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Re: FAVORITE G2 Parts, 1-7-06

HI,

Good question pipo, here is the rest of my circuit implementation:

For caps, I am EXPERIMENTING STILL.

Although not applicable to you, for the ARC D-75 / D-76 series amps I actually use TWO of these supplies !!!, one for the ARC's critical Cross Coupler B+, and another for G2's B+. Its all filtered L1/C1/L2/C2.

Right now, Jeff is using 1979 Photoflashes, series/parallel, about 1,000 uF for C1 and about 1,000 uF for C2, PLUS ( on the G2 supplies - at the C2 location ) a 220 uf @ 400 VDC Panasonic TSHB cap ( DigiKey ) with a MILLS MRA-12 24.9K ohm resistor ( only a MRA-12 ) across EACH of the four TSHB caps, which becomes four paralleled Shunt Regulator resistors, which equals 6.22K @ 48 watts for G2 SHUNT - B+ to ground. All four TSHB caps are located within 1 1/4 inch lead length of Octal Socket's Pin 4, which is G2.

Total capacitance for G2's C2 is thus - 1,000 uF plus 880 uF or 1,880 uF, and those Photoflahes measure LOW in ESR, act like little atom bombs.

If you don't have Photoflashes of that era, TRY the low cost Panasonic TSHB 400 VDCers. I find caps all have different sounds and some work needs to be done with the C's to get it acceptable. For wire, I use 14 gauge stranded copper, not plated in the power supply, and on the Audio Boards, Grounds are hefty Kimber Kable TCX and B+ runs are all paralleled pairs of Kimber Kable TCSS.

Due to low DCR of supply iron, combined with high capacitance / low ESR caps, one MUST always use a 47 ohm CL-80 ( from Mouser ) " Current Inrush Limiter" / Thermistor on the primary of the power transformer, and I just ordered four 8 A. at 1200 VDC Fairchild Stealth diodes for SS rectification from Mouser, as uF4007 full wave bridges blew-up on this supply's severe turn-on surges.

Signal Transformer iron is direct-order from Signal factory in NY USA, and their full line catalog downloadable on-line. Alternatively, for a power trannie, find any equal or greater than 500 VA isolation XFR on eBay with a 120 VAC to 240 VAC capability. ( Gives about 298 to 330 VDC final B+ for G2 ). These are big and heavy, but can't be beat by anything I know of. The Signal Transformer DU1/2 is a very nice part, may be 2.15 ohms as I see in notes, not 2.3 ohms in DCR, darn low, unflappable - stable!!

Jeff Medwin


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  • Re: FAVORITE G2 Parts, 1-7-06 - drlowmu 09:13:57 01/08/06 (0)


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