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Old 7th September 2004, 05:05 PM   #71
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Ok, Aleph 2 parts questions. I'm planning on using 16 fets total per channel, 1 ohm mills MRA-5's on each FET, and i was thinking of using for outputs ...instead of 8 of the .47 ohms in parallel for the output, how about 3 of the .33 ohm MRA-12's. I'm trying to save a few bucks and just wondering if doing this would be ok. Later!

-Matthew K. Olson
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Old 8th September 2004, 04:14 AM   #72
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anyone have any idea on how to use fewer higher power resistor on aleph 2 outputs rather than like 7 or 8 .47 ohm 3 watts?

since i'm using 16 FETs per channel, could I drop the emmitter resistors to .75 ohm mills mra-5's and use perhaps 3 of the .22ohm mra-12's as output resistors? thanks guys!

other options? i'm ordering from percyaudio.com soon i hope

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Old 8th September 2004, 04:34 AM   #73
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Using the 3 .33 ohm output resistors (I think) will increase AC current gain by almost 2X. 3 .22 ohms will increas by +- 1.5X

Decreasing source resistors from 1 ohm to .75 will up bias as will adding 2 fets per rail. Doing both will increase idle current around 2X. Should make a really spunky Aleph, with enough heatsinks. Almost able to push 2ohm loads to 400 W (these are all best case guesses of course)
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Old 8th September 2004, 11:56 AM   #74
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Ok, lets assume I don't want to change ac current gain or bias, i'll stick w/ 1 ohm resistors for source resistors, for all 16 devices, now, since I don't want to use 8 resistors for output resistors, how many mills MRA-12 and what value should I use (to save $$). I'll have a variable resistor for the bias setting (i've actually got a pot in mind and possibly a lighted meter for the back panel to indicate bias :-D). I've got some big sinks, no doubt, but i don't know if it'll be that spunky an aleph

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Old 8th September 2004, 12:04 PM   #75
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The 2 extra devices will up the bias by a factor of 8/6, but that can be undone by your pot. For the output sense resistors, use whatever combination gives you .06 ohms. Very little voltage will cross these resistors, so 1 watt should be fine. Use ohms law to check dissapation.
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Old 8th September 2004, 01:16 PM   #76
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Ok, then 16 1 ohm source resistors, and 3 paralleled .22ohm mills MRA-12's ... it'll give me .073 ohms. That'd work i hope. Thanks!

-Matthew K. Olson
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Old 8th September 2004, 01:47 PM   #77
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As devices are added the bias will increase, but that may not be a problem. I would not worry too much about the resistors on the output since you will be adjusting the AC current gain anyway. Bill
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Old 8th September 2004, 08:48 PM   #78
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ok, time to email percy then !

-Matthew K. Olson
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