Using an Isolation Transformer to Reduce Line Noise

Moose68Bash

In the thread "Dedicated Outlet and Amperage - Part Deux" I asked whether installing an isolation transformer in a dedicated circuit would help eliminate noise from other household circuits.

DarqueKnight answered, "Yes."

Now, as I begin planning to install a dedicated circuit to supply power to a pair of monoblocks, I would like opinions about whether that is a reasonable idea: Would the benefits likely justify the costs?

And, if using an isolation transformer for this purpose seems reasonable, how does one determine the right specs for the transformer? At 115V, 15 amps, input each monoblock's rated power output is 750 watts into 8 ohms and 1300 watts at 4 ohms, and the maximum current output is rated at 160 amps.

My thinking so far is that I will install a dedicated 20 amps, 10 AWG Romex line from a subpanel to a receptacle for the monoblock power cords that is a close as possible to the monoblocks (to minimize the length of the power cords). I plan to use high quality outlets. I would install the outlets in an aluminum box holding the isolation transformer (like a Dreadnought box), if I use a transformer in the circuit.

Any thoughts would be greatly appreciated.

Thank you.

Moose68Bash

I think I figured out how "to size" the isolation transformer for capacity to handle peak current output of the two monoblocks:

2 x (160 Amps x 120 Volts) = 2 x (19,200VA) = 38,400VA

This is one very large and heavy isolation transformer! And probably very expensive!

Is this overkill?

Does it need to be sized for peak current output?

The monoblocks are rated at 15 Amps. At 15 Amps x 120 Volts = 1,800VA, it would seem that an isolation transformer of somewhat higher than 3,600VA would be adequate.

But how much higher to give adequate head room for short "bursts" of >3,600VA load?

Thanks.

RamZet

http://www.amazon.com/Panamax-M4300-PM-Outlet-Clean-Power/dp/B000SXWGDI
That is a Panamax 4300 nine outlet power conditioner. It will protect against surges and clean the noise out of the power lines.

Moose68Bash

RamZet wrote: »

http://www.amazon.com/Panamax-M4300-PM-Outlet-Clean-Power/dp/B000SXWGDI
That is a Panamax 4300 nine outlet power conditioner. It will protect against surges and clean the noise out of the power lines.

Ramzet,

Thanks. I'll check out Panamax products. I need to be sure that any device I install can handle the peak loads of my amps.

F1nut

My thinking so far is that I will install a dedicated 20 amps, 10 AWG Romex line from a subpanel to a receptacle for the monoblock power cords

Since you are installing a subpanel look into one the offerings from SurgeX. You won't need any other power conditioner, surge protection or isolation transformer.

http://surgex.com/products/powerframe420.html

Also models XN120 and SP80

Moose68Bash

F1nut wrote: »

Since you are installing a subpanel look into one the offerings from SurgeX. You won't need any other power conditioner, surge protection or isolation transformer.

http://surgex.com/products/powerframe420.html

Also models XN120 and SP80

Thanks, F1nut. Will do.

Moose68Bash

In following up on the recommendations above -- SurgeEx and Panamax -- I came across Torus Power products.

Has anybody had any experience with them?

Speedskater

Moose in the first part of your second post, you used input voltage and output current to come to an incorrect VA requirement. In a non-technical sense, Volt-Amps and Watts are just about the same thing. The input volts = 115 and the input amps = 15 so the input VA =1725 (that's over twice the amps rating).
Now with isolation transformers we want to be conservative, maybe 2250 VA would be good for one amp. A 5000VA transformer is a big transformer with lots of thermal mass and should be more than enough for both amps. (you don't listen to full volume test tones all day do you?) Even a 3000VA transformer would easily work.
A big problem with large transformers is finding a place to put them. You want it near the listening room, but not to near your equipment. You don't want it in the listening room because some have an audible buzz.
Middle Atlantic has a great paper that shows how to install isolation transformers.

Moose68Bash

Speedskater, thank you. I'll read the Middle Atlantic paper.

Speedskater

The circuit using the transformer with a 240 volt input and then two 120 volt outputs with the system wired as a Separately Derived Source (SDS) is the best one.

Did you find the white paper?
"Integrating Electronic Equipment and Power into Rack Enclosures"

Moose68Bash

Speedskater wrote: »

The circuit using the transformer with a 240 volt input and then two 120 volt outputs with the system wired as a Separately Derived Source (SDS) is the best one.

Did you find the white paper?
"Integrating Electronic Equipment and Power into Rack Enclosures"

Speedskater,

Thank you or sending the specific reference. I found two other papers on the site, and they were not too helpful, although they dealt with toroidal transformers and how to wire them in circuits for AV equipment.. I suspected I didn't have the correct paper. Now, I'll be able to download and read it.

Phil

Speedskater

This is the best way to wire the circuit:

from:

http://www.middleatlantic.com/pdf/PowerPaper.pdf

Moose68Bash

While doing my research on the various options available for cleaning up power from my mains, The Cable Company offered three used Silver Circle Audio 5.0 power conditioners at steep discounts. These are basically 5kVA toroidal isolation transformers prewired with eight audio-grade outlets.

I checked with the managing engineer at Perreaux Industries, who told me that the 5kVA transformer ought to have more than enough capacity to keep the P750 monoblocks supplied. The Cable Company technical advisor agreed and opined that it should also have enough capacity to supply my preamp and CD player, if I want to connect them as well. An Equi=Tech advisor had told me that a 3kVA transformer ought to be adequate.

Next week my electrician will install a dedicated 30 amp circuit to supply the Silver Circle Audio 5.0.

An expensive proposition. I hope it works, and I'll post results when I have some to report.

DarqueKnight

You could also get the power company to install a dedicated transformer for your house. I considered it for my house back in 2009:

DarqueKnight wrote: »

My subdivision is served by underground facilities. The cost, inclusive of digging and trenching, to provide a dedicated transformer at my residence would be $5,635 ($3,968 for equipment, $1,667 for labor). This figure is much less than my total expenditures for inside power infrastructure upgrades: dedicated 20 amp AC circuits, audio grade power cords, AC regenerators, passive power conditioners, and audio grade AC receptacles. It is a very reasonable expense considering my investment in high resolution audio and video equipment. If I planned to be in my current house for a long time, and if the amount of noise reduction would be in the range of 5 to 10 times, I wouldn't hesitate to have the dedicated transformer installed. Averaged over 10 years, the transformer cost would be the equivalent of an additional $47 on my monthly power bill. This is less than my cost would be for a monthly subscription to a digital cable premium channel package ($67) or premium high speed Internet service ($57). I will definitely consider a dedicated transformer or a commercial grade AC regenerator (or both ) for my next house.

I asked the power company engineer if my dedicated transformer request was unusual. His reply:

"No. We often get requests for custom power configurations from customers who want lower harmonic power for their electronics. We also get custom configuration requests from farmers who need to have their power delivery configured so that electric fields don't affect their livestock. The chief complaints being chickens that stop laying eggs and cows that stop producing milk."

Moose68Bash

DarqueKnight wrote: »

You could also get the power company to install a dedicated transformer for your house. I considered it for my house back in 2009:

Yep! That's next!

Did they include digging the rabbit hole deeper and wider in that estimate?

Speedskater

Bringing 8000 Volts into the house doesn't sound like a good idea,
Hey DK were any of Sunday's tornadoes near you?

ZLTFUL

Speedskater wrote: »

Bringing 8000 Volts into the house doesn't sound like a good idea,

I think you are misunderstanding. The transformer being referred to is a dedicated transformer for your own house. Instead of being connected to a transformer with 15 to 20 of your neighbors.
You would still be bringing a typical 110/220 volt service in but you would be the only load on the transformer and it would help segregate you from the potential for additional line noise from other houses.

Moose68Bash

ZLTFUL wrote: »

I think you are misunderstanding. The transformer being referred to is a dedicated transformer for your own house. Instead of being connected to a transformer with 15 to 20 of your neighbors.
You would still be bringing a typical 110/220 volt service in but you would be the only load on the transformer and it would help segregate you from the potential for additional line noise from other houses.

I think you are right about this.

One of our neighbors built a new home with a heavy duty geothermal HVAC system and more electronics than I could ever have imagined -- probably rivals Bill Gates's set up. Sound in all rooms controllable from all rooms, security everywhere, ability to adjust temperature and observe interior from anywhere in the world, etc., etc. An absolutely amazing home theater, complete with replica of a concession stand!

He had TWO dedicated transformers installed because he needed 2200 amps of service for all the equipment in his home.

An amazing project to watch. Took about 5 years to build. Here's picture of the room in the basement where the main panels are located.

ZLTFUL

Yup. Best way to 100% clean power is your very own power grid. Barring that, dedicated transformers are the next best thing.

Speedskater

ZLTFUL wrote: »

I think you are misunderstanding. The transformer being referred to is a dedicated transformer for your own house. Instead of being connected to a transformer with 15 to 20 of your neighbors.
You would still be bringing a typical 110/220 volt service in but you would be the only load on the transformer and it would help segregate you from the potential for additional line noise from other houses.

That makes a lot more sense! But it gets real expensive real quick.

"What they don't tell you about owning an EV"
http://eetweb.com/mag/dont_tell_owning/index.html

Moose68Bash

I misspoke above. The Silver Circle Audio 5.0 only requires a 120 volt, 20 amp circuit.

This will make installation of the dedicated circuit easier.

And, I definitely don't need a dedicated transformer or my own power grid!

Moose68Bash

I installed the Silver Circle Audio 5.0 over the weekend, and I got precisely the result I wanted: A dead silent background.

Consequently, everything Lisa and I listen to is better. The sound across the full frequency range is clearer, more precise, richer and deeper. The bass is profound and moving. The G1 note (~48Hz) on the bass is utterly phenomenal -- the vibration of the string and the timbre of the instrument are virtually as realistic as the real thing. The rendition of Livingston Taylor's whistling on the Chesky Records recording of "Isn't she Lovely" makes him sound like he is in the room -- you hear the air passing through his lips.

The sound stage is even more expansive -- at least six feet on each side of the speakers to the right and left, and the "ceiling" is higher by a couple of feet, and the precision of apparent location is greater.

Enough already. This is one addition to our system that even my wife approves wholeheartedly -- and that means everything to me! I wish I could be more scientific about this, but I have to substitute enthusiasm for knowledge!

Glen B

I'm not surprised at the benefits you've found to using an isolation transformer. I've been using balanced power for almost 9 years now. Immediately noticeable is the reduction of the noise floor, and improvements in bass quality, system resolution and detail. I've gone through several revisions since my first balanced power unit, and have now settled on three separate isolation transformers in a single aluminum and steel chassis, each transformer feeding a separate duplex outlet.

ZLTFUL

Hey Glen...you wouldn't happen to have a parts list/schematic of your final iteration would you?
Been kicking around the idea of building one myself for a while now and I really dig your final product.

Glen B

I don't have a complete schematic, only a basic one I created in response to previous requests like yours. My parts list may not be your parts list. I went DIY not for cost savings, but because I did not like the parts choices in earlier factory-built balanced power units. I decided to build my own with the best quality parts I could obtain, regardless of cost. My current parts cost is by my estimate in the area of $2,000.00 - $2,500.00. The transformers alone are approximately $1,100.00. Duplex outets are Oyaide R-1, at $180.00 each. You could start with a single balanced isolation transformer, and make tweaks and improvements from there.

See the following link to a list of discussions on balanced power projects at HT Guide Forum. My project is at the last link listed.
http://www.htguide.com/forum/showthread.php?28320-Threads-about-balanced-power-projects

Here is another link to my project posted at Audio Review. http://forums.audioreview.com/audio-lab-tweaks-mods-diy/diy-balanced-ac-power-conditioner-5473.html

Here is my basic schematic. The MOV wired across the primary is a Littelfuse iTMOV, which has a thermal cutout and third lead, which can be used in a protection circuit/alarm circuit/LED indicator circuit, to show when protection has failed. I employ the latter, using a front panel LED. The circuit breaker size is determined by the size of the isolation transformer. It is a time delay breaker.

ZLTFUL

You da man! Thanks a ton. Looks like I will have another project to occupy me soon.

Glen B

Raw balanced isolation transformers are not easy to come by. Plitron has a 2,000VA transformer, available for sale as a DIY audiophile special on their website for CAD$343.84. See the schematic and leadouts below.

Plitron 2KVA Transformer, Part # 8575-X0-02: http://shop.plitron.com/search_new.asp?Action=Search&SearchTerm=8575-X0-02&Search=Search

Toroid Corporation of Maryland is another source of good transformers. I have tried their 2,000VA transformer though. It was very nicely made, as are all their transformers, and custom-potted, but I found it susceptible to mains DC (hum and buzz), so make note of that. The smaller sizes don't have that issue in my experience. I use their 250VA transformers. You need to call Toroid's sales department to purchase raw transformers, and specify that you want it potted. Lead time is 1-2 weeks, but in my experience 1 week or less.

Toroid Corp of Maryland: http://www.toroid.com/standard_transformers/balanced_transformers/balanced_transformers.htm

Equi=Tech has factory surplus and seconds on sale from time to time, but its a crap shoot finding a suitable transformer. I was lucky years ago to get the big transformer I'm currently using. Its a Q type, with low inrush current, and high immunity to power line DC, same as they use in their Q and Son of Q products.


Plitron 2KVA balanced isolation transformer schematic. Yellow and Blue are tied together to form the secondary center-tap (0V). Red and Grey are the 60V "hot"/"neutral".

ZLTFUL

I was looking at Toroid last night. Thanks for the info.

I am still a while out from taking this on...think I may even hold off until we build our house in 2-3 years. That will also allow me to do the other steps needed such as dedicated circuits (have one for my HT but the circuit my 2 channel is on is chained together with both upstairs bedroom outlets...I do have a power conditioner on that outlet but there is no easy way to isolate that particular outlet completely).

I don't know what it is about toroidals that makes me smile but that beast of yours has me grinning from ear to ear.

Glen B

Two or three years will go by quickly. The information will still be relevant, and sources should still be there.

FTGV

Nice work Glen.I'm also a believer in the merits of balanced AC having built somthing similar a few years ago after reading Martin Glasband's informative articles.I found a suitable surplus Plitron 2x 60VAC 500VA toroid sans an electrostatic shield,but still offers the benifit of differential CMR.At some point I may upgrade to a larger Plitron as this one is really only suitable for source componets.