Quote:
Originally Posted by Reck45
what all do i need to build a good sounding cmoy with dc input for really cheap? thanks.
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Well, like others have said, read tangent's guide.
Acquiring parts can get expensive, depending on how ritzy you want to go. Ordering from digikey is likely to cost you more than you want to spend.
If you have a real electronics store nearby, you can get some semblance of what you need there. If not, the shack may or may not still have bits & pieces.
to DC power it, you'll want a regulator. If i were doing it, I'd get a 7812 or 78L12 regulator, and associated capacitors. See the datasheet.
Any electronics store and maybe the shack too can sell you a tl082 or tl072 which will basically work as an opamp, and it'll be cheap. You can request a sample ad823 from Analog Devices which will sound better, but if your cans are low impedance, it may not be able to drive them very well.
The truly basic cmoy may not work very well for you. You may want to add a few features, like a rail splitter and perhaps a simple output buffer. Fortunately, you can do all that with little more than some complementary transistors.
See Sijosae's simple class ab buffer - it'll do both jobs:
http://www.headphoneamp.co.kr/bbs/zb...esc=asc&no=225
If you can't read korean, that's ok. But if you can't read schematics, you could be in trouble there
Sijosae uses bc337/bc327 but if you pay attention to the pinouts (which may change the layout) there's no reason you couldn't use 2n2222 / 2n2907 (or pn, or -a versions of same) or whatever complementary small signal transistors you can get your hands on. The shack carries 2n3904 / 2n3906 which should work fine too.
If you go that route, if your DVM will test hfe, match the transistors on the output buffer so that you don't risk a high dc offset.
But the point is, two little bags of transistors can do a lot for you, since you're going the cheap route.
Sijosae's simple class a-b cmoy variant with a free sample ad823 and cheapie little transistors and a regulator on the dc input could be pretty cool. I'd build one myself if i didn't have bigger fish to fry.
People will tell you that you need primo quality capacitors. You don't really *need them. They can be nice, but since you're just starting out, and starting small, get whatever electrolytics will fit on the board for the voltage you're using and shoot for more than .1uf for the input couplers. mylar will do the job. Polypro is nicer, but mylar will work.
If you don't have a DVM, stop by your local Harbor Freight Tools - they'll sell you one with HFE testing for under $10. A couple weeks ago they had one on sale for $3. Not great, but it'll do everything you need for a basic cmoy.
