Discussion of AC mains isolation transformers

[Cornan]

12 minutes ago, spacexpert said:

Never knew this existed, thanks for the link.  I didn't know phase mattered until Lavardin stated that their amp sounds much better with correct phase.

When I first tried a reverse phase power cord it sounded less bright and a little more laid back.  I kept it that way and assumed it to be correct.

 

When I bought the Oehlbach Phaser a couple of years ago I was amazed by the change it brought to the table. Then after a lot of changing in my setup under a long period of time I forgot about the Phaser (hided in a drawer) myself. Recently I remembered it again and took my time to check it. It turned out that the phase polarity was wrong on a couple of PSUs. Wow, instant jump in SQ! I will not forget about it again I can tell you!

 

[Cornan]

55 minutes ago, spacexpert said:

I once touched a ground wire to the negative terminal of one of my speakers and it went away, didn't work on the other speaker though.

 

This definately sounds like a IC problem to me, likely a damage cable on the same side as you experianced this issue. Coaxial cables are the usual suspect, but it could be the speaker cables or any other IC as well.

[spacexpert]

3 minutes ago, Cornan said:

 

This definately sounds like a IC problem to me, likely a damage cable on the same side as you experianced this issue. Coaxial cables are the usual suspect, but it could be the speaker cables or any other IC as well.

I've had three different IC's and a few different speaker cables and the noise doesn't change.  It also doesn't matter which output I put my DAC on. 

 

But... while the IC's are connected and grounded to the DAC, as soon as I select an unused output on my amp, the hum goes.

I can't help but think I can get rid of it, but I just don't know what else to try.

 

[Cornan]

2 minutes ago, spacexpert said:

I've had three different IC's and a few different speaker cables and the noise doesn't change.  It also doesn't matter which output I put my DAC on. 

 

But... while the IC's are connected and grounded to the DAC, as soon as I select an unused output on my amp, the hum goes.

I can't help but think I can get rid of it, but I just don't know what else to try.

 

 

Hmmm, which sources are you using? Are all sources passing the DAC? If it is it might be the cable between the Lavadin IT and your DAC. When you say that your ICs are grounded to the DAC, do you mean normal ICs or are you running separate ground wires? (and if so are they connected to signal ground or elsewere?) It could ofcourse be a ground loop, but to rule out that you´ll need to do a simple diagram over your setup that includes all devices, ICs, AC/DC power cables and separate ground wires (if any).

As an example:  If you have a TV or any other device "separate" to your audio connected to the Lavardin IT you should try to disconnect temporarily it and see what happens.

Actually the best way (and probably the quickest) to rule out ground loops is to disconnect everything and adding one device at a time and listen inbetween changes until you hear the hum again. By this method you will at least limit the search area, especially with many devices connected!

 

 

[spacexpert]

8 minutes ago, Cornan said:

 

Hmmm, which sources are you using? Are all sources passing the DAC? If it is it might be the cable between the Lavadin IT and your DAC. When you say that your ICs are grounded to the DAC, do you mean normal ICs or are you running separate ground wires? (and if so are they connected to signal ground or elsewere?) It could ofcourse be a ground loop, but to rule out that you´ll need to do a simple diagram over your setup that includes all devices, ICs, AC/DC power cables and separate ground wires (if any).

As an example:  If you have a TV or any other device "separate" to your audio connected to the Lavardin IT you should try to disconnect temporarily it and see what happens.

Actually the best way (and probably the quickest) to rule out ground loops is to disconnect everything and adding one device at a time and listen inbetween changes until you hear the hum again. By this method you will at least limit the search area, especially with many devices connected!

 

 

Yeah, I'm running separate grounding wires attached to the metal IC plugs (Van Den Hul The Bay C5).  If I don't all hell breaks loose.  Like a de-tuned radio I get all sorts of static and hiss.  They are chassis grounded along with the subs.

My system is audio only, so the only thing connected to my amp is the DAC, speakers and subwoofers. 

I should mention that I need to be up close to the speakers to hear the hum.  It's also not loud enough to wake my subs out of standby.

So it maybe expected levels of self noise within the amp?

[Cornan]

15 minutes ago, spacexpert said:

So it maybe expected levels of self noise within the amp?

 

Nope, you should really expect it to be silent up to normal listening levels with no music playing. It looks like you have a ground issue going on that you should´nt really have. Unfortunately it could be a headache to sort out. My only suggestion is to remove everything and plug it in one device at the time to try to rule out the source to the problem. It surely sounds similar issues to a defect cable, bad solder joints, bad plugs or insufficient shielding somewhere down the line. 

[mikicasellas]

I am too having issues with my second "new" acquired Topaz 91002-32 / 2.4 KVA / .0005pF, it gets hotter than my first Topaz 91001-22  / 1KVA / .001pF with the same amount of gear connected and also it makes the sound more bright, less clean...?? i am so frustrated, i thought i was going to improve on SQ but went back with this.

 

So being 1.4 KVA more than my previous, it gets hotter and sounds brighter, i was trying to divide the charge of my entire system, putting the more obvious gear on the bigger Topaz:

 

Topaz 91002-32 / 2.4 KVA / .0005pF:

MacMini

DAC

Preamp

Amp

 

Topaz 91001-22  / 1KVA / .001pF:

Receiver

TV

Router

External USB HD

 

I guess it must be damaged, any suggestions?

[Speed Racer]

5 hours ago, spacexpert said:

No, it is a steady pitch coming from the toroidal.   

 

3 hours ago, spacexpert said:

I will confess to being a bit ignorant about balanced mode.  Is the 240V balanced by default, or does that require some funky rewiring?

 

The Topaz units are not toroidal designs.

 

240v in/out is balanced with 120v on each conductor relative to ground.

[Speed Racer]

26 minutes ago, mikicasellas said:

I am too having issues with my second "new" acquired Topaz 91002-32 / 2.4 KVA / .0005pF, it gets hotter than my first Topaz 91001-22  / 1KVA / .001pF with the same amount of gear connected and also it makes the sound more bright, less clean...?? i am so frustrated, i thought i was going to improve on SQ but went back with this.

 

So being 1.4 KVA more than my previous, it gets hotter and sounds brighter, i was trying to divide the charge of my entire system, putting the more obvious gear on the bigger Topaz:

 

Topaz 91002-32 / 2.4 KVA / .0005pF:

MacMini

DAC

Preamp

Amp

 

Topaz 91001-22  / 1KVA / .001pF:

Receiver

TV

Router

External USB HD

 

I guess it must be damaged, any suggestions?

 

Well, you could rewire it to run balanced power. I did that with my 91002-31 2.5kVa Topaz and it ran much quieter and much cooler.

 

Regardless, I would not put the Mac Mini on the same Topaz as your DAC, preamp, and amp. I put all my analog audio gear on one Topaz and put the other gear on a wall outlet or another Topaz. I would isolate your Mac Mini from the DAC somehow (Schiit Eitr would be a good choice) and not plug it into the Topaz with your audio components.

[mikicasellas]

12 minutes ago, Speed Racer said:

 

Well, you could rewire it to run balanced power. I did that with my 91002-31 2.5kVa Topaz and it ran much quieter and much cooler.

 

Regardless, I would not put the Mac Mini on the same Topaz as your DAC, preamp, and amp. I put all my analog audio gear on one Topaz and put the other gear on a wall outlet or another Topaz. I would isolate your Mac Mini from the DAC somehow (Schiit Eitr would be a good choice) and not plug it into the Topaz with your audio components.

 

Would it also be that could have damaged cables inside or bad soldering...don't you think?

 

Running balanced seems very interesting, but i don't have an idea on how to do that...would you be kind enough to share perhaps some pics to see how the connection looks and how to be connected that way?

 

Thanks for the feedback!

[Cornan]

Great to have you around here @Speed Racer. Even if we do not agree on everything your know-how is a great asset here! ?

[Speed Racer]

55 minutes ago, mikicasellas said:

 

Would it also be that could have damaged cables inside or bad soldering...don't you think?

 

Running balanced seems very interesting, but i don't have an idea on how to do that...would you be kind enough to share perhaps some pics to see how the connection looks and how to be connected that way?

 

Thanks for the feedback!

 

I doubt you have bad wiring in your Topaz.

 

I wired mine as follows:

 

Input:
Hot (black) to H1
Neutral (white) to H4
Jumper H2 to H3
Ground to chassis

Output:
Hot 1 (black) to X1
Hot 2 (white) to X4
X2/X3 center tap connected to chassis ground and outlet ground.

 

I had to make a jumper to connect X2 (or X3) to GND.

 

On the socket: When I measure Hot to ground I get 62v. When I measure Neutral to ground I get 62v. When I measure Hot to Neutral I get 124v.

[Speed Racer]

38 minutes ago, Cornan said:

Great to have you around here @Speed Racer. Even if we do not agree on everything your know-how is a great asset here! ?

 

The world would be boring if everyone agreed with everyone else! I still think you are little bit off because of your like of grounding boxes! 

[zilch0md]

10 hours ago, One and a half said:

Temperature and loading results 1000VA 0.001pf 91001-21 transformer.

 

Ambient : 22.7C 

Idle :

Consists of energising 1000VA Equitech transformer and MPD-3 DAC which is on 24/7 . Primary current 0.47A, 239V input 112.33VA.

Lamination temperature : 37.5 C

 

On Load : Ssytem 1 and System 2 on, low level music, maybe 1 Watt output

1.43A, 239V, 342VA input. 

 

Left on load for an hour, Lamination temperature : 38.3 C, Ambient Temperature 24.4 C

 

Temperature readings with a contact K type thermocouple. 

 

Unloaded, you've measured a difference of 37.5 C - 22.7 C = 14.8 C, relative to ambient.

 

Quoting my earlier post:

 

"That's a difference of 17.8 C (32.0 F) between ambient temperature, at floor level, and the top of the transformer core."

 

So, my transformer runs a little hotter than yours, apparently. 

 

 

[spacexpert]

6 hours ago, Speed Racer said:

 

 

The Topaz units are not toroidal designs.

 

240v in/out is balanced with 120v on each conductor relative to ground.

Thanks Speed Racer, I figured that'd be the case.

Regarding the toroidal I was referring to my amplifier.

[spacexpert]

7 hours ago, Cornan said:

Nope, you should really expect it to be silent up to normal listening levels with no music playing. It looks like you have a ground issue going on that you should´nt really have. Unfortunately it could be a headache to sort out. My only suggestion is to remove everything and plug it in one device at the time to try to rule out the source to the problem. It surely sounds similar issues to a defect cable, bad solder joints, bad plugs or insufficient shielding somewhere down the line. 

The manufacturer told me in an email regarding the amp and my noise issues that it has a "complex floating configuration."  Are they talking about the grounding?  I assume so.  With the amp turned on and nothing connected but the power cord and speakers, it has a loud ground loop... once I add my grounded IC's + DAC, the noise drops by 90% and can only be heard a few inches away.  

I will redo my grounding scheme, larger gauge wire, new connections.  That's at least a start.

[Cornan]

1 hour ago, spacexpert said:

The manufacturer told me in an email regarding the amp and my noise issues that it has a "complex floating configuration."  Are they talking about the grounding?  I assume so.  With the amp turned on and nothing connected but the power cord and speakers, it has a loud ground loop... once I add my grounded IC's + DAC, the noise drops by 90% and can only be heard a few inches away.  

I will redo my grounding scheme, larger gauge wire, new connections.  That's at least a start.

 

If the Lavardin IT have a "complex floating configuration" I assume that the safety ground is not passed through to the DC negative/chassi or that it actually have a built in isolation transformer of some kind? If the Lavardin is plugged into the Topaz it could be worth to connect it directly into the AC mains wall inlet instead and have all other devices connected to the Topaz. Just a thought! ?

[spacexpert]

1 hour ago, Cornan said:

 

If the Lavardin IT have a "complex floating configuration" I assume that the safety ground is not passed through to the DC negative/chassi or that it actually have a built in isolation transformer of some kind? If the Lavardin is plugged into the Topaz it could be worth to connect it directly into the AC mains wall inlet instead and have all other devices connected to the Topaz. Just a thought! ?

Interesting.  Lavardin are pretty militant about plugging the amp directly to the wall outlet.  They say no to conditioning and fancy power cables.  I'll certainly give that a go... you never know.

For what it's worth I noticed no sound deterioration when using the Topaz with the Lavardin, and it did block the AC line noise issue I was having.

[Speedskater]

While a Sola ferro-resonant transformer runs hot, a Topaz isolation transformer shouldn't.

As anyone put a 'Kill-a-Watt' meter on a hot one? With load and no load.

At the transformer input measure volts. current  & watts.

[jamesg11]

Will do this next time I power down the Elgar 2.5kVA here (.0005pfd). But it runs warm to very warm, depending on work; not near hot. No hand touch discomfort.

(It does hum a bit - a dc blocker didn't do much really, though I guess I should leave it in for days, not hours, to see.)

[tims]

Anyone please comment if this DIY project from 2005 - the Felicia balanced power conditioner would help with leakage currents as discussed?

 

Schematic here:

Secondaries are running at 15vAC

 

Felicia Balancing Power Conditioner

 

"The principal benefit of the Felicia conditioner, (like the Jon Risch SQ&D Iso Trans project upon which the Felicia was based -
http://db.audioasylum.com/cgi/t.mpl?f=tweaks&m=43988) is power conditioning. Specifically, its very effective at eliminating differential (transverse) mode noise, in addition to attenuating the easier to deal with common mode noise.
The benefits of making the conditioner provide balanced (technical) power are real for components that have a grounded chassis (they're also there for certain other components without 3 prong grounded plugs whose chassis are grounded to other components via various circuitous routes). Specifically, that benefit is minimization of reactive leakage currents to the chassis which causes noise, and in its most extreme form, ground loop hum."

[zilch0md]

17 hours ago, tims said:

Anyone please comment if this DIY project from 2005 - the Felicia balanced power conditioner would help with leakage currents as discussed?

 

Schematic here:

Secondaries are running at 15vAC

 

Felicia Balancing Power Conditioner

 

"The principal benefit of the Felicia conditioner, (like the Jon Risch SQ&D Iso Trans project upon which the Felicia was based -
http://db.audioasylum.com/cgi/t.mpl?f=tweaks&m=43988) is power conditioning. Specifically, its very effective at eliminating differential (transverse) mode noise, in addition to attenuating the easier to deal with common mode noise.
The benefits of making the conditioner provide balanced (technical) power are real for components that have a grounded chassis (they're also there for certain other components without 3 prong grounded plugs whose chassis are grounded to other components via various circuitous routes). Specifically, that benefit is minimization of reactive leakage currents to the chassis which causes noise, and in its most extreme form, ground loop hum."

 

That's a very interesting contraption.  I know just enough to say that all those X-Caps would indeed reduce normal-mode noise, but it seems like overkill, when a Topaz can provide -65dB of normal-mode attenuation all by itself (in addition to -146dB of common-mode attenuation.)  Also:  Common-mode noise sources tend to be more constant, where normal-mode sources tend to be intermittent or even infrequent.

 

See the last page of this pdf:

 

http://www.murata.com/~/media/webrenewal/products/emc/emifil/knowhow/26to30.ashx

 

And:  http://www.controlledpwr.com/whitepapers/electrical_noise_attenuation.pdf

[zilch0md]

On 9/12/2017 at 8:18 AM, zilch0md said:

 

Thanks for your advice!  I've successfully canceled the order for those star-quad RCA cables and have instead ventured into star-quad by placing an order for a GhentAudio star-quad DC power cable - which I'll use with my USB Regen.  I have a Blue Jeans Coaxial cable that rocks, by the way.  They make great stuff at great prices.  

 

I realize this thread isn't the right place for discussion of cables, but I feel compelled to correct some misinformation that has been posted here.

 

 l am still waiting for the Ghent star-quad power cable to arrive, but I've been studying the subject of star-quad cables and have concluded that they are ONLY useful for incoming noise immunity when the signal voltage is quite low - as with microphone cables or line-level signals (i.e. RCA interconnects).

 

When the voltage on the line is higher, as with speaker cables and power cables, the advantage is actually reversed - star-quad cables will inhibit emission of magnetic fields from the cable!

 

Quoting this Canare Star-Quad document:  "Canare Star Quad is designed for use with microphones but is also excellent for all line-level signals (e.g. mixer to power amps)."  AND "The signal generated by a microphone during quiet periods can be very low in level, -70dB to -120dB (0.3 millivolts to 1 microvolt). The cable that must carry this signal to the mixer is very sensitive to Electromagnetic Interference (EMI), Radio Frequency Interference (RFI) and electrostatic coupling of hum and noise."   

 

Note the conspicuous absence of any recommendation for using their star-quad cables for purposes other than microphone or line-level signals.

 

Quoting Blue Jeans Cables:   "Speaker cable is a bit different from a lot of the interconnect cables we handle, in several respects. Because speakers are driven at low impedance (typically 4 or 8 ohms) and high current, speaker cables are, for all practical purposes, immune from interference from EMI or RFI, so shielding isn't required." AND "Canare 4S11 is a "star quad" 14-gauge cable, with four conductors together in one outer jacket; it is popular for bi-wiring (where separate wires run to each of four speaker terminals, two of which drive the high and two of which drive the low-frequency elements of the speaker assembly). When conventionally wired [with two conductors shorted together for each channel], star quad speaker cable has the advantage of reducing the EM field around the cable, which will tend to diminish the effect of the signal in the speaker cable upon nearby interconnects--though this is not, in most applications, a significant concern."

 

They're saying that you can reduce the outward emission of electromagnetic fields from a speaker cable by using star-quad cable, but that there's little concern for doing this.  Again, note the absence of any claim for improving immunity from inbound noise when star-quad is used as a speaker cable (not as a microphone or line-level cable).

 

Quoting a Wikipedia article:   "The combined benefits of twisting, differential signalling, and quadrupole pattern give outstanding noise immunity, especially advantageous for low signal level applications such as long microphone cables, even when installed very close to a power cable."  AND "While the above discussion focuses on preventing noise from getting in (e.g. into a microphone cable) the same star-quad quadrupole configuration is useful for audio speaker cable,^[10] for split-phase electric power wiring, and even for open-wire star quad transmission line. In these cases, the purpose of the star quad configuration is reversed. The star-quad geometry cancels the magnetic fields that are produced by the two pairs of conductors. This cancellation reduces the magnetic emissions of the cable."

 

I therefore seriously doubt there is any advantage to be had by using star-quad cable for anything other than weak, low-voltage signals.  It's especially useful with weak signals running in close proximity to devices that are emitting electromagnetic interference, as seen in the YouTube video where energized transformers are placed directly on top of microphone cables.  With higher-energy signals, it would be a rare situation in which there's anything to be gained by reducing the outward emission of magnetic fields from the cable. 

 

Then again:  Why not use star-quad everywhere?  We get inbound noise reduction with low-level signals (very advantageous) and outbound noise reduction with high-level signals (not so advantageous).  There's only one disadvantage that I've read about - in the Wikipedia article: Roll-off of high frequencies, but this only happens with really long cable runs.

[Speedskater]

Interference and speaker cables is one of the few things that Kurt Denke at Blue Jeans Cable got wrong. While a power amplifier's output impedance is very low at audio frequencies, that may not be true at radio frequencies. RFI can sneak in the speaker cable and go thru the feedback network to the input stage. Jem Brown an EMI/RFI expert often writes about this problem.

[Cornan]

I just want to make this short not to disturb this thread. John Swenson have specificly mensioned the VH Audio Flavor 4 as a good power cable https://www.vhaudio.com/flavor4.html. It is a starquad.

 

Here is some posts from JS about starquad ac mains power cables. I know I have seen more, but I could´nt find them with just a quick search.