Craig Sawyers

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!

ESP-9's turned up. Both headphones and energizer are in great shape. There is only one mains transformer, mounted on the rear panel, and orthogonal to both signal transformers. I have no idea how that is wired up to the voltage multipliers, but it seems to power up fine though and the headphones do not make any untoward noises - with no signal as yet. Common ground on the inputs. Zener strings are 4 x 180V, so it looks like the bias voltage is ~700V. Looks like a good UKP62's worth for a bit of fun, and possibly some half way decent sound quality. Expect I'll have to open the backs of the phones to check for dreaded sponge degradation at least though.

What you been drinking Knucks? - I want some now, right now

I'm actually in shock. Jacob quit? WTF.

I worked as part of a project team that was part Finnish around 5 years ago. Whenever I talked to Mikko on the phone, he was just like this guy - dour and slightly depressing. Now I had worked with Finns many times in the past and I knew that was just the way it is - partly language, partly living in a country where it is dark and minus at lot for a fair chunk of the year, and partly just the way Finns are. But I eventually said to Mikko "Mikko - are you always this miserable?" to which he came back (imagine in the voice of the VHS guy) "Oh - I am known as the cheerful one". So dour for sure, but a keen sense of humour.

I didn't spray the entire board, but I used a conformal pen to specifically insulate the high voltage pads that face upwards (ie though the ventilation holes in the top plate. I've used conformal spray on boards that will or might be working in a damp environment - like wet level damp. It is common on mil spec stuff for that reason.

Ah - thanks for the heads up. With something of that vintage I'll be looking carefully at the rats nest before I even turn it on, particularly dried out electrolytics and the such. It has apparently shipped, so will soon see what I've taken on. Just restored a pair of PRO4AA's. They were in fact the first headphone type I ever bought back in 1974; I recalled they were pretty good so I picked up a cheap pair on eBay. Fairly good condition all said. Foam damping in the cups was dust, so have used a chunk of speaker damping in each after cleaning out the cups. Dried out hardened fluid pads which I've replaced with Brainwavz (bit of a struggle, but I wasn't taking no for an answer). Then the cable that goes through the headband went intermittent - so I've spend a fun hour or two replacing that. Not perfect in sound quality by a stretch. Excellent bass extension, but evidence of a midrange hump and recessed treble. That was in a shootout with (old) Beyer DT990 and AKG K701 both owned since new. All in all I rather prefer the DT990 in terms of overall balance - the K701 is just too bright, kind of the opposite problem of the PRO4AA. But all in all, given the date I bought my original pair and what else was on the market at that time, I think I chose wisely with the old PRO4AA.

Yes indeed - a sad day. He almost singlehandedly reinvented football/soccer in the early/mid '70s. RIP Johan

Well, I did win for UKP62 - or about $90. It has a pair of Koss replacement ear pads, so I'll get a chance to see how bad the foam filled ones are. I've already ordered Brainwavz ones (in black!) for a venerable old pair of PRO-4AA's which they apparently also fit. The original fluid filled ones were as hard as a rock and of course empty.

Nice to see you on head-case Per Anders - you are doing a fine thing for affordable DIY audio modules.

Quite a guy - RIP Grove.

I have two stacked 4 channel power amps (self build - but think in terms of two Emotiva XPA5 in size and power). Damned cat has taken to sleeping on top because it is warm. Took lid off to find the inside covered in a thick layer of ginger cat fur. Hoovered it out as a precaution, but the amps hadn't missed a beat even with a mat of cat on the circuit boards.

Woah - good luck!

I'm in the UK - and maybe it is not as humid as Florida, say, but for a decent part of the year we are close to the triple point of water. No problems with any electronics I have had ever. Including BH (non-SE) and T2. Outside currently 10C and 67%RH

OK - I totally understand that! The founder of Oxford Instruments, Sir Martin Wood used his mechanical watch (no idea which one it was) to find where the 1000 Gauss contours of a magnet were. At that field the second hand would stall. So whereas the test lab would use technology to measure the 1000 Gauss stray field Martin would just use his watch.

Digital Deck Covers *is* in the US

Understood Shelly. Did you see my earlier post about Digital Deck Covers? Quilted black looks good (that is what I bought for my Thorens record deck), but you can have a range of colours and any custom size you specify..