My DATS is fun to play with, but I hate the application that runs it, and it only runs on Windows. It's easy enough to export an impedance sweep to a text file and draw pretty graphs with REW, though. I am also playing with 3rd-party ASIO control panels, and on a recent fresh Windows install, I got Windows running, added FlexASIO before I installed the DATS software, and something interesting popped up in REW Preferences:
Drivers: ASIO
ASIO Device: FlexASIO
[Control Panel]
Driver Type: Windows WASAPI
Input Device:
It looks like if I select the Loopback input device, it only puts sound on the "left" channel, so I can't get Input and Reference Input to lift on the level meter at the same time. If I select the non-Loopback input device, and just set REW preferences like any other stereo interface, the calibration procedure works as expected. I can get a sound card calibration measurement.
The V3 (rev H) box has a 1KOhm resistor with lugs built into the nose of the chassis. Is there any hope that I can use this "black box" hardware to take impedance measurements with REW natively? I've already been inside the case before to fix a loose post, and it's pretty dull inside with very compact SMC devices and only a couple of ICs on the board. I'd be happy to break it open again and document anything that I can identify, though.
I do have a Behringer UMC202HD, and it's installed and configured but not attached, so it's not listed in the control panels above.
Drivers: ASIO
ASIO Device: FlexASIO
[Control Panel]
Driver Type: Windows WASAPI
Input Device:
Line (USB AUDIO CODEC)
Internal Microphone (Cirrus (AB54))
Speakers (Cirrus (AB54)) [Loopback]
Speakers (USB AUDIO CODEC) [Loopback]
Output Device:Speakers (Cirrus (AB54))
Speakers (USB AUDIO CODEC)
It looks like if I select the Loopback input device, it only puts sound on the "left" channel, so I can't get Input and Reference Input to lift on the level meter at the same time. If I select the non-Loopback input device, and just set REW preferences like any other stereo interface, the calibration procedure works as expected. I can get a sound card calibration measurement.
The V3 (rev H) box has a 1KOhm resistor with lugs built into the nose of the chassis. Is there any hope that I can use this "black box" hardware to take impedance measurements with REW natively? I've already been inside the case before to fix a loose post, and it's pretty dull inside with very compact SMC devices and only a couple of ICs on the board. I'd be happy to break it open again and document anything that I can identify, though.
I do have a Behringer UMC202HD, and it's installed and configured but not attached, so it's not listed in the control panels above.
I would argue that the advantage of DATS is the simplicity, which includes the software interface. If you don't like the interface and already have the UMC202HD then building an impedance jig seems to be the clear solution.
It has been common to take an impedance measurement with nothing more than a 1k resistor. Use a 10 ohm resistor in place of the driver to set your level to 10 of something. Replace the driver and see if your measurement falls into the noise or clips, adjust the level if needed, and voila. Trace this into a *.zma file.
Regardless of how you do it, knowing the basics shows what is required.
Regardless of how you do it, knowing the basics shows what is required.
I think the DATS application is OK, in that it does what it says it will do. The problem for me is trying to get a Windows computer spun up to take a handful of measurements. I have lots of machines that can talk to the hardware; two Macs, a Chromebook and a Linux computer, all of which run REW natively. If REW, the application that I'm going to use after I take the readings, can take the readings itself, that seems like a better solution. The UMC202 lives on my desk, not in my toolbox, because it's about 8x the size of the DATS. I tried to build an impedance sweeping bridge for my Apple USB-C ADC/DAC, but it's a little too smart, and only turns on the parts of the device that are connected to a load, so I can't get it to do an "open leads" calibration.
The Intel Mac runs Windows fine, but adds about a dozen extra steps; select new boot device, reboot, try to stop Windows update, start DATS, take sweeps, export files, select new boot device, reboot, start REW, and everything in between. And that's assuming I had the presence of mind to bring the Intel Mac, not the M3 Mac that I actually use all the time. Believe it or not, the DATS application also runs pretty well inside a Wine instance on the Chromebook, but again, that's not on me all the time, and I have reservations about how good the USB interface is on the Chromebook; my Macs both seem pretty resilient.
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Using conventional methods, all you're measuring is the voltage across the driver against a high source impedance.
Pretty much all software can do that. It won't be called impedance or anything special, just a regular level sweep.. or RTA for that matter, it doesn't matter since the impedance is minimum phase. Different methods will just give you different signal to noise ratio.
Pretty much all software can do that. It won't be called impedance or anything special, just a regular level sweep.. or RTA for that matter, it doesn't matter since the impedance is minimum phase. Different methods will just give you different signal to noise ratio.
...Over the entire acoustical AC band with one click. An impedance sweep, like this one, is what I paid $130 for a black box to be able to generate on demand. This is actually six different sweeps that DATS recorded, exported to a numerical text file, and then REW massaged, averaged where appropriate, and rendered in an overlaid fashion. I just wish that I didn't have to use the DATS software to use the DATS hardware.
I posted similar info on this forum a few years ago:
Thread 'Running DATSv3 natively on macOS using REW'
https://www.diyaudio.com/community/threads/running-datsv3-natively-on-macos-using-rew.381943/
Newer versions of REW have made the calibration steps even easier and more straight forward. I‘d use a lower value resistor (something like 10 ohms) for calibration. Using a good reference resistor to calibrate I’m able to consistently measure cable impedances below 100 milliohms with a bit better than 15 milliohms of resolution/accuracy (confirmed with a fancy meter at work).
One REW feature I really like is the realtime visualization of the input signal, it‘s very helpful to show how ambient noise impacts your speaker impedance measurements.
A while back I bought a reel of metal film resistors for a good price. If anybody is interested send me a PM and I can measure a resistor on my micro-ohm meter and mail it you with the value written on it, I’ll even cover the shipping if it’s in the US.
Thread 'Running DATSv3 natively on macOS using REW'
https://www.diyaudio.com/community/threads/running-datsv3-natively-on-macos-using-rew.381943/
Newer versions of REW have made the calibration steps even easier and more straight forward. I‘d use a lower value resistor (something like 10 ohms) for calibration. Using a good reference resistor to calibrate I’m able to consistently measure cable impedances below 100 milliohms with a bit better than 15 milliohms of resolution/accuracy (confirmed with a fancy meter at work).
One REW feature I really like is the realtime visualization of the input signal, it‘s very helpful to show how ambient noise impacts your speaker impedance measurements.
A while back I bought a reel of metal film resistors for a good price. If anybody is interested send me a PM and I can measure a resistor on my micro-ohm meter and mail it you with the value written on it, I’ll even cover the shipping if it’s in the US.
@olen Thank you SO MUCH for this! It's exactly what was hoping for! It may be a while before I try it out, but this thread, that thread, and the 2022 PDF are bookmarked!
I'm very interested in purchasing a resistor, maybe two.Also, have you looked at the input stage on the V3 very closely? I was toying with a small amplifier, and I couldn't get more than about 3.8V RMS before the DATS software oscilloscope started clipping, at least in REW.
DATS are designed to measure small signal parameters of loudspeakers which doesn’t require much drive voltage/power. There are only 16bits so the working range is higher resolution at smaller voltages. For most speakers around 1V you‘re leaving the linear region. Also the DATS functions as a constant current output meaning that the output voltage changes with the load impedance.
With REW you can use any soundcard as an oscilloscope, just be careful because I still remember frying the input of an expensive soundcard when I overdrove it ~20 years ago trying to do something similar.
If you just need a simple cheap oscilloscope I’d see if you can find an old crt scope people often will give them away. If that’s not an option the single channel arduino based ones can at least handle decent voltages (I drove it with 25vrms signal without damaging it - just don't count on them reaching even half of their stated bandwidth.
Send me a PM with your address and I’ll mail you some calibrated resistors at no cost, though it might take me some time to find them in my messy lab.
With REW you can use any soundcard as an oscilloscope, just be careful because I still remember frying the input of an expensive soundcard when I overdrove it ~20 years ago trying to do something similar.
If you just need a simple cheap oscilloscope I’d see if you can find an old crt scope people often will give them away. If that’s not an option the single channel arduino based ones can at least handle decent voltages (I drove it with 25vrms signal without damaging it - just don't count on them reaching even half of their stated bandwidth.
Send me a PM with your address and I’ll mail you some calibrated resistors at no cost, though it might take me some time to find them in my messy lab.
Folks, I'm over the moon. I followed olen's guide on my Windows machine (DATS was already attached, so why not?), "calibrated" R-ref against a more or less random 100w 4-ohm resistor I use for amplifier loading, and I went for broke. No smoke, no fire, so I attached it to a bare driver that's on my desk, and told REW to tell me about it through the DATS interface. Then I pulled up an old impedance measurement from the same speaker using the DATS software calibrated against its own 1k resistor, and...they're quite close enough to be useful. REW even rendered that weird little 6.0-ohm wobble at 1.5KHz that I always thought was DATS being strange. Maybe it's still the DATS hardware being strange, but it's not a difference in the software!
