Re: 30 Hz > 15KHz , 8 W rms , only £ 2477 for 2 .. Valve of course

[David Looser]

wrote

> The principle is sound, like balanced audio circuits, it uses a > transformer with two secondaries of half the primary voltage, > connected in series, with the junction earthed and the load supplied > across the two outer ends. You could get a suitable transformer made > for much less than Russ charges.

A similar technique has been used for years for power-tools etc. on building sites, except that the secondary voltage is 110, rather than 240V. The centre tap of the secondary of the transformer is earthed, thus the voltage to earth of each conductor is only 55V. As a safety technique it has it's value, but what is the advantage when feeding audio equipment?

David.

[David Looser]

. As a safety technique it has it's

Does it? who says it "sounds good?, and why should it sound any different? Frankly if it actually made a hap'th of difference to the sound people would have been doing it decades ago.

Well that's the point isn't it? persuade the gullible that it sounds better, then rip them off.

David.

[Ian Jackson]

Obviously it's the same reasoning concerning the virtues of using balanced twin feeder versus (unbalanced) coax. If you don't do the engineering properly with the coax (no balun etc), twin feeder can be a better bet. Of course, in this case, there's only mains cable which, unlike coax, has no screening).

[David Looser]

"Ian Jackson" wrote

Is it "obvious"? You are talking about signal connections above, but this is a power supply. Please explain exactly how using a balanced mains supply affects sound quality.

David.

[Ian Jackson]

In message , David Looser writes

Sorry. I forgot to add a cynical, satirical, sarcastic smiley. [I'm no good with smileys.]

[David Looser]

OK, message received and understood.

[I'm no good with smileys.]

Nor me!

David.

[geoff]

Last time I looked at that site, they were charging £76 or something for a "low noise" mains flex (apparently it's magically perfect when it comes out of the socket)

So, the last time was, and is, the last time

[Bob Eager]

You were looking at the cheap ones, geoff. The real entertainment is to be had with more expensive items...please do look...!

[Ian Jackson]

In message , Brian Reay writes

I forgot 'MPs'. As I SHOULD HAVE said before..... "I have often wondered who actually buys this sort of stuff. All I can think of is that it's rich people such as stockbrokers, bankers, TV personalities, pop stars AND MPs - people who are essentially non-technical, but simply 'want the best equipment than money can buy."

[Spike]

Have a Google for 'humdinger' (and/or 'hum dinger').

[The Wanderer]

Hmmm, I guess there ain't too many peops who sit in an anechoic chamber to listen to their scratchy vinyl.

I reckon all 'high end' hifi is a con, stick it a normal room with yer average selection of furniture, curtains, etc, and you've just wasted one hell of a lot of money. Of course, no one is going to admit they've been a complete plonker......

Now, where's that old Dansette and the 78 of Danny and the Juniors? :-)

[David Looser]

"Spike" wrote

I don't need to Google for it, I've known about, and used, humdingers for many years, they are used to balance out the hum induced by valve heaters and their wiring. But this isn't valve heater wiring, this is mains wiring, the other side of a double-wound transformer from the heater wiring. So I ask again, explain in detail just how balanced mains wiring affects the sound?

You can't do it can you?

David.

[Spike]

As you know all about hum dingers, and have been using them for many years, can you see any parallels between their modus operandi, and (balanced) mains wiring?

[geoff]

Show me these people with SO much more money than sense

[geoff]

No, I spotted it later

together with the 2.5mm earth lead at 99p / m which looked a bit out of place

[Spike]

David Looser mentioned 'balanced mains wiring'. An attempt to balance valve heater circuits and thus reduce hum from the imbalance can be done via a hum-dinger, the better ones having a resitively-loaded centre tap on the heater tranny. The idea is to balance the heater wiring to ground and thus reduce unequal currents. It does not seem unreasonable that 'balanced mains wiring' might do the same thing, thus reducing the effect of stray fields on the internals of the equipment. Whether this is done through transformer design, or in some other way, doesn't really matter.

[Spike]

Possibly, but that's not what he said, which was why I quoted his words.

[Jim Lesurf]

I'd assumed that the *currents* in a closed loop like the heater wiring pair would already be close to equal. But that a 'hum dinger' or 'balancing' was to get the *potentials* to have equal but opposite values. Thus reducing electrostatic/capacitance couplng from heater into cathode, etc.

Again, I tend to assume that any food audio kit will have a sensibly designed PSU, so have a transformer, etc, able to do its job. Also, my understanding is that UK mains tends to be *unbalanced* by intent with the neutral as near zero potential as practical. And hence kit would be designed to accomodate that - not for assuming the neutral and live had potentials of equal magnitude.

For similar reasons I have doubts that it is 'safer' to arrange for the neutral to have larger potential swings relative to a grounding.

But then I do tend to have my doubts about many of Russ Andrew's claims and 'theories'... :-)

Slainte,

Jim

[David Looser]

"Spike" wrote>

Yes I can see a parallel, I can also see the differences. The heater wiring runs right into the valve, the mains wiring does not. The mains input is fed to a transformer primary, so the currents in the live and neutral conductors are equal and thus the resulting created external magnetic fields pretty much cancel out. The electric fields from the two conductors will be different, but at the distance these will be away from the low-level audio circuitry (you have remembered *not* to wrap the mains flex round the audio input cable haven't you?) the effect is negligible. In any case *any* mains wiring in the vicinity will have an equal effect regardless of whether it's there to feed the audio amp or not, or are you proposing to run the entire house off balanced mains?

The humdinger has been around since the 1930s, had this "balanced mains" idea been effective it would also have been around since the 1930s.

David.

[David Looser]

Eh? The amplifier's mains transformer provides common-mode isolation between the mains and the power supply to the amp. So you can keep the loudspeaker at mean earth potential regardless of whether you are using balanced mains or not.

David.