Craig Sawyers

What scope, what probes? Highly specified Tektronix probes only handle 300V for a x1 and 450V for a x10 non-destructively. Generic probes can be much less, or poorly specified.

This is the reason that Krell went over to some sort of dynamic biassing scheme, because running flat out class A was just not reliable. I had a late model KSA100 that demonstrated that perfectly. Typical Krell battleship construction, with superb engineering, and two fan cooled heatsink chimneys. Power transistors were rebranded as KrellA and KrellAA. It blew up three times in my ownership - same symptom each time, power transistors going into second breakdown failure accompanied by lots of smoke. Lat time it happened was after I had sold it on eBay for quite a lot of money. The buyer was actually on his way to collect from about 150 miles away - and I thought I'd turn it on so he could listen to it. Major league failure with plumes of smoke; phoned him in the car, apologised profusely and he went back home. This time it had taken out the drivers too, and the associated driver load resistors had ignited and burned part way through the board. Replaced the sand, using generic high power transistors and NOS obsolete drivers. Dremelled out the char and coated with conformal coating before replacing the load resistors. Worked perfectly, and the guy honoured the sale, paid the money after auditioning and off he went leaving positive feedback. I've also seen the same generation of KSA50 ignite too. But it is all down to component stresses - high power class A puts a combination of high voltage and high current through the power devices all the time. Smoothing caps and power transformers likewise need to be carefully thought about, since they are running flat out all the time too. But non-linear distortions, including induction distortion are much lower than class B or AB, which is why high end users like it.

I just love you guys - I'm still laughing five minutes in

Let's hope those few days stretch on and on and ......

And Cantor spent years in a sanitorium, such were the rigors of contemplating infinities.

I'm with you on that. I'm very selective what I leave on. Low power solid state small signal gear: Preamp (solid state), yes. Active crossover, yes. DtoA yes. Power amps and anything with tubes (8-channel power amp, CD transport, T2, BH original), no. If I'm going to do any serious listening, I power up whatever the heat generators are and have a coffee and sandwich - and everything is on song by then. But even with a solid state electrostatic amp, I definitely would not leave it switched on - parts are stressed both in temperature and voltage - and I would not want to leave a set of expensive electrostatic phones with bias permanently applied. Made that mistake with a pair of ML Aerius speakers and the film eventually disconnected itself (later ML's only trigger bias when music was detected, so they knew they had a problem).

Weirdly late to this thread. I just put together a retro system - simply because I had the stuff kicking around collecting dust for an eternity since I am incapable of throwing stuff out or selling it, and I wanted to remind myself of what this kind of gear actually sounded like. Thorens TD150/M75ED with original signal cable, Quad 33, Quad 405 into Koss ESP-9. I even had to fix the 33 (one channel dead; edge connector) and 405 (power transistors blown on one channel and terminally noisy 071 op amp on the other) before I could listen! It is frankly amazing how far we have come in music reproduction - that set up sounded at best a resounding "OK-ish". Fatigue set in within one disc. But it left me reaching for my primary headphone systems (T2 clone/Stax, or Dyna-something and selection of dynamics) or main loudspeaker system (Transporter streamer, Tortuga LDR passive, and Linkwitz LX521) with massive relief.

^This!

Have a great day!

^That is bloody glorious - totally mad but glorious! But I'll take your marbles and up you a glass armonium, designed by Benjamin Franklin

I'm with you on that. The DT990 (old version) is streets ahead of the K701 in neutrality.

It does make you wonder STAX's move to PEEK film rather than their tried and trusted mylar is behind some of this erratic behaviour. Looking at the material properties alone, PEEK is higher performance in pretty much all areas, so I can see from an engineering perspective why the change; water absorption alone is 0.1% as compared with 16% for mylar, which might be thought rather important for a component in an electrostatic transducer. But there seems to be a few reports of degraded performance over time - either sticking to a stator, or a drop in sensitivity of one side. The only mechanism I can think of is that the film is not getting enough charge so the force drops, so maybe it is not the mechanical properties that are so important and it is down to the processing detail of applying a highly resistive film and making a reliable contact to it. I had a pair of Martin-Logan speakers that happened to - the connection to the film failed.

Have a great one!

I'm a firm believer in showing products who's boss.

Bloody hell. I've chanced on an accident shortly after it has happened too. And you know what - if you were a few minutes earlier.....is what it goes though my head. The only biggy I've been personally involved with was back in 1991. I braked into traffic on black ice, and slewed out of control into the rear wheel cluster of an oil tanker. Blew his rear wheels and buckled his wheel rims. Blocked the whole freeway (the A1, UK). Got away with front impact whiplash. So I went out that evening and had the biggest steak and most expensive bottle of wine in celebration of being alive.

Dublin, Ireland. When you visit the Book of Kells, you exit through this library. It is just as mind-boggling as this picture shows. Any of you who get to Ireland for whatever reason, this is a must visit. We were there early Feb.

For some weird reason I read that as "nipple simulation". OMG - that looks like something that I make. A keep-one-hand-in-your-pocket test fixture.

There is an old Orpheus on eBay Germany at the moment for Euro24k item 301907794353. And another for UKP17.5k item 141918737646. Don't all rush now. At least the old ones don't have the silliness of the knobs and tubes magically sliding out of the case of the new amp.

I think that is more to do with (a) the thickness of the block - to (air) season timber you reckon on 1 year for every inch of thickness for hardwoods (b) it is basically half a log which is almost guaranteed to have massive internal stresses and (c) the growth ring density varies hugely from the center to the edge of the photo, and that puts enormous internal stresses on the wood. That log has seen some major seasonal changes - the growth ring density varies by a factor of 50 or so - might even be higher. The way to think of wood as as a stack of straws following the grain of the wood - in life they carry the sap up the tree. In the photo you are looking at the end of the straws, and it is through that cut end that moisture is lost. Since the density of "straws" varies according to the density of growth rings, moisture is lost differentially across the log, building stress. What I'm saying is that it is almost inevitable that the wood I'm looking at is going to crack in some way, usually following the growth rings. Often blocks are supplied with a wax capping over the end grain to prevent the wood from cracking during transport, but that is no guarantee. I brought some cocobolo (an eye wateringly expensive rosewood) blocks into the house too quick, and I could hear them ticking as the damned stuff cracked. I've also cut thick veneers (~2mm) out of blocks, and after a short time they warp concave or wavy as a result of internal stresses There is basically nothing you can do though. Even if you were to run some theoretical glue down the cracks, the wood would simply find the next highest internal stress and crack there. Look upon it as a feature that adds character to the wood. Forgot to mention that when I'm making something (I'm a trained amateur) I cut and plane all the parts oversize and then bring them into the house for a month or so, so that the humidity is right and the wood gets its final moisture content sorted out. The parts move around a bit, hence machining oversize. Then I plane and thickness to final size and assemble and finish. All this is the same reason you make drawers with enough vertical clearance. Seasonal changes in humidity can cause the height of the drawer to change by a percent or so - and if you make a nice piston fit when the humidity is low it will jam absolutely and immovably solid when the humidity goes up.

Well, the good news is that the ESP-9's are working just fine. Centered image, clean sounding, no hum problem (some have that, apparently). Of course they are transformer based, so have the limitations associated with that. But hey - for sixty quid (~$90) it is difficult to go wrong, unless as you say you end up with a basket case.

The formula that worked with CMH was that of a highly polished and scripted sitcom about three non-politically-correct guys, who also had an interest in cars. I suspect that is what is going to happen over on Amazon Prime too, but with a budget to make your eyes water. Trailer for the new Top Gear is much more politically correct. Welcome to the latest PC BBC. It has a woman in it. And a Friends celebrity. And a Stig. And a guy who gets travel sick. Hmm; we'll see.

Done. It was like tar. Washed down the boards with alcohol and toothbrush, cleaned everything else carefully, and reassembled with some speaker wadding where the foam used to be. Diaphragms hold charge really well, so leakage seems to be minimal. So far so good; close to putting music through them.

The end of an era. RIP Ronnie Corbett.

Are you still aroundround Duggeh? Happy birthday!