| Products > Test Equipment |
| Looking for an audio analyzer |
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| 1audio:
For FFT if your doing more than testing analog amplifiers accuracy (i.e. looking at musical waveforms) there is software http://www.qsl.net/dl4yhf/spectra1.html Spectrum Lab that will show much more than a typical FFT. if you are looking at acoustics there are several with ARTA being more versatile for both electronics and acoustics. REW is a good room and speaker equalizer package and there are many more. You can do well with any of a number of soundcards, the best are in the $600-1K range or something like the new standalone stereo boxes from Lynx or RME for around $1500. I have a QA401 and find it does what its intended to do quite well. You can get about 10 dB better for about 50X the price with the latest APX555 but that seems like a small ROI. Any of these are far beyond anything you can encounter acoustically. You can find more on these specifics at http://www.diyaudio.com/forums/design-build/ |
| DaJMasta:
Spectrum Lab looks like a really great visualizer for FFTs, and I'm similarly surprised that it's free! I think my aim is gradually being swayed towards a really high quality audio interface over a dedicated audio analyzer. The analyzer will have its specified software suite, will have better input protection, and will probably have more output level flexibility whereas going with an interface means wider software compatibility (much more likely to just be an ASIO driver or similar), potentially built in mic preamps, and a lower noise floor for a given price. While I do intend to be testing some of my own designs, I won't be testing in an industrial environment so input protection may not be a top concern, and having a preamp and phantom supply built in takes another part out of the chain for doing the microphone measurements. Something like the RME Babyface Pro, for as ridiculous as its name is, offers very impressive noise floor, on par with the AP 2700 series analyzers according to their numbers, and has built in preamps for something like $750 - which may be still a bit high vs the QA401 given that the a preamp box probably won't cost the remainder, and either is considerably under a "full on" analyzer's price. |
| deadlylover:
Look up on the old audio analysers made by Panasonic and ShibaSoku, there are a few models that hold up today in terms of residual THD+N like the Panasonic VP-7722A which gets about -112dB(0.00023%) THD+N @ 1kHz 2.5Vrms, 30kHz BW, you'll have a tough time approaching that with a studio audio interface + software combo due to the limitations of our current ADCs. Those old instruments can be controlled by GPIB so you can get some pretty graphs that way and they have a monitor port in which you can perform FFT on the post-notch signal, I've attached an example below, the second harmonic is at -139dBr but I couldn't quite figure out how to make it scale properly in ARTA. :P Great thing about these old analysers is that if you only need quick and dirty distortion results, there's no need to boot up a PC or anything and they can read individual harmonics up to the 5th at the touch of a button, too easy. The ShibaSoku 725 series don't include the generator, but in return you can get -120dB THD+N @ 30kHz BW performance with some easy modding so they are still very capable machines today. I think unmodded they did around -116dB, which still eats anything alive except the AP flagships, not too bad for maybe $500 used eh? The dScope started at around $3000 or so IIRC, it'll probably do everything you need but it's a biiit out of reach for hobbyists IMO (which I'm assuming this is more for hobby/learning use as otherwise you'd already have gone for an Audio Precision ahahah). ^-^ |
| _Wim_:
The OP wrote: "I'm a musician with a bit of a fascination with audio gear, and it's been a fairly longstanding goal of mine to do some measurements to characterize the sound of different instruments, techniques, spaces, etc.. I'm also interested in being able to characterize the performance of my gear - frequency response, THD+N, etc - both as a reference for further experiments and so I can see the effect of different configurations or modifications." The way I read this, is he wants to tweak his equipment to a get better sound, and understand the effect of the tweaks. His goal is not to get better numbers only (he does not work for a commercial business where it can be interesting for marketing to build the first 32 ENOB-dac with an SN of 194db :-) so all audiophiles consider this the next Walhalla and sell their house to buy this new gear). So we should advice gear that is : - capable of measuring “audible” differences (and a bit below audioble so the cumulative effect of multiple changes is also possible) - relatively easy to use and to understand (he will not use this 8 hours a days, 5 days a week…) - affordable (so the OP can spent the rest of his available budget on other nice gear for an electronics lab :-) ) So I think the recommended QA401 will be perfect for measuring the electronics (differential inputs are a very big plus), and use a sound card with ARTA or equivalent software (he can play around with as many free tools he wants) will get him going on the acoustics side. I recommended this as an “ex-audiophile”, as once upon a time I also really believed in the benefits of using ultra expensive audiophile capacitors, ultra-low jitter clocks, buying expensive signal cables… :-[ and wasted quite some money doing that until I started reading. One of the things that cured me from my “audiophile illness” was the following software tool:http://www.foobar2000.org/components/view/foo_abx It allows you perform blind ABX comparison between two music tracks. For example you can test if you can hear the difference between a compression less music and MP3@320, the effect of 0.01% THD added, the effect of some phase distortions,the effect of adding some reflections …) For manipulating the audio tracks (THD distortion, phase distortion, low and high pass filters, adding reflections) use the typical musician tools which I suspect will be not an issue for the OP. By doing lots and lot of ABX testing (use a good headphone) you will be amazed how difficult it is to actually hear some differences. For example I was really sure I would be able on any music to recognize MP3 (even at 320kbps) from compression less, but this proved to be not so easy. :o Combine this with a good book on psychoacoustics and acoustics, and you soon realize you will have been wasting your time on the wrong things (and the wrong audiophile gear). Your new goals will be to manage early reflections in your listing room, having a speaker with constant directivity and having multiple subs in many positions to get a reasonably flat frequency response in this modal sound region. All of these are dictated by the way sound waves travel (and the wavelengths involved) from the speaker to your ear, and the way our hearing works. The electronics cannot alter these new goals (only exception, having a speaker with steers the sound beams using DSP and multiple speakers). So once you know your electronics are “good enough” (which should not be a problem for modern affordable gear), you can start tinkering on how the fool the laws of physics… |
| Ice-Tea:
In the interest of learning how to crawl before you can run... have you considered an Analog Discovery (2)? All the instruments mentioned before in this thread are several order of magnitude better than this but you may find it easier to guage what you need when you have worked with something that fails your criteria... http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/ |
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