spectrum analyzer, audio range - Page 1
Forum section: electronics / testgear

author: neslekkim
author_rank: Super Contributor
timestamp: April 20, 2016, 09:06:24 am
content: If one want to use an spectrum analyzer to see what is happening in the hearable audiorange, maybe 0-100khz (ok, a bit over hearable), to see what is happening with outputs from vco, lfo, filters etc (synth design), what is available then?can be software/computer based, or hardware, but preferably not so expensive.seems like spectrumanalyzers normally starts around 100khz?

author: Fungus
author_rank: Super Contributor
timestamp: April 20, 2016, 09:15:02 am
content: You can probably use your PC sound input for that.

author: neslekkim
author_rank: Super Contributor
timestamp: April 20, 2016, 10:15:27 am
content: yes, but bitrate is typically 16bit if lucky?, and max rate 44khz?, or are there better ones?, 24bit and 192khz would be helpful I guess.the point is to see the harmonics of notes.i wonder, the Analog discovery, maybe there is something in that package...

author: neslekkim
author_rank: Super Contributor
timestamp: April 20, 2016, 10:21:59 am
content: hm, an MDO in software version is probably what I'm looking for.. with max 100khz or thereabouts..

author: krivx
author_rank: Frequent Contributor
timestamp: April 20, 2016, 10:30:14 am
content: Soundcards don't extend to DC and you will need some extra instrumentation and some care to come up with a calibration process if you need quantitative measurements.If you don't need amazing dynamic range or phase information a DSO with FFT will do a lot of this.

author: kayvee
author_rank: Regular Contributor
timestamp: April 20, 2016, 10:43:38 am
content: You may want to check this thread out:https://www.eevblog.com/forum/projects/analog-disovery-as-audio-analyzer/

author: neslekkim
author_rank: Super Contributor
timestamp: April 20, 2016, 11:48:29 am
content: Quote from: krivx on April 20, 2016, 10:30:14 amOk, so the scope (I have an rigol ds2202a), would be fast enough?, so it's time to start learning to use that scopeQuote from: kayvee on April 20, 2016, 10:43:38 amPerfect!(and I hate this stupid 60 second post limit on this forum)

author: Performa01
author_rank: Super Contributor
timestamp: April 20, 2016, 12:13:50 pm
content: Quote from: neslekkim on April 20, 2016, 11:48:29 amYou'll need a decent dynamic range for audio, which rules out any 8-bit DSO.You might want to have a look at this:https://www.eevblog.com/forum/testgear/fft-spectrum-analysis-reviewed/

author: krivx
author_rank: Frequent Contributor
timestamp: April 20, 2016, 12:18:16 pm
content: Quote from: Performa01 on April 20, 2016, 12:13:50 pmI would disagree, you just need decent dynamic range for hi-fi audio. For VCO and filter testing 8-bit can be fine.

author: JPortici
author_rank: Super Contributor
timestamp: April 20, 2016, 12:36:40 pm
content: If you only want to see the spectrum, use any barely decent external sound card. It's linear enough until 18kHz. A daw and an equalizer should be enoughOr, if your OS of choice is windows:http://www.sillanumsoft.org/index.htmand Audio Xplorer if you're on a mac.You build modular synth too, don't you?

author: Messtechniker
author_rank: Frequent Contributor
timestamp: April 20, 2016, 02:09:33 pm
content: If the results in the enclosed graph (distortion of a passive crossover with old caps)are good enough for you then by all means go for a good sound card and some free or low costwindows fft software like Audio tester, for example.Yours - Messtechniker

author: neslekkim
author_rank: Super Contributor
timestamp: April 20, 2016, 02:19:30 pm
content: ah, cool, all I want is to try to find the effect of various designs for synthesizer (analog moog etc)

author: Fungus
author_rank: Super Contributor
timestamp: April 20, 2016, 02:23:40 pm
content: Quote from: neslekkim on April 20, 2016, 11:48:29 amYou own a Rigol DS2202S and you're asking this...

author: neslekkim
author_rank: Super Contributor
timestamp: April 21, 2016, 12:31:19 pm
content: Quote from: Fungus on April 20, 2016, 02:23:40 pmHaha, yes...

author: neslekkim
author_rank: Super Contributor
timestamp: April 22, 2016, 05:38:43 pm
content: Quote from: JPortici on April 20, 2016, 12:36:40 pmI have collected lots of noiceboxes, Moog Werkstatt, Doepfer Dark Energy I and II (And DarkTime), PatchBlocks, Axoliti, Minibrute, Korg Volca, Korg Minilogue, Korg Monotribe, and soon an Moog Minitaur..And also are trying to build some myself, and problably going to get rid of some of the hoard, but I wanted to try to see if I can use some tools to see the effect of the various filters and such.For instance, the Doepfer Dark Energy I and II, looks similar, one based on CEM3394, have totally different sound than the model II

author: FearLabs
author_rank: Contributor
timestamp: April 23, 2016, 01:17:05 am
content: I would recommend checking out any pro/semi pro music supply (guitar center, sweetwater, etc....) and getting a 96k sample rate or better audio interface. You will get a very linear 24 bit dynamic range as standard, and some have sample rates as high as 192k.There is a free program over on the Home Theater Shack forum called "REW: Room EQ Wizard" (requires forum membership). This program does in-depth realtime FFT analysis and can quickly output frequency response plots, and will tell you THD, THD+N, etc. Also includes a great signal generator (pink noise, white noise, sine wave, lock sine to FFT, sweeps, etc).Most of these soundcards show a noise floor below 120dB FS, I usually set the graph to show 140 dB range. You can see harmonics way down in the noise if needed.Obviously bandwidth gets questionable below 20hz, but usually can do down to 5hz depending on the interface. I measure up to 40khz usually. Perfect for audio. It's not about the bandwidth, its about the dynamic range and linearity. Even a basic $200 interface will outperform most scopes in this regard.Also some traps: These have minimal input protection and can handle +4dBu signal levels but not much more. Also the input impedance is great for line level signals but probably not for high impedance work, so that's something to keep in mind. I/O is generally balanced, although unbalanced operation is easy. Also watch out for ground loops, it's easy to show mains hum down a ways if you don't keep that in mind, especially testing unbalanced signals.Not perfect, but with some simple considerations, you can get really professional measurements at little cost this way. If you built a piece of audio gear and want to test for frequency response and THD, it's *almost* perfect.

author: amirm
author_rank: Regular Contributor
timestamp: April 23, 2016, 05:24:44 am
content: Quote from: FearLabs on April 23, 2016, 01:17:05 amJust a quick correction that you no longer need to go to Home Theater Shack for REW. You can download it directly from its own site:http://www.roomeqwizard.com/REW is not complicated to use but can be quite non-intuitive at first. I have written two parts of a tutorial for room measurements to help with that:http://www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-1.4/http://www.audiosciencereview.com/forum/index.php?threads/room-measurement-tutorial-for-dummies-part-2.5/The rest of your post was very good.

author: neslekkim
author_rank: Super Contributor
timestamp: April 23, 2016, 08:35:20 am
content: Quote from: Fungus on April 20, 2016, 02:23:40 pmI guess you didn't see this then:

author: neslekkim
author_rank: Super Contributor
timestamp: April 23, 2016, 08:43:39 am
content: Quote from: FearLabs on April 23, 2016, 01:17:05 amAh, I have been thinking about these audio interfaces, but not gotten that far, but this information makes me want to check it out earlier.The only ones I know of is the Focusrite Scarlet, have 96khz, 24bit, do you have other brandnames that I should check out for te 192khz ones?The music-shops here seems to be flooded with focusrite stuff, but then again, I might have not been looking too closely at this..

author: timb
author_rank: Super Contributor
timestamp: April 23, 2016, 10:26:53 am
content: The Focusrite Scarlet Solo and 2i2 are both pretty good for use with audio analysis software. There's also the Tascam US 2x2, which is in the same class as the two Focusrite units mentioned above (that is to say, 96kHz@24bit).I've heard good things about the Steinberg UR12 as well, which is 192kHz@24bit.Here's a small list of good quality USB interfaces (scroll down to the bottom for a table listing specs):https://www.trueaudio.com/rta_usb.htmTrueRTA is also a great software package.

author: neslekkim
author_rank: Super Contributor
timestamp: April 23, 2016, 10:38:20 am
content: ah, those steinberg interfaces seems interresting, nice price also, found them at lot of the sellers here, so it's only me that didn't know these brands.Interresting that all these are usb2..

author: billfernandez
author_rank: Regular Contributor
timestamp: April 24, 2016, 07:02:55 pm
content: Quote from: neslekkim on April 23, 2016, 08:43:39 amIf you're really serious about this, I'd recommend looking at the Quant Asylum 401http://www.quantasylum.com/content/Products/QA401.aspxwhich was made for this kind of work, and has a number of important features, including inputs and outputs that are: calibrated, floating, and handle higher levels than most PC sound boards. It also comes with its own audio analysis software. I don't have any direct experience, but I've been shopping for affordable audio analysis capabilities and I've been seriously considering buying this for my own needs.

author: Loboscope
author_rank: Regular Contributor
timestamp: April 24, 2016, 09:38:30 pm
content: I can recommend the analysis-software ¨hpw-works¨ for measuring audio circuits [http://hpw-works.com/].There is a 30-days trial available.You need a really good audio-interface to make the most profit from this really professional software. I use interfaces from RME [http://www.rme-audio.de/]. RME offers really good, professional and reliable audio gear and interfaces.Grretings, Jürgen