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Old 21st August 2002, 03:28 PM   #1
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Default Improving current source for Aleph

I just started modifying one of my A75 into Aleph 2 today.
Since it's A75 I have available 50V regulated power supply for the input stage. I was thinking about using it for differencial pair current source and somehow improving it as well. Any suggestions?
Any improvements when current increased? What would be recommended value then?
The drain resistors (392 ohm) would be connected to output stage supply.
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Old 21st August 2002, 03:59 PM   #2
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http://diyaudio.com/forums/showthread.php?threadid=5380

May be you two should combine the two thread and cook up something ....
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Old 21st August 2002, 05:34 PM   #3
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He's talking about output current sources and I'm talking about input.

It's a shame that something so nice has to be dismantled, but some people do anything for better sound. This might well be the first DIY Aleph with TO3 output devices. I'm also playing with idea of turning it into Aleph X instead of Aleph2, don't know yet.

I like the way the transformer is isolated from the rest of the circuitry. I also used special damping materal for vibration reducing. Also I used Panasonic HFQ capasitors for PS (quite a lot of them).
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Old 21st August 2002, 05:38 PM   #4
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It's been my best work so far and it looks like it still remains with an upgraded interior.

Checking other threads I noticed that Harry placed 5 green LEDs instead of zener with a small bypass cap. Is that the best that can be done?

The heat sink are removed. This allows for easy access in case of repair, modification. As you see mounting TO3 devices is not as easy as those plastic ones and special bars had to be used.
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Old 21st August 2002, 06:07 PM   #5
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It has something as a coffee machine !

Very big, and what a good job!
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Old 21st August 2002, 06:11 PM   #6
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Mmmmm, I love those 'capacitor-fields'!
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Old 21st August 2002, 06:18 PM   #7
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That's the detail of AC connection circuit. I got special circuit from ML 23.5 which supposedly removes DC component from AC. I'm using triak for switching and some people expressed concern it might introduce some noise. Is it true?
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Old 21st August 2002, 06:20 PM   #8
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That's the way front end board is mounted. The input jacks are directly connected from the other side.

I wonder how it all gonna look when I start my p2p, in those days I was firm believer that PCBs are better.
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Old 21st August 2002, 08:52 PM   #9
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And now everything is apart. Time to do some mods.

I only hope that my questions in the beginning is still drawing attention.
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Old 21st August 2002, 09:22 PM   #10
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Exclamation Is that the best that can be done?

No......... By the way do not power the front end current source from a seperate supply from the output stage or you can end up with the turn on/off thump from hell if the supplies come up or down at different rates!

H.H.
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