AC Filtering, Grounding Boxes, Linear PSU and Balanced Power.

[Speed Racer]

archetype,

 

I would use this thread as a guide instead of the one we are currently in:

 

https://www.computeraudiophile.com/forums/topic/29662-discussion-of-ac-mains-isolation-transformers-started-wposts-moved-from-quotlps-1-troubleshootingquot-thread/

 

You can easily stay within budget buying a used Topaz isolation transformer or two off of eBay. Read the thread....my sound quality improved noticeably by following John Swenson's advice. 

[Speed Racer]

I would look for a 1.8 to 2.5 kVa Topaz unit if you can as the price difference is small and the extra power handling ability can be important. 

 

The B&K Precision 1604A is listed to 1.25 amp continuous. That's not much. I don't see these as a reasonable solution.

[Speed Racer]

1 hour ago, allhifi said:

archtype: ALSO, dispense with the idea and use of the Tripp-lite strip --it's a BAD idea. 

Consider a simple, but well -built (removable IEC) power strip instead.

 

pj

 

Why? The TrippLite PS series of power strips are great.

[Speed Racer]

50 minutes ago, allhifi said:

 

TrippLite = Great ! Seriously ?

 

Please forward me the EXACT model number --and price.

Then, I will forward you what I consider "really good" (compared to TrippLite would be considered superb) power extender --at a comparable price.

 

peter jasz 

 

How about the TrippLite PS2408RA for $48.25.

 

There is nothing wrong with these power strips. They are well made and, as John Swenson tells us, putting everything on a single power strip "dramatically cuts down on the impedance between boxes, significantly lowering noise generated by leakage loops."

[Speed Racer]

15 minutes ago, Johnseye said:

A great strip would be the Shunyata Venom PS8.  High quality outlets and cable with no conditioning.  Overpriced for a PDU?  Sure, but it's great.  TrippLite is "good enough".  You probably don't need anything better, but if you believe in power cords and outlets get something great.

 

There is no way I am going to spend that kind of money ($1,000 plus) when I can do better using a used $135 Topaz isolation transformer and an inexpensive quality power strip.

[Speed Racer]

1 hour ago, allhifi said:

 

In that case, you are good to go !

 

Why not post for everyone what you think is a better power strip for similar money?

[Speed Racer]

I don't really see anything that would cause one to conclude that the Hammond is better made than the Tripp Lite or vice versa. Why do you think the Hammond power strip is better made? The price is certainly higher (50% or more) on the Hammond units for the same feature set.

 

It would seem to come down to features. The Hammond has the plugs much closer together which is bad if you are using any wall warts. But, that same design feature could make the Hammond better if you are not using wall warts since the plugs are closer which should reduce the impedance between devices.

[Speed Racer]

What devices are you going to plug into this power strip plugged into the Topaz?

[Speed Racer]

Ah, I see. You are one of those folks that believes that $1000 power cords make a real discernible difference. Now I understand.....

[Speed Racer]

Just now, archtype said:

Everything.... Freya, Swagman PSU for Mani, Pioneer turntable, OPPO CDP, Modwright Powersupply for OPPO, 2 Class D monoblocks, Gallo Subwoofer Amp.    I have ordered a Kill-a-watt and will be checking my peak current draws (I don't listen to high volumes much at all). 

 

Regardless of your measured power draw, I would get a larger capacity Topaz isolation transformer than you think you need. I would get a 2.5 kVa unit if you can find one. Another benefit is that you can get a 2.5 kVa unit with .0005pf instead of the .005pf on many of the lower capacity models.

[Speed Racer]

33 minutes ago, Cornan said:

2. Add a DC blocker pre the floating IT. I know this is not recommended by JS, but very beneficial to SQ IMO.

 

How does adding a DC blocker help sound quality when the isolation transformer blocks all DC offset??

[Speed Racer]

Just now, Cornan said:

 

I would'nt know the tech details, but I know for a fact that it does improve SQ. Even if the battery chargers is not connected to the batteries they still decrease SQ of a floating IT in my experiments. Connecting them directly to the AC wall outlet and having a DC blockers pre the floating IT is a major jump in SQ.

 

Well, the technical details say what you are suggesting makes no sense. The isolation transformer blocks DC offset so plugging the isolation transformer into a DC blocker does nothing other than maybe reducing hum from the isolation transformer. The power coming out of the isolation transformer will not have any less or more DC offset with the DC blocker in place or not.  

[Speed Racer]

50 minutes ago, Cornan said:

 

Well, can you from a tech perspective explain why there is a vast improvement in SQ with this configuration?

 

That's the point, there isn't an explanation and there can't be a "vast improvement in SQ" just by putting a DC blocker in front of an isolation transformer. If you say that hear the difference, I will counter with expectation bias....

[Speed Racer]

8 minutes ago, EuroChamp said:

 

A DC filter in front a transformer blocks existing DC, which would bring the transformer into saturation, because the DC would pass the huge coil with almost no resistance.

 

You mean "which could bring the transformer into saturation". That's not likely to happen UNLESS you pick an isolation transformer that is too small for the job.

[Speed Racer]

9 minutes ago, Cornan said:

 

If there is a word I truly hate it is the word expectation bias. It is the most worthless word ever used in the audiophile world. It tells you nothing about anything. Expectation bias is the most subjective word that you can dig up, so I do understand why you want to use it in defence. But common, bring something more firm to prove your statements! 

Really, why is a DC blockers useless in a tech point of view?

 

"Expectation bias" is a phrase that fits well here. The DC blocker is doing a job the isolation transformer will do too. Removing the DC blocker does not change the power coming out of the isolation transformer.

[Speed Racer]

Just now, Cornan said:

 

Not true! ITs is very sensitive to DC offsets. Why? They cannot handle the the pressure from DC noises. A DC blockers releive the pressure from the IT and let it perform optimal.

 

Of course they can, if sized properly. Isolation transformers with iron cores, like the Topaz, are far less susceptible to saturation than toroidal transformers.

 

How much current can the ATL DC Blocker you use handle?

[Speed Racer]

Do you notice how all the pages on the ALT web site talk about fronting toroidal transformers?

[Speed Racer]

36 minutes ago, Speedskater said:

How are writers like at 6moons able to write so many words about nothing? If you connect a wire to a RCA chassis connector just like in the 6moons photo, it will be a noise/interference antenna.

 

a single wire to ground with surrounding layer of stuff does not act as a filter.

 

Amen. I was looking at the date to see if that 6moons review was written on April 1st......

[Speed Racer]

On 7/6/2015 at 10:43 AM, Jud said:

 

$16,000. Hope there's something cheaper that works reasonably well.

 

I'd like to hear how that Smc Audio AC Nexus Power Enhancer is any better than a good isolation transformer at 1/48th the cost....

[Speed Racer]

Speaking of isolation transformers, I found that my 2 channel setup was using no where near a tenth of the power my Topaz 2.5kVA isolation transformer could provide. So I decided to wire it to do balanced power which would make it a 1.25kVa balanced isolation transformer.

 

Before plugging anything in, I measured: hot to ground and got 62vdc; neutral to ground and got 62vdc; and hot to neutral and got 124vdc. My "Kill A Watt" measured 124vdc as well. So plugged components in one at time and all worked as expected.

 

The first thing I noticed was that the Topaz is now silent. No more audible buzz. The second thing I noticed was that it ran much cooler. Theoretically, the power line noise should be reduced even more. I can't say that I hear any difference...but I can't say that I don't. If there is a difference, it is certainly subtle. However, the difference running without the isolation transformer is not subtle. I still say the biggest gain my system gained in sound quality was when I first put everything on the audio side on the same power strip plugged into the Topaz isolation transformer.

 

Anyway, going to balanced power has been an interesting experiment. I have a second Topaz isolation transformer that I can use to test for sound quality differences at a later date. For now, I am content.

 

 

[Speed Racer]

50 minutes ago, Johnseye said:

How did you wire it to do balanced power?

 

I searched on the Internet for a while and found this:

 

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

Output:
Hot 1 (white) to X1
Hot 2 (black) to X4
Jumper X2 to X3 and connect to chassis ground and outlet ground.
 

[Speed Racer]

1 hour ago, One and a half said:

Nice report there. Not putting words in your mouth,  did the bass feel more presence and quieter background? 

 

On a better note, the Transformer in balanced mode still delivers 2kVA on the output. If the temperature went down, the balanced network removed what was responsible,  my guess would be harmonics from the load. The closer the two voltages are to each other to ground, the better the harmonic reduction. 

 

Since there is no neutral in the strict sense, but two live conductors,  a GFCI needs to be fitted on the output of the Transformer.  Now there are GFCI with markings for line and neutral, don't use those. There are 2 pole RCBO that will do the job properly and protect the Transformer from overloads,  and sadly they are about 10 times the price of a regular GFCI. 

 

Hook up the kill a watt again and crank the system really loud, and measure the amps. It might work out to be 6.5A. Choose a 10A RCBO for economy, or 20A to go the full hog of the Transformer,  up to you. 

 

Don't worry, the RCBO won't trip on a large audio transient.

 

Thanks for the information.  Is something like this what I am looking for:

 

http://www.graybar.com/store/en/gb/circuit-guard-automatic-set-15a-125v-portable-gfci-line-cord-18-in-l-92138873

[Speed Racer]

2 hours ago, zilch0md said:

Here's an amazingly relevant video, for those seeking a better understanding of the relationship between an isolation transformer's inter-winding capacitance and leakage currents:

 

Stray-Currents, compensating-currents and ground-loops in Transformers

 

 

 

The Topaz has the "shield" to lower the effect of stray capacitance between the primary and secondary windings.

 

In the video example, there was 160pF stray capacitance between the primary and secondary windings. Is that the same as 160pF interwinding capacitance? Does that mean that my Topaz has .0005pF stray capacitance?

 

If that is the case, while the isolation transformer in the example video "leaked" 12µA at 230v and 50Hz, my Topaz leaks .0000226µA at 120v and 60Hz. That's a whole hell of a lot better! No wonder it has 146dB of common mode noise reduction. Wired up to deliver balanced power, there is supposed to be about 20dB more common mode noise reduction. 

[Speed Racer]

The balanced configuration cancels X amount of common mode noise at the device. So, whatever makes it through the interwindings and on to the power cable is partially canceled.

 

Even if I weren't getting better common mode noise reduction, I like the fact that the isolation transformer is running both quiter and cooler.