Topaz Low-Capacitance Isolation Transformers - for Affordably Clean Power
Dec 15, 2019 at 10:50 AM Post #407 of 543

oneguy

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Yeah. The change in hum is most noticeable when my monitor is functioning. For example, whenever I change tabs in internet explorer, basically any type of action the monitor is making the Topaz will definitely take note and you can hear it.
My theory: the power factor (true power divided by apparent power) is being reduced causing an increased amp draw which is causing an increase in magnetostriction (what causes the hum).

-transformer hum is due to magnetostriction which is caused by a magnetic field
-the magnetic field in a fixed transformer (resistivity and coil length not changing) is directly related to current flow (actual amps)

I say power factor because in your example of the changing tabs in internet explorer I doubt the true power (measured watts) is increasing with such a simple task. If the true power isn’t changing then it has to be the reactive power increasing which in turn causes the apparent power (volts multiplied by actual amps) to go up.

https://www.mgmtransformer.com/faqs/why-do-transformers-hum/

https://www.allaboutcircuits.com/textbook/alternating-current/chpt-11/practical-power-factor-correction

On a semi-unrelated topic here’s a good read on noise that I think was posted in thi thread earlier:

http://www.surplussales.com/Transformers/Pdfs/tp-91092-31_N.pdf

Under “Special Noise Problems” it talks about “Extreme Transverse Noise” and adding a capacitor to reduce this. In my topaz transformer tear downs I’ve noticed that the -31 transformers don’t come with the capacitors to reduce this form of noise.

Transverse noise isn’t directly related to your specific issue but adding a capacitor that reduces transverse noise may also reduce the overall reactive power in your system. You’d have to run the numbers to see if you can match the two capacitor values for those separate problems (or at least get them close).

I incorporated such a capacitor in my transformer transformer boxes that I build for the transverse noise reduction aspects.
 
Dec 15, 2019 at 6:22 PM Post #408 of 543

bequietjk

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@oneguy

You know what man I used to be skeptical when people talked about how moving your mouse and using your keyboard can have an impact on sound because of the fluctuations and electrical aspects of when they are in use, and I can tell you now that I have finally experienced it.

As of right now, I've dialed my PC fans down to silent so that my room is pretty damn quiet, and the only thing making noise, really, is the 1KVA Topaz (what my PC is conncted to). With that, i can hear the hum actuate everytime I use my mouse. Every little movement that is made, every scroll. It isn't loud of course, but I can hear the Topaz go "eh... eh. eh." Everytime I make a mouse movement. And my mouse is connected to my monitor, which is now connected to my 500VA Topaz.

The benefit I see here is I finally see and hear how electricity at it's very roots, no matter where it comes from is all connected and every little detail matters.
 
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Dec 27, 2019 at 5:04 AM Post #409 of 543

chrisdrop

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I just wanted to say a big "thank you" to this info-packed thread, especially to @zilch0md for putting starting / continuing the whole story. I have spent 2 days reading the whole history. I can't say that I have grokked everything but I have learnt a lot and have a ton more reading via links from this thread.

I am working through a painful noise issue that I will perhaps post about elsewhere as it is not Topaz related and as said in an earlier post on this thread:

That's the insidious thing about noise: You don't know it's there, until you get rid of it!

Any and all info has been greatly appreciated!

Best,
Chris
 
Dec 27, 2019 at 7:54 AM Post #410 of 543
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Thanks Chris,

As evidenced by many great posts, there are several contributors here who have a much better understanding than I do on how to make the most of these low-capacitance ITs. The good news for the common audiophile is that you can accomplish a lot, just by inserting an appropriately sized Topaz between your mains and your loads. But do's and don'ts can make a difference, so my hat's off to you for studying the entire thread - and for your obvious enthusiasm.

Mike
 
Dec 27, 2019 at 2:48 PM Post #411 of 543

chrisdrop

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I realise I am stoking an old thread, but I will ask anyhow :) I have continued my reading on this topic, on the other forum that has a lot to say on this topic... The hole is deep!

In seeking a UK-based isolation transformer (so much advice on US systems, less on UK), I came across the below unit. I can't find a capacitance rating in the same form as the Topaz units. Is there any way to derive the value from the spec?

https://www.aldetronics.co.uk/product/it-15-isolation-transformer/

Given that this has a switch for floating/ grounded - if it was sufficiently low capacitance, and I got 2 units with sufficient VA, it could serve both functions in a serial setup I believe. Does that seem rational?

In very short, I'd like to use this in front of a valve headphone amp. Either of 2 excellent valve headphone amps I have used in my home have buzz that I'd like to eliminate.

Further, I have used a single https://airlinktransformers.com/product/conditioning-balanced-power-supply-cbs1500 that did not sort my issue. After grazing on this thread, I wonder if it actually didn't isolate. It is also possible that I plugged two things into it, nullifying my experiments.

Tx for any thoughts!
 
Jan 12, 2020 at 7:25 AM Post #412 of 543

oneguy

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I realise I am stoking an old thread, but I will ask anyhow :) I have continued my reading on this topic, on the other forum that has a lot to say on this topic... The hole is deep!

In seeking a UK-based isolation transformer (so much advice on US systems, less on UK), I came across the below unit. I can't find a capacitance rating in the same form as the Topaz units. Is there any way to derive the value from the spec?

https://www.aldetronics.co.uk/product/it-15-isolation-transformer/

Given that this has a switch for floating/ grounded - if it was sufficiently low capacitance, and I got 2 units with sufficient VA, it could serve both functions in a serial setup I believe. Does that seem rational?

In very short, I'd like to use this in front of a valve headphone amp. Either of 2 excellent valve headphone amps I have used in my home have buzz that I'd like to eliminate.

Further, I have used a single https://airlinktransformers.com/product/conditioning-balanced-power-supply-cbs1500 that did not sort my issue. After grazing on this thread, I wonder if it actually didn't isolate. It is also possible that I plugged two things into it, nullifying my experiments.

Tx for any thoughts!

AFAIK, from the the information given on the website, there isn’t a way to determine the capacitance.
 
Jan 16, 2020 at 2:25 PM Post #413 of 543

oneguy

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Keeping the thread going this some pics:
54402702-13FC-4F78-94EB-F275E64DB3F8.jpeg 08075486-D856-43A9-BDA8-83BF028BE3A9.jpeg 85DCAEEB-9112-4708-9DD7-B8AF5734ED71.jpeg

I wired one of my 5kVa’s to output balanced power and attached it to a 10 receptacle power strip with 10 AWG wiring and rhodium receptacles. Input into the transformer is 8 AWG with a rhodium plug.

In balanced configuration the transformer runs about 60-70F cooler and has no noise at all. Also, my LH Labs LPS4 used to make a faint high pitch noise when powering my 20G through the USB port. The noise is now gone.

Overall I’d say it was worth the $225 in upgrades and two nights of work.
 
Jan 16, 2020 at 4:51 PM Post #414 of 543

L0rdGwyn

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Jan 16, 2020 at 5:14 PM Post #415 of 543

Zenvota

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Keeping the thread going this some pics:


I wired one of my 5kVa’s to output balanced power and attached it to a 10 receptacle power strip with 10 AWG wiring and rhodium receptacles. Input into the transformer is 8 AWG with a rhodium plug.

In balanced configuration the transformer runs about 60-70F cooler and has no noise at all. Also, my LH Labs LPS4 used to make a faint high pitch noise when powering my 20G through the USB port. The noise is now gone.

Overall I’d say it was worth the $225 in upgrades and two nights of work.

Stunning. I have a 1kv .005 unit thats very noisey. Im going to try replacing it with a .0005 unit if that doesn't work ill have to research balanced power xD

I pulled the trigger just now on a used MGE UPS 91002-31T 2.5kVA. $210+shipping, I thought that was a pretty good price from the reading I've done.

https://www.ebay.com/itm/MGE-UPS-91...83.l44720.c10&nordt=true&rt=nc&orig_cvip=true

Spec sheet: http://www.pacificparts.com/vends/mge/images/t1.pdf

Seller lists a "30 DAY WARRANTY!!!!." That's four exclamation points...I trust him. Curious to see how it improves my listening.

very nice unit. What components are going on it? whats your chain like?
 
Jan 16, 2020 at 5:21 PM Post #416 of 543

L0rdGwyn

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very nice unit. What components are going on it? whats your chain like?

Thanks! That's a tricky question as my chain is in a state of flux at the moment, lots of things being bought, sold, or built, so I will say what it will be in 1-2 months.

SW1X DAC II Special
Glenn OTL
Single-ended triode amplifier of my own design (build is in progress)
ZMF Auteur

I plan to add the ZMF Vérité Closed later this year. Yes, I am a tube junkie :ksc75smile:
 
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Jan 16, 2020 at 5:46 PM Post #417 of 543

oneguy

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I pulled the trigger just now on a used MGE UPS 91002-31T 2.5kVA. $210+shipping, I thought that was a pretty good price from the reading I've done.

https://www.ebay.com/itm/MGE-UPS-91...83.l44720.c10&nordt=true&rt=nc&orig_cvip=true

Spec sheet: http://www.pacificparts.com/vends/mge/images/t1.pdf

Seller lists a "30 DAY WARRANTY!!!!." That's four exclamation points...I trust him. Curious to see how it improves my listening.

Lol, I just pointed that listing out to my friend. It was quite a good deal. There are deals to be had out there but you have to be patient and search the far corners of eBay. My 5kVa units were $320 shipped and $175 shipped.

I’d consider anything anything south of $350 total for 2kVa and above to be a good deal.
 
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Jan 16, 2020 at 5:52 PM Post #418 of 543

Zenvota

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I think one caution with the larger units is under loading them. I tested a 20w headphone dac/amp combo on a 1kv unit and it did not sound good, but on a 250va unit sounded excellent.
 
Jan 16, 2020 at 6:05 PM Post #419 of 543

L0rdGwyn

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Lol, I just pointed that listing out to my friend. It was quite a good deal. There are deals to be had out there but you have to be patient and search the far corners of eBay. My 5kVa units were $320 shipped and $175 shipped.

I’d consider anything anything south of $350 total for 2kVa and above to be a good deal.

Oof, well tell your friend I say sorry! But I am glad my instincts were correct. Looks like my renewed interest in getting one of these transformers happened on the right day.

I think one caution with the larger units is under loading them. I tested a 20w headphone dac/amp combo on a 1kv unit and it did not sound good, but on a 250va unit sounded excellent.

Thanks, I'll keep that in mind. Worst case scenario this unit will be moved to my two-channel setup and I will get a smaller transformer for my headphone rig.
 
Jan 16, 2020 at 6:33 PM Post #420 of 543
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I’d consider anything anything south of $350 total for 2kVa and above to be a good deal.

I think one caution with the larger units is under loading them. I tested a 20w headphone dac/amp combo on a 1kv unit and it did not sound good, but on a 250va unit sounded excellent.

Any guidelines on what size unit does one need? My setup consists of:
- Music server PC which is NUC based (so very low power)
- Lampizator Amber DAC
- GOTL headphone amp
- Another headphone amp being built by Glenn
- Couple other headphone amps, but they're not all powered at the same time...

Also, can anyone confirm (or dispute) the claim that being under-loaded is bad (and therefore bigger is not always better)?
I mean is it possible that the 1kva that @Zenvota used initially was just faulty?
 

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