NEW Aleph-X calculation sheet: AXE-1 - Page 7 - diyAudio
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Old 21st October 2005, 06:22 AM   #61
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Hello Owen,

the sheet wasnīt made for veryfying power claims but to find out wich combination of bias, ac-current-gain-power supply voltage and number of fets suits the builder of an Aleph Clone best and to get a bit of a feeling wich parameters you need to change to get the desired result.

I never said that the Alephs didnīt reached their specified power but that the published bias didnīt match the published power at 50% ac-current-gain.
If yours has 50% then it also will have around 3.8A of bias, if the bias is lower then the ac-current-gain will be higher. Since you build the amp yourself you could easily measure ac-current-gain and bias and see if the sheet works out.

William
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Old 14th December 2012, 02:27 AM   #62
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Hello everyone ! Could someone please convert this file to a pdf ? http://www.diyaudio.com/forums/attac...leph-power.zip
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Old 14th December 2012, 06:06 AM   #63
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Hi, I could but what would be the use of it?
You can't calculate things in a PDF.

William
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Old 23rd July 2013, 04:46 AM   #64
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hi! i have a couple of really basic questions about building an aleph xa.
ive built a pearl2 and im working on an aleph p1.7, but im very new to this and amplifiers seem to have their own requirements/considerations.

1) if i had a heatsink rated at 0.23 or 0.20 c/w, how many of them would i need to achieve 0.06c/w or thereabouts?

2) does an aleph power-amp require a regulated power-supply or is this a bad idea? it seems exact supply voltages are required to achieve a particular power output goal. or do we just build an unregulated ps with a crcrc filter network and not care about voltage fluctuation?

3) how do we set ac current gain? im under the impression two resistors do this.. what is the ratio/relation? Is there a drawback to haveing an ac current gain over 50%? say 55 or 60%?

4) are there any boards for this build that can easily accomdate 16jfets or 20 ..or 24..? And which fets need matching? do all of them need to be matched, or are matched quads ok?

5) is it possible to easily create a lower drawing standby mode to save power/heat when not in use?

6) active or passive (thermistor) inrush protection which is needed?

Last edited by FormosaWest; 23rd July 2013 at 04:54 AM.
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Old 23rd July 2013, 07:52 AM   #65
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Hi,

1. You can calculate the heat resistance like normal resistance so 3x 0,3°K/W gives 0,1°K/W
2. a regulated supply would be nice as the absolute dc offset depends a bit on the AC voltage. It would consume quite a bit of power though. I think most if not all people build them unregulated as C-R-C or C-L-C
3.yes two resistors. Easiest way is to measure it as there are a lot of factor to account for. 55 or 60% is possible, 50% sounds better. Just try. There are quite a lot of discussions about AC-Voltage -Gain
4. donīt know
5. yes but why, the amp heats up quite fast (30-60min) and sounds OK when cold. I donīt think itīs worth the trouble
6. both is possible, Iīm using an active one

William
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