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Chip Amps Amplifiers based on integrated circuits

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Old 13th June 2008, 08:12 AM   #21
Nuuk is offline Nuuk  United Kingdom
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Quote:
Is a 3mm thick aluminium plate sufficient to sheild the amp from the toroidal?
This is very much a 'suck-it-and-see' question. You may get away with no shielding. More depends on your routing of the various wires in the amp.

Have a look around at some of the chip-amps people have built and see how close the transformer is to the amp circuit, and what sort of shielding they have used. There are many published pictures of chip-amps on this forum, and in the Gainclone Gallery at Decibel Dungeon.

Alternatively, just mock up your amp on a piece of board and see if there is any hum.
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Old 13th June 2008, 08:27 AM   #22
Nordic is offline Nordic  South Africa
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I envy you guys with the toroids... at least you can fit them into the same case as the amp... I need at the minimum a shoebox sized space for my two EI trannies, and lifting them requires a strong back....

I would not stress the tranny voltage that much.. it is not a class-a amp requireing it to draw insane amounts of power the whole time... in stead it can put out nice power peaks but get to take a break in quieter moments in the music (something we are loosing with all the compressed rubbish out there... I am so enjoying Portis Head's Third CD, it sometimes uses those silent to violent moments to slam a 3d image to the front, it feels like a statue of water bursting up from the sea's surface... then for balance you need to finnish it off with Rammstein's Rossenrot).

Anyhow, I digress, but we are all passionate about music aren't we?

Lets think of it this way you will 60%of the time listen to very low output levels, probably below 5W output, as long as you don't turn the volume up until the protection kicks in and the sparks start to fly.

You control the output, you have the volume control.

By your questions I take it you are starting out in DIY, so I will suggest you get those 24 or 25V trannies.... you will thank me when you want to build your next project... most of the first discrete projects you will attempt, will ask for 35VDC.

I agree with Nuuk look at the photos on the site, I have seen some pics and thought, that would never work.... but they do... and it keeps moveing the goalposts...

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Old 13th June 2008, 09:21 AM   #23
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on the other hand , people are just too worried about sqeezing out the last wattage out of the chip.

if you are not running 8 ohm , get the 18V tranny , you will propably never now the difference ,but that depends on how you listen to your music and how far other houses are to yours.
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Old 13th June 2008, 09:48 AM   #24
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Nicootje, you really make my heart bleed of compassion.
NOT !

Overhere it is more difficult to locate squared ones in both the right size and secondary Vac flavor, decent ones that is.
(the exception is attempting to find NOS 18Vac toroids)

I stuck each of the 3875 channels in 2 small identical NOS metal cases and sandwiched the two with plastic stand-offs, neuw hum.
The cases i got free of charge and the toroids for less than a $five each. Still need to install auto switch-on/off boards one day, i've been using extension cords with a switch button for them since day-1.
But you know how it is when you've practically finished something and moved on to the next.
Don't laugh at me, piccy
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Old 13th June 2008, 10:33 AM   #25
Nordic is offline Nordic  South Africa
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Jacco you must be the best stocked DIYAudio member.... man I'd love to do some "affirmative shopping" through your stuff...
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Old 13th June 2008, 11:01 AM   #26
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Likely, but question yourself whether i don't spend more on audio parts each annum than the entry ticket of commercial gear that some people can babble several years about at this forum alone.
Finding stuff for less is addictive though.

After i hacked the LM3875 amps, Steve Slater did send me some of his lovely amp feet.
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Old 13th June 2008, 12:00 PM   #27
Nordic is offline Nordic  South Africa
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Are you bragging or moaning?
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Old 13th June 2008, 12:01 PM   #28
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Lately, moaning.
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