Let's start a thread on DIYed headphone amps and your listening impressions on the amps, and of course tips on where to buy the needed components and how to build these.
Recently, I got interested in headphones again (started to use headphones in the late 80s and early 90s), not because I got tired listening to my little digital amps (charlize and amp6), in fact, after re-experiencing the joy of listening to music upclose with the use of headphones, I treat this little headphone amp more as a sibling of digital amps. Common descriptions used with digital amps like clarity, presence, impact, separation, faithful reproduction of timbre are also present in my A47 headphone amp. Considering however the fact that music is being piped directly to your eardrums, the negative side of using headphones and headphones amp is that you can't play it really really loud, without adversely affecting your hearing. Also, since there's not much space between the "speakers" and your ears, you will have a hard time hearing a sense of depth in the production of music. Be that as it may, it still is a very good alternative to good and faithful reproduction of music.
I started on this project last week, and I think it took me around 3 days to finish the whole project. I worked on it only during the night, after work. I'll post some pictures first. Medyo pangit lumabas kasi celphone lang gamit ko
This is the front of the amp (the black ugly looking box at the bottom is the where the amp6 is assembled, with its own voltmeter). I used crappy car spray paint, used honda red or somethin, a yellow led, a simple off-on switch and a blue alps 50k potentiometer.
As you can see from the inside, I used a perf board, costs around P30 each. For the trafos, I used a 15v 1-ampere one from DEECO, price is around P120.00. The yellow caps you see are polypropelene .47uf 250v caps as input caps. From my readings, people who are experienced in building headphone amps, didn't actually hear much difference between boutique caps and generic polyprops, thus, I opted for the cheaper alternative.
From the first picture, you can barely see 2 opamps sitting on their respective sockets, connected parallel to each other for that much needed current boost to drive low impedance headsets like AKGs, Philips or Grados. However, if you think your cans are easy to drive, you can do a CMOY which uses 1 opamp only. I used burr-brown OPA-2132PAs which I bought when I was in the States last year. Btw, by using sockets, you can do opamp rolling to find the sound you like. If you want bloated bass, to compensate for your bass weak headphones, go for the burr-brown OPA2604. It has a recessed mid, big bass and highs. For resistors, I used 1/4watt 1% precision metallized resistors (blue ones). From the second picture, you can see 2 tall caps, these are filter caps after the rectifier diodes (1N4001s), caps are 2200uf 35volts. Btw, I used 1n4001s since these amps don't require much headroom as far as current goes. After the big caps follows 2 regulators for (-) and (+) lines. I used 7912 and 7812s for these, fixed 12 volts output, cost is around P80. I think there could be better alternatives for these regulators, audio wise, but I was on a tight budget and in a hurry.
After the regulators, another set of caps, these are japanese made like the brown ones, around 470uf 25v.
For wiring the audio side, I used my old trusted beldens, the same ones I used on my charlize and amp6 digital amps. This is the link of the forum post where I based my construction,
http://www5.head-fi.org/forums/showthread.php?t=135742I hope you find this thread interesting enough to give you a little nudge towards the DIY path. This is a very easy project to do, but very rewarding and satisfying at the end.
