XIPHOS AMP OVERDRIVE
5
BUILD NOTES
Clipping diodes
The Heavyhand uses BA282 diodes, which clip at a slightly higher threshold than standard silicon diodes
such as 1N914 (approximately 0.82V compared to 0.7V). These diodes are out of production and hard to
find in the old-stuck market.
Now, the closest option is the BAS33. These clip at around 0.8V, still significantly higher than the 1N914
and only slightly lower than the BA282. We’ve compared the curves on a Peak DCA75 and confirmed
that they closely match the BA282 across the current test range.
The only problem is that the BAS33 went end-of-life in early 2022. Availability is still high, but
eventually they’ll join the ranks of the others.
Drive potentiometer
The Drive pot is 150kC in the original, which is an odd value (though not impossible to find). R3 and R4
have been added as tapering resistors to approximate the value and curve of a 150kC using a 250kB pot.
If you use 250kB, then use
360k
for R3 and
22k
for R4. This method is far from exact, though, so try to
use a 150kC if you can find one.
C9/C10 capacitor
C9 has been added as a film cap alternative to the 4.7uF electrolytic used in the original. Film caps
are better quality for signal coupling, and 4.7uF is much higher than necessary in this position, so it’s
recommended to use C9 and omit C10.
Knobs
Since the two lower pots are very close to the lower toggle switch, it’s recommended to use 1/2” knobs
for these two. The upper two knobs can be 3/4”. This is the cosmetic look we used for the
, which uses the same drill template.
