[Gmd]

Hi, I don't post here that much but I wanted to show you guys my first amp. I went with the cmoy design to start with something easy and I ended up using all my parts from radioshack (I am a poor college student and after buying all my headphone equipment I can't afford the better parts, lol). Anyways here are some pics of it.

Front View:
http://members.cox.net/reftekari/HeadphoneAmp1.jpg

Rear View:
http://members.cox.net/reftekari/HeadphoneAmp2.jpg

As you can see from the pic I decided to make it wall powered instead of battery operated. Even though I am only using the LM741 opamps it sounds pretty good to me, not as good as the OBH-11SE but pretty decent. The only problem so far is the radioshack volume pot which is very poor quality, it doesnt turn on until I have it turned to almost half way and at lower volumes the sound is uneven with more coming from the left.

 

[Dreamslacker]

Very nice work..

Well.. Maybe you can swap the opamp for a BB OPA134 or a low cost AD chip some time later.

A black or gold knob would suit the black enclosure better.

And what's that I see? A poor college student with HD600's + Equinox cable upgrade + Creek OBH-11SE?

Haha... Looks like I'm a really really poor junior college student then....

Maybe you can try and get the cheap imitation ALPS pot. At US$6, they are supposed to have very good tracking.

Tip: If your sources don't have DC offset, remove the input capacitor. If you capacitor is a cheapy from Rat Shack, chances are that it's ruining your sound.

 

[blip]

Wow... I only wish I could be that poor.

The creek is a beautiful thing.

Anyway, I like your amp... It is very well finished and clean... Good job! I hope that the one I'm building over Christmas vacation looks half that good.

 

[Gmd]

heh, I am poor becuase of buying the creek and senns

 

[scottder]

I really like the way you have that setup, I am going to be building a CMoy (with a hansen PCB) in the near future. This is mostly for use at work, so I am thinking of going the wall wart route, what did you use for the wall wart? and is it difficult to wire up?

Also, what enclosure is that?

 

[Gmd]

I am using the OBH-2 power supply that came with the creek amp and simply kept the same circuitry inside that was used for the 9volt source but added the DC plug. I dont know the exact model number of the enclosure I got but it is the 5x2" one that radioshack sells. Only problem is my final design is extremely light and the cables move it around. My next amp I would like to get an enclosure that has more depth and a little less height to it.

 

[scottder]

Interesting, thanks for the info. Still up in the air how I will lay this thing out. Good job though with limited resources.

Scott

PS maybe some rubber feet on the enclosure will help...guess it depends where you'll be using it most.

 

[tangent]

You've got a good case there, Gmd, but the innards need some work.

Quote:

Even though I am only using the LM741 opamps it sounds pretty good to me

I confess to being mystified that it doesn't sound like total crap. At 20 kHz, the 741 can't even manage to pass a sine wave without massive distortion -- it flattens the sides due to its low slew rate. If you had to use a Radio Shack op-amp, you'd be a lot better off with the TL082. At least that will pass an audio singnal without massive distortion, and it's got JFET inputs so it's a lot easier to use it. Please replace this chip at your earliest convenience -- it will make a difference.

Quote:

The only problem so far is the radioshack volume pot which is very poor quality, it doesnt turn on until I have it turned to almost half way and at lower volumes the sound is uneven with more coming from the left.

Sounds like you've either got it hooked up wrong, or you used a linear-taper pot. You need an audio taper pot. The Radio Shack audio taper stereo pot isn't very good -- it's got a bit of grit to the sound when turning the knob, as I recall.

 

[Gmd]

Hmm, I will try indeed try out the TL08, as for the volume pot, it is the stereo audio-taper pot that was recommended in the Cmoy article, however it is a good possiblility like you said that I wired it wrong. I could not find any schematics for wiring and I had to do some guess and check for the inputs, outputs.