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Chip Amps Amplifiers based on integrated circuits

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Old 19th February 2010, 11:13 AM   #1341
frank1 is offline frank1  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
Frank,
Don't let this put you off. Your observation was correct, there appeared to be something wrong. What saved the situation was 92dB speakers. 89dB speakers requiring twice the power for the same volume would cause the amp some ill-needed stress. 86dB speakers would be unsuitable.
Thanks Andrew, it doesn't put me off.
I know just how much heat these chips can generate.
SPIKE is not a saviour, it is an absolute last resort for these chips to save themselves.


Frank

(With all his heatsink fins nice and cool, outside the box!)
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Old 19th February 2010, 11:36 AM   #1342
ratza is offline ratza  Romania
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I understand perfectly your points of view, guys, because I was also worried about heat and that's why I performed the tests. 10W are WAY too loud for my ears. The heatsink will be moved outside for sure, but in the future. I lack some tools for wood work and I'm too lazy to go buy them.
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Old 21st February 2010, 03:48 PM   #1343
frank1 is offline frank1  United Kingdom
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Default Heatsink in a box

Just look at this one:

Remember the laws of physics?
I truly believe that a lot of folk here think that heat disappears forever into a "heatsink" as its name implies!

http://www.diyaudio.com/forums/attac...m-dscf0182.jpg
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Old 22nd February 2010, 05:55 AM   #1344
ratza is offline ratza  Romania
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Heh, at least it has venting holes. Mine doesn't have even those
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Old 28th February 2010, 08:14 PM   #1345
mravlca is offline mravlca  Slovenia
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Question LM1875 with DC servo

I bought this case on e-bay, cost about 50€. Currently there is SMPS psu but I'm thinking to put in 80VA transformer with snubber, I have to decide in near future.

Regards Aleš

p.s. Also the wiring needs to be re-done.
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Old 3rd March 2010, 11:53 AM   #1346
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Default Minimal LM1875 with chinese eBay board

My latter chipamp, fitting into a parallel switch case..
no caps into signal path nor feedback,
and external connection for AC or DC power supply
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File Type: jpg 05.jpg (337.4 KB, 596 views)
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Old 3rd March 2010, 11:54 AM   #1347
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pentium II heatsink!!!
Well done good sir!

LM1875s as well. You have decent speakers i would imagine!

Last edited by Rainwulf; 3rd March 2010 at 11:57 AM.
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Old 3rd March 2010, 12:14 PM   #1348
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Yessir !
saying the truth, it came from an ancient Celeron (Slot A) 300MHz..
(cooling enough for this 2xLM1875, but not enough for my former 2xLM3886 )

and (talking about Truth ) you can see my ufficial speakers ( BEHRINGER: B2031P )
EntryLevel but so honest speakers..

former photos showed you a no-cost recycling experiment, taking speakers and xover from an unused car audio setup..
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Old 14th March 2010, 08:50 PM   #1349
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Default My new 3875T Chipamp

While I was waiting for some OPT's to arrive for another project, I decided to revisit my little chip amp and redo it. I built the orginal version about 8 years ago. Since then I have learned alot and decided to rebuild it into the form you see.

The LM3875 is operated in inverted mode and has +/- 25V rails with 4500uF on each rail. 1000uF of it is right at the chip. Had some HexFred diodes laying around so I threw them in as well. To put the mandatory Blue LED needed for a chip amp I wound an extra coil on the tranny. Used 8 wraps to get enough juice to light it properly.

The bottom plate is 1/2" thick aluminum plate. The chip is clamped to the plate and insulated with a mica insulator. Pretty pleased for a weekend worth of work to keep me out of trouble.

While it doesn't sound like my 300bSET it does sound good. Solid bass and good detail. Good enough to go to college with my son.

I have some spikes for feet to allow air to flow underneath, but need to get a M6-1 tap on Monday
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Last edited by SGregory; 14th March 2010 at 08:53 PM.
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Old 16th March 2010, 03:10 PM   #1350
grigore is offline grigore  Romania
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Default My chip-amp, ver.1-LM3886

This amplifier is hand wired in air. It sounds good. I will come with the new version. I want to confess that I'm a chip-amp fan.
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File Type: jpg DSC05139.jpg (487.5 KB, 546 views)
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