6 Channel LM3886

[Jean]

Hello,

Here is my current progress with a 6 channel lm3886 based amplifier. I am thinking about mounting all 6 LM's down the center to a thick copper or aluminum bar. I will most likely use a two tier method, mounting a single transformer under the boards.

Suggestions ?


[IMGDEAD]http://www.briangt.com/gallery/albums/6chLM/audio_027.sized.jpg[/IMGDEAD]

 

[karma]

copper would be nice

 

[G4ME]

what size toroid are you looking at?

personally i would put them on the sides, as that gets more air convection, but if you go big enough on the center bar i am sure you will be fine.

 

[Leolabs]

Try to look inside of a MBL or Plinius intergrated amplifier.

 

[Richard.C]

you are too strong!!
i only want to kown....how to paste a picture in the post?

 

[renfrow]

You might also consider a heat sink like this one found at http://www.apexjr.com/new.htm, just over halfway down the page. It's predrilled for a boatload of TO-3's, but, you could drill your own holes...

Tom.

 

[zaibz]

6/8 channel LM3886 amp, with SMPS?

Im in need for a multichannel amp, 6 to 8 channels. I have decided to use the LM3886 chip, but still open for other ideas, as nothing have been purchased or written in stone yet. Im borrowing this old post from 2005.

Im thinking of ordering the chipamp.com pcb's, and use a SMPS to deliver the power.


Is it possible to use this SMPS from connex to power up 6 LM3886 channels in the same enclosure.

SMPS800RE
+-32V

Will there be any problems with hum, noise or other ground-related issues, and would the PS be able to deliver enough "juice"?


Am I right in assuming +-32V is a bit high for 4 ohm load?

Can another solution be to make 2 separate 4-channel amplifiers with this SMPS:
SMPS500R
+-24V

The same questions regarding hum and power does apply here too.
This is my first post on this forum, and i dont have alot of experience with electronics.

 

[AndrewT]

...........Am I right in assuming +-32V is a bit high for 4 ohm load?.........

You are right, but it is manageable if you take care to ensure your 4ohms speakers are of moderate reactance and you have normal domestic listening, where P average ~-20dB ref maximum output and you keep the chips cool.

NS have a graph showing the typical Heatsink required for operating temperatures at 150°C.
I always suggest you double the size of the sink for our typical use.

If for +-32Vdc (=64Vdc) and 4ohms with ambient temperature at the heatsink = 25°C, NS show 2C/W, then use 1C/W for each channel.
6 channels would require an enormous heatsink with a rating of 0.17C/W