Blue Magic ?

[gtrmac]

The Blue Magic schem from GGG calls for a 6.8uF polarized cap off the source of the MOSFET. Is it advisable to use a Tantalum cap here? I can't find anything else with this value. If so, how many volts should I use?

[petemoore]

Don't exceed battery or supply voltage [wallwarts may stray from what they're marked as] for what your caps are marked...supply voltage plus some headroom...16v caps with 9v supply is what you'll probably find.
 I've used 10v caps, but I don't like to.
 make sure you follow the polarity of caps marked as polarized.

[gtrmac]

Thanks, I guess I'll have to use Tantalum caps. I haven't found anything else at 6.8uF. Even these are only available at 35V locally.

I hope that Blue Magic lives up to it's name.

[Boofhead]

You could use a 4u7 in parallel with a 2u2, that will give you 6u9 - the difference to a 6u8 is below human detectability (and part tolerances).

You can find 6u8 non-polar electrolytics fairly easily.

[Ge_Whiz]

I hope that Blue Magic lives up to it's name.

I can assure you that it does, although I raised the mid-boost capacitor from 500pF to 1500 pF (1.5 nF) to be able to hear the difference. Tin ear, I guess. Oh, and I put a 4k7 resistor in between the drive pot and ground to stop the drive pot going right down to zero ["Hey? Where did the sound go, dude?"]

[Paul Marossy]

I like my Blue Magic!  

[WGTP]

I would suggest you use a socket there and try a 4u7 or 10uf electro to adust the bass.