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

[YashN]

I wouldn't bet on me loving your hollow state amplifier.

Both my Preamp and 15W/Class A have THD of something like .0002% (perhaps a little lower?) due mainly to active device matching and front end balancing .

A friend nicknamed my15W Class A "The Holo Amp." ( as in Holographic )

 

So yours would be a Holo Hollow amp?

[YashN]

No, it's fully solid state

 

Ah, the Holoss!

[YashN]

Here is my SET Tube Amp that I made with my own hands (PCB by George @ Tubelab, KT-88 by Electro-Harmonix and other tubes from Russia, Transformers by Elcor).

 

It doesn't care about others' THD figures, just outputs fantastic sound with the fastest dynamics I have ever heard:

 

 

 

It's very heavy. I have not even yet added a choke as well as Russian Motor Start Caps.

[YashN]

Just as well we don't live in the E.U. as they are likely to ban such power thirsty relics from the middle of last century !

 

No way!

 

Instead they (more precisely Poland) gave birth to this, which is arguably one of the best DACs you could ever hear, especially when it comes to DSD:

 

 

[YashN]

This is where I'm headed - from reading everything I can find on isolation transformers ...

 

Like minds, like minds, Mike. Gathering a lot of info so that it all clicks into place in my mind at one point.

 

The graphic looks great, I was thinking of ding some as well.

 

Keep it up!

[YashN]

Nice:) I also get more pleasure out of things that I've built myself than commercially available (though life is short :)

 

Thanks Life's too short not to learn a new thing every day

 

Want to build another?

 

I could do it even better now (double box design, chassis and woodwork, better parts, motor cap, choke, etc...).

[YashN]

Apparently, this is just the nature of unregulated inductive energy transfer between two (1:1) coils - the efficiency drops as the load increases. I'm startled that I'm having to figure this out on my own after all the reading I've done about isolation transformers. You would think that someone, somewhere, would have mentioned this in the articles they've written about isolation transformers. Perhaps the authors I've been reading simply don't know this (or they assume that every reader does), but the voltage increase can be bad news if you use an oversized transformer for your load, which everyone seems to universally recommend. And if you start daisy-chaining your isolation transformers (with those having grounded secondaries preceding those with floating secondaries), with each of them being oversized, it gets even worse.

 

Good points and great investigation as well.

So, my low-budget, noise-eating, Rube Goldberg contraption will soon look like this (with the 110V voltage regulator heading up the chain):

 

[ATTACH=CONFIG]19797[/ATTACH]

 

And then... I can start listening and comparing this crazy daisy-chain to just plugging the DAC and amp straight into the wall outlet, or with and without the 1604A floating secondary transformers. (Note that my "source" components, an iPad 3 and the USB Regen, are powered by independent battery packs.)

Looks great, love what you brought to the 'table'!

 

This guy's review of the APC voltage regulator is compelling and fun to read. Seriously, this is funny and informative:

 

Very interesting observations, especially when it comes to the Mullards (ugh!).

 

Listening impressions are forthcoming...

 

:-)

 

Mike

 

Looking forward to those!

[YashN]

Curious if anyone here has/is using these Firewall modules from LessLoss?

 

Firewall Module: Current Conditioning Unit | Audiophile Current Conditioner

 

Every review and comment I've read looks positive and that has me wondering why these aren't mentioned more often. They've apparently be around a few years. Reasonably inexpensive at ~$200 each module.

 

 

Cool find.

 

I have come across the brand a few times in other forums but hadn't gone to this actual product page. Nice one.

 

There's an AC Line filter plug thingie from Furutech that has great reviews too.

[YashN]

The apparently only filter high frequency noise being based on skin effect.

 

Thoroughly interesting, monteverdi.

[YashN]

This guy's review of the APC voltage regulator is compelling and fun to read. Seriously, this is funny and informative:

 

http://www.amazon.com/review/R1JVVQBKB01MPA/ref=cm_cr_dp_title?ie=UTF8&ASIN=B00009RA5Z&channel=detail-glance&nodeID=172282&store=electronics

 

Still laughing while reading this! HAHA!

 

I can't laugh out loud because my gf is napping.

 

Repressed laughter bouts.

 

Then I'm on to reading your listening impressions!

[YashN]

I've already done some listening and I'm really impressed by how clean everything sounds so far, but I haven't done any A/B testing. I can't stop grinning, though that's for sure. Dead quiet, inky black. :-)

 

Here's how each component is powered, currently:

 

iPad 3 > CCK > 0.7m Supra cable

internal battery

 

USB Regen and the DAC's USB module

Anker Astro Pro 10,000mAh LiPo battery, set for 9V output

 

Metrum Acoustics Octave MkII DAC

117.5V from Mains > APC LE1200 > Tripp-Lite is500 > B&K Precision 1604A

 

Metrum Aurix headphone amp > Sennheiser HD800

109.9V from Mains > APC LE1200 > Tripp-Lite is500

 

:-)

 

Verrrrrry nice!

 

Well worth it.

[YashN]

Here's another interesting testimony promoting the use of an affordable isolation transformer, from a guy who sounds pretty seasoned:

 

What does an Isolation Transformer Line Conditioner do?

 

I agree with his remark on RFI / hash and the use of affordable isos. I only partially agree about his assessment of existing power supplies because I think power supplies in existing equipment are not always very well made (check John Swenson's technical writing on his Power Supply at Uptone Audio).

 

As for power cords, I don't agree with him: at least in my system, my DIY power cord made a great difference for the amp.

 

I am planning to make several more power cords, one for the AC Filter box (which looks to want to morph into a fuller power conditioning and grounding unit as days go by), one for the iMac, and one for each of the digital components.

 

The geometry and shielding are going to be crucial so that all the good RFI/EMI cleanup and impedance matching of he AC filter box are not partially lost from generic power cables.

 

It's going to be very interesting (it's also quite some work).

[YashN]

Anyway, this configuration just sounds great, with a much lower noise floor. It feels a bit like sculpting where the subtraction of the material (noise in this case) reveals additional details of the statue and results in a much smoother finish.

 

Very interesting to see your setup, feedback and research results, Larry. Thanks for sharing.

[YashN]

I found this "accessible" article that describes how a transformer's output voltage changes with the Power Factor (PF) of the load.

 

Comforts me in my own decision to investigate Power Factor Correction for the AC Filter Box.

[YashN]

Yes, a floating secondary does not incur a shock hazard as long as the safety ground remains intact all the way to the outlet into which the appliance is plugged and the user at no time touches both the hot and the neutral within the appliance. Touching one or the other is perfectly safe with a floating secondary (but don't try this!)

 

In other words, an isolation transformer with a floating secondary does NOT equate to using a cheater plug:

 

[ATTACH=CONFIG]19816[/ATTACH]

 

 

Great info, Mike.

[YashN]

Anyway, there is no doubt that the Tripplite in it's standard configuration with the balanced transformer sounds better than with it's ground lifted.

 

Agreed it is surprising that the DAC and AMP sound better plugged into the balanced transformer, rather than having the DAC on it's own isolation transformer. One explanation could be that the amp and DAC are tightly coupled with the XLR connections, and that the extra isolation creates a ground loop or induces noise.

 

I found a local transformer company that had built a prototype balanced transformer for audio use that never hit the market. I'll talk to them next week to learn the cost, minimum order size and lead times for an order. Perhaps we could do a group buy?

 

Awesome to see what you both brought to this thread, Larry and Mike. Thanks.

[YashN]

...a Triton chassis grounding device by Miguel himself, and relayed over at WBF.

 

Very reminiscent of Shunyata's devices.

 

 

[YashN]

Last night's reading and this morning's reading:

 

1. Philip Giddings on EMC

2. Coilcraft Application Notes - whole section on EMI/RFI filtering

3. Murata - Differential and Common Mode Noise

4. VAC - Design Skills for Common Mode Chokes

5. Various sections by Ott on cabling, shielding, EMC

 

Considering the choke and winding and 4 above, I don't see a lot of info and sometimes some contradictory information.

 

 

 

The two windings I have seen are sectional and bifilar. Lukasz's initial winding was bifilar, but I think sectional could be better, provided you get the winding direction correct. Now, for that correct winding direction, this is where I think I have seen contradictory info, it looks like VAC above says opposite winding directions should be used, but I believe on AudioCircle, someone says the winding has to be in the same direction.

 

A couple more things that are good to think about for a proper implementation is the temperature and operation efficiency interplay of these chokes (Curie temperature) as well as their efficiency under mechanical stress.

[YashN]

One is a rather simple Audiophile Line Filter box which uses affordable filter boxes, and the second one a fuller AC Power Conditioner build with a transformer.

[YashN]

Now, for that correct winding direction, this is where I think I have seen contradictory info, it looks like VAC above says opposite winding directions should be used, but I believe on AudioCircle, someone says the winding has to be in the same direction.

 

Figured it out with pen and paper, and with the knowledge from Physics class where we had a couple of useful mnemonics, one being the right hand thumb rule and the other being the North and South rules.

 

So, the common mode noise causes flux to accumulate within the choke, where it is lossy, and hence the choke impedes transmission of CM noise further.

 

Cool beans, so I know how to improve those filter lines now.

 

Further reading on CM noise and Differential mode noise (for USB) showed that one can also consider common mode chokes for the signal lines. Worth some tests with my new shorter USB cable prototype too.

[YashN]

A great article by Chuck Counselman on Common-Mode Chokes.

 

It's always interesting to see Ham people solving interference issues as the problems they face are more dire than ours, except sometimes we do face the same type of interference.

 

The article has some great illustrations about using chokes on power cables, namely a couple of them mentioned in one section and a pic of one choke near the wall-wart power supply.

 

I wired up my DIY probe circuit to an oscilloscope program on the computer, so it could be interesting to probe low-level signal while adding a clamp-on ferrite and monitor the effects like this.

[YashN]

More accessible are papers by (but they still require some studying) :

Jim Brown

 

I was reading the early page of his guide to RFI/HAM yesterday. Very informative relative to chokes, and of course, cables acting like antennas (both receiving and radiating). The latter is what has been bothering me a lot concerning RFI.

 

Makes me wish I had plenty of large Common Mode Chokes so that I could add some especially around the Ethernet cables, etc...

 

One thing I could do is put the Cable Modem further away from the main computer and audio equipment. It was necessary to put it in the vicinity of the main computer when I was using the iMac's internal Wi-Fi router through Ethernet Sharing (very, very stable). But now with the use of the Linksys router, I can put the Cable Modem much further.

[YashN]

Found a few transformers I could play with:

 

1. One from the powered subwoofer from a malfunctioning LG Bluetooth system

 

2. One from the power supply from an old VCR

 

3. One from the power supply from an old DVD player

 

[YashN]

Some very good information on wiring for Residential AV systems - The Truth by Exact Power.

 

Starts with 4 myths and then goes on to much, much more:

 

National Electrical Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Important Things to Remember When Installing AV Equipment . . . . . . . . . . . . . . . . . . . . 2,3

Simplified Grounding Guidelines for Audio, Video and Electronic Systems . . . . . . . . . . . . . . 4

Grounding (Myths, Bootleg Grounds and More...) . . . . . . . . . . . . . . . . . . . . . . . . . 5, 6, 7

Neutral-Ground Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Intersystem Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Power Quality Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 9

Benefits of Specialty Isolation Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Electrical Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Common-Mode Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Electrostatic (Faraday) Shielding in Power Transformers . . . . . . . . . . . . . . . . . . . . . . . . 12

Radio Noise (RFI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Power Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Stray AC Magnetic Fields in Homes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14, 15

AC Magnetic Field Strengths from Different Wiring Types & Plug-In Power Supplies . . . . . . . . 16

Surge and Spike Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Types of Surge and Spike Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Surge Suppressors and Noise on Safety Ground Wires . . . . . . . . . . . . . . . . . . . . . . . . . 19

North American Product Safety Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Typical 120-Volt Receptacles Used For Electronic Equipment . . . . . . . . . . . . . . . . . . . . . 21

Receptacle Wiring – Common Errors and the Correct Way . . . . . . . . . . . . . . . . . . . . . . . 22

Dealing with Electrical Inspectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 23

Common AC Wiring Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23, 24

Calculating System Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Calculating Amplifier Circuit Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Single and Multiple Circuit Sequencer Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 25, 26

Symmetrical (Balanced) Power Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Wiring Methods for Separately Derived Systems (Isolation Transformers) . . . . . . . . . . . . . . 27

Typical Three Phase Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29, 30

Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 32

[YashN]

Haven't yet experimented with my transformers as I'm trying to see if it's better to use them in the circuits they currently are in, or else remove them completely.

 

Saw this very cool video (and the 3 or 4 next ones after this are great too) from Afrotechmods: