QA401 Audio Analyzer
16-Nov-2020: In late October a massive 82-hour fire destroyed AKM Semiconductor's ability to deliver parts, including the AK4490 DAC and AK5397 ADC used in the QA401. A replacement product (called the QA402) has been announced.
18-Jan-2021: A short run of the QA401 has been built, and we may do one more. But for now, QA401 can be purchased. Note that the new build requires SW release 1.920 or later. If you need a replacement unit for a legacy install, please contact the sales email address.
29-Feb-2021: The QA401 has been retired due to the part availability issues mentioned above. The QA402 will be the replacement product. Availability is expected in March.
The QA401 is our second generation of audio analyzer--the follow-on product to the QA400.
The QA401 can perform a wide range of basic audio measurements, making it a cost-effective addition to your bench. Unlike a sound card, the QA401 offers isolated and differential IO with input handling up to +26 dBV. And unlike a sound card, accuracy is absolute and achieved through 0.1% thin film resistors instead of a tedious measurement and calibration process.
The product brief goes into more details on the specifications and graphs of QA401's performance: The QA401 has the margin to measure measure 99% of consumer and pro products out there today.
The QA401 can operate standalone, or in concert with the QA450 Programmable Load as shown in the video below. Combined, these two products can automate much of the testing your pre-amp, audio effect or high-power amplifier might need during production.
The QA401 can be automated using Microsoft's DotNet tools, making it a snap to customize measurements or integrate with other test equipment. If you aren't interested in writing code to automate the measurements, then Tractor can likely provide just about all the measurement automation you might need without the need to write any code. See the post here for more information. With Tractor, you can be making basic audio measurements, including amp efficiency and output impedance, and storing the results of your product by a serial number to a cloud database in minutes. And then query that database to analyze yields are margin to spec.
Finally, if you want to use the QA401 with your favorite ASIO-enabled audio analysis software such as ARTA or MATLAB, there's a 3rd party ASIO driver for the QA401 available on Github.
As with all of our products, the QA401 generally ships within 24 hours of ordering (and often same day). We ship all over the world. And all of our products come with a 15-day no-questions-asked return policy.
The QA401 doesn't come with any cables or accessories. Most likely you already have the right USB cable (A Male to B Male) and it's a shame to send yet another cable that will just be thrown away. And for the audio connectors, it's just too hard to anticipate your connection needs. Some connectors we find useful are below:
BNC Shorting blocks. These are useful for verifying the noise floor (see the Quick Start guide) of the QA401 and also are needed if you want to make single-ended measurements. Whether a true short, 50 ohms or 75 ohms doesn't matter much. Just get a dozen from your favorite vendor and you'll find them invaluable in the lab.
Short, flexible BNC cables. These are very useful for patching between the QA401 and QA450 or other instruments. These are very flexible, can make tight bends and the price can't be beat. The 6" length is great if the QA401 and QA450 are stacked atop each other. Reliability has been reasonable.
Heavy duty USB cable. The QA401 can consume up to 600 mA or so. While lighter gauge (skinny) USB cables can be used, it's possible the skinny USB cable will have too much voltage drop on some USB ports--and this can raise the noise floor of the QA401. Ideally, you want to find a USB 2.0 Male to B Male cable with 24AWG power conductors.
QA401 User's Manual (may not be latest version....see your install)
More Reading: What do you want to measure?
Power Amps (5W to 1000W):
- Measuring Amplifier Noise with the QA401 and QA451
- The Basics: Power Amps
- Measuring a 300W Class D Amp
- Fast Tube Amp Characterization
- MERUS MA12070 Class D
- Evaluating Class D Amps with the QA401
- Swept Measurements
- Automated Amp Testing
- QA40x and IMD Measurements
- Rapid DAC Evaluation
- Measuring DAC performance using Notch Filters
- Measuring DAC performance using Notch Filters #2
LDO and Component Noise
Outboard Processing Gear
- Automating EQ TEsting using Masks
- Characterizing a Tone Knob using Expo Sweeps
- Quantifying Fuzz
- RIAA and User Weighting
- Automating EQ Tests
- QA401H, REST and Python
- Low-cost Test Setups
- QA401 Headless and Linux
- Tractor: First Look
- QA401H, Ubuntu and VirtualBox
Fast Tube Amp Characterization with the QA401