PC audio test set

[rock soderstrom]

Are there any Digilent Waveforms users here? You can also use it with the sound card/audio interface.
https://digilent.com/reference/software/waveforms/waveforms-3/start

 

[jaddie]

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.

That's the price to pay for the 100MHz BW.

For audio measurements, nothing beats a soundcard with a proper front end, which unfortunately does not exist commercially. I had to build one.

You might take a look at the Quantassylum current offering, QA403. It's max input is +32dBV, while it's max output is off a bit at +18dBV, which is about 10-12dB off what we would really like to have (and more would be better), but the overall performance is quite excellent for an off-the-shelf device. There is a current issue with it not having an ASIO driver, but that will probably right itself as it did with the QA401. The issue is the attenuators and gain structure which aren't under control with ASIO, though we had that issue with the QA401 too, and dealt with it using a .toml file and the normal host software. A bit of a PITA, but the advantages of the box made it all worth while. Hopefully at least the same thing could happen with the QA403. This only limits usage with REW and other generic apps, the included host measurement app is more than complete.

 

[12afael]

I use room eq wizard too and I also use fab filter pro q3 a lot. the matching eq feature is very useful to compare stuff.

 

[jp8]

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 It's not a bad program, a bit outdated graphically, but the function is okay.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.

I'm having the same stability issues with audiotester and have stopped using it. REW provides more features, but it has its quirks as well. Maybe it's due to the Behringer UMC202HD ASIO driver, but REW resets the ASIO interface each time I start/stop a measurement or the generator. Very annoying. And the UI doesn't have the look & feel of a measurement instrument. Virtins has a true measurement instrument UI, but allegedly has a steep learning curve.

Without a Frontend (aka Sound Card Interface), using a Sound Card for audio measurements limits you to the input/output impedances and voltage ranges of the audio interface. A well known example of a Frontend is this interface by Pete Millett. But as it has only one BNC input and output, its versatility is limited, IMHO. So I designed and built my own frontend. In this thread on diyaudio, it was discussed how a modified Behringer UMC202HD audio interface could be used for audio measurements. The thread contains not only discussions of improvements to the UMC202HD, but also examples of a.o. filters and an Autoranger. In post #705, I shared my Frontend design. Admittedly, I would not encourage anyone to build an exact copy of what I made, but it might serve as a source of inspiration.

Jan

 

[rock soderstrom]

And the UI doesn't have the look & feel of a measurement instrument.

+1

Maybe it's due to the Behringer UMC202HD ASIO driver, but REW resets the ASIO interface each time I start/stop a measurement or the generator. Very annoying.

Have you also tried ASIO4ALL?

 

[Tubetec]

I think the biggest shortcoming of the desktop interface is the typical USB power supply arrangement ,
I was able to achieve a 14db reduction in the measured noise of my interface over a bandwidth of 100khz by splitting the audio and Xmos supplies on two seperate rails .

Im using the SSL2 as a measurement front end for REW , it gives the options of balanced mic ,line and Hi-Z inputs , followed by a very low noise low distortion preamp ,
The noise of the interface itself very much lower than anything you plug into it .

The one downside is theres no repeatabillity with the standard pot gain control ,
So each time you set it up you need to calibrate the input and the plumb those numbers into REW ,
so that your readings are correct , its a minor enough complication .

 

[Gold]

The one downside is theres no repeatabillity with the standard pot gain control ,
So each time you set it up you need to calibrate the input and the plumb those numbers into REW ,
so that your readings are correct , its a minor enough complication .

Just goes to show everyone has different likes and dislikes. That's the main reason I don't use REW. Having to setup and keep track of the calibration drives me nuts. I always have that doubt that it isn't doing what I think it's doing.

 

[warpie]

Unless I'm doing something terribly wrong, I've never had any problems with repeatability. I just use line I/O that don't have pots, I save/ load the calibration file and it's ready to go every-time I open the software...

 

[Tubetec]

Most desktop audio interfaces have line in via the mic amp , almost never direct into the A/D
Sure you can use the line or mic in at minimum gain , and be sure of the calibration ,but then you need an external level raising amp with switched gain steps , for instance to investigate noise .

Of course I'd rather a front end with switched gain/attenuation steps for measurement ,
REW doesnt know the gain of the interface unless I tell it ,
If I have a precise attenuator at the input , say with 5-10-15-20 db gain reduction steps I can easily subtract the amount of attenuation from the reading Im seeing on the screen ,

 

[warpie]

You can get a very decent 4-ch interface quite cheaply nowadays. These usually have 2 Mic/Line/DI inputs with pots and 2 Line Ins without pots.

 

[Ike Zimbel]

Has anyone looked at the Quant Asylum offerings?

 

[Newmarket]

Has anyone looked at the Quant Asylum offerings?

Yes. IIRC they have been referenced in this thread ?

 

[Tubetec]

A relay based attenuator that works in conjunction with REW would be nice , it already has some ability for communiucation with external devices built in ,

Speak of the devil , I just opened up REW and theres a new version 5.31 available for download ,
best grab that ,

 

[Ike Zimbel]

Yes. IIRC they have been referenced in this thread ?

Yep, I now see that I missed that

 

[Ivan K.]

Some good answers... Here are a couple more: Jan DIdden is (was?) selling a a sound card front end kit called the Autoranger. It works with Focusrite and similar products. Jan is the former publisher of Linear Audio and the technical editor of AudioXpress magazine. This is the last email I have: Jan Didden <[email protected]>

Also, Audio Precision One and Two, tested and refurbished (and later, more expensive models) are available for reasonable prices from Duke Aguiar (@ieee.org) or sound-logic-la.com. He also makes a USB dongle to run System One & Two from WIN 10 computers.

 

[ruffrecords]

Unless I'm doing something terribly wrong, I've never had any problems with repeatability. I just use line I/O that don't have pots, I save/ load the calibration file and it's ready to go every-time I open the software...

I always use the Scarlette line in and turn the gain to minimum and cal just once.

Cheers

Ian

 

[warpie]

Some good answers... Here are a couple more: Jan DIdden is (was?) selling a a sound card front end kit called the Autoranger. It works with Focusrite and similar products. Jan is the former publisher of Linear Audio and the technical editor of AudioXpress magazine. This is the last email I have: Jan Didden <[email protected]>

Also, Audio Precision One and Two, tested and refurbished (and later, more expensive models) are available for reasonable prices from Duke Aguiar (@ieee.org) or sound-logic-la.com. He also makes a USB dongle to run System One & Two from WIN 10 computers.

I might be wrong but I believe Jan stopped making these some time ago(?)

 

[jp8]

Yup, Jan Didden stopped selling his autoranger. If you want an autoranger frontend, you might want to check out the thread on diyaudio, the link to which I posted in post #24. User lykkedk posted his ideas for an autoranger on the last pages of this thread.

Jan

 

[blue_luke]

Dang!
With all the experience I claim to have, I completely forgot about the input/output interface!
Go ahead, you can have one on me!
I checked the Pete Millet interface and it seems to do a very good job. I have a lot of respect for Mr. Millet.

Funny how this hobby, of audio recording, consist eventually of many 'sub-hobbies' like building my own guitars and basses, building test instruments to test the audio devices I build....
A friend of mine the other day, as I was having him listen to some of my music made me realise that :
- I composed the music
- I play it on a guitar I made
- recorded with a microphone I built
- trough my own designed and built preamps
- listened trough amplifier and speakers I designed and built

Never tought I would be such a busy man when retiring!
And the wife keeps me busy also!

Anyway, back to the subject....
I REALLY dig all the advise I received on this subject, thank you all for your time.
I have quite a lot to read and try.
Yesterday I downloaded REW and found my UMIK-1 and found that my old 40 years old Tannoy are remarquably flat!
I also downloaded the AudioTester V3 (trial version) and intend to try it during the next few days. It looks promising.
I also think seriously in investing in a hardware solution.
I looked at the Quant Asylum system, but at 590US$ (about 2 billions CAN$) I can't go that far, a good deal still considering all of what it does.
I am leaning toward the Virtin system as suggested by Beatnik. affordable ('round 250US$) for the basic interface that covers my needs.
I have looked at DSO and the affordable ones are all Chinese and look terribly cheap. I don't trust.

For an interface I found many relay input selector board with relay step attenuator. Use a stereo card for balanced line. There are many models for around 50$ or so... This could be a good start for building an input interface for the sound card.

 

[jp8]

+1

Have you also tried ASIO4ALL?

I have tried it long time ago (2020-2021 or so) and could not get it to work back then. Don't remember why anymore. I also tried FlexASIO, but did not work either. But your suggestion triggered me to try once again, because in the meantime, both REW and ASIO4ALL saw new releases. And guess what: it works flawlessly now . Thanks for triggering me!

Jan