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Posts by wakibaki

Yes, but not in this case, when it's only 75ohms. Amplifiers' input impedances are typically in the 1000s of ohms. When the output impedance starts to approach these values, then the output volume will fall. Since the amplifiers input impedance typically does not vary much with frequency, unlike phones, there should be no effect on the overall output quality except for the SNR, and no noticeable effect on that in this case.w
Some of the most productive engineers I have known had the most untidy desks. I work untidy, I can mostly lay my hands on anything. I think it's best not to try to adopt a working style that is not your own. w
Very nice. Pleased with it? w
You say you've got 40~50dB of attenuation in there, that sounds like a lot to me, so I ignored it, and offered a guesstimate of what I thought would be a good starting point, bearing in mind that I expect you to experiment. You obviously want to be operating closer to 10 on the output scale rather than 1, so you can achieve this by losing a fair chunk of signal voltage across a series resistor. The DAC O/P impedance is negligible, so a 220k resistor will reduce the...
2.5vrms/75ohms output will drive many phones without any amplifier. It will certainly drive virtually any amplifiers input impedance without issue. Not only that, it will drive many phones to unbearable volumes. The stock Crack has 120ohm output impedance, so it is a distinct dis-improvement on your DAC run stand-alone. I guess all this is complicating the task of composing a suitable reply. I'd just put a large value series resistor in each DAC channel's input to the...
I found these:- http://www.ebay.co.uk/itm/Toroidal-230V-Mains-Transformer-15VA-0-6V-0-6V-/300976618233?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item46139abaf9   In this case the primary and secondary swap roles, but this is dual both sides.   This is the bias supply:-       w
Doh! I picked a tx with a CT secondary, when what is required is a CT primary. I must be a bit distracted.   Here is the latest iteration of the depletion MOSFET design. I have carefully made these stacking boards 100mm square, this is the best value/size on sites such as seeedstudio.com and iteadstudio.com. 10 ea. of these cost ~U$75.     The bottom layer, the amplifier, has a largely unbroken copper plane on the upper surface, the upper 2 layers have largely...
Thanks. Yes, I was a bit depressed for few weeks, but then you realise that you are still alive, and you still have to fill the remainder of your life, which is all any of us are doing anyway. What used to give meaning to my life still gives meaning to it, and although I build things to use, building is fun in itself. I have built one side of the electrostatic headphones complete down to the cable and connector. The other side is just a little hand-fettling away. Now I...
τὸν κρατοῦντα μαλθακῶς θεὸς πρόσωθεν εὐμενῶς προσδέρκεται. w
Don't use plumbing solder. Don't use solder of unknown content. Buy some leaded multicore flux-bearing electronics solder, preferably 63/37 eutectic with a mil-spec flux. It's nice, but not essesential, to have different gauges for fine and coarse work. w
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