets on the circuit, or the rest of the circuits in my new house/neighborhood, would give me a warm fuzzy. Possibly nothing more. I won't know unless I try.
My old house, where I began my plunge into this hobby 11 years ago, had a dedicated run from the breaker box. I drew the line at incoming AC due to that fact. I made a couple of homebrew pc's, but that was the extent of my AC experimentation. Now that my rig is on a shared circuit, I am willing to give isolation/conditioning a try to see if it makes a difference. Nothing ventured, nothing gained.
Yes, in my experience, isolation transformers are susceptible to hum. Equi=Tech "Q type" transformers are designed to be less susceptible to DC. Plitron Lo-No transformers are also supposed to be quiet.
As makers are trying to save on costs, transformers are getting worse and worse when it comes to N&V.
I have found Japanese units much better than European ones, followed by US makes for 50Hz regions, in that order.
Maybe your trying to fix a problem that doesn't exist? Just my preference but I like to identify problems before I try to remedy them. Measuring noise on your AC with an oscilloscope would be a first task. Then you can determine with some certainty what you need.
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