[uncola]

thanks zilchmod I think I finally get your point about the uniqueness of the topaz' design and now I realize balanced isn't a cure all for noise.. I was just curious about the difference between attenuation and "cancellation" that balanced does.. it's a shame we don't have any info other than "20db" about balanced... too bad we can't get a transformer winder guy to post here

 

[zilch0md]

thanks zilchmod I think I finally get your point about the uniqueness of the topaz' design and now I realize balanced isn't a cure all for noise.. I was just curious about the difference between attenuation and "cancellation" that balanced does.. it's a shame we don't have any info other than "20db" about balanced... too bad we can't get a transformer winder guy to post here

No kidding! I want someone who can explain it a lot better than I can.

 

[johnzz4]

So I tried putting my Topaz inline before the PSAudio P3 again and it was buzzing and vibrating away (never did that before). It seemed to be running fine until I checked the info on the P3 and it was getting 136V. I quickly took the Topaz out and voltage returned to 117. Repeated to confirm.

I was at 12% incoming THD from the Topaz while the voltage was ridiculously high.

The moral of this story is to take my previous THD info with a grain of salt since it appears my Topaz is malfunctioning. Sigh.

 

[zilch0md]

So I tried putting my Topaz inline before the PSAudio P3 again and it was buzzing and vibrating away (never did that before). It seemed to be running fine until I checked the info on the P3 and it was getting 136V. I quickly took the Topaz out and voltage returned to 117. Repeated to confirm.

I was at 12% incoming THD from the Topaz while the voltage was ridiculously high.

The moral of this story is to take my previous THD info with a grain of salt since it appears my Topaz is malfunctioning. Sigh.

Thanks for sharing that disclaimer, but I'm thinking your Topaz might still be functioning perfectly.

Transformer hum is almost always due to DC on the AC mains and the source of DC current can be very transient - here today, gone tomorrow, or from one minute to the next. We know that your Topaz wasn't humming previously, but suddenly started humming today. What are the chances that the transformer itself has changed internally? So, again, I think you've got some DC on the mains that you didn't have previously.

There are DC blockers out there that some people have placed in between the wall outlet and their transformer - just to stop a transformer from humming - and not necessarily isolation transformers - but transformers that reside inside their audio components.

The Emotiva CMX-2 has received several reviews saying that even the small toroidal transformers in DACs or amps were humming before they put the CMX-2 inline. It may not be the "best" solution for common-mode or normal-mode noise, but it has a great reputation as a DC blocker. By the way, the CMX-2 has huge heat sinks, which I've read can get very warm to the touch if it's having to do a lot of DC blocking.

There's another device, called the AVA HumDinger DC Blocker. Read their description of what it does:

http://www.avahifi.com/products/humdinger-dc-line-blocker

I think it's really cool that your PS3 has proven that humming transformers are NOT something you want to silence by just putting them into a baffled box (as some people do.) A jump from 6.5% THD to 12% THD (on the power coming into your PS3 from the Topaz) is all the proof I need for arguing that any transformer that is humming is not delivering clean power. There's been quite a lot of discussion on the ComputerAudiophile threads about whether or not to use DC blockers to silence humming isolation transformers. Your THD measurements make it obvious that audible humming equates to higher THD on the output power.

I'd be curious to find out if your Topaz hums the next time you plug it in - or if it hums were you to take it to another building. I doubt that it will continue to hum with any persistence. I just think you have some intermittent DC coming in on the mains.

And I wouldn't be surprised to find out that your PS3 has a DC blocking circuit right up front, on the inputs.

 

[zilch0md]

Also: Read this post made by none other than Nelson Pass, on the subject of building a DC blocker to stop transformers from humming:

http://www.diyaudio.com/forums/solid-state/2080-dc-filter-post15973.html

And here's an informative review of another DC blocker product:

http://www.isol-8.co.uk/hres/hfc19_isol_8_72dpi.pdf

But THIS is the best article I've found on the subject of DC on the mains and how to block it:

http://sound.whsites.net/articles/xfmr-dc.htm

Here's another DC blocker (for the EU market), with a good sales pitch for why you might want one:

http://www.jenving.com/products/view/dc-blocker-md01-16-eu-3024000378

 

[Leo-]

Hey Mike

I don't have a kill a watt, but I'm not keen on underizing a transformer. These things like to get on fire or explode rather spectacularly when they do. Seen it more times than I should already. Therefore I thought of just adding up the nominal ratings of the transformers to be powered and that's about it. Im guessing I will end up with something around 800 VA - could not confirm the numbers yet, which would end up between a .75 and 1.25 kVA models. If I understand well, it would not be an issue to have a Topaz close to electronics or speakers, is that right? Total overkill I know, some other day I pressed play with the volume at about 12 o'clock. The sofa was displaced by a few centimetres before I could get hold of the volume knob, not kidding you!

 

[zilch0md]

Haha! I hate it when that happens!

You'll be fine doing the arithmetic instead of using a Kil-A-Watt. Regarding the magnetic influence of the transformer, I had similar concerns initially, but I've since learned that they're designed to get all the flux happening in close to the coils and then there's the usual, "radiation falls off with the square of the distance," so if you leave a gap as large as the transformer itself, you'll probably be fine.

 

[johnzz4]

Thanks for sharing that disclaimer, but I'm thinking your Topaz might still be functioning perfectly.

Transformer hum is almost always due to DC on the AC mains and the source of DC current can be very transient - here today, gone tomorrow, or from one minute to the next. We know that your Topaz wasn't humming previously, but suddenly started humming today. What are the chances that the transformer itself has changed internally? So, again, I think you've got some DC on the mains that you didn't have previously.

There are DC blockers out there that some people have placed in between the wall outlet and their transformer - just to stop a transformer from humming - and not necessarily isolation transformers - but transformers that reside inside their audio components.

The Emotiva CMX-2 has received several reviews saying that even the small toroidal transformers in DACs or amps were humming before they put the CMX-2 inline. It may not be the "best" solution for common-mode or normal-mode noise, but it has a great reputation as a DC blocker. By the way, the CMX-2 has huge heat sinks, which I've read can get very warm to the touch if it's having to do a lot of DC blocking.

There's another device, called the AVA HumDinger DC Blocker. Read their description of what it does:

http://www.avahifi.com/products/humdinger-dc-line-blocker

I think it's really cool that your PS3 has proven that humming transformers are NOT something you want to silence by just putting them into a baffled box (as some people do.) A jump from 6.5% THD to 12% THD (on the power coming into your PS3 from the Topaz) is all the proof I need for arguing that any transformer that is humming is not delivering clean power. There's been quite a lot of discussion on the ComputerAudiophile threads about whether or not to use DC blockers to silence humming isolation transformers. Your THD measurements make it obvious that audible humming equates to higher THD on the output power.

I'd be curious to find out if your Topaz hums the next time you plug it in - or if it hums were you to take it to another building. I doubt that it will continue to hum with any persistence. I just think you have some intermittent DC coming in on the mains.

And I wouldn't be surprised to find out that your PS3 has a DC blocking circuit right up front, on the inputs.

Thanks for the thorough response. The hum isn't my concern.. I've read a lot about DC creating hum. My concern is that the voltage isn't 1:1 anymore. 117V in and 136V out. Can the DC affect voltage as well?

 

[oneguy]

Even the SurgeX devices offer common mode and normal mode filtering: http://espei.com/catalog/pdfs/product-sheets/ESP-SurgeX-Product-Line-STANDALONE.pdf

I've been running an SA-1810 for about a year plus now. I really like the power surge protection and it was the only thing that could get the noise out of my Bottlehead Crack when I added Ethernet over Power in my apartment a few weeks ago. The Crack was the only gear that I could audibly tell was effected by this change.

I may be looking to try an isolation transfer next to see if it gives any benefits in my system.

 

[zilch0md]

Congrats on the SA-1810 fix for your Bottlehead Crack's discernment of noise.

For some reason, I just remembered how, when I was little, my dad would always mow the lawn on Saturday mornings, starting in the front yard, then bringing the mower around to the backyard, still running - all while I was still asleep in a bedroom at the rear of the house. The funny thing is that, I wouldn't wake-up, sometimes actually startled into waking up, until he was finished and turned the mower off. The abrupt silence would wake me. The noise of the mower had come into my sleep-state consciousness very slowly, getting louder slowly, as he moved from the front yard to the back, but when he silenced it, THAT would wake me up. It happened again and again - almost every Saturday morning - at least until I was old enough he started waking me up himself with, "It's time to wake up and mow the lawn!"

Sudden elimination of a noise for which we had no knowledge is a wonderful thing. Unfortunately, the only way to find it is to spend money on gear that has helped others and find out for yourself if any improvement can be made for the power coming into your gear. When it comes to power conditioning, YMMV greatly.

 

[zilch0md]

Here's a great troubleshooting chart by Hammond Manufacturing, on the subject of transformers that are overheating:

https://www.hammondpowersolutions.com/innovation/overheating/

As a point of reference, with my 500 kVA Topaz 19095-32 having been energized for several weeks, seated on the floor of my den, while not loaded, my laser thermometer measures a maximum (peak hold) temperature (a couple of spots on top of the core) of 105.0 F (40.6 C), with an ambient temperature (of the flooring, 12 inches away from the transformer) of 73.0 F (22.8 C).

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

 

[zilch0md]

But for having a circuit breaker, not necessarily a bad thing, in my opinion, here's a great six-outlet power strip for use on the output of a Topaz isolation transformer, that has all the outlets spaced close together (to minimize impedance between outlets and, thus, to deliver the same voltage to each component, discouraging audibly noisy leakage currents), no surge protection (which only creates common-mode noise; surge protectors, if used at all, should be placed between the wall outlet and the transformer), no LED or incandescent pilot light, and no rocker switch - ideal for maintaining clean sound on the output of the transformer:

The 1.5-ft. cord is great for use with Topaz/MGE/Daitron -32 models, that have a dual-outlet receptacle, instead of screw terminals, as seen on the -31 models (with which you would be hard-wiring an outlet strip and can make the cord as short as you want.)

http://www.tripplite.com/not-for-pa...6-hospital-grade-outlets-1.5-ft-cord~PS602HG/

https://www.amazon.com/dp/B0016HIMTC

https://camelcamelcamel.com/Tripp-Lite-Medical-Grade-Patient-Care-PS-602-HG/product/B0016HIMTC

Here's an even more robustly constructed power strip, also with closely mounted outlets, also having a circuit breaker, but no other bells or whistles, that's available with as many as 8 outlets. Read the impressive specs:

https://www.hammfg.com/electronics/outlet-strips/standard/1584h.pdf

https://www.amazon.com/HAMMOND-1584T8DH6-POWER-STRIP-OUTLETS/dp/B005T920A0
(The picture shown is a six-outlet version, but model number is for the 8-outlet version.)

http://www.newark.com/hammond/1584t8dh6/power-strip-8-outlets-15a-120v/dp/50H6010
(The picture shown is correct.)

http://www.nextwarehouse.com/item/?1744543_g10e
(The picture shown is a six-outlet version, but model number is for the 8-outlet version.)

IMPORTANT: Do not use the second outlet of your transformer in combination with a power strip on the first outlet. This will completely defeat the goal of minimizing the distance between outlets into which your components are plugged (it will defeat the goal of discouraging leakage currents.) Going by what John Swenson has preached on this subject, I wouldn't even use two identical power strips on the same transformer, because the distance between an outlet on one power strip to the outlet on another power strip could create too great an impedance between those two components.

 

[zilch0md]

On the subject of surge protection, as I've stated earlier in this thread (which feels more like a blog than a discussion, thus far), MOVs (metal oxide varistors) can actually create common-mode noise while reducing normal-mode noise, so the last place you would want to insert surge protection is after your Topaz transformer has done such a fine job of removing common-mode noise!

Transformers have an intrinsic ability to provide surge protection - up until the voltage spikes become so high that the transformer is beyond saturated and holes are burned through the insulation on the primary windings, creating a permanent short. But... If you live in an area of frequent lightning strikes and you want to protect your gear and your transformer with a surge protector, this is about the best surge protector I've seen -- rated at a whopping 5100 joules, it also comes with two, detachable power cords - one that's 10-ft. long and the other, only 18-inches!

Note that its internal circuit breaker will pop when the load exceeds 12 Amps (which works out to only 1440 VA or 1.44 kVA, with a 120V line). A 1.8 kVA isolation transformer could pull 15 Amps, exceeding this surge protector's 12 Amp limit. Given that 1440 VA is 80% of 1800 VA and that your rms load should be at 60% of peak transformer capacity, I seriously doubt a system that's properly sized for a 1.8 kVA transformer could pop this surge protector's 12A circuit breaker. It is, after all, made for "home theater" systems. Those peak voltage demands that your amplifier might place on a 1.8 kVA (15 Amp) transformer are very short in duration, and would not be likely to pop a 12 Amp circuit breaker. (Circuit breakers tend to behave more like slow-blow fuses than fast-blow.) If your transformer is rated at anything less than 1.8 kVA, all the better, but you would't be able to use a transformer rated higher than 1.8 kVA.

YMMV, so it's best, of course, to use the following 12A surge protector ahead of a 12A or lower transformer (1.44 kVA or lower) - if you absolutely must have a surge protector, at all.

http://www.tripplite.com/isobar-2-o...ter-10-ft-cord-5100-joules-low-profile~AV2FP/

http://www.tripplite.com/shared/product-pages/EN/AV2FP.pdf

https://www.amazon.com/Tripp-Lite-Isober-Conditioner-AV2FP/dp/B007U86LZI

https://camelcamelcamel.com/Tripp-Lite-Isober-Conditioner-AV2FP/product/B007U86LZI

If you think you can get by with only 1440 joules of surge protection ahead of your transformer, I like this two-outlet Tripp-Lite unit that plugs directly into the wall outlet:

https://www.amazon.com/Tripp-Lite-Protector-Suppressor-ISOBLOK2-0/dp/B0000510R4

It's currently priced at only $22.91, at Amazon, and given that it has a "Protection Present" LED that will warn you when its MOVs have literally become worn out through repeated use, you can easily replace this unit with another one at little expense.

It also offers the advantage of being rated at 15 Amps, which is high enough to support a 1.8 kVA transformer, even at peak load.

All this is offered with the reminder that transformers naturally offer a good deal of surge protection, so I personally run my 500 kVA Topaz 19095-32 without any upstream surge protection, but I might regret that decision some day. We don't get thunder storms very often in the Dallas area, compared to somebody living in Denver, for example.

 

[uncola]

I got a used surgex sx1120rt on eBay for a cheap price because of all this surge protection talk. Cut off the 20 amp plug and screwed on a Chinese copper plated 15 amp plug and its working great.. doesn't buzz like my tripplite isobar8 even if I put my ear against it. I can't hear any improvement but I already had a nice filtered power bar

 

[zilch0md]

Here's a short article that gives examples of common-mode vs. normal-mode noise sources.

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

You can think of common-mode sources as generally being more constant or persistent, where normal-mode noise sources are intermittent and even rare (lightning, electric motors kicking on, etc.)