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blue_luke

Well-known member
Joined
Dec 13, 2008
Messages
174
Location
Montréal, Québec
Hello all :)

I've jumped back on the circuit design bandwagon. Temporarily going out of retirement to design and build some projects I need/want... you know the gist :)

I am searching the web for a software that would do test on audio circuits using my RME BabyFace pro

Free or buy, I am used to pay for what I use.

Something that measures S/N ratio THD, IMD, freq response etc...

Of course I am not after replacing a 25K$ Audio Precision test set and I don't foresee testing AD/DA converters anytime soon.

Do you have suggestions?

I have all the hardware equipment already, mostly Heathkit stuff bought in the early 80's, half are of the beige and half are Blue/white series...
If you know what I am talking about you are an old fart like me! :)
But this equipment is bulky, still work very well but need a lot of maintenance every time I want to use it!
It is tired!

I have been looking at those PCscope that looks quite interesting.
It consist of an interface that connects trough a USB cable (isolated) and then a software on the PC turs this thing in a very potent oscilloscope, freq generator , voltmeter etc...
Also very affordable, like a few 100's$, OK with me, up to a few K$, which I can't afford....
There are quite a few of these, PICO, Siglent, Tektronix, Hantek etc...

Any comments?

Luc
 
Thanks for that!
I just found that https://audiotester.de/
It seems pretty nice but no update since 2010?
Anybody tried it?
It is very reasonable price.
I bought it years ago, and at least on my PC it is no longer particularly stable. It's not a bad program, a bit outdated graphically, but the function is okay.
I would still prefer a different solution. Maybe invest a little more money or REW, which is completely free.
 
Hello all :)

I've jumped back on the circuit design bandwagon. Temporarily going out of retirement to design and build some projects I need/want... you know the gist :)

I am searching the web for a software that would do test on audio circuits using my RME BabyFace pro

Free or buy, I am used to pay for what I use.

Something that measures S/N ratio THD, IMD, freq response etc...

Of course I am not after replacing a 25K$ Audio Precision test set and I don't foresee testing AD/DA converters anytime soon.

Do you have suggestions?
I use REW and the Quantassylum QA401, either with the QA software or using the QA401 interface with REW. Both are excellent, but some things are easier in each.

I have all the hardware equipment already, mostly Heathkit stuff bought in the early 80's, half are of the beige and half are Blue/white series...
If you know what I am talking about you are an old fart like me! :)
But this equipment is bulky, still work very well but need a lot of maintenance every time I want to use it!
It is tired!
Both of the above will blow the Heahkit stuff out of the water in termsl of performance and speed. There is a learning curve to any software of course. I've used Heathkit, HP and Tek hardware. The software is much better. No going back.

One note, with REW you can use many different audio interfaces. As far as response goes, you can calibrate any interface and comp out an response anomalies. So with an interface, it gets down to 3 things: required maiximum output, noise, and distortion. The Tascam US-2x2HR is my current choice for off-the-shelf. The QA401 is discontinued, but the current unit QA403 should be in production (and is better anyway). https://quantasylum.com/
 
Do you have suggestions?
I have RMAA, Audio Tester and REW, all free versions. All have their strong and weak points.
The most complete is REW.
I have been looking at those PCscope that looks quite interesting.
The big problem with all these solutions, including PC scope is the lack of a proper front-end.
You must be ready to add a number of input attenuators, output amps, balancing/debalancing circuits.
There are quite a few of these, PICO, Siglent, Tektronix, Hantek etc...
You may confuse Digilent wirth Sigilent. The latter makes oscilloscopes, multimeters asnd signal gens. The former have a series of "Analog Discovery" platforms that have some definite advantages over a soundcard solution, but, again, lack a proper front end.
 
You may confuse Digilent wirth Sigilent. The latter makes oscilloscopes, multimeters asnd signal gens. The former have a series of "Analog Discovery" platforms that have some definite advantages over a soundcard solution, but, again, lack a proper front end.
It depends on what you mean by proper front end. The software directly controls the dedicated front end module. So calibration is automatic and ranges change with settings.

On the down side the front end isn’t quiet enough for low level audio measurements. The Waveforms software will recognize an ASIO driver so you can also use any audio interface you want. You can keep both the AD2 and an audio interface connected at the same time.
 
It depends on what you mean by proper front end. The software directly controls the dedicated front end module. So calibration is automatic and ranges change with settings.

On the down side the front end isn’t quiet enough for low level audio measurements. The Waveforms software will recognize an ASIO driver so you can also use any audio interface you want. You can keep both the AD2 and an audio interface connected at the same time.
You probably want several things.

1. A switchable 600 ohm load plus a switchable 20dB attenuator for measuring maximum output levels.
2. A transformer balanced signal source followed by a switchable attenuator. The reason you may need the former is if you want to test a mic pre and accidentally turn on phantom power, there is a good chance you will fry your interface. The reason you want the latter is because digital interfaces do not produce low distortion, low noise, low level signals. A -60dBu 1KHz signal from a 16bit convertor has typically 1% distortion and a 36dB S/N ratio. If you send a 0dBu signal from the same source via a 60dB attenuator the distortion will be tiny and the noise level close to that produced by the attenuator itself.
3. A switchable input loading resistor for making EIN measurements.
4. XLR connectors on the input and output..

I designed a simple front end some time ago:

CTC-Audio-Test-Interface-MK2-2024-04-08-20-53.png

Cheers

Ian
 
It depends on what you mean by proper front end. The software directly controls the dedicated front end module. So calibration is automatic and ranges change with settings.
The affordable models have limited input and output range (+/-25V and +/-5V respectively). Even the most expensive one is far from being able to push a decent piece of pro audio gear into its limits.
On the down side the front end isn’t quiet enough for low level audio measurements.
That's the price to pay for the 100MHz BW.
The Waveforms software will recognize an ASIO driver so you can also use any audio interface you want. You can keep both the AD2 and an audio interface connected at the same time.
For audio measurements, nothing beats a soundcard with a proper front end, which unfortunately does not exist commercially. I had to build one.
 
I use AudioTester, REW, ARTA, YMEC, Visual Analyzer and have RMAA but don't use it any more.

My "go to" is usually AudioTester with a Focusrite 2i2 Gen 3. Will be getting a 2i2 Gen 4 soon as it has higher A/D DR and lower output impedance.

AudioTester was last upgraded in February 2023.

For noise measurements that exceed the DR of the 2i2 I use a TI PCM4222 EVM and for super-low (-140 dBc residual) 1 kHz distortion measurements I use ULDO-Nacho with the 2i2. The one thing I don't like about the PCM4222 is that it "leaks" Vcm out of the input XLRs.
 

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