Which Audio Analyser?

This is where we talk about testing, measuring and repairing things. Sometimes we have to repair the equipment we use to test, measure and repair other things. It's an endless cycle of fixing the broken things we need to fix other broken things.
Audio1Man
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Re: Which Audio Analyser?

Post by Audio1Man »

Hello AnalogJoe
I have an APIB USB ADAPTER that drives the System One. System Two & Cascade under ApWin 2.24 that runs OS from XP, Vista, Win7, Win8 & Win10. My next batch is due from my assy. house 31 Aug. I should have some overages after filling my back orders in Sept. http://www.sound-logic-la.com, duke.aguiar@ieee.org
AnalogJoe
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Re: Which Audio Analyser?

Post by AnalogJoe »

Audio1Man wrote: Wed Aug 19, 2020 6:51 pm Hello AnalogJoe
I have an APIB USB ADAPTER that drives the System One. System Two & Cascade under ApWin 2.24 that runs OS from XP, Vista, Win7, Win8 & Win10. My next batch is due from my assy. house 31 Aug. I should have some overages after filling my back orders in Sept. http://www.sound-logic-la.com, duke.aguiar@ieee.org
Hey Duke, I already got one of those from you but I will be ordering another one soon, a friend of mine borrowed (stole?) mine before the quarantine, so I'll be needing another one.
Gold
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Joined: Sat Dec 01, 2007 6:20 pm

Re: Which Audio Analyser?

Post by Gold »

Since there was talk of analyzers in the Cohen/Transamp thread I thought I'd update this thread. I've given up on using the iPad/iOS. There just isn't much available. I got a Microsoft Surface Pro3 used and I'm liking Windows 10 with touchscreen. Most of the analyzer software I've tried has dropdown menus and radio buttons. They are well suited to touchscreen operation. I have a keyboard cover for it but I'm thinking of getting a little blue tooth keyboard and touchpad so I can leave the Surface in the rack at eye level.

I got a BitScope first but that was a fail. The model that is currently available for purchase doesn't have their arbitrary waveform generator. It can't generate white or pink noise.

I got a Native Instruments Kontact2 USB interface. I've been playing with REW but it's slow going and I don't trust what I'm seeing. I need more experience with FFT and swept sine measurements to feel confident I'm getting accurate results in REW.

I recently got an Analog Discovery 2. I'm hoping since it has dedicated hardware I can get comfortable taking these measurements. It doesn't have a low noise floor but that's not a big concern until I feel confident in the measurements.

I was kicking around the idea of selling my AP P1 and getting a Sys1 with FFT. I've abandoned that idea. I bought the P1 new. It's been babied and I would get a quarter of what I payed for it. I also like the button per function UI. It took me a long time to be able to get around on it and I feel comfortable with it now. I have never used AP software and realized it would be a steep learning curve. I don't want a steep learning curve now.

It seems like all this stuff is coming down in price. The new Dscope is $3400. It's really nice. In a few years I expect there will be more options.
jaddie
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Joined: Tue Apr 26, 2022 7:20 am

Re: Which Audio Analyser?

Post by jaddie »

I use both the Quantassylum QA401 with the QA software, and REW. For the interface, I have a Tascam US2X2HR and a Motu 4Pre, but I also use the 3rd party driver for the QA401, and use it with REW.

Both the QA software and REW have their points. For scripted, automated testing, QA wins because REW can't be automated. QA also wins in the calibration aspect, the software "knows" the QA401 and it's capabilites, voltages and levels are accurate out of the box, and the software controls the QA401 input pad directly. REW has no idea what voltage it takes to push an interface to 0dBFS (not to mention the input controls make it arbitrary anyway), but it can easily be calibrated using an external volt meter. And, REW includes a means of running an auto-cal routine on your test rig to cal out any response bumps. I keep cal files for all my interfaces at all sampling rates. That same cal file feature lets you normalize response plots for equalized systems. Load the RIAA curve into a cal file, and you can sweep the response of a preamp and plot normalized (flat) results as deviation from RIAA ideal. Pretty slick.

But for me the real deal-breaker was when John Mulcahey included extensive multi-tone test signal generation in REW. You can get it to produce a signal made up of 40 or 50 tones similar to that which Deane Jensen proposed in this "Spectral Contamination" paper. And that's outside of nearly every other measurement system's capabilities, included in REW for free.

REW can also plot the results of a non-synch analog sweep, as may be found on a test record or test tape, using the Max Hold function in the RTA. Again, not something QA even considers. Missing from both, however, is any means of quantifying time-base errors as in WOW and flutter on analog recording systems. You can see the results with REW, but there is no means of simple measurement of weighted flutter, or scrape flutter.

What's really nice is that you can suggest a feature to John, and he may eventually include it in REW. I believe that's how we got full complex multitone. My next suggestion will probably be to add more features to the generator, like tone-bursts and AM.

As to interfaces, I chose the Tascam US2X2HR because it can produce up to 20dBu output ( a couple dB less for lowest distortion), and not many consumer intefaces can do that. The Motu 4Pre is very nice too, but without that maximum level output. I have high level buffer project in the works with the target of +32dBu or higher, intended to drive big transformers into saturation. But so far it's just a box of parts.

An interesting exercize is getting QA and REW to replicate a distortion measurement exactly. They don't precisely agree. Not sure why.

And one final word about interfaces, particularly the QA401. Find yourself a hefty USB cable with large gage wires. The QA401 is a bit bloodthirsty for current, and scrawny USB cables will push you into high noise. I also made a rig to externally power the QA401, but it hasn't really been necessary. The US2X2HR doesn't suck much current, and the Motu 4Pre is externally powered.
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mediatechnology
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Re: Which Audio Analyser?

Post by mediatechnology »

Thanks for joining us!

I looked at the Tascam US2X2HR before choosing the Focusrite 2i2. I honestly thought the Tascam was a better interface but wasn't sure if it would run in Linux. The Focusrite 2i2 doesn't list Linux as being supported but it is. Have you ever tried Linux with the Tascam? The Tascam US 4x4 is claimed to be USB 2 class compliant. https://wiki.linuxaudio.org/wiki/hardware_support

I run both Windows an Linux boxes and for transfers the Linux machine is usable. For audio tests Linux is a non-contender.

For software I'm currently using both AudioTester and ARTA. I need to test drive REW again.
jaddie
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Joined: Tue Apr 26, 2022 7:20 am

Re: Which Audio Analyser?

Post by jaddie »

I have played with Linux, but not for audio testing. In general I find it to be too much trouble without a lot of benefit, so moved on. In my work I deal with Win machines, tons of them, Win10, 7 and XP (yeah, Xp...which is now eXtra Painful). One facility had some Linux machines, but users had so much trouble with them we moved to Win10 for familiarity. My workshop/test machine is a Win10 desktop, my daily driver is macOS. The only reason I'm not testing with macOS is the QA stuff. Prior to that purchase I've used REW for years on the Mac with no issues.

It's odd too, because my first exposure to a computer OS in the early 80s was UNIX! And my first computer FFT machine was a TEF, which IIR was CP/M, 8 bit ADC, 5.25" floppies, and you got some really good info out of it. And a longer arm.
jaddie
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Joined: Tue Apr 26, 2022 7:20 am

Re: Which Audio Analyser?

Post by jaddie »

There's an REW version for Linux.
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