Craig Sawyers

Happy birthday!

RIP Petrov - the man whose calm action saved us all from Armageddon. Another cold war movie worth watching is By Dawn's Early Light.

I note they don't mention how much the whole process costs. Darned impressive though.

Deep fried in Beijing. Crunch crunch.

Oooh - a Wall reference

Happy birthday - you have a great day, and forget about the diet for 24 hours!

Yeah - RIP Mr Stanton. Another one, which won't be commonly known, is Nikolaas Bloembergen. He was one of the pioneers of non-linear optics, which was one of the topics of my research degree. In fact he was one of three recipients of the Nobel prize for Physics in 1981. I'd kind of lost track of the years, because he got to the fine old age of 97 (which means that he was younger than I am now when I was at University; which is very sobering). http://physicsworld.com/cws/article/news/2017/sep/12/laser-spectroscopy-pioneer-nicolaas-bloembergen-dies-at-97

Happy birthday! Have a great one.

That is just as shocking now as it was when it originally happened. I was working in London at University College when the Prof came in and said "one of my old students, living now in New York has just emailed - planes have crashed into the twin towers and one has collapsed; I thought it was a bad joke, until I checked on the web". No more work got done. All the the business tower blocks in London were evacuated in case we were a target too (given our close ties to the US). As I traveled home, there was total silence on the underground - everyone was kind of in shock about what was happening in New York (and the attack on the Pentagon, and Flight 93). I'd lost track of the fact that it was 16 years ago.

Where our daughter lives in Australia, the really common big one is the Golden Orb Weaver. Non poisonous (although they can give you a nip), but a big bugger with a body length (not including legs) of 5cm. They keep to the forest floor during day, and come out at night and spin their webs across forest paths in serious quantity - so walking at night can be an "adventure"!

Acetate failure - must remember that The casework also runs stinking hot. The four EL34's for each channel are horizontal between a slotted bottom panel and a perforated cage. I thermocoupled the cage - 80C (175F) and easy enough to be hazardous. This particular amp was only made for two years because the failure rate was so high that many did not even get out of the factory without needing their first repair. The only reason the guy had this amp was Anthony Michaelson gave him it (he'd done that industrial appearance design for Michaelson; although the electronic design is marginal to say the least, it does look good)

Not really relevant to the thread, but kinda related to old circuit boards. I was recently fixing a friend of a friend's Michaelson Odysseus power amp - which had a single sided board. Apart from a new set of EL34's I noticed a power resistor that would wobble if poked it. Turned the board upside down, and this is the horror story I found. Lots of thermally marginal parts too close to the board, resulting in toasted board, and multiple levels of repair by others. Needed two 47 ohm power resistors one of which was O/C, and both of which were 2.5W parts dissipating 3W. Replaced them with 7W jobbies.

I thought it sounded like early Genesis, complete with Peter Gabriel dressed up in an outrageous costume Or even better, early Pink Floyd, who invented a whole lexicon of nonsense:

I so wish that was true - I'd want to be a Beef Twister or Turnip Shepherd! But is is spoof, alas. Appendix 5 of this tome http://privatewww.essex.ac.uk/~matthew/Papers/Woollard_1881Classifications_no illustration.pdf has the 1881 UK census classifications. It is all very dry and oh so sensible. Unfortunately.

This is actually yesterday. I went on a one-day advanced navigation course in the (English) Lake District, in Langdale. This was navigating with contours only, and the trainer provided maps that only had contours, and the symbols for cliffs etc. But nothing else - no roads, paths, streams etc etc. So the focus was in knowing where you are - where were you last, where are you now, and what will you see next. A further key learning point was how to move efficiently - basically I didn't - so I have a whole history of walking to unlearn. Fascinating stuff And this is the map. contours map.pdf

Oh bugger

Well, I can cheerfully report that the mad phono stage sounds absolutely stunning. I've been going through record after record and depending on what I'm listening to I've giggled, sung along and wept depending on what I've got on. Kind of standard with the territory it takes a long time to warm up. There are three servos - one to null the voltage across the cartridge to zero. One to null the output of the input stage to zero, and one to null the output of the second stage to zero. Given that every stage runs hot, and that there are two of these per balanced channel it takes a while to sort itself out and stabilise. It will remain on permanently. Thank heavens it does sound stunning - given the overall cost of circuit boards, parts (lot of em), and time in build and test, layout and procurement of the shunt regulator boards etc - I would have been royally pissed off if it had sounded not good!

It is so very good to hear that everyone is safe and sound (and posting again!) after the horrendous winds and rain over recent days.

My usual stunt is to replace a tyre that has a puncture, just to get the new one punctured in less than a week. (reply to Grahame's post...)

I know what you mean about inductors. The disadvantage is you have to get the value large enough to prevent weird oscillatory behavior. You can get a similar filtering effect with RC-RC-RC filtering too. But the diodes are ultra fast soft recovery type (MUR820 - 25ns recovery) so generate very little hash indeed. And an R-core transformer is inherently split bobbin - one side is the mains winding and the other the low voltage secondaries. So they pass hardly any hash because the interwinding capacitance is tiny.

The horror, the horror. Basically this is the final Erno Borbely design. It is a current mode phono stage, where the cartridge looks into close to zero impedance. First stage with parallel J40/K170, and a power stage to drive the passive RIAA. Then a 40dB gain stage with power stage to drive the output. It can be configured many different ways: No feedback first stage, with input R of about 4 ohms for higher R moving coils Feedback first stage which reduces input R to tiny value for low R moving coils. Can be run single ended or balanced input, and single ended or balanced output. I've set it up as a no-feedback version, fully balanced IO. There is a bal2unbal board which I currently have not wired in. Shunt regulator for each board, layout by moi. Dual power supply, each with dual bridge rectifier and lots of smoothing cap.

Lucky man - any version of the CAT is impressive (and pocket-crunchingly expensive). Counter-intuitive if you look at the board area that is film capacitors, but it apparently sounds and measures superbly.

Slowly completely my bat shit silly phono stage. Currently working on a grounding scheme to remove 200mV (!!)of hum on the outputs. I'll post pics once sorted.

Hey - welcome back dude!

Don't for heavens sake try to have a barbecue in that, because you can't have your kayak and heat it. Which reminds me of the chess convention. After a few drinks in the hotel bar, they were sat in the lobby having a loud discussion about the matches that they had won that day. Eventually the manager came and threw them out on the basis that he did not want chess nuts boasting in an open foyer.