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Old 7th May 2009, 10:57 AM   #21
Vigo is offline Vigo  Sweden
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I have another of topic question.

Is it possible to get 15w from mini aleph in 4 ohm?
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Old 7th May 2009, 02:13 PM   #22
juma is offline juma  Germany
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Absolutely, but you'll need almost the double bias current to achieve it.
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Old 7th May 2009, 04:07 PM   #23
Bengali is offline Bengali  United States
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Quote:
I have another of topic question. Is it possible to get 15w from mini aleph in 4 ohm?
I would like to be able to do this as well since my mini-A
is driving Mag. MMG's. Sound is excellent, just a little more
power would do it.

Perhaps Grey or Mr. Pass would be share their wisdom
in modding the mini-A to be able to do this.

Thx!
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Old 9th May 2009, 09:05 PM   #24
Beftus is offline Beftus  Netherlands
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In building my mini Aleph using BrianGT's PCBs. I've got the PSU board finished, now I'm building the amplifier boards. The Excel sheet states "R6 is not used". Do I have to install a jumper wire instead of R6 or nothing at all?
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Old 10th May 2009, 04:43 AM   #25
pchw is offline pchw  United States
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My Mini-A has been up and running for over 3 weeks.
As of now, evening in SF Bay Area, it is at about 50C, 22C above ambient.
Since I want to use the amp in summer as well, I think this will give me a good margin with the exception of the days at over 95F.
The rails are approx. +/- 15.5VDC, and the bias is at approx 1.4A. I have 8ohm, 6 ohm, and 4 ohm speakers. So, what kind of max output power I am getting when different speakers are hooked up? Is there any magic formula that I can use to estimate the rated power when the speakers are at certain impedance?

Thanks!!
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Old 10th May 2009, 06:07 PM   #26
juma is offline juma  Germany
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Quote:
Originally posted by pchw
... Is there any magic formula that I can use to estimate the rated power when the speakers are at certain impedance?
Thanks!!
Yes, it's called Ohm's law (see attachment).
Reading Mr. Pass' articles on Zen and FirstWatt series will totally disperse the magic, you'll be stuck with knowledge only
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File Type: gif ohm's_law_wheel.gif (56.4 KB, 317 views)
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Old 10th May 2009, 07:12 PM   #27
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by pchw
...... Is there any magic formula that I can use to estimate the rated power when the speakers are at certain impedance?

Thanks!!
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File Type: zip aleph-power.zip (11.2 KB, 136 views)
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Old 10th May 2009, 08:46 PM   #28
pchw is offline pchw  United States
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Quote:
Originally posted by juma


Yes, it's called Ohm's law (see attachment).
Reading Mr. Pass' articles on Zen and FirstWatt series will totally disperse the magic, you'll be stuck with knowledge only
Yeah, my trouble is to know how to apply :-) I thought I knew how, then after I read the Aleph-30's service manual, it say 30W into 8 ohms, and 40W into 4 ohms, my method didn't arrive the same numbers for the Alpeh 30. So, it was wrong
I will go back to read Papa's articles again.

Choky,

Thanks for xls. A quick question, how do I find out the AC Current Gain from the Mini-A?

Thanks!!
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Old 10th May 2009, 09:48 PM   #29
wim is offline wim  Netherlands
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Beftus, RS-Components has several 3R rsistors in stock. number 506-4447 for example. In one day delivered.
Succes.
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Old 10th May 2009, 09:57 PM   #30
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by pchw


.......

Choky,

Thanks for xls. A quick question, how do I find out the AC Current Gain from the Mini-A?

Thanks!!

easy - feed it with some sine signal - say 440 to 1000Hz

measure small voltages across one by one source resistors of output mosfets

if they are similar , then AC gain of CCS is 50% ( meaning that CCS contribution to output is exactly half )

if not - alter value of resistor from output to base of Aleph CCS small bjt , which is responsible for modulating aleph CCS
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