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Old 16th July 2001, 06:38 PM   #11
scrazy is offline scrazy  Taiwan
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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...!
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Old 17th July 2001, 05:50 AM   #12
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Default 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
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Old 17th July 2001, 12:56 PM   #13
jam is offline jam  United States
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Default 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?
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Old 17th July 2001, 08:35 PM   #14
hifi is offline hifi  Sweden
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do you hear any AC humm through it or is it silent??
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Old 18th July 2001, 01:47 AM   #15
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Jam, Just got back from Singapore a few moments ago so no advancement on the pre-amp this week

I notice a parcel is waiting for me to collect so hopefully the boards have finally arrived so I can continue with it.

Cheers,

Pete
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Old 18th July 2001, 02:33 AM   #16
scrazy is offline scrazy  Taiwan
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Quote:
Originally posted by hifi
do you hear any AC humm through it or is it silent??
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
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Old 18th July 2001, 02:39 AM   #17
jam is offline jam  United States
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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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Old 18th July 2001, 10:24 PM   #18
hifi is offline hifi  Sweden
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i think the problem in my amp is my trafo...cus if i move the speaker wires around the hum increases...and decreases...but i will try with a cap across the zener....

/micke
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Old 19th July 2001, 06:52 PM   #19
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http://members.tripod.de/Promitheus/ground_amp.htm
read here a few ideas about grounding amps maybe you can find something that can help you improve your hum.
Ilias
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