[Avro_Arrow]

What volume pot are you using? Blue Velvet?
 
The metal nose of the volume pot is not connected to any of the pins.
If you get humming involving the volume pot, try running a wire from
one of the screws in the back to ground. That will usually cure it.
 
Adding the buffer will increase the output power considerably as well
as improve the sound quality. A TO-220 BUF634 is easy to work with
and hard to kill.

 

[shake]

Quote:

What volume pot are you using? Blue Velvet?
 
The metal nose of the volume pot is not connected to any of the pins.
If you get humming involving the volume pot, try running a wire from
one of the screws in the back to ground. That will usually cure it.
 
Adding the buffer will increase the output power considerably as well
as improve the sound quality. A TO-220 BUF634 is easy to work with
and hard to kill.

Yes sir, alps rk27 50k.
 
I soldered a wire directly from the body to ground, but I might have to try with the screw cause I can't get the solder to stick to the body; it's made of some fantastic unsolderable metal.
 
Is noise at high volumes expected?  What can I do to reduce that?
 
The amp gets plenty loud already (32ohm headphones).  Isn't the sound quality more reliant on the opamp?  I'm assuming this because the buffers only increase current.  How can they improve SQ?
 
I had hoped this would be my last amp for a while, but since I screw up so much, I think I'll have to try again.  Next time I'll be more careful with the layout.  But this is going to have to last a while.  I'm running out of money and I'm supposed to be busy studying for the mcat and doing med school and navy applications.
 
Oh, and something really really hilarious is whistle testing the amp, I killed the left channel of my DAC.

 

[Avro_Arrow]

I know what you mean about soldering to the body of the pot...i just stick a wire
under the screw.
 
The buffer isolates the op amp from the load. That way, the op amp only has
to drive the buffer, not your headphones, letting it sound it's best.

 

[shake]

Would ebay be a safe enough bet on the buf634?  I can get 2 for nearly the same price as one from digikey.
Would the to-220 package be stackable/worth stacking?

 

[Avro_Arrow]

Probably safe enough...I haven't heard of any fakes yet...
 
Yes, they can be stacked as well.
You might want to try just one to start to see if you are
driving it hard enough to need a heat sink.
Run it in low bandwidth mode to start.
 
Whatever package the BUF634 is in, it is still the same silicone inside.
The package just determines how much room it takes up and how
much power it can handle. The TO-220 version can handle the most
power as it can be heat sinked the best.