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kevin gilmore

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kevin gilmore last won the day on May 10

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  1. actually a krell master reference pair of monoblocks will drive any headphone electrostatic or dynamic. just need to add a bias supply. 800 volts peak to peak.
  2. i'm sure ray would be happy to sell you one of his new amps, only $10k.
  3. there are a few units with the tube front end that have been built. less than 5 i think. boosting the front end high voltage will increase the power in the current mirror that follows the tube. so you might have to change some of those parts.
  4. would need a higher voltage opamp. otherwise should work.
  5. pretty sure all of my boards have the holes electrically isolated.
  6. so over at ASR, people have commented today that topping said that they used a step down transformer on the output of the step up transformer, an no capacitive load. flat out fraud this is... and completely meaningless published specs. if someone paid attention during the design process and actually used a real 120pf load, or even headphones, they would know how fucked up this is. the topping a90d may be decent. but my testing in the past indicates that stuff with huge amounts of open loop gain, and then huge amounts of feedback to get those magic distortion numbers usually sound like crap. this thing, and their power amp all use one switching power brick to make the positive voltage and then another switcher internally to make the negative voltage. so a switcher driving a switcher. not a great idea.
  7. and yet the audio precision actually reports .0008 % thd at 1khz. so much for that being worth anything. sure looks like about 10 volts per microsecond slew rate. pretty grim at higher voltage levels. winding transformers correctly really is not that hard. too bad the lundhal transformers won't fit inside the box. hmm, there is that size thing again. (usa_love) what really gets me is the really poor soldering job, probably there is a significant failure rate of topping products in the field. And yet led lit sails that makes you think there are tubes inside. my guess is that the koss box sounds better than this, for roughly the same price. quoting from someone who knows how to actually make transformers like this.. quote In a transformer winding, inter-turn capacitance is generally negligible compared to inter-layer capacitance. We can approximate the winding self-capacitance within a small factor by considering only the capacitance between winding layers, approximating the layer to a conductor sheet. The highest capacitance arrangement is when each layer is wound in opposite directions, so left to right on the first, right to left on the next. That's because the first turn of the first layer is opposite the last turn of the next layer, so there's twice the voltage per layer between those turns. As the energy stored in the self-capacitance goes as the square of the voltage, this more than offsets the lower voltage difference at the other side of the windings. A lower capacitance can be obtained by winding each layer in the same direction, returning between layers, so left to right, then left to right again. The voltage between layers is now uniform at the per layer voltage. end quote transformers made this way have to be partially done by hand. no winding machine currently available does this. its why esl63 replacement transformers are $500 each.
  8. ray maybe lies a little on the specs ?? left is 20khz sine wave, 15ma peak, bottom is 20khz sine wave 1800vppss right is 20khz square wave 500v/us, top is current bottom is voltage, 1800vppss would have to be more than 1000v/us to hit 200ma peak. only apex part that does that is the pa194, price for 4 is $1600. slewrate.PDF
  9. ray's facebook page.and people taking pictures of his not at axpona, axpona show. and then sending them to me. time for me to taunt ray. ray does not have the balls to do a real statement piece.
  10. you calculated incorrectly. lets start with $3495 for the darkstar component. and then add $6500 for the a10 equivalent. lets just call it $10k. ray should be ashamed of himself for selling something less than woo audio's 23es price. the 200ma is peak. there is no way to actually shove 200ma into the headphones with 450v power supplies. with a square wave at 20khz, the best you can do is 40ma peaks if you are using the 500v/us version. sure hope ray is smart enough to actually use the 5.1k safety resistors, otherwise this thing could actually kill its owners if something stupid happens.
  11. birgir pointed me to this. hvrv portable 闲鱼宝贝详情 (goofish.com) published price is $380 plus shipping. someone that reads chinese should buy one.
  12. i was going to be much less friendly. the file you are looking for is where it should be.
  13. no posted price on ray's amp yet. has to be built better than the viva. audio valve out of business, so get your solaris while they are still in stock. then pray that it does not break. no one going to come close to the $400 price.
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