# QA40x **URL:** https://forum.quantasylum.com/c/qa40x/15.md?page=4 [Latest](https://forum.quantasylum.com/latest.md) · [Categories](https://forum.quantasylum.com/categories.md) **Page:** 5 --- ## ["Object reference not set to an instance of an object" when using "-HEADLESS"](https://forum.quantasylum.com/t/object-reference-not-set-to-an-instance-of-an-object-when-using-headless/1714)
**Author:** [@JesseAusMon](https://forum.quantasylum.com/u/JesseAusMon)\ **Replies:** 1\ **Last updated:** [February 11, 2025, 10:22pm UTC](https://forum.quantasylum.com/t/object-reference-not-set-to-an-instance-of-an-object-when-using-headless/1714 "2025-02-11T22:22:55Z")
Hi, I am currently using application V1.202 on my QA403. I have small issue when I launch the QA40x application in headless mode (-HEADLESS) mode from within a C# (Dotnet) application and send the following commands ov… --- ## [dB and THD don't line up on graph](https://forum.quantasylum.com/t/db-and-thd-dont-line-up-on-graph/1717)
**Author:** [@Johnr6697](https://forum.quantasylum.com/u/Johnr6697)\ **Replies:** 2\ **Last updated:** [February 9, 2025, 7:26pm UTC](https://forum.quantasylum.com/t/db-and-thd-dont-line-up-on-graph/1717 "2025-02-09T19:26:15Z")
I just installed v1.210 of the software. When I run an automated graph of frequency vs distortion, the THD numbers don’t line up with the dB scale on the graph. For example, -60dB should coincide with .1% but instead, li… --- ## [Bitmap light mode for printing](https://forum.quantasylum.com/t/bitmap-light-mode-for-printing/633)
**Author:** [@sluggoaudio](https://forum.quantasylum.com/u/sluggoaudio)\ **Replies:** 8\ **Last updated:** [February 5, 2025, 2:08am UTC](https://forum.quantasylum.com/t/bitmap-light-mode-for-printing/633 "2025-02-05T02:08:18Z")
While I prefer to use dark mode when working with my 403(easier on my eyes), would it be possible to export the bitmap in light mode to save printer ink? --- ## [QA40x Application 'Poof' v1.209](https://forum.quantasylum.com/t/qa40x-application-poof-v1-209/1691)
**Author:** [@beachside](https://forum.quantasylum.com/u/beachside)\ **Replies:** 7\ **Last updated:** [January 22, 2025, 8:07am UTC](https://forum.quantasylum.com/t/qa40x-application-poof-v1-209/1691 "2025-01-22T08:07:30Z")
I now have two laptops where the splash screen comes up, but the application GUI is not shown. The QA403 device is detected by the PCs and shown in Device Manager. One laptop is Win 11 and the other is Win 10, so nothin… --- ## [QA403 intermittent behavior](https://forum.quantasylum.com/t/qa403-intermittent-behavior/1680)
**Author:** [@etl17](https://forum.quantasylum.com/u/etl17)\ **Replies:** 4\ **Last updated:** [January 21, 2025, 4:43pm UTC](https://forum.quantasylum.com/t/qa403-intermittent-behavior/1680 "2025-01-21T16:43:40Z")
I am experiencing a weird issue with my QA403. I have tried with both the latest 1.209 version, as well as, the latest stable 1.202 The firmware is version 60 After hardware reset the device seems to be functioning pr… --- ## [QA40x Crashing immediately on startup](https://forum.quantasylum.com/t/qa40x-crashing-immediately-on-startup/1683)
**Author:** [@jeff.audiocontrol](https://forum.quantasylum.com/u/jeff.audiocontrol)\ **Replies:** 3\ **Last updated:** [January 21, 2025, 4:19pm UTC](https://forum.quantasylum.com/t/qa40x-crashing-immediately-on-startup/1683 "2025-01-21T16:19:29Z")
New user here. I just inherited a QA403 box that a former co-worker used to use when he was here. I set the box up and installed the software. When I start the software, I see the splash screen for just a second, and … --- ## [True headless mode for QA40X application?](https://forum.quantasylum.com/t/true-headless-mode-for-qa40x-application/1676)
**Author:** [@SoSi](https://forum.quantasylum.com/u/SoSi)\ **Replies:** 3\ **Last updated:** [January 15, 2025, 11:04pm UTC](https://forum.quantasylum.com/t/true-headless-mode-for-qa40x-application/1676 "2025-01-15T23:04:18Z")
I am using the REST API to control a QA403 from a complex LabVIEW application. This application is executed in a productive environment and automatically controls the data acquisition. Therefore, the window of the QA40X … --- ## [More on Multitone?](https://forum.quantasylum.com/t/more-on-multitone/712)
**Author:** [@VAR](https://forum.quantasylum.com/u/VAR)\ **Replies:** 13\ **Last updated:** [January 9, 2025, 8:44pm UTC](https://forum.quantasylum.com/t/more-on-multitone/712 "2025-01-09T20:44:55Z")
I was wondering if there was more info on multitone as it pertains to the QA40x. Have read the AP note on it and several threads on ASR, but would like just a bit better understanding of what it is telling me. For instan… --- ## [Uninterupted generator signal while doing Acquisitions](https://forum.quantasylum.com/t/uninterupted-generator-signal-while-doing-acquisitions/1653)
**Author:** [@breedj](https://forum.quantasylum.com/u/breedj)\ **Replies:** 2\ **Last updated:** [December 21, 2024, 12:11pm UTC](https://forum.quantasylum.com/t/uninterupted-generator-signal-while-doing-acquisitions/1653 "2024-12-21T12:11:18Z")
I noticed that an acquisition enables the sine wave generator and then disables it again after the acquisition has finished. I found out that this pulsed behaviour results in different measurement results compared to a c… --- ## [Triggered acquisition via REST API](https://forum.quantasylum.com/t/triggered-acquisition-via-rest-api/1641)
**Author:** [@Elmar](https://forum.quantasylum.com/u/Elmar)\ **Replies:** 7\ **Last updated:** [December 21, 2024, 1:41am UTC](https://forum.quantasylum.com/t/triggered-acquisition-via-rest-api/1641 "2024-12-21T01:41:20Z")
I am using the REST API to control the QA403 to measure some specialty equipment. I would like to use the triggered acquisition via the REST API. Would it be possible to add this to the API? --- ## [Mask for pass/fail - usage and subject matter training suggestions](https://forum.quantasylum.com/t/mask-for-pass-fail-usage-and-subject-matter-training-suggestions/1657)
**Author:** [@tspacker](https://forum.quantasylum.com/u/tspacker)\ **Replies:** 1\ **Last updated:** [December 21, 2024, 1:38am UTC](https://forum.quantasylum.com/t/mask-for-pass-fail-usage-and-subject-matter-training-suggestions/1657 "2024-12-21T01:38:31Z")
I am working on an amplifier that I want to create some pass/fail tests for. I have never used mask files before, so I wonder if there are any guidelines or getting started guides that I could read up on as someone who h… --- ## [Windows7pro compatibility](https://forum.quantasylum.com/t/windows7pro-compatibility/1652)
**Author:** [@RossandCrawford](https://forum.quantasylum.com/u/RossandCrawford)\ **Replies:** 1\ **Last updated:** [December 20, 2024, 2:13pm UTC](https://forum.quantasylum.com/t/windows7pro-compatibility/1652 "2024-12-20T14:13:05Z")
Will the new QA403 analyzer work with my Windows7pro desktop PC? --- ## [Audio Streamer Evaluation using QA403](https://forum.quantasylum.com/t/audio-streamer-evaluation-using-qa403/1646)
**Author:** [@Protegimus](https://forum.quantasylum.com/u/Protegimus)\ **Replies:** 3\ **Last updated:** [December 15, 2024, 10:18pm UTC](https://forum.quantasylum.com/t/audio-streamer-evaluation-using-qa403/1646 "2024-12-15T22:18:51Z")
Hello, I’ve read the “Rapid USB DAC Evaluation” so have part of the story and done some digging to see if there is any documentation available as to whether the QA403 can be used to test a network audio streamer. The s… --- ## [1/3 octave display](https://forum.quantasylum.com/t/1-3-octave-display/1615)
**Author:** [@Westerdahl](https://forum.quantasylum.com/u/Westerdahl)\ **Replies:** 14\ **Last updated:** [December 10, 2024, 7:52pm UTC](https://forum.quantasylum.com/t/1-3-octave-display/1615 "2024-12-10T19:52:02Z")
Would it be possible to get a visualizer like the THD bar graph, but showing 1/3 octave bars? --- ## [Buffer size constraints](https://forum.quantasylum.com/t/buffer-size-constraints/1642)
**Author:** [@Elmar](https://forum.quantasylum.com/u/Elmar)\ **Replies:** 2\ **Last updated:** [December 9, 2024, 8:53pm UTC](https://forum.quantasylum.com/t/buffer-size-constraints/1642 "2024-12-09T20:53:25Z")
Hi, For my measurements I would like to use larger measurement buffers than the software allows at this moment. I have quite some lag in my system, and I would like to compare the immediate response being sent out (=wit… --- ## [Automated Test Graph Watts vs Freq](https://forum.quantasylum.com/t/automated-test-graph-watts-vs-freq/1589)
**Author:** [@YamahaCA](https://forum.quantasylum.com/u/YamahaCA)\ **Replies:** 46\ **Last updated:** [November 27, 2024, 5:10pm UTC](https://forum.quantasylum.com/t/automated-test-graph-watts-vs-freq/1589 "2024-11-27T17:10:19Z")
Looking for an automated test for watts vs freq. My goal is to see how the watts change with a set input value across the freq spectrum. I am not sure what to select from the Automated Test Tab --- ## [Controlling averages via REST API](https://forum.quantasylum.com/t/controlling-averages-via-rest-api/1620)
**Author:** [@breedj](https://forum.quantasylum.com/u/breedj)\ **Replies:** 9\ **Last updated:** [November 13, 2024, 6:55pm UTC](https://forum.quantasylum.com/t/controlling-averages-via-rest-api/1620 "2024-11-13T18:55:33Z")
Is there a way to set the amount of averages via the REST API without using LoadFile? Is there a way to reset the averages buffer via the REST API? If the averages are set to x and I call DoAcquisition x times after th… --- ## [Difference between left and right channel (QA403)](https://forum.quantasylum.com/t/difference-between-left-and-right-channel-qa403/1273)
**Author:** [@yegolebi](https://forum.quantasylum.com/u/yegolebi)\ **Replies:** 17\ **Last updated:** [November 11, 2024, 2:11pm UTC](https://forum.quantasylum.com/t/difference-between-left-and-right-channel-qa403/1273 "2024-11-11T14:11:49Z")
I recently received my unit and am in the process of learning all the features. One thing bothers me though, the loopback measurements from the right channel are worse than the left channel. THD is worse by about 4-5 dB… --- ## [Get n-th harmonic of acquisition by API](https://forum.quantasylum.com/t/get-n-th-harmonic-of-acquisition-by-api/1618)
**Author:** [@breedj](https://forum.quantasylum.com/u/breedj)\ **Replies:** 4\ **Last updated:** [November 9, 2024, 8:28am UTC](https://forum.quantasylum.com/t/get-n-th-harmonic-of-acquisition-by-api/1618 "2024-11-09T08:28:29Z")
I’ve been using Arta and Steps for years before I got the QA403. The Steps program was able to create a graph which plots the first 6 harmonics over frequency which is assential when designing an amplifier. I think I nee… --- ## [QA403 real input impendace?](https://forum.quantasylum.com/t/qa403-real-input-impendace/1601)
**Author:** [@Christian](https://forum.quantasylum.com/u/Christian)\ **Replies:** 9\ **Last updated:** [November 8, 2024, 4:44pm UTC](https://forum.quantasylum.com/t/qa403-real-input-impendace/1601 "2024-11-08T16:44:13Z")
Hi All, New user here - just waiting to receive my unit. Meanwhile, I am preparing my lab. I need to measure AC voltages at about 100Vrms and thus need an external differential attenuator to protect the inputs of the de… --- ## [Out of a sudden, software fails to connect QA402](https://forum.quantasylum.com/t/out-of-a-sudden-software-fails-to-connect-qa402/1606)
**Author:** [@IDC\_Dragon](https://forum.quantasylum.com/u/IDC_Dragon)\ **Replies:** 10\ **Last updated:** [November 4, 2024, 10:56pm UTC](https://forum.quantasylum.com/t/out-of-a-sudden-software-fails-to-connect-qa402/1606 "2024-11-04T22:56:24Z")
In mid-operation, the GUI software fails to detect the hardware and I’ve been unable to recover. At the lower left there’s a text on orange background “Connect the QA402. See File-\>Device to change”. First I was afraid … --- ## [Auto close of QA app for continuos REST api request](https://forum.quantasylum.com/t/auto-close-of-qa-app-for-continuos-rest-api-request/1596)
**Author:** [@Chan](https://forum.quantasylum.com/u/Chan)\ **Replies:** 3\ **Last updated:** [October 31, 2024, 8:20am UTC](https://forum.quantasylum.com/t/auto-close-of-qa-app-for-continuos-rest-api-request/1596 "2024-10-31T08:20:16Z")
I using Python to make the continuous REST api request, but the QA software will auto close when runtime is long (30 minutes onwards). Is that any solution to it? --- ## [Is this how to measure THD+N when using a notch? Numbers seem too high (likely user error)](https://forum.quantasylum.com/t/is-this-how-to-measure-thd-n-when-using-a-notch-numbers-seem-too-high-likely-user-error/1592)
**Author:** [@Michael1](https://forum.quantasylum.com/u/Michael1)\ **Replies:** 2\ **Last updated:** [October 19, 2024, 10:31am UTC](https://forum.quantasylum.com/t/is-this-how-to-measure-thd-n-when-using-a-notch-numbers-seem-too-high-likely-user-error/1592 "2024-10-19T10:31:21Z")
I found a couple of older, unresolved topics on the matter, but haven’t found a good answer. Essentially, I’m trying to measure a high end DAC - specifically the differential output of an ES9039SPRO @ 4Vrms. According to… --- ## [How to change format of triggered expo chirp?](https://forum.quantasylum.com/t/how-to-change-format-of-triggered-expo-chirp/1588)
**Author:** [@Michael1](https://forum.quantasylum.com/u/Michael1)\ **Replies:** 2\ **Last updated:** [October 15, 2024, 11:03pm UTC](https://forum.quantasylum.com/t/how-to-change-format-of-triggered-expo-chirp/1588 "2024-10-15T23:03:46Z")
I can generate a chirp using the software, and it gives it to me in 32-bit float format. However, my DUT expects either 16- or 32-bit signed little endian samples. As such, I loaded the software-generated chirp in Audaci… --- ## [Scaling control elements of the software](https://forum.quantasylum.com/t/scaling-control-elements-of-the-software/1579)
**Author:** [@cfortner](https://forum.quantasylum.com/u/cfortner)\ **Replies:** 3\ **Last updated:** [October 15, 2024, 2:13am UTC](https://forum.quantasylum.com/t/scaling-control-elements-of-the-software/1579 "2024-10-15T02:13:32Z")
Hi, I’m very happy with my QA403 but there is (in my setup) one issue: I’m working on a laptop with a 15" screen. The measuring windows size is ok, but I have to scroll down every time I want to start the generator f… --- ## [QA403 stopped connecting Windows 10](https://forum.quantasylum.com/t/qa403-stopped-connecting-windows-10/1586)
**Author:** [@rmod](https://forum.quantasylum.com/u/rmod)\ **Replies:** 2\ **Last updated:** [October 15, 2024, 1:59am UTC](https://forum.quantasylum.com/t/qa403-stopped-connecting-windows-10/1586 "2024-10-15T01:59:21Z")
My QA403 stopped connecting to the QuantAsylum software in Windows 10 - was working previously. The software just says “Connect the QA403…” in orange. I’ve tried all the USB ports - same issue. I’ve tried re-booting/pow… --- ## [Using Expochirp to measure a DAC's Frequency Response expectations](https://forum.quantasylum.com/t/using-expochirp-to-measure-a-dacs-frequency-response-expectations/1585)
**Author:** [@VAR](https://forum.quantasylum.com/u/VAR)\ **Replies:** 8\ **Last updated:** [October 13, 2024, 3:18pm UTC](https://forum.quantasylum.com/t/using-expochirp-to-measure-a-dacs-frequency-response-expectations/1585 "2024-10-13T15:18:13Z")
I had posted in another discussion here (Frequency response not working in mirror mode…) about using an expochip .wav file to measure the frequency response of a portable media player. I purchased another player which ha… --- ## [QA402 Input Range Violations using Differential Inputs](https://forum.quantasylum.com/t/qa402-input-range-violations-using-differential-inputs/1486)
**Author:** [@Buckskin](https://forum.quantasylum.com/u/Buckskin)\ **Replies:** 59\ **Last updated:** [September 30, 2024, 10:28am UTC](https://forum.quantasylum.com/t/qa402-input-range-violations-using-differential-inputs/1486 "2024-09-30T10:28:11Z")
I’ve been struggling to produce an attenuator for use in high power amplifier testing with the QA402 and have encountered yet another mystery. My latest iteration is composed of a simple voltage divider to be connected … --- ## [Power Output Impedance Automated test](https://forum.quantasylum.com/t/power-output-impedance-automated-test/746)
**Author:** [@VAR](https://forum.quantasylum.com/u/VAR)\ **Replies:** 34\ **Last updated:** [September 26, 2024, 12:23am UTC](https://forum.quantasylum.com/t/power-output-impedance-automated-test/746 "2024-09-26T00:23:58Z")
I ran the Power Output Impedance automated test on a power amp and am not sure of what to make of the result- I could not find any wiki on that test… --- ## [Generate "User Provided" waveform with QA403](https://forum.quantasylum.com/t/generate-user-provided-waveform-with-qa403/1555)
**Author:** [@Peter\_T](https://forum.quantasylum.com/u/Peter_T)\ **Replies:** 8\ **Last updated:** [September 24, 2024, 2:40pm UTC](https://forum.quantasylum.com/t/generate-user-provided-waveform-with-qa403/1555 "2024-09-24T14:40:12Z")
Hello, I’m kindly asking for support on the following matter. I would like use the Generator to output a “User Provided” waveform with the QA403. According to the Wiki (DAC Output Block Diagram · QuantAsylum/QA40x Wi… [Previous page](https://forum.quantasylum.com/c/qa40x/15.md?page=3) [Next page](https://forum.quantasylum.com/c/qa40x/15.md?page=5)