Using RMAA Audio Analyser to measure Oscillator Distortion - Page 1
Forum section: electronics / testgear

author: enut11
author_rank: Super Contributor
timestamp: September 24, 2017, 06:32:27 am
content: HINot much on RMAA (RightMark Audio Analyser) on this forum but hoping someone can helpI am new to PC based measurements, in particular audio analysis software.I bought an ASUS U7 USB external sound card and installed the free RMAA software on my Win 10 PC.I was able to complete a soundcard loopback test with the following results: THD+N 0.007%, SNR 93dB. I noticed a lot of LF noise on the spectrum plot. Not sure if this is normal or what to do about it.Anyhow, I now want to measure my homemade audio oscillator noise and distortion. When I connect it to the ASUS U7 line-in and adjust levels to -1dB in RMAA, as per instructions, I can see the 1KHz spectrum results along with all the harmonics. The spectrum plot responds to frequency changes on my audio oscillator so the signal is getting into the U7.My problem is that I do not know how to save and analyse the audio oscillator waveform. I keep getting 'no sync' error message. At the moment I am calculating the THD using an XL spreadsheet but it is a little tedious. I would rather rely on the automatic calculations in RMAA but have not worked out how to do this with an external signal source.enut11

author: _Wim_
author_rank: Super Contributor
timestamp: September 24, 2017, 01:41:07 pm
content: I think RMAA needs the input signal to be synchonized with its output.For what you want to do, I would recommend ARTA (http://www.artalabs.hr/) It calculates THD and THD+N automaticcally vs the main peak, can do automatic normalizing and many many other things. The only limitation in the free version is that you cannot save measurements (you can take screenshot off course).

author: b_force
author_rank: Super Contributor
timestamp: September 24, 2017, 03:20:44 pm
content: I would also recommend ARTA, but there are lots of other programs out there.RMAA works, but is very limited.It's made for just 'sweeping' test gear to be able to compare them.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: September 24, 2017, 04:25:38 pm
content: http://www.audacityteam.org/home/is one of many too

author: enut11
author_rank: Super Contributor
timestamp: September 25, 2017, 12:10:02 am
content: Thanks @blueskull, @_Wim_, @b_force and @f5r5e5d. Forum members to the rescue once again. Perhaps I am expecting too much from RMAA. I will give ARTA a go.enut11

author: Alex Nikitin
author_rank: Super Contributor
timestamp: September 25, 2017, 08:43:24 am
content: I useAudioTester.CheersAlex

author: enut11
author_rank: Super Contributor
timestamp: September 27, 2017, 04:05:23 am
content: Currently evaluating the following PC based measurement software:ARTAVisual AnalyserQARTAAudio TesterWill report back when I find one that is affordable, powerful and easy to use. A tough combination!enut11

author: b_force
author_rank: Super Contributor
timestamp: September 27, 2017, 05:49:52 am
content: Quote from: enut11 on September 27, 2017, 04:05:23 amDo you have a link to this one, or does it have a typo?not able to find it?

author: enut11
author_rank: Super Contributor
timestamp: September 27, 2017, 08:48:27 am
content: Quote from: b_force on September 27, 2017, 05:49:52 amOops, it is DAQARTA and it sounds very interesting from the web info that I have read.http://www.daqarta.com/index.htmAnyway, RMAA is not up to the task of measuring external instruments, so scratch that one.enut11

author: Loboscope
author_rank: Regular Contributor
timestamp: September 27, 2017, 09:17:27 am
content: I use "hpw-works" for testing my audio-gear [http://www.hpw-works.com/] and I am very satisfied with this software. Together with a good audio-interface (RME for example) it gives very precise results.However, it is not free (but indeed a bit expensive), although it is possible to test it free for 30 days.

author: enut11
author_rank: Super Contributor
timestamp: September 27, 2017, 10:05:43 am
content: Thanks. Yes, HPW and RME look to be professional grade tools so outside the scope of this project.Same for Matlab. Pro stuff and I could not see how to get a low cost license unless I was a student and eligible for a campus license.enut11