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Old 13th February 2011, 02:24 AM   #1661
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I love the heatsinks...

dave
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Old 13th February 2011, 02:55 AM   #1662
bbm3 is offline bbm3  United States
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Originally Posted by planet10 View Post
I love the heatsinks...

dave
They work very well.
I wish I could find more.
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Old 13th February 2011, 06:14 AM   #1663
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Originally Posted by planet10 View Post
I love the heatsinks...
Me too. I would even have put them on top of the case to show them off.
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Old 13th February 2011, 11:49 AM   #1664
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Originally Posted by norture View Post
Here's my LM3886 based amp. Acquired the heatsink from local supplier, and the PCB came pre-assembled overseas (from China I think).

The PSU is a DIY SMPS, taking 12V inputs with 20V CT DC-outputs. This is because the SMPS produces no audible hum on the speakers. The amp just seems dead without any signal ;-) A little underpowered because I don't have the time to rewound the EL transformer

Placed the whole lot on my study desk

Here are the attachments, as the previous links might have broken.
I like the thick power wires going from your power supply to the amp modules.
I see so many amps in this thread that have nice thick wires from the amp to the speakers, yet have tiny strands going between the amp and the power supply module.
Makes no sense at all.
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Old 13th February 2011, 12:24 PM   #1665
AndrewT is offline AndrewT  Scotland
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Originally Posted by Rainwulf View Post
I see so many amps in this thread that have nice thick wires from the amp to the speakers, yet have tiny strands going between the amp and the power supply module.
Makes no sense at all.
you have not considered the filter effects that can be gained by selecting appropriate resistances and inductances in the route from transformer to speaker.
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Old 13th February 2011, 12:43 PM   #1666
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No i have not, i have always relied on the psu to safely filter out any noise, and make sure the amp modules can use the full voltage of the power supply without sagging due to resistances in the PSU lines.

It seems to be counter intuitive to have resistance in the power supply lines that limits the max current that can flow, but then use thick speaker cable to make sure that current is NOT limited.
I would think sag in the power rails would be avoided, isnt that why regulated power supplies exist?
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Old 14th February 2011, 08:05 AM   #1667
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Quote:
Originally Posted by Rainwulf View Post
I see so many amps in this thread that have nice thick wires from the amp to the speakers, yet have tiny strands going between the amp and the power supply module.
The opposite of what makes sense.

dave
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Old 14th February 2011, 08:59 AM   #1668
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Im sorry i dont understand what you mean.
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Old 14th February 2011, 09:27 AM   #1669
AndrewT is offline AndrewT  Scotland
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Capacitance alone cannot work as a filter.
It needs rC or LC to create the filter.

The secondary winding and the wiring from transformer to rectifier to smoothing bank provide both resistance and inductance (as well as capacitance) and then the smoothing capacitance can operate as a filter.

The wiring from the smoothing capacitance to the amplifier and the rail trace impedances act with the decoupling capacitance to create a second line of filtering.

0milli-Ohm and 0milli-Henry with C is not a filter.
1mOhm and 0.01mHenry with C is an effective filter.
2m-Ohm and 0.02mHenry is a more effective low pass filter.

20Apk to the speaker and 0r002 is a voltage drop of 40mVpk between the smoothing and the decoupling.
This can never be zero mVpk, no matter how big you make your cords/cables/plates!!!

Now tell us you don't use filtering.
You use it all the time, but did not realise that what you originally said is complete balderdash.
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Last edited by AndrewT; 14th February 2011 at 09:32 AM.
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Old 14th February 2011, 01:22 PM   #1670
troystg is offline troystg  United States
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PCB filter banks provide short term transits with local reserves and music is not continuous.
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