mains Voltage

[Arkless Electronics]

In times past electronic gear used to be fitted with mains voltage selectors which selected the appropriate tapping on the transformer primary. This was because the transformers used were designed deliberately to be run close to saturation to improve regulation. If extra turns were wound on the primary to increase the saturation margin, the increased resistance would result in poorer regulation.

When a transformer saturates the inductance falls and the primary current rises. Saturation can be caused either by running the primary on too high a mains voltage or by having some DC on the mains (which is effectively is similar, but only occuring each cycle, rather than every half cycle). It only takes ~100mV of DC offset to cause toroidal transformers to buzz (owing to a lack of air gap in the core, toroidals 'hard limit' when saturated).

Early power supplies were unsophisticated, so it was important not to compromise regulation, but modern regulated power supplies can be supplied with a transformer that has a much larger saturation margin, and hence no need for a mains voltage selector.

However regardless of the margin of saturation, if the laminations are loose they will buzz, simply due to the AC nature of the mains supply.

Excellent!

[Floyddroid]

Steve, you could contact Airlink, who should be able to supply a balanced mains transformer with 220v output. Be cheaper than a mains regen unit.

Which one Ali the bus 1500 or the bps2000?

[Edwardlon]

Interesting thread.

For the past few weeks I have been trialling a friend's Isotek 2k "Qube" powering my preamp, amp, DAC and music computer.

In a word - transformative.

Much cleaner sound, insightful, rounded, more natural.

Took it out of circuit for a few days and difference very clear.

After Munich I may well get a trail unit of the Power Inspired AG1500 to see if another step change.

E

[Ali Tait]

Which one Ali the bus 1500 or the bps2000?

Either would be fine, I'd probably go for the larger, just cos. :-)

[Edwardlon]

What is an easy way of measuring the quality (with audio in mind) of domestic mains electricity?

Ed

[struth]

possibly the easiest is to borrow a mains regenerator. if it improves things then your mains isnt perfect. if it doesnt, then dont worry

[Edwardlon]

possibly the easiest is to borrow a mains regenerator. if it improves things then your mains isnt perfect. if it doesnt, then dont worry

True. However I'm always wary of the placebo effect - no doubt having been caught out many times. Nice to have reassurance with measurable stats. But having said that I do think I got a marked difference using an ISOtek Qube recently so perhaps an AC regen (such as that provided by Power Inspired) will be as obvious.

I see that you have the AG1500 regen unit. Did you notice a significant difference?

Interestingly in June's edition of HiFi News' there is a relevant comment (p116) on this subject. The comment also discusses the idea of "Variable MultiWave" which, to me as a layman, seems contra intuitive to a pure wave (as done by say the AG1500). But like you the comment says to try things out.