mini aleph build questions

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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!!
 
pchw said:
... 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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juma said:


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 :bawling:
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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pchw said:


.......

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
 
wim said:
Beftus, RS-Components has several 3R rsistors in stock. number 506-4447 for example. In one day delivered.
Succes.

If the French postal service works just as reliably like ours my 3R resistors should arrive soon. Fellow forum member korben69 has been so nice to send me two for free.

I ordered the majority of parts @ www.hifituning24.de and was confident I could find the 3R resistors @ Stuut & Bruin or Radio Twenthe. Well, so such thing. A value of 3R is an American value. In Europe it's either 2R7 or 3R3. That left me without 3R resistors and myself not willing to fork out a ridiculous amount of money on shipping for two resistors costing a few cents each.

BTW RS-Components doesn't appear to have 3 ohm 3 watt resistors...
 
Beftus said:
A value of 3R is an American value. In Europe it's either 2R7 or 3R3.

This has nothing to do with America, Europe or whereever there manufacturer comes from. It's just the question if the resistors are offered in E12 or in E24 value range.

After quick google and quick look http://www.logwell.com/tech/components/resistor_values.html seems to be good reading on this topic.

Greetings,
Chris
 
CfM said:


This has nothing to do with America, Europe or whereever there manufacturer comes from. It's just the question if the resistors are offered in E12 or in E24 value range.

After quick google and quick look http://www.logwell.com/tech/components/resistor_values.html seems to be good reading on this topic.

Greetings,
Chris

Aha, it's slowly starting to make sense to me! :)
 
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