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kevin gilmore

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kevin gilmore last won the day on April 26 2017

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About kevin gilmore

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    Staximus Maximus, Stax Mafia's Chief Cook and Bottle Washer

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  1. kevin gilmore

    digital attenuator

    that one is indeed 3 layers, extra complete ground layer in the middle. forgot about that one.
  2. kevin gilmore

    digital attenuator

    its a 2 layer board. not sure why it is being detected as 3 layers
  3. kevin gilmore

    current feedback electrostatic amp

    easy, low cost, no adjustments, only hv supplies etc.
  4. kevin gilmore

    The ultimate DIY? A Stax SRM-T2!

    thermal grease lasts forever. I have a jar with original Newark part number on it, and its 50 years old. Still good. the stuff contains aluminum oxide or silicon oxide, or various other compounds in silicone and for voltages less than about 2.5kv its an insulator. Although it can have more capacitance than you might think.
  5. kevin gilmore

    Technical Assistance/Advice Thread

    v- is actually -370v and vref3 is -350v take a closer look at the original schematic
  6. kevin gilmore

    Hifiman Jade II

    history lesson (unless birgir says otherwise) As far as I can tell the first stax amplifier to use differential cascode circuit is the srm-1 first introduced in 1979 long before hifiman was even a company
  7. kevin gilmore

    Hifiman Jade II

    The srm-001 is an opamp driving a fet that drives a transistor (cascode) into a load resistor and is cap coupled to the output. (cascode differential) The jade2 is an opamp driving a transistor that drives a mosfet (cascode) into a load resistor and is cap coupled to the output. The calculation of output capacitance is flat out wrong as the middle of the cascode is AC ground. (cascode differential) Just about identical. Obviously the jade2 consumes a bunch more power and puts out a bunch more power. I own 2 hifiman products. Both are built like shit. I'm unlikely to buy hifiman products ever again.
  8. kevin gilmore

    Raal Requisite SR1a

    uberamp2 in single ended form. then you don't need the resistor box.
  9. kevin gilmore

    Hifiman Jade II

    The circuit is more like the srm-001 blown up by a bunch. So opamps input, solid state version of grounded grid output stage, resistor loaded, and capacitor coupled output. Positively ancient design by any standard. Did not even replace the power resistors with current sources. Saying that the output capacitance is that low because the two devices are in series clearly shows no understanding on how that design works. And the series output inductors are not a great idea either. The headphones may be decent, I don't know because I have not heard them, but there are so many decent headphone amps out there that buying the hifiman version seems like a waste of money.
  10. 2 grhv, 2 grlv78xx,2 grlv79xx, 1 main board, 1 mini t2 please
  11. kevin gilmore

    goldenreference low voltage power supply

    it may have something to do with the minimum voltage. But I have not tested it.
  12. kevin gilmore

    goldenreference low voltage power supply

    someone needs to check this, works as single rectifier with center tapped transformer, or a pair with dual secondaries. Up to 72vdc, perfect for GRLV caps are 100v rated, 1uf is 0805 size, 10uf is 2220 size I can certainly do a bigger version with different fets for higher currents and lower voltages. .9 x 1.1 inches syncrectifier.zip
  13. kevin gilmore

    goldenreference low voltage power supply

    going to make it a replacement for the 4 pin diode bridge, should fit in all boards with that pinout. something like this
  14. kevin gilmore

    goldenreference low voltage power supply

    coming soon, synchronous diode bridge using lt4320 and power fets lower dropout voltage, much less switching noise
  15. kevin gilmore

    some questions about electrostataic amp

    1) go and find complementary parts that work at 900v that are not obsolete 2) the load is more than you think. up to 20ma at 20khz 3) protect the diaphram 4) takes minutes to charge, quality of resistor is meaningless 5) 717 and 727 definitely have emitter follower output stages with current sinks.