Friday, May 1, 2009

Crappy Pictures

I've been meaning to post for some time now, but my camera battery died and I can't, for the LIFE of me, find the charger.

So this update will be mostly full of pictures taken by my phone.


I've only been able to listen to my new (old) turntable using my old receiver. I wanted to see if it was holding it back.

So I looked around for phono preamps, so I could maybe plug that into another speaker amp or one of my headphone amps. If I wanted to spend less than $100 I was pretty much limited to DJ models (probably fine, just something in the back of my mind steering me away from anything with the word DJ on it) and cheapos. So, naturally, I searched for DIY solutions. One of the first (edit: the first) results was a thread over at diyaudio about the Very Simple Phono Stage.

It was essentially an opamp, power supply, and a bunch of resistors and caps! The comments in the thread said it sounded pretty good, and the justification included some kind of keeping-it-simple argument, which made sense to me.

I had an extra OPA2132 opamp from my cmoy (since in my cmoy there is now an OPA2107, which sounds much better in that application), and I figured I could just make it battery-powered (using a psu for the cmoy, since I had yet another opamp available) for the time being, since I didn't want to make something that I had to plug directly into the wall. I don't think I'm ready for that kind of thing yet. Also, the toroidal transformer recommended by the author was like $35.

The parts total was around $20, not including the opamps of course, but the resistors, caps, enclosure, sockets, a switch, and some RCA plugs.

I made a test version on breadboard (for my project, which I have yet to complete lolololololololol)

At first it sounded like crap, then I realized the output caps were too small by a factor of a thousand lol. Then I bought nonpolar 4.7uF electrolytics, slapped 'em in, dropped some Empire Strikes Back soundtrack in the Kenwood, and I was blown away.

Nothing I have ever owned has ever sounded that good.

And this was the breadboard version, with all the extra resistance from the mechanical connections, all the extra parasitic capacitance from the untrimmed resistor and capacitor leads, etc etc.

I cased it up yesterday afternoon, and I seriously think I got high off of the solder fumes. Not a good thing. Anyway, here's what it looked like halfway done:

And all cased up:

Instead of making a screw terminal for the grounding wire that all turntables (should) have, I soldered a wire (not seen) from ground and had it press against the metal base. That way, I could just attach the groundwire as shown:

I'm listening to it right now. I've been listening to it for hours. It sounds so good.

Also, I moved my speakers and receiver, they sound much better now! My bookshelf speakers are on a bookshelf lol. And I'm less worried about the music coming from the speakers resonating with the tonearm and creating an ugly feedback sound since they're relatively far away now.

This is my third Spring at college, and every Spring, around the same time (before finals) I've undertaken and finished a project. I guess it's the aggressive procrastination at work :DDDD
From top to bottom, and in chronological order, the cmoy headphone amp, the alien dac, and the very simple phono stage.

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