04.24.2015
Mutant Hot Glue DIY assembly manual v1.05
PG19
HEXINVERTER ÉLECTRONIQUE, 2015
STEP_0F: Compressor Calibration
•
The THAT4130 Dynamics Engine IC, which is the heart of the analog compression circuit, benefits from having
its symmetry bias trimmed for least distortion.
You can use the module just fine without it, but the audio
passed through the compressor will have its symmetry distorted somewhat.
•
If you do not own a function generator and oscilloscope, you can use a sine wave oscillator and something like
the Jones O’Tool module
•
If you use a sine wave oscillator
: try to use the most symmetrically accurate one you have – digital is probably
best for symmetry. We don’t care about vertical resolution/bits of the waveform here, so there is no benefit to
analog – it’s the symmetry you want to look out for during this test.
STEP 0:
Begin by generating a sine wave, as shown below. Insert this sine wave into the Compressor IN jack.
Use a sine wave around 8Vpp @ 1kHz – exact numbers are not important, but,
do make sure it is centered symmetrically about
0V!
STEP 1:
If you are using an oscilloscope, clip your probe to the
gnd
and
SYMMETRY TEST POINT
clips on the back
of the module which you installed earlier. If you are using an O’Tool, patch into the COMP output.
