Craig Sawyers

The 2nd Affair A middle-aged couple had two beautiful daughters But always talked about having a son. They decided to try one last time For the son they always wanted. The wife got pregnant And delivered a healthy baby boy. The joyful father rushed to the nursery To see his new son. He was horrified at the ugliest child He had ever seen. He told his wife: 'There's no way I can Be the father of this baby. Look at the two beautiful daughters I fathered! Have you been fooling around behind my back?' The wife smiled sweetly and replied: 'No, not this time!'

This thread has been moribund for too long. The 1st Affair A married man is having an affair With his secretary. One day they went to her place And made love all afternoon. Exhausted, they fell asleep And woke up at 8 PM. The man hurriedly dressed And told his lover to take his shoes Outside and rub them in the grass and dirt. He put on his shoes and drove home. 'Where have you been?' his wife demanded. 'I can't lie to you,' he replied, 'I'm having an affair with my secretary.. We had sex all afternoon.' She looked down at his shoes and said: 'You lying bastard! You've been playing golf!'

Meanwhile, back in the UK

You're tapping a rich vein of speaker porn Knucks!

Each power amp weighs 220lbs, and the centre preamp 155lbs. Lighweight it is not.

Designed by a guy called Steve Sells. I hired Steve straight from University back in around 1990 when I was running Engineering at Wharfedale. We were planning to re-launch Leak, and I said to Steve "Design the best power amplifier you know how. Exotic components, silver wiring, multilayer boards - no problem". He designed a stunning piece of work. When I took it to the Audio show in London, and wired it to the speakers, a sound like a quiet tinny radio came out. Turned out the shorting straps were still on the back of the speakers - and Steve's amp was playing the cables into a short circuit. The sound came from the force between the cables. Took off the shorting straps and pow! Awesome. Fast forwarding several decades, and Naim likewise let him off the leash. And Statement was the result.

The notorious test of cartridge/arm, the pressing marked A11 is the real killer. My Zu/DL103, SMEIV (with damper) and Garrard 401 tracked it like a champ. And frightened the bejeezus out of me at the first cannon shot! This is what the grooves look like:

Looking at the TP schematic, the noise is limited by the input resistors of 2k2. The native noise of the OPA1632 is an equivalent noise resistance of 100 ohms (ignoring 1/f noise). Even so, with 2k2 input resistors the input circuit SNR should be ~ -120dBu, which is still pretty darned impressive.

Common mode rejection is critically dependent on resistor tolerance in a balanced amplifier like the OPA1632. I'd have to look it up but I think 0.1% resistors will mean a CMRR of -60dB. And at that level you need to make sure they thermally track too, and have very low voltage coefficient. All that hoohah with discrete component tolerance and CMRR is why THAT have adopted everything on a chip with laser trimmed resistors and bootstrapping to make the common mode impedance huge. The InGenius devices get to -90dB CMRR, the only real disadvantages are the pretty average SNR of -105dBu because the internal impedances are in the tens of k range and 5ppm distortion. That is where the OPA1632 with truly impressive low noise of 1.3nV/rootHz and ridiculously low harmonic distortion of 0.22ppm wins big time.

Doris Day - RIP. Always a joy to watch her classic movies. A long life, decidedly disastrous in her choice of men, and rather reclusive in later years. And RIP Brian Waldon, UK political journalist, MP and rottweiler interviewer. His political interviews and comment was a much watch on a Saturday morning in the 80's is he put politicians on the rack.

Good way to match to that accuracy is to make four of the resistors into Wheatstone bridge. Feed with a DC voltage that makes sense (say 10V), and check for a null between the arms. If the resistors are worst case 0.1% all the wrong way, you'll get a voltage of 0.2% of 10V across the arms, or 20mV. So you now mess with your resistors until you get a voltage of less than 20mV. Then you know they are matched to better than 0.1% In an odd quirk of history, Wheatstone also designed musical instruments, the most famous of which is the concertina.

It is very difficult to find any explicit data on asymmetrical JFETs, other than that they are rare and used mainly in high RF work or similar specialised applications. I think is is almost certain that the ones we typically use in audio are symmetrical.

Happy birthday Shelly!

The horror, the horror....

70's was the era of, well quite a bit. It was definitely the decade that fashion forgot. Flared trousers got so outrageous I used to wear bicycle clip when driving to stop my feet getting tangled up with my trousers, and them dangling in the dirt on the floor.. Oh and shirt collars with rounded ends. And I was so proud of my centre parted hair. At least I never got into platform shoes. I looked in hindsight such a dork.

Definitely not a mash up. Now I've seen Paul Simon perform this live (with Sting singing backing vocals). But this is better. In fact the best IMO

The whole capacitor thing is interesting. Back in the day I developed a supermarket security gate to detect product tags and hence shoplifting, which for a few years was in use globally. This used two audio frequencies superimposed on a 20Hz triangle wave. The amp was class D (quite something for thirty-odd years ago) and hence needed an output filter. Designed one, and bought the bits - chunky inductor, and polypropylene capacitors. First thing was that the inductor melted, and that was when I found out about proximity effect. The second thing was that the capacitors howled like a banshee being tortured with a hot poker. Anyway the capacitor thing was really interesting. I tried a variety of manufacturers, and found that acoustic output was determined by tight winding of the foils. Second that axial tubular ones were quieter than radials. That was down to the manufacturing process for the radials. First the foil is wound on a cylindrical former. The former is pulled out and what remains is squashed flat. The voids that are inevitably left cause the noise through electrostatic forces. The quietest were cylindrical audio capacitors - a design now made by Kimber. Far too expensive for the product of course. But I found Roderstein axial ones that were also silent and cost much less. Roderstein is now owned by Vishay. Anyway, it was an interesting exercise. As far as I know no-one tests audio grade caps by passing an audio band signal through them (of an amp or so) and listening to them. Any acoustic output is (a) frequency dependent and associated with mechanical resonance in the capacitor structure and (b) is clearly associated with a loss mechanism. Aha - found a few left over - they were MKP1845, and Vishay still make them https://www.vishay.com/docs/26023/mkp1845.pdf . Just E6 values, which is a pain.

RIP a legend whose face we never saw.

Apparently only 100 made in around 1979 https://www.theanalogdept.com/reference.htm

Thorens Reference. Rare as hen's teeth. So rare I've never seen one for sale - and probably could not afford it even if I did.

I put Pearl tube coolers on mine. The idea is that the glass envelope runs at a lower temperature, which is reckoned to be a good thing. The jury is out whether it does what it says on the tin, but none of my output tubes have failed. So far. That was a bit of a fatal statement thinking about it ? For clarity that is on my Gilmore T2, not the Stax hot plate.

I think the word is "thermally challenged", and just a very basic unregulated power supply.

Alas they did not do Echoes. At 20-odd minutes it would have used up a lot of the concert. That original 1972 pompeii gig was superb. Two of the best of Mason's comments last night were "We're not the Australian Roger Waters!" and "I toured with Roger Waters, and he was jealous about using the gong. But tonight I get to use the gong myself!" (For Set the Controls for the Heart of the Sun) The very best recent version of Echoes was also at Pompeii in 2006 with Gilmore and Wright. The bass guitarist is the same guy that played last night.