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Klaus 26th May 2003 07:47 AM

Aleph amp bootstrap - where to go?
Hi Aleph DIY freaks,

one question regarding the bootstrap capacitor in the Aleph power amp current source. I searched in the past but didn't find anything. So sorry if I'm asking again…

Looking into the schematics of Aleph1.2 and 2 show the bootstrap cap ending at the speaker output = the feedback branch "behind" the series output resistor. In smaller Alephs this cap pin is connected to the emitter of the current source bipolar transi. So "before" the series output resistor. When I have learned one thing here, than, that everything in Nelsons schematics has a reason – so what it is? Which bootstrap solution is better for what?

Thanks for your comments!



wuffwaff 26th May 2003 10:49 AM


the reason for doing this was probably a nicer PCB layout.
I donīt think that there is any advantage or disadvantage connecting it before or after the resistor (wich is very small!).
This topic has been on the forum a while back but I canīt find it at the moment.


Klaus 27th May 2003 08:46 AM

former tread - keyword for search?
I can not find the old stuff about this, could anyone help me with a keyword? Tx!

wuffwaff 27th May 2003 02:57 PM

try something like c5 or c2 or 220uF but like I said, it doesnīt make any difference.


Klaus 27th May 2003 04:02 PM


Thanks, William!

Got to know, that there shall be no sonical differences. But still missing an explaination...

It does not matter. I used Marks downunder-PCBīs for Aleph4, so my solution is fixed.



wuffwaff 28th May 2003 10:48 AM

well the explanation is that the difference between the two points is a few millivolts and thus unimportant relatively to the large output voltage swing.


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