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The
Deathklaw
is a redesign of the older Zero Point Dual Delay project which is a PT2399-based delay circuit. It features
two PT2399 chips in series for longer delay times and fits in a 1590B size enclosure. There were several design
objectives mapped out for the update:
Change the dry signal-through from non-inverted to inverted stages.
This makes the design similar to all the
other PT2399 designs I've done, and brings the output volume of the circuit closer to unity.
Increase the filtering.
The biggest complaint with PT2399 designs is noise and with two of these chips in series
the potential for noise at longer delay times increases. The Deathklaw has increased low-pass filtering without
compromising the overall feel of the delay (which is akin to a tape delay).
Re-arrange the controls.
The pot controls on the ZPDD were below the "Ghost" switch which is something I
never liked. The Deathklaw moves the pots to a better location on the enclosure.
Simplify to the Ghost switch.
This switch has been changed from a DPDT to and SPDT, and a buffer is used to
isolate the subdivision delay from the main delay. The ghost repeats are lower in volume than the main delay and
are used to add texture to the delay circuit.
All these changes improve upon what was already a very popular project at madbeanpedals and is, no doubt, one of the
more feature packed 1590B delay projects out there.
Controls
Mix -
The amount of delayed signal mixed in with the dry guitar sound.
Feedback -
The number of delay repeats from one to "infinity".
Delay -
The total amount of time delay from slap-back to around 1sec.
Ghost -
Adds an eighth note subdivision to the delay repeats.
Notes
D5 (the green LED) needs to be soldered to the bottom of the PCB. This should be done
before
installing and
soldering a socket for IC2. The use of the LED is a mod invented by forum member
midwayfair
. It's purpose is to
prevent the input of the PT2399 circuit from overloading/clipping with high amplitude signals. You can substitute
other colors for the green, but I have found that green seems to have the least impact on the output of the
PT2399.
If you don't want to use the Ghost switch, omit R13, R14, R15, C12, Q3 and the switch.
You should be able to substitute other transistors for the two BC550, but mind the pinouts.
You can sub other JFET transistors for the MPF102 such as the J201 or 2N5457, if needed.
The FDBK pot should give you "endless" repeats around 3/4 of the way up. After that, the delay will go into self-
oscillation.
Mod idea: try substituting (or socketing) a higher value for C22 (100n). This may alter the character of the delay
repeats slightly.
Summary of Contents for Deathklaw
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