Heavy Metal: my new Signal DU Balanced Iso Transfomer

drumminman

I have a DU-3 that I've been running my power amp off and it has produced very good results. It's easy to hear the bump in clarity and smoothness compared to plugging the power amp directly into the wall. I've been thinking for a while of getting a larger tranny as the 1500 watts the DU-3 is rated for when wired in balanced mode might not provide enough juice during transients and peaks. Haven't particularly noticed this, but then I came across a DU-5 for a very good price so I pulled the trigger.

Pics below are wiring it and setting it up. The sucker weighs 90 lbs by itself so I mounted it on a piece of cabinet grade plywood with casters on the bottom. Makes it much easier to slide into the cabinet.

drumminman

More pics of the work in progress, in reverse order with the completed unit in the first picture. I'm using a Jena Labs outlet, and Chris Venhaus Teflon insulated copper wire. Probably will add a top plate for protection. With this in place I've plugged my other two analog pieces (linestage and powered sub) into the DU-3, with the CDP having it's own smaller balanced tranny. The DU-5 wired in balanced configuration is rated to 2.5 kva; should be plenty to keep my PA from being power starved. Looking forward to taking everything for a test drive.

EndersShadow

Holy Crap... whats that for again?

drumminman

Provides balanced power and isolation from the AC line. IME balanced power dramatically lowers noise coming in over the AC line. The overall effect is a smooth liquid sound throughout the frequency range, reduced glare, richer lows-mids-highs.

These signal trannies are perfect for this, plus the diy instructions are pretty simple. Jon Risch over at AA posted them years ago, and this is the third one I've built. You can find them on ebay, usually for ridiculous money. I got a great deal on this one.

pitdogg2

I'd like more info on this. Is this better than a dedicated outlet? Cost?

drumminman

It's a different animal altogether. I built this based on Jon Risch's instructions which can be found here: http://www.geocities.ws/jonrisch/catch2.htm

Lots of companies sell these as finished products, but they're usually very expensive, and they use toroid transformers. According to JR, E-I trannies are much better for filtering as " . . . Toroidal transformers tightly couple the AC line to the secondary in a wideband manner. This means more noise, not less, will get through to the secondary windings. Also, toroids tend to saturate much more abruptly than E-I core transformers, and need to be over rated by a much larger factor to avoid compressing the dynamic range of a power amp or other electronics."

My technical knowledge is too limited to go into much more explanation here.

Glen B

I have been doing something similar for the past 9 years, but with toroids. Apart from reduction of an already low system noise floor to vanishing, noted benefits include greater transparency and detail, and increased low frequency weight and extension.

I believe that ancillary parts make a difference. Internal wiring is OCC silver and copper, outlets are Oyaide R-1, IEC power inlet is 20A Furutech gold, all hardware is non-ferrous, including bronze transformer mounting bolts, and breaker is Carlingswitch hydraulic/magnetic.

Speedskater

Some of Jon Risch's instructions may be difficult for others to follow, especially the section about grounding.
This Middle Atlantic paper has much better instructions.

"Integrating Electronic Equipment and Power into Rack Enclosures"
'Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems'

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

FTGV

Nice project Dman,simple and effecteive.I'm also using a balanced AC feed for my source components. After reading some of Martin Glasbands papers a number of years ago I just had to DIY my own.

txcoastal1

So when using the xfmr are you wired in 220 stepping down or are you 120 to 120

Sweet

FTGV

120 volt input.On the output one side is at +60vac the other -60.Ground is at the center tap so you have a full 120 volt swing.

txcoastal1

Any need for breakers or fuses on the output side?

Would there be any issues or necessity using my Furman power conditioner

FTGV

It is highly recommended to have a GFCI recepticle on the output side.On the input side use an appropriately sized fuse or breaker.

jeremymarcinko

Wow, very cool stuff. I don't think I am smart enough to do anything that might start a fire or kill me.

txcoastal1

jeremymarcinko wrote: »

Wow, very cool stuff. I don't think I am smart enough to do anything that might start a fire or kill me.

Just stay away from PFB

drumminman

FTGV wrote: »

It is highly recommended to have a GFCI recepticle on the output side.On the input side use an appropriately sized fuse or breaker.

I have a Jena Labs receptacle on the output side and a 15 amp fuse on the primary (input) side. Never thought about a GFCI, but it's probably a good idea. As far as wiring goes, this Signal Unit can also be wired to account for funky voltages. In the pic I have it wired for 120 on the primary side stepping down to 110 on the secondary. When I measured it with the multimeter it was 110, too low so I changed it to 120.

txcoastal1

Drumminman, and Fred...Thanks for the insite as I think I will be working on putting one of these together. Would like to throw out a couple more questions....as i am intrigued

Up until a couple years I thought isolated grounding was superior but a couple years ago when Buc-ee's incorporated a large UPS system for the vital equipment i.e. servers/pc, fuel controllers, my video equipment bonding came to the table. As I look at this isolation transformer I would think (hit me over the head) an isolated ground would be a better method for the Iso/xfmr.

So if I am understanding correctly this would be my string of components:
Breaker box>>>dedicated 20amp breaker>>>DU-5 with Isolated ground>>>20amp GFCI>>>quality receptacle>>>Furman Elite 20pfi>>>audio gear

What or where would you change this string and why? I don't really believe in over kill.

I have experience in failure of PLC/NLC (power line carrrier/network line carrier) devices due to noise. Along with tube gear picking up noise from either inhouse/city dirty power

So am are my thoughts on the right track or am I just being Frankenstein

Thanks

FTGV

The center tap on the output (secondary) side of the xformer effectively becomes a new isolated ground.Here is a good read from the man that first championed the use of balanced AC power.http://www.equitech.com/articles/enigma.html

txcoastal1

Thanks Fred,

Summary:
Isolation transformer 101

http://www.equitech.com/articles/enigma.html

http://www.polkaudio.com/forums/showthread.php?158746-Heavy-Metal-my-new-Signal-DU-Balanced-Iso-Transfomer&p=2023304#post2023304

http://www.geocities.ws/jonrisch/catch2.htm

http://www.signaltransformer.com/sites/all/pdf/DU-SU.pdf

DU-5 $696

drumminman

txcoastal1 wrote: »

So if I am understanding correctly this would be my string of components:
Breaker box>>>dedicated 20amp breaker>>>DU-5 with Isolated ground>>>20amp GFCI>>>quality receptacle>>>Furman Elite 20pfi>>>audio gear

What or where would you change this string and why? I don't really believe in over kill.

Disclaimer: I'm one who is pretty good at following directions, but my knowledge of EE is limited. I don't really have the background to discuss power line noise and theory - I read what others have done and the effect they're reporting and then decide if I want to try it.

Having said that, the only thing I question above is why the Furman Elite?

Also, remember that when wiring a Signal DU tranny for balanced power remember that the current capacity is reduced by 50%, so in effect a DU-5 becomes a DU 2.5. That's why I added the DU-5, I thought my DU-3 was not able to deliver all the current my power amp was needing during loud passages.

As far as pricing goes, buying new from signal is an option, or you can watch ebay. The only catch is you may have to be patient. I paid $270 including shipping for mine.