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The recently released QA472 low noise preamplifier provides a reliable way to increase small signals for testing purposes. You can learn more about QuantAsylum by reading the HoT review for the QA403 audio analyzer here.
What's new in this latest version of the preamp?
The QA472 costs almost 33% more than the previous model it replaces but it now includes two preamplifiers.
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Pre1 has an XLR input for convenience and it features switchable phantom power. Pre1 has a low noise spec of -122 dBV. That is really low and it makes testing typical tube preamplifiers an easy and reliable job.
Pre2 is based on an entirely different circuit design, this JFET input has an input impedance of 1MΩ and a fixed gain of 30dB. With this simplified circuit the noise floor drops to -134dBV.
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WHAT'S IT FOR?
Unlike other preamplifiers we discuss here on High on Technology, this one is intended for testing purposes (not necessarily recording audio though you probably could).
When combined with the QA403 Audio Analyzer you have the makings of a very high quality toolset to look at frequency response and noise in an acoustic environment (you would also need a flat response microphone).
For someone building boutique microphones, testing large diaphragm microphone capsules for output performance and consistency could be another very useful application.
In-ear monitor manufacturers need special tools for testing their products, the QA472 could be a very consistent preamplifier for such applications.
Testing your studio microphones for noise and frequency response could be accomplished with excellent uniformity and consistency not available with even high end microphone preamplifier solutions (you would also need a QA403 for such testing).
POWER SUPPLY
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This new model is powered by a fully isolated USB power source so if you're using a USB Hub with several outlets to power other QA boxes (like the QA403 Analyzer) you can just branch off that to power this little box too. You'll need to provide your own USB cable but the current demand of the preamp is very low and the DC-to-DC power system means ultimate isolation for your test measurements.
EPILOGUE
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If you're using the QA403 Audio Analyzer the QA472 Dual Preamp provides a very useful, precision, reliable and repeatable source of gain for use in evaluating circuits and hardware.
For more information check out the QuantAsylum web site and forum (do a search for the company address link). You'll find a legion of dedicated users who are improving their audio with these tools.
Thanks for reading High on Technology, Good Music To You!
©Feb 2024 by Mark King, it's not ok to copy or quote without written permission
