Variac vs. Isolation vs. Balanced Transformer? ALL

Undertow, although on the high side, 128V is within the ± 10% utility company voltage tolerance in North America. The voltage at my house has always varied between 121.0V and 124.5V depending on the time of day. Coupled with the small no-load voltage boost from my isolation transformers around 1.5% and I'm typically looking at peaks of around 126.4V. I once called up the manufacturer of my equipment to enquire about maximum tolerable line voltage and was told not to worry, that the components are designed to tolerate up to 130V with no problem.

Gbart, You are absolutley right… They are built to tolerate 110 to 130 volts… However that is not the range they sound best in! For sure the best sound comes from most gear in the 115 - 118 range… Mainly this is due to circuits sound more hyped up or "Grainy" with higher voltage mostly from amps bias being thrown off, gotta remember this gear is built and tested on a bench running a variac of sorts feeding them dead on dialed in voltage for testing. I have heard regenerators and even cheaper monster power centers (yeah the ones with the cheesy red digital readout) sound pretty good when knocking that voltage down.. The higher the voltage the less beef you get it seems, thinned out, less amperage, bass is not as strong, and most people complain their gear sounds bright but its simply the wall outlet is really high!

Trust me I had one time solid state amps that had manual adjustable bias banks on the transistors.. I was running about 126 volts from the wall… Brought the bias MA into range to counteract it and bam they went from ragged, tipped up mid fi sound to nearly the best smoothest balanced gear I had experienced! Now of course this was not a solution, because as you say you would go crazy daily going inside with mini screwdrivers adjusting the gear each time to get optimum bias etc… due to your varying voltage from the house.. This is why killing the issue off at the front right from the outlet and leaving the gear at the factory set adjustment would be best. Anyway I have made a decision and purchase..

Balanced / isolation transformer… It will have about a 5% loss bringing my wild voltage down to about 122, and in theory in turn give me 61 volts per phase on the output plenty low enough now being split into a balanced load for any gear to run much more optimally for the most part. Nothing fancy, nothing current limiting or adjustable just one continous clean output more or less regardless what the wall is doing, each leg will not vary much more than between 58 to 64 volts lets say which is not gonna be any kinda real shocker vs. how much difference there seems to be when running straight AC at 115 vs. nearly 130! Big difference in audio and video in my opinion.

By the way hi grade test equipment for accuracy and hospital gear and instruments are of course very sensitive much like your audio gear and for best consistent performance trust me they DON'T trust the Power company to get them 110 to 115 volts all day! They take many steps and pieces of power gear to make sure this is done internally.

Thanks for the suggestions.         

As far as iso vs balanced...

http://mysite.verizon.net/vze22yzp/id10.html

There are regulated transformers such as Sola (MCR series), Stabiline and Powerware (50Hz) that will correct (95V to 130V) but I doubt you'll want to be in the same room.

Undertow,

128V is pretty high. You must go through a lot of burned out light bulbs.

Are you sure the volt meter you are using is giving you a correct reading of the voltage? Is the meter displaying true RMS or peak?

I am looking to keep the system self contained and moveable vs. hardwired built in. I will have to take advantage of existing circuits for the time being. it
Undertow 06-02-09:

You still could get by using one main isolation transformer and a small panel. Especially if your main electrical panel is in a basement and is exposed and easy to connect to.

Of course you will need to hire an electrician to do the job.

Install the transformer and new panel close to the existing panel. The electrician can easily move the existing audio branch circuits to the new panel.

I would suggest buying a transformer with a 240V primary and 120V secondary. You may have to get one with a 120/240V secondary and just parallel the two secondary windings, 120V out.

Here is the kicker though... You will need one more smaller transformer. This transformer will be a buck transformer connected between your main electrical panel and the primary winding of the main iso transformer. The buck transformer, (configured as an autotransformer), will lower your now 256V mains down to 240V.

Balanced / isolation transformer… It will have about a 5% loss bringing my wild voltage down to about 122, and in theory in turn give me 61 volts per phase on the output plenty low enough now being split into a balanced load for any gear to run much more optimally for the most part. Nothing fancy, nothing current limiting or adjustable just one continous clean output more or less regardless what the wall is doing, each leg will not vary much more than between 58 to 64 volts.........

5% loss? Please explain the 5% loss.

NEC 2005 Code Article 647. Same for 2008.
http://www.equitech.com/support/647.html

Note, the neutral is connected to ground. The 120V out for power use is two ungrounded hot conductors.
.

Jea48, I purchased a Balanced transformer that will be 60 - 60 v out… The 5% loss is supposedly just from going thru the transformer, it is a 1000 va size, and I am told by the manufacture there will be about a 5% loss in voltage essentially giving you a slight step down in the process.

AS for light bulbs I have been using the ergo style flourescent newer curly Q looking type with no issue, but they have their own balast circuit built into the base which is why I think they cost more so this is probably why they don't burn the element as they are stepped way down from that internal ballast anyway unlike a cheapy 50 cent incandescent bulb.