AMZ Mosfet Boost just built and sounds weak and distorted?...

[Xavier]

This was a surprising one. I've just built one following Dragonfly's vero layout. Now that my soldering skills are better, with such a simple and small layout I didn't expect to have any problem, but I'm having....

It sounds weak (lower volume than bypass) and distorted. Checked everything, voltages are right, R2 is 62k, and even I've tried with an audio probe -sine wave at 1kHz-. Normal wave at the gate, huge boost at drain with clipping at the lower half of the wave , slightly more volume at the source but also with the same clipping.

Before the output cap (.1u, that is 100n right?) I have exactly the drain signal (huuuge boost), but after the cap I have a weak and distorted signal. I've tried another cap with the same value without any result.

I can accept the BSIAB giving me headaches because it's a relatively complex circuit, but this one? 

[spudulike]

Check the trace cut is clean under the output cap, and check for any crud between the cap and the ground jumper next to it. Make sure your output wire actually comes from the cap and not a trace either side (dont ask me how I know this ...  )

[Steben]

If you're having the right voltages and right signal at the drain, I don't see what's the problem. It will probably be something with the board/connections.
Is you're protection diode connected in the right polarity?

[Xavier]

If you're having the right voltages and right signal at the drain, I don't see what's the problem. It will probably be something with the board/connections.
Is you're protection diode connected in the right polarity?

Up and working !!!!! the problem was the wrong value of the output cap. I put a 10n instead of 100n. As always, human error.

Tried first with a 5kA pot and boost only occured at the last 75%. Funnily enough, I've used a 10kB, as I didn't have any 5kB available, and the problem is exactly the same. Not the right value, but still?....

Sounds more linear than the LPB1, but it has less character. At high settings seems to distort, but after checking the signal with the audio probe, it shows a pure clean signal at the output, only 4 TIMES LOUDER