QA401 Audio Analyzer

Regular price $449.00 Sale

The QA401 is our second generation of audio analyzers, following the QA400, which made serious inroads into the market in terms of price and performance. 

The QA401 adds full isolation, making measurements of certain amplifier typologies a snap. Differential inputs and outputs were also added, as was a 20 dB attenuator.  

All of these make the QA401 an ideal instrument for measuring high power amplifiers directly. The QA401’s input stage overload detection is wicked fast, powered purely by gates—no software.  The QA401 input is rated to 56.4Vpp with the 20 dB attenuator active.  We’ve tested the input with the attenuator OFF using a variac set for 25Vrms (70.5Vpp) and are pleased to report the fault could be sustained indefinitely.

The front panel also lets you know when the attenuator is active, giving you additional piece of mind just before you connect to the monster amp you’ve been working on.

The QA400 achieved a performance level that was better than just about any sound card out there. The QA401 takes that to the next level, besting the QA400 by 4-8 dB in most measurements.

And unlike a sound card, where you are dependent on the setting of the gain pot for your absolute measurements, the QA401 front end relies on precision 0.1% resistors to ensure impressive accuracy without any calibration. No volume knobs to worry about. No re-calibration at each measurement session.

The input stage to the AK5397 ADC consists of a relay attenuator, an OPA1612 buffer, and an OPA1632 diff amp.

The QA401 bypasses the Windows Audio Subsystem to ensure that your measurements aren’t clouded by a third party app changing gain settings. This is important to understand, because it means you aren’t able to use just any software with the QA400 and QA401.

The QA401 software has been evolved from the QA400 software to better cope with the higher resolution converters. For example, the signal path was converted from floating point to double precision.

The FIFO depths in the FPGA have been dramatically expanded, ensuring we can improve functionality, as we have with the QA400, for well into the future.

Programmability has been a key driver in all of our products. Instead of communicating across antiquated interfaces with non-type-safe languages, our products and interfaces take advantage of modern type-safe languages, making it easy for you to write high performance interfaces that communicate to a device on your desk or across the world.

Specifications (specs are subject to change without notice)

Mechanical

   

Dimensions

 

177w x 44h x 97d (116 mm deep when BNC connectors are considers)

Weight

 

420 grams

Case Material

 

Aluminum, anodized and powder coated

     

Analog Input

   

Input Connector

 

Differential, BNC x 2 for Left and BNC x 2 for Right

Input Z

 

100K Ohm

Input Coupling

 

AC, Fc = 1.6 Hz

Input Full Scale, No Attenuator

  5.6Vpp Single Ended (one input grounded) = 6 dBV = 2 Vrms
+/- 2.8 Vpp Differential = 0 dBV = 1 Vrms

Input Full Scale, With Attenuator

  56.4 Vpp Single Ended (one input grounded) = 26 dBV = 20 Vrms
+/- 28.2 Vpp Differential = 20 dBV = 10 Vrms

Input Overload Protection

 

Yes, automatic overload protection up to +/- 56.4V

Input Noise Floor

 

-113 dBV (Input Shorted, atten off, 20 to 20 KHz, 32K FFT, avg 5, Hann, 48 Ksps)

THD

  -108.5 dB
(Loopback, single ended, L- shorted to ground, atten off, 32K FFT, 5 Hann, 48Ksps, – 10 dBV)

Isolated

  Yes. The PC USB and digital section is fully isolated from the analog section (infinity ohms). Difference between the PC ground and the analog ground must remain below 30V.
     

Analog Output

   

Output Connector

 

Differential, BNC x 2 for Left and BNC x 2 for Right

Output Z

  ~47 ohms. Output stage is OPA1612 with series 47 ohm provided for protection against capacitive loads and accidental short circuits.

Output Coupling

 

DC coupled, with user adjusted offsets to reduce differential offsets to <300 uV (note 1)

Isolation

  Yes. The PC USB and digital section is fully isolated from the analog section (infinity ohms). Difference between the PC ground and the analog ground must remain below 30V.
     

Accessories Included

   

In the box

  There are no accessories included in the box. You will need:
1) USB A to B cable to connect the QA401 to the PC.
2) BNC cable to connect the QA401 to your DUT
3) BNC terminators (0 ohm, 50 ohm, 75 ohm) will be helpful for some types of measurements