Discussion of AC mains isolation transformers

[jas]

I will rephrase.

 

The BK Precision was effective in increasing SQ when fed by the Mac. AC interference may be reduced or stopped from the wall, or not, I can't say. Your Hammond Iso may be equally effective.

The BK Precision could handle the load of the Mac desktop computer. I hear little or no buzz from it when under load.

I actually use 2 Topaz units on 2 dedicated circuits in different parts (front end/back end) of one system and hear next to no buzz and much better SQ than not using 1 or none of them.

I can't can't comment on the isolator you referenced. 

 

 

 

[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.

[One and a half]

Transformer buzzing?  Read on!

 

Transformers can buzz, the EI types like a Topaz or even a toroid type like an Equitech, due to mechanical issues, but often it's electrical. I'm not going to entertain the idea of a DC blocker, they need a bit of care to build, then it's really hit and miss. Buzzing is caused by transfer of harmonics from the secondary to the primary, and with no place to go, the harmonics swirl around the primary in a loop and the buzz continues. The frequency is a little higher than 50/60Hz, and when the transformer is energised, it makes a loud growl then settles down. Well the buzz continued on....

 

The other day, my audio system is setup (on a temporary basis) in a different part of the house, mainly to check the room for rattles, hum, and reflections. The Equitech balanced transformer (1000 VA) plugged into the wall and made a very noticeable buzz and was really annoying. Everything was plugged into the Equitech even a small 230V/120V 100VA transformer. buzzed.

There's not much to fix mechanical wise, it has been a few years since this device was in service, maybe something wrong with it? Plod on.

Being downstairs, and one spare receptacle from the garage 2000 VA Topaz left, and a 20m extension cord was used to feed the Equitech.  Powered up everything & lo, the buzz and noise vanished 😀 Happy Days!

 

The long lead with the upstream Topaz found a nice lossy path and the room is quiet. In testing music, there's still a difference when running AC directly from the wall and with a balanced supply in that:

 

a) the bass is tighter, and the room doesn't rattle with Sade - Love Deluxe - 'No Ordinary Love'

b) It's easier to distinguish the spread-out soundstage, where instruments and vocals are easy to pick out

c) some gain with stage height

 

The effects are similar when USB or Ethernet has noise mitigation, applied although the bass improvement is solely due to the balanced transformer(s). The room is not that quiet, to detect a blacker background, so once other furnishings are in the room, this may show itself. In the meantime, there's the dedicated line to run from the Topaz, that's for the future as part of the renovations.

[Speedskater]

When dealing with power transformer buzz, the first thing to check using a 'Kill-a-Watt' (or similar) meter is the AC line voltage. Over the decades AC line voltage has been slowly creeping upwards (the opposite of shrink-inflation). So an older transformer designed for a lower voltage can be very unhappy with high line voltage. 

[One and a half]

While @Speedskater mentions higher than nominal voltage can affect the buzz, in thinking more on the buzz reduction the other day. By adding in the Topaz 2000VA transformer, must have provided enough inductance to slow down the current pulses from the various amplifiers and linear supplies, or literally take the edge off the pulses.

 

The voltage at my house is fairly stable at 230V +/- 3V, measured by a mixture of Kill a Watt, Monster Power conditioner and analog meters.

Used to be 240V, but in line with the euro/IEC standard now the 400V/230V system. To provide for various IT devices, the house 120V (50Hz) varies about the same, but half the 230V variations. 

 

When the Equitech was plugged directly into the wall, the low impedance of the house network has not enough to reduce the noise created by harmonics/current pulses. in the primary I do recall reading in the Equitech Q manual, that an isolation transformer fitted to the upstream of the Equitech is a 'highly recommended' practice, now I know why that it is so.

[barbz]

Apologies for the silly question. My understanding was that transformers had a fixing winding to deal with the output voltage however from what I understand some like the torus avr2 elite can vary their output based to ensure consistency (or that's my understanding from reading the marketing).

 

How does the ave2 elite achieve this when the input can fluctuate?

 

Thankyou

[Speedskater]

It has a stepping function. It switches voltage taps as the voltage changes.

[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?

[JohnSwenson]

2 hours ago, gererick said:

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?

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.

[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

[oneguy]

44 minutes ago, gererick said:

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

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 same goes for the MGE / Eaton T100 family of transformers. These are basically slightly newer versions with slightly less noise suppression. 

[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?

[oneguy]

@gererickyep, the 91005-31 can’t be tuned. I’m staring at one right now as I swap the electrical sockets near my audio equipment in my new house. 

[Speedskater]

Power transformers often boost the secondaries a few volts.  If the primary and secondary are both the same voltage, you could reverse them (i.e. the input to the secondary) and get a few volts drop.

 

A 'buck/boost' transformer could be added, but boy that gets complicated real fast.

[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.

[Speedskater]

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.

[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.  

[Rsbrsvp]

Hi Friends.   I have a Topaz isolation transformer in balanced mode.  .00005 

 

Would something like the Puritan Audio PSM 156 improve on the Topaz or should they not be used together?  ANd if they could be used together, what should be the order?

[Iving]

3 hours ago, Rsbrsvp said:

Hi Friends.   I have a Topaz isolation transformer in balanced mode.  .00005 

 

Would something like the Puritan Audio PSM 156 improve on the Topaz or should they not be used together?  ANd if they could be used together, what should be the order?

 

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.

[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.

 

[Iving]

17 minutes ago, gererick said:

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 leakage, which John definitely talks about in the first few pages of this thread.  

 

Yes I recall that discussion, and kept notes for reference.

My system has never sounded "cleaner".

I found that small plug-in type conditioners - the ones that just hang in a wall socket - should remain exactly there. Not plugged into strips or other conditioners.

Whether (compared with none) a conditioner sounds better after a Topaz (ime not before as Rsbrsvp asked) is surely a matter of suck and see.

The difference between his proposed generic multi-outlet PSM 156 and my EVO3 Titan is that the latter has only two outlets intended for power amps not source components. So his mileage may vary for that reason alone.

[Sagittarius]

I have a couple of questions for @JohnSwenson . I have come across the linked post while reading through this thread and I am curious about two points mentioned in it :

 

First: Leakage Current "is formed by capacitances in the PS between AC line and DC output generating a voltage between AC line and DC output. When a low impedance connection is formed between the DC output of one PS and the DC output of another PS these voltages form a current flow " 

My first questions is: Would the use of symmetrically balanced power reduce these voltages which cause the leakage currents with one phase counteracting the action of the other phase?

 

Second: "The current itself is not the problem, it is the voltage developed by the current flowing through an impedance. So decreasing the impedance of part of the loop can decrease the voltage resulting in less effect on audio if you do it right. OR you can block the leakage loop altogether."

My second question is : Is it it possible to decrease the impedance in another part of the loop other than at the power input of the audio equipment by connecting them to the same power strip? More specifically, would the products designed to connect the signal grounds and/or chassis grounds of the equipment in an audio system to a common point achieve the same effect (e.g. Shunyata Altaira, Puritan Audio Route Master, Synergistic Research Ground block, etc). If this has the same effect, it could open the door to using multiple isolation transformers of different sizes for different equipment in the same system or starting with smaller ultra isolation transformers for the sources and line level equipment if a large enough one is not available right away. 

 

 

[Rsbrsvp]

I have compared my Topaz .0005 with power strip to my PSM156 and to my ears the 156 definately reduces noise substantialy more.   The sound is so much more detailed, clean, tight- like day and night.    Now- does it sound better than the Topaz option?  Not sure...  The Topaz option to my ears is a whetter, fuller bodied, more tonally saturated sound.   It is kind of like solid state (PSM156) vs Tube (Topaz).

 

I dont understand technology and you guys can talk about impedence and leakage all day;- and I dont get it at all- but my ears hear two very valid forms of purifying mains noise.   Check out the revieews on the PSM156--- go to audio circle-   people are floored by it.

 

It seems that there are many ways to get good results...  Maybe something like the PSM156 increases impedence and leakage but makes up in other ways.....  Ways- I do not understand.......      Honestly- this contest is a matter of taste- and only the ear can decide..

[Savolax]

1 hour ago, Rsbrsvp said:

I have compared my Topaz .0005 with power strip to my PSM156 and to my ears the 156 definately reduces noise substantialy more.   The sound is so much more detailed, clean, tight- like day and night.    Now- does it sound better than the Topaz option?  Not sure...  The Topaz option to my ears is a whetter, fuller bodied, more tonally saturated sound.   It is kind of like solid state (PSM156) vs Tube (Topaz).

 

I dont understand technology and you guys can talk about impedence and leakage all day;- and I dont get it at all- but my ears hear two very valid forms of purifying mains noise.   Check out the revieews on the PSM156--- go to audio circle-   people are floored by it.

 

It seems that there are many ways to get good results...  Maybe something like the PSM156 increases impedence and leakage but makes up in other ways.....  Ways- I do not understand.......      Honestly- this contest is a matter of taste- and only the ear can decide..

What kind of power strip did you use? Generic store one or maybe something fancy?

[Rsbrsvp]

25 minutes ago, Savolax said:

What kind of power strip did you use? Generic store one or maybe something fancy?

SOmething I got on Amazon.  Around $35.   No filtering, no surge protection,- just a power strip...  Hard to find them these days...