Discussion of AC mains isolation transformers

[gererick]

17 hours ago, Speedskater said:

That's from over four decades ago! Electrical safety has gotten more serious since then.

Okay, thanks.  
 

From an earlier post on pg 1 of this thread,  a .0005 pF capacitance isolation transformer is “a very good surge suppressor as well. Most of the energy in high power surges is contained in high frequency components, which get suppressed by the low capacitance, thus it is quite an effective surge suppressor without needing any other special circuits to achieve this.” 

 

As my caps are at the output end, the thousands of volts referred to in Superdad’s post should be suppressed after passing through the transformer.  Perhaps that is why Topaz felt comfortable installing Aerovox caps there, the same place I have mine. 

 

I had a surge a year or two ago.  The surge took out my porch light , at least two outlets including a GCFI, a fuse in my tankless hot water heater, some light bulbs, a receiver in m a ceiling fan, tripped breakers and I don’t remember what else.  (this has happened once in 21 years here).  I have an isolation transformer for my two audio/video systems.  None of that equipment was affected, and no fuses blew.  The caps should be okay for a short period as relates to safety, and I’ll unplug it before a storm rolls through.

 

I will be wiring thicker gauge cable from the panel to a junction box with an audiophile-grade outlet.  I will put an audiophile fuse in the junction box before the outlet for additional surge protection, and will plug the transformer into that.

[gererick]

9 hours ago, NovaInfinity said:

I currently have a -31 Topaz with 500VA and I can't fit the entire full chain on it, namely the computer. I can fit everything else including a streamer that my DAC can plug into that I can hook to my computer via ethernet to get the music.

 

My question is, is something like the below enough to isolate the rest of the chain from noise if I put it between my computer and the streamer?:

https://www.digikey.com/en/products/detail/icomtech,-inc./2005674/14837293

 

Or would the signal from the computer either be muddled in some way due to its own power noise or whatever noise it produces will still travel to the streamer and down the chain? I'm not confident I can find something that can fit my computer's large power requirement as well with the .0005 capacitance. Unless there are better options I'm not aware of.

I have a surplus .001 pF 1.0 KVA Topaz P1001-22, with a duplex outlet if you are interested.  It does not have the .0005 pF spec but is close.

[gererick]

The voltage coming onto my power strip fed by my isolation transformer is 124.4 volts.  My two amps each draw 425 watts or so.  When they are turned on, the voltage is 126.6.  Is there a way to lower the voltage that doesn’t hurt sound quality?

[gererick]

On 2/16/2023 at 9:33 PM, JohnSwenson said:

Many isolation transformers have "taps" which are slightly different secondary voltages. These are usually screws where the wires that go to the output jack are connected. You can lower the voltage by connecting the output wire to a different tap.

 

John S.

Thanks, John.  Voltage from the wall is 121.0.

 

The IT is a Topaz 5 KVA, hard-wired, wired with balanced outputs, X1, X3, X2, X4, with X3 as ground and X2 no voltage.

 

X1 is 62.8 volts at the screw, as is X4.

 

I don’t expect I have more screws or taps to choose from, but I am unsure if I am interpreting your post correctly.

Rick

[gererick]

28 minutes ago, oneguy said:

which model do you have?
 

With the -31 and -69 Topaz/MGE units the taps provided don’t adjust output voltage in small increments. You can only get the espoused output ratios. 
 

I currently have two 5 KVAs and a 2.5 KVA. Overall I’ve had about 15 of them (-31, -32 and -69). All the terminal style ones have been this way. 

The model is 91005-31.

 

I understand that one option may be to put an autoformer between the wall outlet and the Topaz, but have to get more info as to whether one can be spec'd to my needs and whether the impact on sound quality is negligible.  

 

Or perhaps a different make and model that would allow output voltage adjustments?

[gererick]

Thanks.  It’s a thought, but if I presently have 121 volts becoming 126, I would think reversing the inputs and outputs would mean 116 volts?

 

Functionally, variac might work but wouldn’t be a good solution.

 

Voltage stabilizers are out there also, but probably not a good solution either.

 

PSAudio power regenerators allows the user to fix the voltage, so there should be something out there not too complicated.

[gererick]

On 2/23/2023 at 8:43 AM, Speedskater said:

Well if you had old legacy/boutique equipment, 116 Volts would be good.

So:

a] how big is the transformer?

b] what is the total current or power that all the plugged in components draw?

(a little 'Kill-a-Watt' meter might be a handy thing to have when dealing with AC power.

 

Note that modern hi-fi components with a SMPS (Switch Mode Power Supply) don't care what the AC line voltage is.

Hi, it is a 5.0 KVA but balanced so it is 2.5 KVA.  The total current draw is 1,000 to 1,100 watts.  

[gererick]

8 hours ago, Iving said:

 

I used to run 2 x Topaz (smaller one dedicated to digital source components) after an Isotek Titan GII. 

When the GII went to heaven, and Isotek graciously replaced it with a new EVO3 Titan, I now run the 2 x Topaz from the wall and the EVO3 downstream of the larger one - dedicated to power amps only - a natural role for its high current capabilities.

It's a much better arrangement.

I do think combined use is beneficial.

Thus I would recommend Topaz then conditioner rather than vice versa.

It depends on the conditioner and whether the conditioner has filtering that negatively impacts sound quality.  In the first few pages of the thread, John Swenson and/or others talk about that.  To me, the point in using a Topaz or equivalent is to get protection from surges and significant reduction in noise with no filtering and with a Tripp Lite power strip to reduce or eliminate  leakage loops, which John definitely talks about in the first few pages of this thread.  If you have a power conditioner after the Topaz (instead of a power strip as John recommended), you may be introducing leakage loops depending on how it is wired.  A Topaz that is wired balanced can reduce noise further according to many who tried it.  Mine is balanced but I didn’t do a proper A/B comparison.