My Aleph5 clone working!

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scrazy

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Joined 2001
#1
#4
Very Nice !

Rule of Thumb

55 - This is hot, but I can leave my hand here for a while
65 - This is hot, I can touch it, but I don't want to leave my hand here!
75 - Too hot to touch

First two probably OK for an Aleph, though Nelson will tell you you want the former. Later may be a problem !!

Kitchenware shops sell thermometers for cooking roasts etc - the kind you poke into the meat. Don't know what they cost, but should be able to handle the temp range.

PS: Send some photos to Desmond at Passlabs ( mailto:dharrington@passlabs.com )

cheers .... mark
 
#9
Noisy Zener

Scrazy,

I would put a 1 to 5uf capacitor across the zener.
You could also try replacing the resistor feeding the zener with a current source.

Jam

[Edited by jam on 07-16-2001 at 07:53 AM]
 
#11
I get these heatsinks from heatsink factory(In Taiwan).
They build & sale all kinds of heatsinks I think....
The smallest ex:for TO-220.
The largest ex:for cooling some machine...
But for DIYer the price is too high,because of the quantity.
But this is my only way to get these big guys building my Class A amplifier...! 🙂
 
#12
Capacitor

Jam, I believe the value you suggest may be too large for noise suppression. While under ideal circumstances it won't make any difference, one may be tempted to use an electolytic capacitor for that value. Electros provide quite poor performance at high frequencies and I would suggest a lower value capacitor with better HF characteristics would be better.

Cheers,

Pete
 
#13
Taming Zener Noise.

Pete,

I should have have mentioned that the capacitors I would use are Black Gates or Os-Cons. I have also used tantalums to good effect. All these capacitors have excellent high frequency characteristics.
If the thought of an electrolytic bothers you a .47uf or 1uf film and foil capacitor works just as well. I arrived at the above values after a lot of experimentation. Too small a value will not work as well as the noise is pretty broadband.
Before you add the capacitor you have to set the zener current, too low a value and the noise will be a lot higher. Then consider replaceing the resistor that feeds the zener with a another current source (a current diode works well here), which will further reduce the noise and improve the current sources rejection of rail (power supply)noise.

Cheers,
Jam

P.S. By the way, how is your pre-amp project doing?
 
#16
hifi said:
do you hear any AC humm through it or is it silent??
Click to expand...

When I am very close to the bass driver,there are some hums, no hiss..
This is acceptalbe,but I think it can improvement...

questions:
Now my aleph configuration :
Each channel using two big Capacitors & one transformer.
and the GND of each channel is seperate and NOT attach to the amp case.
1.Should I connect TWO channel with TWO GND point(why?)?
2.Should I make a chasis GND to reduce the noise(why?)?
3.Any comment for reduce the little hum?(all that just because my poor layout skill?)

thanks all
 
#17
Hifi,

It is pretty quiet. Also I should note that some zeners are noiser than others, and if you decide not to use a capacitor you should select one that is less noisy (1/2 watt zeners seem to be less noisy).

You could stack a few led's togther in place of a zener and this would be quieter (you would have to change the current source resistor as the voltage drop would be different).

Jam
 
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