[xsb7244]

Some audiophiles have converted the Signal DU-5 to balanced power.  This is suppose to be a big bang for the buck power conditioner.  A new one goes for $696.94  or buy used.  Anybody have a diy balanced Signal DU-5?

[jea48]

Some audiophiles have converted the Signal DU-5 to balanced power.  This is suppose to be a big bang for the buck power conditioner.  A new one goes for $696.94  or buy used.  Anybody have a diy balanced Signal DU-5?

In case you are not aware, when configured, wired, as a balanced power output the transformer is only good for 23 amps max. ( Two secondary windings in series with one another.)

If the transformer is configured, wired,  with the secondaries in parallel the transformer is good for 46 amps max.

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


Bill Whitlock, 9/4/2012
 Overview of Audio System Grounding & Interfacing.
Page 201

So-Called “Balanced Power”
• Properly called SYMMETRICAL power
• Has very seductive intuitive appeal
• NOT similar to balanced audio lines in any way!
• Uses transformer having 120 V center-tapped secondary
• Both line and neutral output blades are energized at 60 V
• Although advertising often implies endorsement, NEC seriously restricts
its use – because it’s potentially dangerous!
• ONLY FOR PROFESSIONAL USE
• NOT to be used with lighting equipment, especially screw-base bulbs
• MUST have GFCI at outputs
• Only technical function is to reduce leakage currents
• Leakage currents are trivial system noise sources
• Reported noise reduction generally less than 10 dB
• Any real benefit likely due to its clustered outlets
This is an example of “marketing gone wild” if ever there was one!

http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

[Speedskater]

Yes, Mr. Whitlock and other experts have been writing that for years.

It makes more sense to wire a big isolation transformer like this:


From the Middle Atlantic paper:

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper"
&
"Addendum to Power Distribution White Paper "
http://www.middleatlantic.com/resources/white-papers.aspx

[jea48]

Yes, Mr. Whitlock and other experts have been writing that for years.

It makes more sense to wire a big isolation transformer like this:


From the Middle Atlantic paper:

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper"
&
"Addendum to Power Distribution White Paper "
http://www.middleatlantic.com/resources/white-papers.aspx

It would be nice if someone were to experiment and test the efficiency of an isolation transformer with its two secondary windings configured as Middle Atlantic suggests.  Basically, splitting the two secondary windings of one ISO transformer and ending up theoretically with two isolated secondary windings.
(Two separately derived AC grounded power systems that are in phase with one another.)

Things worth knowing,
If one secondary winding is used to power an integrated amp how will the dynamic load placed on the secondary winding affect the primary winding and subsequently affect the other secondary winding that may be used to power a CDP? Is the isolation of the two windings for the better or the worse in the end?
Would it be better to just parallel the two windings and get twice the KVA storage available power for peaks of dynamic power demand of an amplifier when called upon?

[Speedskater]

I think that just doing it as in the above drawing will in most cases get you 99.9 % of the way.  The only case where it might matter is if the power of the amp is large compared to the transformer.

[jea48]

I think that just doing it as in the above drawing will in most cases get you 99.9 % of the way.  The only case where it might matter is if the power of the amp is large compared to the transformer.

Maybe, I really can't say one way or the other as I do not have any hands on experience or hands on experience of others that I can site.... I have a small 2Kva ISO transformer I could try some experimenting with.

The important thing for members, that may be following this thread, is to remember if they configure, wire, an ISO transformer as Middle Atlantic suggests is each secondary winding has a max available power rating of half the name plate rating of the transformer. Example, if the name plate rating of a transformer is 5Kva then each of the two secondary windings is good for 2.5Kva (20.8 amps) max each.  If configured, wired, in parallel for straight 120V out the full 5Kva  (42 amps) max power is available for the  connected loads.

One other thought I would like to throw out there for your consideration would be the transformer effect, "transformer principle", for induced voltage Bill Whitlock spoke of in his 2012 seminar, "An Overview of Audio System Grounding and Interfacing" .
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Jim

[Speedskater]

Even better, read the rather deep paper:

"Ground Loops: The Rest of the Story"

Bill Whitlock, AES Fellow  and Jamie Fox, P.E.

This paper was presented at the AES 129th Convention, 4-7 November 2010, San Francisco, CA, USA

ABSTRACT

The mechanisms that enable so-called ground loops to cause well-known hum, buzz, and other audio system
noise problems are well known. But what causes power-line related currents to flow in signal cables in the first
place? This paper explains how magnetic induction in ordinary premises AC wiring creates the small voltage
differences normally found among system ground connections, even if “isolated” or “technical” grounding is
used. The theoretical basis is explored, experimental data shown, and an actual case history related. Little
has been written about this “elephant in the room” topic in engineering literature and apparently none in the
context of audio or video systems. It is shown that simply twisting L-N pairs in the premises wiring can
profoundly reduce system noise problems.

http://xa.yimg.com/kq/groups/20963848/268252969/name/Whitlock-Fox+-+Ground+Loops+.pdf

[LP1]

Interesting topic since a few years ago I bought  a surplus Signal Transformer DU-10 at the suggestion of a friend to use as an isolation transformer. Unfortunately, I am not a DIY'er and have no idea how to make use of it. The thing weighs a ton and would seemingly be pretty effective.

Any suggestions? Thanks.

[Speedskater]

See the paper linked in my reply #2, it has everything that you or your electrician needs to know.  But remember that 240V is not for amateurs.

[LP1]

Thanks for the response. If I have a dedicated line coming out of my panel, I assume I want to install the transformer between the panel and the outlet, if feasible?

[jea48]

Thanks for the response. If I have a dedicated line coming out of my panel, I assume I want to install the transformer between the panel and the outlet, if feasible?

Interesting topic since a few years ago I bought  a surplus Signal Transformer DU-10 at the suggestion of a friend to use as an isolation transformer. Unfortunately, I am not a DIY'er and have no idea how to make use of it. The thing weighs a ton and would seemingly be pretty effective.

Any suggestions? Thanks.

 Power capability of a 10KVA transformer.

Configure, wire, the primary to be fed by 240V.
10,000Va / 240V = 41.67 amps FLA x 125% = 52 amps. Minimum wire size #6 awg copper.
Breaker size 2 pole 60 amp. 

[xsb7244]

Here is a thread about balanced power.

http://www.diyaudio.com/forums/power-supplies/226414-balanced-power.html

[xsb7244]

LP1,  Here are two threads about your Signal transformer.

http://www.audioasylum.com/cgi/vt.mpl?f=tweaks&m=181841

http://www.audioasylum.com/cgi/vt.mpl?f=tweaks&m=184199

[xsb7244]

LP1,   2 more threads about your Signal transformer.

http://www.polkaudio.com/forums/showthread.php?158746-Heavy-Metal-my-new-Signal-DU-Balanced-Iso-Transfomer

http://www.polkaudio.com/forums/showthread.php?158869-Balanced-Iso-Trannies-all-around

[jea48]

Yes, Mr. Whitlock and other experts have been writing that for years.

It makes more sense to wire a big isolation transformer like this:


From the Middle Atlantic paper:

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper"
&
"Addendum to Power Distribution White Paper "
http://www.middleatlantic.com/resources/white-papers.aspx

For those of you who may be following Speedskater and my responses regarding the wiring diagram above from the middle atlantic white paper, the secondary of the transformer IS NOT configured, wired, as a balanced output power system.
 The diagram uses a single ISO transformer with 2 secondary windings and uses the 2 windings independently of one another creating 2 independent 120V grounded AC power systems.
Winding polarity orientation is observed so both 120V power sources are in phase with one another. In other words if a volt meter is connected between each of the 2 hots of each secondary winding the voltage will measure 0V nominal. Not 240V nominal.   
 

As for using an existing 120V 20 amp dedicated  branch circuit to feed a  ISO transformer that is larger than 2.5Kva or 3Kva I cannot see any advantage what so ever.
Va = volts x amps
  120V x 20 amps = 2400Va

In the case of a 10KVA transformer there is a very good chance the 20 amp breaker would trip open from the high inrush current trying to energize the primary winding of the transformer.
Jim

[LP1]

Thanks all. The $64,000 question is whether I should install the transformer close to the panel or wire it according to the Middle Atlantic paper to plug it diectly into my dedicated outlet? I was planning to do the latter. I already have a dolly and a steel box. Also, I don't think I have room by my panel.

[jea48]

Thanks all. The $64,000 question is whether I should install the transformer close to the panel or wire it according to the Middle Atlantic paper to plug it diectly into my dedicated outlet? I was planning to do the latter. I already have a dolly and a steel box. Also, I don't think I have room by my panel.

A 10KVA EI transformer will exhibit a fairly noticeable 60Hz hum. Not sure you will want to hear that in your audio room.

As for installing a cord and plug on the 10KVA transformer and plugging it into the wall outlet I doubt the 20 amp circuit breaker will handle the initial inrush current without tripping open. Even if it does hold the 2 paralleled primary windings will make one hell of an inductor connected to the 120V 20 amp lines.

There is no advantage in connecting a 10KVA transformer to a 120V 20 amp dedicated branch circuit.
It could do more harm than good.
A 120V 20 amp branch circuit is only good for 2400Va max, minus VD (voltage drop) on the line.   

   

The $64,000 question is whether I should install the transformer close to the panel or wire it according to the Middle Atlantic paper to plug it diectly into my dedicated outlet?

Where did you read in the white paper or diagrams where it is recommended the transformer should be fed from 120V? Every drawing shown shows the primary of the transformer fed by 2 ungrounded conductors.

The best isolation from the primary and secondary windings of a transformer is to connect the primary winding to the two ungrounded conductors of your electrical panel, 240V.

If you are seriously thinking about installing the transformer you should hire an electrician to install and wire the unit. He will work with you where, is the best place to install the transformer. He will wire the transformer to meet NEC and AHJ (Authority Having Jurisdiction) local code in your area. There is a lot more than you think involved.
Jim

[LP1]

Thanks Jim. I have absolutely no technical skills, so would hire an electrician to install. I will speak with my electrician (who will no doubt think I'm insane) about whether what you suggested is feasible with my panel. If not, I have a very heavy paperweight.

[Speedskater]

Sorry, I have been off-line for a week.
a] If you have a choice, a 240V primary is better than a 120V primary.
b] Placing the transformer near but not in the listening room is a good idea. But remember that a big transformer can make noise and it has a large magnet field.
c] It's always a good idea to arrange your power outlets so the length of AC cables form unit to unit is as short as reasonable.