Benchmark V Opus 21

MGDeWulf · « **Reply #20 on:** 6 Apr 2005, 09:11 pm »

Quote

Your link also includes your article 'AC and You - a New Era'. In the 8 years since you wrote it have your conclusions changed? Specifically, with the advent of many balanced AC transformers/conditioners, do you still think transformers as generally negative?

From Paul

You bring up a good point Paul. Truth be told, I haven't considered the statements made in that article in a long time. It was obviously made prior to the advent of balanced transformers for high-end audio use. That second article is a little crusty, now that you bring it up. I believe it was correct when written, but times have changed. (The first article, I still stand by)

Though I haven't totally ignored the possibility of balanced transformers. Last year I contacted (e-mailed) the company largely responsible for manufacturing them, and they did not respond to my inquiries. Maybe they read my article and decided not to take a chance. At the time I didn't really want to buy one, so I let it drop. But, the article still gives an impression that I don't neccessarilty want to give. I think I should strike it....

Good listening,
Marty

Steve · « **Reply #21 on:** 7 Apr 2005, 12:29 am »

An interesting experiment would be to install a DPDT switch, near the power cord, and connect it so that flipping the switch will reverse the two AC leads (white and black leads for USA). The NEUTRAL wire (green for USA) is not fiddled with. It remains connected to the chassis for protection.

Occam · « **Reply #22 on:** 7 Apr 2005, 12:48 am »

Steve - A minor/major point, I believe you meant to say "The GROUND wire (green for USA) is not fiddled with." rather than "The NEUTRAL....", but your intent was clear to me.
Indeed, that is exactly what I do, with a front mounted DPDT, center 'off' toggle switch, that combines the functions of 'on-off' and AC phase reversal, which provides hours of fun for the whole family.

MGDeWulf · « **Reply #23 on:** 7 Apr 2005, 01:12 am »

Andy Bartha has built a number of power supplies for me, and he always uses a built in 3-way power switch. Which is cool, but if you know that the proper ground potential is important enough to put a 3-way switch on, why not wire it up right the first time and not need a switch? BTW, andy wires the equipment for the lowest potential, so I don't need the switch - but it's there.

Just a thought...

Marty

Steve · « **Reply #24 on:** 7 Apr 2005, 01:17 am »

Actually no. I meant to say Neutral wire. When talking to electricians, neutral is the term for the green wire.
I use white as ground, black as hot, and green as neutral, earth ground.

Occam · « **Reply #25 on:** 7 Apr 2005, 01:20 am »

.... which is the whole point behind (perfectly) Balanced AC, so you don't need that mains phase reversal (by switch or hardwirng...)

Steve - while were obviously talking about the safety ground/earth (green), I've never heard this wire referred to as neutral.
http://sound.westhost.com/psu-wiring.htm#4.0

What country is your electrician from?

Steve · « **Reply #26 on:** 7 Apr 2005, 01:24 am »

In theory, yes. But it has to be done very carefully, or problems can develop.

Occam · « **Reply #27 on:** 7 Apr 2005, 02:44 am »

Quote from: Steve

In theory, yes. But it has to be done very carefully, or problems can develop.

What are you referring to? Balanced power? Chewing gum?
What DOESN'T require care in this complex world?

Assuming you're referring to balanced AC-
Both 60V ac antiphase lines should be properly fused/switched. I realize we shouldn't run some of our 'Golden Oldies' on balanced AC as the Neutral (regardless what your electrician calls it) might be connected to the chassis, but rational folks haven't done this for 25 yrs.
Other than the above, what are those areas I need to be concerned about, specifically? In my own $30 diy balanced power conditioner, I've never had any problems, but I want to be very careful, lest problems develop.

TIA

Steve · « **Reply #28 on:** 7 Apr 2005, 04:02 am »

Quote from: Occam

What are you referring to? Balanced power? Chewing gum?
What DOESN'T require care in this complex world?

Assuming you're referring to balanced AC-
Both 60V ac antiphase lines should be properly fused/switched. I realize we shouldn't run some of our 'Golden Oldies' on balanced AC as the Neutral (regardless what your electrician calls it) might be connected to the chassis, but rational folks haven't done this for 25 yrs.
Other than the above, what are those areas I need to be concerned about, specifical ...

In Illinois, green is always considered "neutral" and white is refered to as "ground" or "common". Black is called "hot". Grew up with that distinction. No big deal to me.

Wasn't refering to balanced AC, but balanced interconnects. The problem with lowest potential Marty is discussing has to do with transformer leakage, from primary to secondary.

Having a balanced AC transformer may or may not solve the problem as there is leakage between primary to secondary in any transformer, and the leakage would have to be balanced, the question is how well balanced.

With balanced ins or outs, the possible problems have to do with the design used, so it can be complex. Could have to do with interstage transformers (IT), a phase splitter of some sort, or extra power supply needed in the design, or maybe some other problem not necessarily found in non-balanced coupling.

Balanced coupling is usually if not always more complex than non-balanced designs. Doesn't mean it cannot be done, just more complicated with more chances of problems. The question becomes which has the least side effects.

Russtafarian · « **Reply #29 on:** 7 Apr 2005, 08:45 pm »

Occam wrote:

Quote

I realize we shouldn't run some of our 'Golden Oldies' on balanced AC as the Neutral (regardless what your electrician calls it) might be connected to the chassis, but rational folks haven't done this for 25 yrs.

Is that why my mid '80s Quicksilver monos hummed like crazy when I replaced the cheap lampcord power cables with chassis-grounded power cables and plugged them into my Equitech? I ended up snapping the ground prong off the cables just to shut them up. Any way to fix this with these amps or do I just stick with an ungrounded AC cable?

Russ

Occam · « **Reply #30 on:** 7 Apr 2005, 10:28 pm »

Russ - when a component with neutral tied to the chassis ground (common practice many years ago, but a strict UL no-no) and fed symmetrical balanced AC, the chassis would go live with 60v AC, not enough generally to kill, but you'd certainly know

if that were the case.... Were you feeding the component with balaced power from the Equitech? Does the Equitech have a GFI on its balanced AC outputs. If it does, and the mains Neutral were tied to the mains Ground, the GFI would trip....

Are all the components plugged into the Equitech?
If not, is the Equitech plugged into the same oulet/circuit as the rest of the non-Equiteched components?
If the answer is 'no' to both of the above questions, it could well be a typical ground loop hum. That'll teach ya a good reason to avoid grounding a component to the mains ground that previously wasn't. No 'good' deed goes unpunished. Feel free to add an IEC inlet or hadwire, using a SHIELDED powercord, but you must make sure to leave the ground prong of the inlet(or the ground hardwire) unconnected, which leaves the shield on the powercord acting as a Faraday shield, FWIW.

Russtafarian · « **Reply #31 on:** 8 Apr 2005, 02:20 am »

Thanks Occam. Yes, all the gear was plugged into the Equitech and the GFCI didn't trip. But those Quicksilvers sure did hum when they were grounded to the Equitech. The present power cords are not shielded but I have a bunch of Volex cords arriving tomorrow. I'll hardwire the Volex into the amps and not connect the ground. That should help.

Last night I got out my voltmeter and measured the chassis potential of all my gear. Everything was wired up right (standard power plug orientation gave the lowest AC voltage) except the CD player. Flipping the phase of the CD power plug did open up the sound of the player. Cool! I guess I'll have to add this to my short list of cheap system tweaks: beer, pillow behind my head, and now AC phase correction.

Occam · « **Reply #32 on:** 8 Apr 2005, 03:38 am »

Russ - You're quite welcome, but the kudos belong to MGD who is largely responsible for informing the obscessive. I'm sure I learned of this from BFS many years before that article.
When you hardwire the Volex, make sure you fold back the mylar shield and the uninsulated wire snuggled underneath it, as well as the ground wire itself, and then insulating. The only thing you want electrically connected at the amp end is the 'live' and 'neutral' lines. The molded plug on the Volex has its own sonic signature, which I sorta like, but changing the plug, or a starquad cord (which isn't shielded but has its own form of noise rejection) or a .......

Russ - I'd certainly like to hear of your progess and travails in this. There is a specific Volex thread -
http://www.audiocircle.com/index.php?topic=18044

andy_c · « **Reply #33 on:** 9 Apr 2005, 07:42 pm »

Hi guys,

Here is an explanation for the existence of a non-zero AC voltage to ground of a component chassis that's not safety grounded. Thought it was a good read, just in case anybody hasn't seen it.

Steve · « **Reply #34 on:** 9 Apr 2005, 08:47 pm »

The "simple" solution of balancing the intput or output is fine, except adding extra parts and/or stages nearly always lowers the sound quality.

I think one wants a minumum of hum and as high of audio quality as possible, which means as few of sonic robbing parts as possible.

Most, or at least a portion of the hum problems occur, as the author rightly states, in the design/layout/constuction:

Another problem is Too much gain in the component. For instance an amp with an input sensitivety of .5v for full output is, in my opinion, way to high.

Even with a passive preamp, that kind of sensitivity is unnecesary. Afterall, a CD player is typically capable of 2 vrms out. By lowering the gain of components, it would be easy to lower the hum by a factor of 5 or more. This, along with proper construction/design should lower hum dramatically.

Another problem could be room resonance. If a resonance of 10db occurred at 60 c/s, any 60 c/s hum problems would be accentuated.

Occam · « **Reply #35 on:** 9 Apr 2005, 10:53 pm »

andy - Thanks for the reference. As per usual, Douglas Self's technical expertise is always excellent. And also, as per usual, he illustrates that thought process of a certain type of engineer who doesn't have to listen to their own creations as measurement is totally adequate.

From the reference, Doug Self writes -

Quote

It has been suggested that balanced mains has miraculous effects on sound quality, makes the sound-stage ten-dimensional, etc,etc. This is obviously rubbish. If a piece of gear is that fussy about its mains (and I don't believe any such gear exists) then drop it in the river.

Based upon? I wouldn't think that his conclusion was based upon listening, as he freely admiits he doesn't listen to his own amps durring development. Or comparisons after completion. I guess it is sufficient to mock the over the top hyperbole of those subjectivist audiophiles and conclude the thought experiment totally free of empirical verification.
Perhaps Mr. Self uses his audio eqipment in a bucolic environment with those few neighbors consuming electricity with all draws with no noise, hash, harmonic distortion.... otherwise he'd throw any equipment with a toroid lacking interwinding shielding (almost all of them) in that river....

Sadly, the only rubbish I see is how someone can be both a fine engineer, and a pisspoor scientist.

andy_c · « **Reply #36 on:** 12 Apr 2005, 04:19 am »

Well, I should have put a caveat about his anti-subjectivist rants in my post I guess

.

My main purpose was to point the reader at some schematics that show pretty clearly how the AC voltage that was under discussion gets there, not to spread his general philosophy.

My approach to reading his stuff if to find the useful information and ignore the rest. And I've found plenty of useful information there.

Andrew B. · « **Reply #37 on:** 12 Apr 2005, 08:10 am »

It seems to me that the example he gives of two double-insulated units creating a ground path through the interconnect can also be avoided by using a non-conductive interconnect... in the case of my system that would mean swapping from a digital coaxial interconnect to an optical one.

In fact my experience is that this degrades the sound quality slightly but of course there could be other reasons for that.

Andrew

skrivis · « **Reply #38 on:** 12 Apr 2005, 05:09 pm »

Quote from: Steve

In Illinois, green is always considered "neutral" and white is refered to as "ground" or "common". Black is called "hot". Grew up with that distinction. No big deal to me.

Rascist! Just kidding.

I've always heard green=neutral...

If you look at typical Leviton sockets, there's a green terminal and it's not for neutral, it's ground. Do they sell special Illinois versions of their products???

Occam · « **Reply #39 on:** 12 Apr 2005, 05:32 pm »

Andy,

You're absolutely right. There was no reason for me to get all 'het' up over your link to Douglas Self. I also link to his site for explanations which are consistently excellent.
By way of explanation, I guess the fact that I'm currently working on a balancing power conditioner might have something to do with it...