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acg last won the day on March 25 2018

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About acg

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    I can't jump puddles
  • Birthday 31/07/1973

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  1. Oh yeah, and two pair of replacement horns ready to go onto the stack...
  2. Small steps... So, finally, the shelf bass traps are complete and in place. They were done in fits and starts but we got there in the end. I love having them in the room with the cane facing and the lovely wood tops...the room feels nicer to be in just for their presence. The vinyl flips have also worked out well, here's one with the lid up to show how they work. Will have to resist the urge to treat them just like a normal shelf and just load the top of them up with "stuff" but it is a handy place to put the tablet that controls digital playback. Talking about digital, Mark Dohmann was here last night and he did the "in-house" final setup of the Helix2/MC Anna for me. What a pleasure to meet the man in person and what great service. We stayed up well past my bedtime listening to various curiosities from Talk Talk among others and finished with a nasty old John Lee Hooker record. What has that got to do with digital? Well, nothing really, but the little 1's and 0's have just been o.w.n.e.d.
  3. It does seem to. Fs certainly changed with different stuffing regimes, with more light and fluffy poly being the most effective in my situation. It also reduced the internal 100Hz resonance such that it was no longer measurable (at least not in the setup I was using) and no longer audible. So if you are worried about the dimension induced resonance my advice would be to open a bag of the most lightweight poly wall/ceiling insulation you can find and play a little. I would not bother myself with heavier stuffing, just super light stuff. Nice river shot earlier...I'm jealous that your stream still has water.
  4. Maybe next Christmas... Although stuff is still getting done. The plan, assuming the temperature is bearable in that little tin shed, is to get back on the lathe next week or so to sort out the front half of the upperbass horns.
  5. How interesting! Thanks @Ian McP Seems a similar trajectory to mine...
  6. I have MC Anna on a Helix 2 with Schroder CB arm. It is some kind of magic...
  7. Dunno, but from the little I've read the DS is manufactured with a different xformer to the one with which it was designed. If you want inexpensive you need to buy mass-produced off-the-shelf transformers which may or may not be ideally suited to the application. Whenever I use a transformer these days I avoid off-the-shelf and get them custom wound for the exact purpose but they are much more expensive that way. I don't know what Clay uses, but his gear does sound very good. Clay, I would be interested to audition this creation when you have it ready.
  8. I think the ASR/Directstream thing came down to PSAudio cheaping out on the transformers. Just like "oils ain't oils", transformers ain't transformers...
  9. @TRAUMFAENGER, Sebastian, I designed them myself and had them fabricated locally.
  10. What I love about modern valve amplifier builds is the possibility and benefits of mixing old and new technologies. Lately, I've been sneaking an hour here and there to advance the electronics projects and have managed a few small milestones. Have a look at the photo below... That is the RIAA correction filter for one channel of my upcoming LCR phonostage. Two handsome Slagle inductors on mumetal cores, some Jupiter copper foil caps and some custom cut TX2575 Z-foil resistors that should make a frequency response flat line out of the very wobbly riaa cut of the records. It all sits on a 4mm thick aluminium plate that in turn sits inside an off-the-shelf EMI/RFI box which in turn will sit inside a 4mm thick steel sarcophagus in an effort to maintain a very low noise floor in the circuit. It sits between a pentode first stage and triode second stage. So, above is a nice example of the old-school purists method of sacrificing resources and real-estate with rats-nest wiring. So the tubes have to be supplied 6.3vdc and I had alook through my pcb box to find a challenging build using paralleled LT3042 ultralow noise LDO's. These things are tiny...0.5mm pitch MSOP. I've never soldered them before so decided to order the parts and give the little psu a go. See below, it worked... That green pcb has two 6.3V 1A power supplies including all rectifier diodes, filter caps and heat sinking (later two items under the board). I hand-soldered the little bugger and it took a couple of hours but it worked first time! Those big (haha) yellow 1205 caps make the LT3042 look tiny. What is not shown is that little green pcb is going to be connected to two relatively huge EI filament transformers. Anyway, that is my rather extreme example of modern and vintage electronics used in the same component, a RIAA phonocorrector. Can't wait to get it finished.
  11. @norman, the smoothing capacitor/s is important in a linear power supply, especially when there are not enough AC volts in comparison to the DC volts required. In your case, where you are looking for 12VDC but are using a 12VAC mains transformer, have 2.5v loss across the rectifier (which is a lot for low voltage, you should be able to get this to less than a volt with better rectifiers) I would be looking for at least 5,000uF smoothing capacitor, preferably 10,000uF so that the ripple after the rectifier will not cause the LDO to turn-off every cycle when the level of the sine drops below the output voltage plus the dropout voltage of the LDO. The more smoothing capacitance you have the less ripple you have going into the LDO which means that the sinewave troughs are higher and the LDO is less likely to turn off. Then you need to consider the regulation of your power transformer, which is basically a number that lets you know how much the AC voltage it supplies will drop under higher load conditions i.e. when pushing plenty of current. EDIT: My advice, twist all wire pairs together regardless of whether they carry AC or DC
  12. @candyflip @t_mike I was not game to go straight with the chinese tank so I purchased one of these. It is very quiet, is dual frequency, is German made, has an Australian warranty, and fits Owens kit with only a little bit of dremel work on a couple of nuts on the kit.
  13. @vdH, the steel plate touches only the foam, nothing else. The foam has to be chosen such that it can support the steel plate, and the glue such that it adheres to both the foam and the steel. The foam is slightly larger than the steel plate.
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