QuantAsylum QA401 User manual

QA401 Quick Start

Download & Install the
QA401 App
1. Download the QA401 Application
2. Make sure you opt to install drivers
3. After installation is complete, click the
icon on your desktop

Navigation:
Scrolling the Panel
Depending on your window size, the full
control panel might not be visible. If it’s not,
click part of the panel without any control
and drag up or down to expose more UI

Connecting the Hardware
1. Plug in the QA401 hardware with a USB
cable (not supplied). The OS should
recognize the hardware, finish installing
it and then you should see the
application configure and connect.
2. Once connected, you’ll see an
indication in the lower left corner

Starting Acquisition
1. Scroll the control panel so that you can
see the Run/Stop button.
2. Press the Run/Stop button. When it is
illuminated, you are running. You
should see yellow spectrum data
appear.
3. Disable the attenuator. When you click
the ATTEN button, you should hear a
relay click inside the QA401.

Shorting the inputs
1. To measure the noise floor of the
device, you need to short the inputs
with a low impedance shorting block
(not included). These are often called
“shorting blocks” or “terminators”. You
can find these for sale on Amazon or
your favorite component supplier.
Search on “bnc 75 ohm terminator”.
The precise impedance isn’t important,
it just needs to be less than a few
hundred ohms.
2. If you do not short the inputs, then
you’ll measure the noise of the internal
input resistors—and the noise
contribution from the inputs 100K
resistors can be quite high.

Making a noise
measurement
In the application, press the PWR button.
This will enable the reporting of measured
power in the indicated bandwidth. Confirm
this is around -120 dBFS. If not, verify you
have correctly connected the input shorting
blocks.

Loopback Connection
Leave the L- shorting block applied and
using a BNC cable (not included) connect
the left + output to the Left + input

Loopback THD
Measurement
Hold the control key while pressing the
GEN1 button. This will bring up the GEN1
context menu. Change the amplitude to -16
dBFS. This is the sweet spot for THD
measurements on the QA401

Using Knobs
1. Press the THD button. Increase the FFT
depth to 32K. To change a knob setting,
click on the knob and drag up or down
until you see the value you desire
appear in the on-screen indication. A
small “LED” will light on the knob to
indicate it can be dragged.
2. You can also use your mouse wheel to
adjust knobs. Just move the mouse over
the knob, click and you’ll see the “LED”
light. You can then use your mouse
wheel to adjust the settings.

THD Measurement
With the output connected to the input, this
is called “loopback” made. You should see a
THD figure around -110 dBFS

Need more help?
Contact: Suppor[email protected]
The PDF manual is available from the application
Select “Help -> Launch Help”
Or, check in the installation directory
C:\Program Files (x86)\QuantAsylum\QA401\Documentation