Craig Sawyers

Maybe its an age thing - when you get to my almost walking frame age actual lectures are a dim and distant memory

And here's one for those of a mathematical persuasion Wherein it is related how that polygon of womanly virtue, young Polly Nomial (our heroine) is accosted by that notorious villain Curly Pi, and factored (oh, horrors!). Once upon a time (1/t) pretty Polly Nomial was strolling across a field of vectors when she came to the boundary of a singularly large matrix. Now Polly was convergent and her mother had made it an absolute condition that she never enter such an array without her brackets on. Polly, however, who had changed her variables that morning and was feeling particularly badly behaved, ignored this ignored this condition on the basis that it was insufficient, and made her way amongst the complex elements. Rows and columns closed in from all sides. Tangents approached her surface. She became tensor and tensor. Quite suddenly, two branches of a hyperbola touched her at a single point. She oscillated violently, lost all sense of directrix, and went completely divergent. As she reached a turning point, she tripped over a square root that was protruding from the erf and plunged headlong down a steep gradient. When she rounded off once more, she found herself inverted, apparently alone, in a non-euclidean space. She was being watched, however. That smooth operator, Curly Pi, was lurking innerproduct. As his eyes devoured her curvilinear coordinates, a singular expression crossed his face. He wondered, was she still convergent? He decided to integrate improperly at once. Hearing a common fraction behind her, Polly rotated and saw Curly Pi approaching with his power series extrapolated. She could see at once by his degenerate conic and dissipative terms that he was bent on no good. "ArcSinh!" she gasped. "Ho, Ho," he said. "What a symmetric little asymptote you have. I can see your angles have lots of Secs." "Oh, Sir," she protested, "keep away from me. I haven't got my brackets on." "Calm yourself, my dear," said our suave operator. "your fears are purely imaginary." "i, i," she thought. "Perhaps he's not normal, but homologous." "What order are you?" the brute demanded. "Seventeen," replied Polly. Curly leered, "I suppose you've never been operated on." "Of course not," Polly replied quite properly, "I'm absolutely convergent!" "Come, come," said Curly. "Let's off to a decimal place I know and I'll take you to the limit." "Never!!" gasped Polly. "Abscissa!!!" he swore, using the vilest oath he knew. His patience was gone. Coshing her over the coefficient with a natural log until she was powerless, Curly removed her discontinuities. He stared at her significant places, and began smoothing out her points of inflection. Poor Polly. The algorithmic method was now her only hope. She felt his hand tending toward her asymptotic limit. Her convergence would soon be gone forever. There was no mercy, for Curly was a heavyside operator. Curly's radius squared itself; Polly's loci quivered. He integrated her by parts. He integrated her by partial fractions. After he cofactored, he performed Runge-Cutta on her. The complex beast even went all the way around and did a coutour integration. Curly went on operating until he had satisfied her hypothesis. Then, he exponentiated and became completely orthogonal. When Polly got home that night, her mother noticed that she was no longer piecewise continuous, but had been truncated in several places. But, it was too late to differentiate now. As the months went by, Polly's denominator increased monotonically. Finally, she went to L'Hopital and generated a small but pathological function which left surds all over the place and drove Polly to deviation. The moral of our sad story is this: "If you want to keep your expressions convergent, never allow them a single degree of freedom."

One night when his charge was pretty high, Micro Farad decided to get a cute little coil to let him discharge. He picked up Millie Amp and took her for a ride on his megacycle. They rode across the Wheatstone Bridge, around the sine wave, and into a magnetic field next to a flowing current. Micro Farad, attracted by Millie Amp's characteristic curve, soon had her field fully excited and he couldn't resistor. He laid her on the ground potential, raised her frequency, lowered her resistance, and pulled out his high voltage probe. He inserted it in parallel and began to short circuit her shunt. Fully excited, Millie Amp cried, "Mho, Mho. Give me Mho!" "Ohmigod, this is good," shouted Micro. With his tube at maximum output and her coil vibrating from current flow, her shunt soon reached maximum heat. The excess heat had gotten her shunt pretty hot and Micro's capacitance was rapidly discharging, ... draining off every electron. They fluxed all night, trying various connections and sockets until Micro's bar magnet had lost all of it's field strength. Afterward, Millie tried self-inductance and damaged her solenoid. But it didn't phasor. With his battery fully discharged, Micro Farad was unable to excite his transformer. So they ended up by reversing polarity, and blowing each other's fuses.

Usually an anechoic chamber is used with conductive or ferrite loaded wedges which looks like an infinitely large environment - so trying to simulate free field, especially when the anechoic is big so you can get a good distance between antenna and DUT. I've tried finding stuff on alternatives using rf reflective walls (ie bare copper), and drawn a bit of a blank.

You stand a pretty good chance with Kimber - Ray Kimber was a recording engineer before he set up the company, and developed the woven speaker cable to stop thyristor light dimmer crud from getting back up the PA amps, getting into the feedback loop and then coming back down to the speakers as a buzz. He'd be pretty keen to get immunity measurements as a quantitative selling point for his cables. Cardas too, I would think, MIT, Nordost and others. Martin Colloms (HiFi Critic) has been trying to get a cables consortium together, part of the aim of which is to substantiate subjective claims with real-world measurements.

The other good idea is to route all the power cables closely together. That minimises the loop area that could inject airborne RF interference into the ground, or radiate common mode interference that is coming up the power or ground lines. Might be worth trying an air cored toroid in series with the overall ground. That way you keep the protective ground connection, but now have a high frequency block to stop utility ground shit from getting up the earth. Make a wooden donut maybe 6 inches in diameter, and wind as much heavy gauge green/yellow wire as you can around it. Wire in some very safe manner in series with the overall system ground.

Well, that sure is a pair of ebony erections

Original (low bias) SR-lambdas were the same - the baffles and electrostatic units were a single glued assembly.

Although Bob did his own attenuator using the Goldpoint roll-your-own version (and so deliberately chose 1dB per step), other commercial switched attenuators like the DACT, and attenuator transformers like Sowter http://www.sowter.co.uk/transformer-attenuators.php are available in fine step versions. The DACT fine is 0.5dB per step(!) But I'd certainly go for the more standard Goldpoint or DACT set up, with big steps for the first few, then 2dB per step thereafter. I find 2dB per step works well for me.

Boy am I feeling dumb! Been totally fooled by where the emoticons were. Then just happened to notice the smiley on the reply toolbar. Then click show all on the popup. Of course you all knew that. I can sometimes be a little slow on the uptake

Ah - there's the problem. For your preferred listening levels, and source output voltage you definitely need attenuation to centre the -12dB point of your Goldpoint. And yes, I guess that the gain of the amp could be changed. But going to say 40dB from 60dB has to done with a little care to make sure it is still stable at the lower gain, or at least has not picked up any overshoot.

FWIW the T2-clone also has a gain of 1000. My D-A has an output of 3Vrms and that puts the DACT at pretty much centre travel at the typical loud level at which I listen. Takes maybe three clicks each way to compensate for recording level differences. Half way on a DACT is -28dB, and the steps are 2dB over most of the range.

Classic! James May in a 500hp go kart that the New Stig threw around the track faster than anything else they have tested. Richard Hammond in a 1 mile race between a VW Beetle and a Turbocharged 911 - the beetle having been dropped vertically from 1 mile and falling under gravity. Oh yes!!

Just latching onto this thread - but if your friend can phone international call Russ Andrews. They recable K701's with Kimber stuff. I have a pair with that cabling - and they do it themselves. Phone them on +44 1539 797302 which is John Armer's personal line and mention my name - I'm sure that they will tell you the secret methods of disassembling the beast.

No - they are precisely the same as in your photos - absolutely no closure of the vent. Now, courtesy of your blu-tak idea, they have exactly the same sound as the Lambdas when you push the cans closer to your ears (what you describe as squeak/fart).

Yes - SZ3-1487. What is the relevance of that? And what am I missing with earpad height? Yeah - I know you're going to say it is already in this thread somewhere

I'll have to have a browse though those - looks good. And sorry to be a smart ass (well, not sorry at all really) but I looked it up and - I was right. CMB at 160.4GHz

Much more solid and tactile low and mid bass. Kick drum really kicks now. But it goes beyond that - the whole voice thing sounds cleaner in some way too. Maybe there is a helmholtz thing going on between the large void between the ear and the diaphragm, and the little (leaky) void that colours the midrange in some way.

Um - blackbody radiation with a peak at 160GHz. Cosmic microwave background?

Had a real panic yesterday. Took the SR007's apart to do the blu-tak port mod. Got them back together and plugged them into the T2 - bad distortion on RHC. Serious panic sets in. Turned out to be a dead 2SJ79 that was causing one output to be at -250V. Just blew coincidentally with the blu-tak mod. The astonishing thing is that with a dead driver transistor for the grounded grid output EL34, the damned amp was still working - all that happened was that the output clipped and distorted - and of course the headphone diaphragm was biassed one way. J79 replaced and all is sweetness and light again.

Interesting. Distortion on right channel, at high-ish listening levels. Well actually very high levels. Got it on the bench - One of the RHC outputs was sitting at -250V. Took about three minutes (after the endless fixing screws had been extracted) to find a dead J79. I suspect that it must have been weakened as a result of the earlier C3675 saga. Anyway, all sorted now. Just reset the batteries, and button it up again.

Have a great one Mike!

Snakes in a pool.

Well, that depends on the money. If you pay relatively little, you will have to spend some money fixing them. If you buy a pair that has been restored, you will pay much more. I bought mine for £300 and then spent another £250 and a lot of time to bring them completely up to original specification. Bear in mind that these are very old loudspeakers, and like a classic Ferrari need restoration and TLC. Mine are 1964 built.

Indeed - the ESL57 has a horrid impedance curve - with a big 35 ohm peak at around 70Hz and then falling to less than 2 ohms at 20kHz. It seems that tubed amps (which is all there were when the speaker was launched) cope with this better than semiconductor ones, which can sometimes run into current limiting and self oscillation. The idea of damping factor, which is important with coned loudspeakers to control their motion, is not really relevant to electrostatics (where the moving mass is only a few milligrams) - so the much higher output impedance of tubed amps is not a disadvantage. FWIW I use a second hand Audio Research D125 to drive mine, set to the 8-ohm taps.