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acg

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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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    Toowoomba
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    Australia

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  1. 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.
  2. 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...
  3. @TRAUMFAENGER, Sebastian, I designed them myself and had them fabricated locally.
  4. 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.
  5. @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
  6. @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.
  7. @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.
  8. Don't want it to go over 40C, prefer 35C, but still getting used to the whole system. Was 37C here yesterday, so it does not take any heating whatsoever for the water to reach 40C and it ain't going to cool quickly on its own with our summer temperatures, hence the additional reservoir of water to spread the heat load.
  9. Yes, I use a 0.2 micron filter so no aquarium pump for me. Today I am modifying an old 20 litre water cooler/esky to cycle my water through so that I can keep cleaning records and not have to wait for the water to cool down. It's bloody warm here in Qld, and it does not take much cleaning to warm up already warm water. Clean some records >> dump the warm water into the 20l cooler >> start the filter pump >> take a new, cooler usc tank-full of water from the the clean side of the filter >> load-up the next spindle of records >> keep cleaning. Owen was kind enough to sell me three spindles so I can have two spindles on the drying rack and one in the usc at any one time.
  10. I've built one of these... http://www.pmillett.com/LR_phono.html It is good.
  11. Dave, are there ways to look at LF with a higher frequency resolution? The lowest strings of a double bass, bass guitar or even a cello tends to hit a room mode right where I stand at my desk. It is really distracting, and if a VPR or two can be used to reduce that effect I will be very happy. I've never had bass as soft or textured or powerful as I have it now with the Bass Cannons and room modes are very easy to find just walking about the room. The listening chair seems to be the best spot for bass because it is right in the middle of the axial walls and I have the windows directly behind me letting plenty of LF out of the room. Regarding the VPR's, I should get in and order some foam so I am ready to make them up at Christmas.
  12. I had a client like that/me. The scope of the (large) project kept getting bigger, more complex, and troublesome and eventually we had a falling out over it. Me: You can't just keep shifting the finish line every couple of months, it's a waste of my time. Client: Just get it done already, you are costing me too much. He didn't stop and I couldn't hit that moving target.
  13. White powdercoating is done. This is a mockup of the 5 under-windows stands that will double as big-ass bass traps and support for the vinyl flips that will sit atop them. I apologise for the dark photo, it is very bright outside. Plenty to do to finish them, but progress is being made. I've plonked a few timber tops on them just to make sure things fit as intended and all is good. These are the ends for the vinyl flips... My mate Al will be getting a visit from me soon so I can use his tablesaw to trim up some wood to go inbetween the ends. The new TT is in the house... Industrial matt black just like the rest of my kit...and Aussie made to boot. Also in use is this software based vacuum tube curve tracer/tester. It's The Biz, and will be a big help when matching tubes and designing the tube preamps (shown with a 45 ST in a socket).
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