Craig Sawyers

Have a great day Mike!

CHM must be loving all of this. It'll be interesting how the three NPC old blokes sitcom with cars thrown in works out.

Have a truly great one Birgir!

Two people who broke the UK in one picture - the privileged Oxford University (so-called dining) Bullingdon Club, Criterion for entry: rich. Cameron and Boris Johnson in the shot. Fills me with the urge to defecate.

Meanwhile, a hero's welcome for Trump to Scotland

Have a great one! Happy birthday

No way am I going to trust my machines to this POS. W7pro64bit is just fine thank you. There are all sorts of horror stories about corrupted hard drives, unrecoverable situations and dead machines out there. To kill off W10's pop up insisting I upgrade (which was installed against consent almost as a virus) I used this https://www.grc.com/never10.htm Ha Ha - double post was a result of installing W7 updates at the same time!

No way am I going to trust my machines to this POS. W7pro64bit is just fine thank you. There are all sorts of horror stories about corrupted hard drives, unrecoverable situations and dead machines out there. To kill off W10's pop up insisting I upgrade (which was installed against consent almost as a virus) I used this https://www.grc.com/never10.htm

Have great one, Justin!

Britain is entirely in shock, as is Westminster. First British politician to be murdered in 25 years, first woman politician ever. 40 years old, two young children, shot and stabbed to death in broad daylight around midday yesterday outside her political surgery (see below), which she was holding in the public library. The 50 year old perpetrator walked calmly away, and was arrested by police. He apparently shouted "Britain First" - which is an ultra-right murky organisation. It seems he has a long history of mental problems too. Flags at Westminster and Buckingham Palace are at half mast. Political surgery. Politicians are accountable to their electorate, and all (or most) hold regular events at which people can come and have a one-on-one meeting to discuss their concerns and issues that their MP can help with. Even the Prime Minister does them. Campaigning for the In/Out EU referendum has been halted.

Harpy eagle, the ultimate apex raptor. Claws second only to a grizzly. Crap quality vid though.

Agreed. I'd like to know the precautions that must have been taken in machining and polishing the Be mirror substrates for the JWST http://www.nasa.gov/feature/goddard/2016/james-webb-space-telescopes-golden-mirror-unveiled . 6.5 metres diameter, 20kg per segment and 18 segments = 360kg of beryllium.

Very few audio products use beryllium, even though it is close to being the ideal material in terms of young modulus/density ratio. Used in the 1970's in the classic Yamaha NS1000M speakers for HF and midrange units. Surprisingly not particularly toxic in the metallic state - it is the soluble salts that are the killer. The mirrors in the James Webb Space Telescope are all of machined beryllium, gold coated.

For rating transformers I use a free simulation package from here http://www.duncanamps.com/psud2/ . For a capacitor input filter (the usual sort) the transformer VA rating is always significantly higher than the power delivered to the load. This is entirely a result of the pulse-like capacitor charging current. Just as a for instance, Tx with 100V, 1ohm secondary, bridge rectifier, 10,000u capacitor and 700mA load. Power to load = 0.7 x 135V = 94.5W. VA from Tx = 1.8 x 99 = 178W. This is typical - you need somewhere about 1.5 to 2 times the VA rating for the Tx than is delivered to the load. The other way to do this is to use the nomograms in a classic paper by Schade (Proc IRE, July 1943, 341-361, "Analysis of Rectifier Operation, O. H. Schade). There is an update with measurements in Linear Audio, V8, Sept 2014, 83-127 "The Otto Schade Method, A practical design method for Rectifier Circuits" by Rudolf Moers. All of this agrees with http://sound.westhost.com/power-supplies.htm which concludes with Transformer The voltage is determined by the power that you need from the amplifier. Calculate power from the formula ... P = Va² / R Where P is power in Watts, Va is RMS speaker voltage, and R is speaker nominal impedance The supply voltage (allowing only for basic losses) is calculated as follows VRMS = Va * 1.1 Where VRMS is the transformer secondary voltage (for each supply rail) VA Rating - Class-AB The minimum VA rating suggested is equal to the amplifier power. A 50W amp therefore needs a 50VA transformer, or 100VA for stereo 50W amps. Larger transformers (up to double the amp power rating) will provide a 'stiffer' power supply, and this may be beneficial. For continuous operation at full power (never needed for hi-fi but common for guitar amps), the transformer should have a VA rating of up to 4 times the amplifier power. It is suggested by some transformer manufacturers (and no doubt gleefully adhered to by many amplifier makers) that the VA rating needs only to be 0.7 of the maximum amplifier power. While this will work well enough in most cases, you will not have a 'stiff' power supply - a more appropriate term would be 'soggy'. The DC voltage will collapse as more current is drawn. VA Rating - Class-A The minimum VA rating suggested is at least 4 to 5 times the amplifier power. A 20W Class-A amp therefore needs a minimum of an 80-100VA transformer, or 160-200VA for stereo 20W Class-A amps. Transformer rating may need to be as much as 10 times output power, depending on amplifier topology and quiescent current [2]. The constructor needs to be able to work this out, or transformer failure is likely.

^This.

This surely is a fucked up world we're living in. 50 confirmed in Orlando. Jeez. Out of a clear blue sky. Europe is far from immune. The Charie Hebdo killings in Jan (12 dead) and the mass attacks in Nov (130 dead), both in Paris last year, show that. And we're not immune in the UK either - last attack was the London bombings (52 dead), and that was 12 years ago - time's ticking for us too. Let's not forget the Madrid train bombs in 2004 (191 dead), the Mumbia attacks in 2008 (157 dead), in the Phillipines 40 separate terrorist bombings in the last 16 years (720 deaths), and the worst of all 9/11 (2977 dead). All numbers not counting many, many thousands of injured, or terrorist deaths. Absolutely all Islamic extremists, alas - a tiny, tiny minority of right minded Muslims, but boy do these bastards get the lion's share of publicity, may they rot in hell. And pretty much all home grown.

2nd one is better than first. Or maybe I have partially acclimatised....

Where is the Darwin Award when you need it? http://www.darwinawards.com/darwin/darwin2014-09.html or even the legendary http://darwinawards.com/darwin/darwin1995-04.html

Isn't that the TV channel that shows old episodes?

That is whole new levels of insanity. Watched the whole thing, of course.

That is all we have in the UK, except it is 230V (well 240V in reality).

Well it can only be down to a hum loop somewhere, induction through stray magnetic fields from the transformer, or ripple on the DC output from the regulator. Also, are you hearing the 60Hz fundamental, or the second harmonic at 120Hz? What does the mains power look like - ie is it symmetric or asymmetric? Just firing ideas - cause of hum can be a bitch to find. But once you find the cause, it will seem to be blindingly obvious....

Is it mechanical hum from the transformer, or electrical hum that you hear in the headphones?