Products > Test Equipment
Looking for an audio analyzer
ruairi:
I haven't used the Quant, but will probably pick one up for fun this year.
I have owned an AP system one and it is a wonderful, huge and powerful beast. But it is unsupported, and not trivial to set up. FFT is very powerful and missing on the older S1.
Jens' project looks great but again learning what to do is more important than waiting for "better".
_Wim_:
--- Quote from: alex89 on January 07, 2017, 11:25:04 pm ---
* JensH Audio AnalyzerThe last one is not yet a product available in the market but it seems the more promising to me. I haven't followed the entire discussion on diyaudio.com but it looks like will give better performance compared to a QA401 and also ASIO support. I'd like to hear your thoughts.
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Looks at first glance like a very nice produc, but would like to see a performance summary first. The hardware is certainly up to the task, and the fact that is supports ASIO will make it much more attractable then the QA401... Thanks for pointing this unit out to us.
Assafl:
--- Quote from: jackenhack on January 07, 2017, 02:42:57 pm ---
--- Quote from: _Wim_ on January 04, 2017, 07:49:14 pm ---
--- Quote from: jackenhack on January 04, 2017, 07:43:29 pm ---I'm currently finishing up a headphone amplifier build and I got the QuantAsylum QA401 when I started developing the amp. With todays extremely low noise and distortion figures on op amps, You'll hit the bottom of what the analyser can measure very quickly. I had to build a twin-T notch filter and get hold of a extremely low THD signal generator to be able to measure below -108dB THD. Getting a industry standard Audio Precision is the dream, but they are way to expensive for me...
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But the question is, why would we need to see lower than that? It can be fun as a technical exercise, but it will not improve the sound quality we hear any moreā¦
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Going down the rabbit hole is part of the fun. I want it to measure as good as possible.
Sent from my iPad using Tapatalk
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There is also the QA aspect of this - if you designed your channels to measure very low, any noisy component or problems in the amplification stages will pop up in the THD+N. They may not be audible, but you production run has a problem. It is no longer a Blameless amp.
I think that is the reason companies like Bryston measure very low and add a cert sheet to every amp - QA. I do not have the ability to measure (nor hear) that low - but their amplifiers are very nice (every bit as nice as every other blameless amplifier).....
ci11:
Going back to the OP's 2 applications, monitoring a FFT from complex audio signals in real time is quite a different matter than using an ultra pure sine wave to measure the THD+N of a circuit. These are very different needs, if only one devices is used to satisfy, that device would need to be of instrument grade and capable of doing so.
For the first applicataion, B&K at the high end and AudioControl at "everyday" price levels come to mind. The signals come from microphones and go into a device that "analyzes" and displays the level in each frequency band. They respond fast but depending on the sophistication of the device, price varies. AudioControl RTA boxes sold for years around $200 with a microphone, but there are no bins or frames to poke into. B&K, the Danish sound & vibration expert that supplies everyone from NASA to Mercedes Benz made very competent microphones, mic pres and analyzers, but again, their output reflects the need to characterize a complex audio signal and sort out that hairball in a meaningful way. Their tools weed out the chafe.
For developing circuits, every "chafe" is meaningful, because some glitch that happens at -100dB has a root cause, perhaps originating from somewhere else at -110dB. In the time domain, scopes that see reliably see these glitches are highly prized, and many tools have been developed over the years to catch these elusive glitches more reliably and visibly, precisely because they need to find the root cause. In the frequency domain, the need and technique is no different - just because it's not evident at -60dB where it is clearly audible does not mean there is no problem at -100dB. Simply putting on a set of good headphones will reveal significantly more normally inaudible glitches - that's why recording studios use all 3 ways to monitor a session - the soffit-mounted 15" monitors, the mini's on the console meter bridge and headphones. Any engineer who lets a mix go to tape without first getting all 3 right would not have a job for long.
An expensive analyzer like an AP or Rohde & Schwarz can do both, but they are not cheap and is not an casual purchase, unlike a USB soundcard or a freeware FFT. But these instruments are made by seriously competent people with very demanding customers, and their findings are not compromised by a budgetary constraint or makeshift construction. Of course, there is a component of brand value in their price, but in the long run, it really comes down on how much the user needs to rely on their findings, and what value they place on these findings.
ruairi:
--- Quote from: ci11 on January 08, 2017, 02:40:37 pm ---Going back to the OP's 2 applications, monitoring a FFT from complex audio signals in real time is quite a different matter than using an ultra pure sine wave to measure the THD+N of a circuit. These are very different needs, if only one devices is used to satisfy, that device would need to be of instrument grade and capable of doing so.
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Why are they different? REW, a free and very well supported piece of software can do both with it's signal generator and FFT. It won't do stereo but I find that it's rarely a limitation.
Your point does get to the heart of something though - that everyone has a slightly different approach to measurement. I for example am not very interested in THD+N as a metric, with out proper filtering PSU hum (especially in tube gear) can be a contributor that doesn't have a huge subjective effect. I'm more interested in the harmonics, when I see higher order harmonics I am more concerned.
The O.P. needs to start his journey of measuring to understanding what it is that he needs.
--- Quote ---Simply putting on a set of good headphones will reveal significantly more normally inaudible glitches - that's why recording studios use all 3 ways to monitor a session - the soffit-mounted 15" monitors, the mini's on the console meter bridge and headphones. Any engineer who lets a mix go to tape without first getting all 3 right would not have a job for long.
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This is not the case. I know many very famous engineers who never use headphones and who never check on the mains (lots of newer studios don't have mains and in older spaces they often sounded dreadful)."
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