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CMoy Wall power

post #1 of 4
6/4/11 at 11:04am
Thread Starter 

So as part of another project I'm working on, I'm adding in a cmoy based amplifier. I don't even want to think about the cmoy till I get the first couple of parts done on my project but I need to design a power supply thats suitable for the later cmoy.

 

Now this will be powered strictly from the wall, no batteries wanted/needed. I have a couple of questions that I still havent been able to answer after alot of searching. Now my first-most requirement is cost, I need this to be really cheap. This is not going to be a hifi design but I still would like it to be as free from noise as possible.

 

So the questions..

 

(1) How much power do I really need? The original schematic with batteries uses 18V but how much is necessary. For headphones I use IEMs, right now being Nuforce NE-700.

 

(2)Which wall-wart? I keep seeing that it has to be isolated but I can't really find any that list isolation. All recommendations I found are pretty expensive or non-existent(can't find any modern day info). Its pretty simple and easy to add a voltage regulator so I really don't care about that. Is isolation really that important or is this a audiophile need.

 

 

Thanks for any answers, this small part has totally hampered my designing.

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post #2 of 4
6/4/11 at 11:58am

Getting an Isolated wallwart is important. If you build a "traditional" Cmoy with a rail-splitter it is 100% essential. When you build gear with grounds that dont agree they do battle until one of them looses. The isolated transformer keeps that from happening. 

 

You don't need much power. ~250mA will cover most Cmoys. 

 

You may want to give yourself a few more volts, more voltage is moar better!!111 and not really *that* much more expensive when your building wall supplies. 

 

MPJA sells isolated AC wallwarts for cheap, plus an AMB s25 and your rocking for cheap. 

http://www.mpja.com/powersupply.asp

http://www.amb.org/audio/sigma25/

 

This also reduces the voltages you have to work with because all the mains wiring stuff is done for you.

 

Ooh, and as a last part, are you 100% sure you want to build this into the rest of the project? Ignore me if I read this wrong, but combing the amp & (Im guessing) DAC makes upgrading parts so complicated. Totally separate enclosures can still be very compact/transportable if thats your concern here. 


Edited by nikongod - 6/4/11 at 12:09pm
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post #3 of 4
6/4/11 at 1:34pm
Thread Starter 

The overall project is an AV switch. I want to switch between two RCAs through an IR remote. One output goes to a HT receiver and the other goes to the cmoy so I can use headphones. I just figured it would be easier and neater to keep the two in the same enclosure and share power since they have similar power requirements. Since this isnt a hifi project (not even listening to music via it), I really doubt I'll be upgrading it. Just want a relatively noiseless system that can drive the headphones to decent levels.

 

I suppose since the original CMoy called for 18V power, I'll get a 24V for some extra head room especially since I'll be using a regulator.

 

Thanks for the links. Are all those wallwarts on that site isolated, I don't see any indication they are. The s25 seems like a simple schematic, I had a similar idea in my head except with out the bridge and the associated caps since I don't plan on using AC power. Dunno if I'll buy the PCB, depends on how I'm gonna end up laying out this project.

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post #4 of 4
6/6/11 at 3:23pm
Thread Starter 

Any other options? Really not going for audio quality here, just need something that works without a super amount of noise.

 

Shipping costs really kill me for going to exotic places for 1 item. Anything off digikey or mouser v_v?

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