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kevin gilmore

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kevin gilmore last won the day on May 10

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  1. depends on what kind of power supply is inside. if its a switcher, it might benefit the input caps for a 30 second slow ramp. if its a linear supply, probably does not matter.
  2. my orbi is getting glitchy too. replacement is $1500. likes to drop the dns once a week. i'm getting 1194 download and 24 upload. if i get the newest orbi, i can get up to about 1600 download with top xfinity tier. i don't need that yet, and then i would have to upgrade every switch in the house to 2gb or faster, and those are expensive too. also looks like i'm going to get a atsc 3.0 tuner very soon. there is a chicago station now that is broadcasting 4k cartoons. 3 stooges in 4k is da bomb.
  3. i don't remember. definitely can add 1 wire and not use it in shunt mode.
  4. you are going to need to change the lt1021 to the 5v version and recalculate the resistor ratio. 3v across the current source is not enough for it to work properly. even 5 volts is cutting it close. the minimum tested voltage for this design is 12v output.
  5. clever idea but you then need a jumper block.
  6. switch the tubes. if the hum does not move, its the headphones.
  7. unless one of the tubes is slammed to one of the rails, rebiasing is not going to help. but you should measure the dc output voltages.
  8. cp1117n is normally closed, so no output voltage. you need to power it to turn the hv on.
  9. kgsshvpssicfetsinglenewleftfatsws - cadcam.zip 12/25/2015 definitely on the google drive.
  10. i posted this elsewhere. here is a copy Its all about size (as in core cross sectional area) and maximum flux before saturation. its obvious from the graphs above (posted elsewhere) that the core saturation of the eha5 transformer is about 1.4 tesla indicating the cheapest of core materials. better and much bigger transformers are available from lundahl and edcor. which will both give 20hz to 20khz +0 -1 db and will actually do 1800vpp with a 50 watt amplifier over the full frequency band. without series resistors. without filters. as far as i can tell lundahl does not specify maximum field strength. edcor does and its 2.01 tesla. there are custom c cores with magic materials that can do up to 2.5 tesla. these are a bit expensive. the ll1630 mentioned above (posted elsewhere) will NOT do this. core size is too small. you need a transformer with a minimum of a 30 watt core. The 60 watt edcor are MUCH better. the ifi iesl which is extremely sensitive to power amplifiers is yet another example of a poor design with a tiny transformer. does not matter how carefully you wind the core if you drive the transformer into saturation. the result will be a box about 3 times the size of the eha5. and a weight of about 20 lbs. cost about $600. nope, no cheap way of doing this.
  11. here is a link to simmcon's takedown of the eha5. its mandatory reading for everyone. https://www.audiosciencereview.com/forum/index.php?threads/topping-eha5.42149/post-1712440 in other news, birgir sent me a srd7 to test. in other other news, i have finally found a company that will sell me cores and bobbins in small quantities. so making electrostatic transformers becomes a possibility.
  12. so here are some more pictures, obviously faked. This is the kgsshv-carbon built by birgir and given to tyll as one of his 2 reference amps. Into a standard 120pf load. right at the limit of my scope probe, have to find the higher voltage probes. first picture 20 volts per division, next 2 are 50 volts per division. all are 10khz square wave. reference cap beginning to bubble due to heat.
  13. well if i used one of my digital scopes, then did an edit on the computer and then played it back on the scope, its probably fairly easy. but on a real analog scope, it would be some kind of impossible.
  14. So a person accused me of faking my scope picture, because it had to be my signal generator. And that the amp performed better at the higher gain setting. I completely disagree. Q15 has no emitter resistor and the resulting gain of just this transistor is 30db. which makes the miller capacitance absolutely huge. which is why you see two different slew rates. the first bit is due to the output amp (everything left of r12 which is a diamond buffer driving a pair of current mirrors driving another diamond buffer). The second bit is due to Q15. edit: shenzen audio is now selling these things brand new in the box on ebay for $50 off. soon it will be $100 off.
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