Great news 
Also be sure in linux soundsettings (the graphical one) that the inputs / outputs are at 100%
The available in/outs can be seen with aplay -l, the in REW/system available ones can be seen with aplay -L
For a start I don't recommend you to spend to much time with /etc/asound.conf. It should not be necessary when "just" using REW. asound.conf is a kind of alias, nickname configuration file, but for sure it's usefull for many things. But it's another story.
Jesper.
Sometimes the showing of the right soundcard in REW preferences can trick me. Sometimes I just reboot my linux mint laptop with the Behringer, and / or DAC etc... plugged in, instead of fiddling around... sometimes it's just more easy, just a hint.
Also be sure in linux soundsettings (the graphical one) that the inputs / outputs are at 100%
The available in/outs can be seen with aplay -l, the in REW/system available ones can be seen with aplay -L
For a start I don't recommend you to spend to much time with /etc/asound.conf. It should not be necessary when "just" using REW. asound.conf is a kind of alias, nickname configuration file, but for sure it's usefull for many things. But it's another story.
Jesper.
OK! First time I feel I have proper control on REW! Calibration was easy. I remind you that this is my diy soundcard but it shares the same audio codec and the front end that Jesper transplanted to his Behringer, so I think it's comparable. Everything works, however there is something to resolve. For some reason, it seems REW handles my soundcard as a 16 bit device or something like that, I don't know how to fix it.
Edit: Perhaps it's not the bit depth. It seems to exceed 0dB without clipping so problem with scale?
Edit: Perhaps it's not the bit depth. It seems to exceed 0dB without clipping so problem with scale?
Attachments
Nice to see @JohnPM here
@MagicBus
You can calibrate both generator output and RTA input.
If you calibrate both, you can actually use the RTA as a voltmeter
(Actually @Salas teached me this)
Regarding input/output bits. If i choose the Behringer as both in/out I have 32bit in/out
If I e.g. choose default in/out, I only have 16bit in/out, so REW knows about the soundcard.
You can also see howto use AES17 "notch"
Please see attached pictures for better explanation.
Jesper.
@MagicBus
You can calibrate both generator output and RTA input.
If you calibrate both, you can actually use the RTA as a voltmeter
(Actually @Salas teached me this)
Regarding input/output bits. If i choose the Behringer as both in/out I have 32bit in/out
If I e.g. choose default in/out, I only have 16bit in/out, so REW knows about the soundcard.
You can also see howto use AES17 "notch"
Please see attached pictures for better explanation.
Jesper.
Attachments
I have built Valve wizard's gen to pair with a hand held oscilloscope for basic signal tracing. I thought to try it but it seems very unstable with REW. Perhaps because I have calibrated it in loopback mode and it gets confused with the external gen? If I don't figure it out I'll ask in the REW measuring thread.
BTW, make sure you set FFT length at least at 64k and enable coherent averaging. It makes significant difference.
BTW, make sure you set FFT length at least at 64k and enable coherent averaging. It makes significant difference.
Guy's happy Easter if you care about that, that is
I suddenly remembered, or more like the opposite, that I did not post here my finding's with my Cosmos APU notch when I discovered the correct way of taking the sweep's to have a more precise measurement of the notch and so on...
Anybody find the use of a notch with REW interessting, should take a look here :
https://www.avnirvana.com/threads/m...notch-cannot-measure-the-correct-depth.11825/
(Thread is not only about the Cosmos APU, also with some experimentation I have)
John is helping me out (again) to fully understand the use of a notch filter.
I have seen Archimago taking measurement's with his Victor's osc. to reach -150dB
I can reach -143dB with my hacked Behringer (@MagicBus balanced board)
Not that I really need this, it's just for the sport of it, nothing else... Think i reached the limit here...
Please note, that it's actually not necessary to "check" the manual fundamental, as long as you keep the system calibrated.
Looking at the picture show's that I unchecked this box, and having the same value's.
Jesper.
I suddenly remembered, or more like the opposite, that I did not post here my finding's with my Cosmos APU notch when I discovered the correct way of taking the sweep's to have a more precise measurement of the notch and so on...
Anybody find the use of a notch with REW interessting, should take a look here :
https://www.avnirvana.com/threads/m...notch-cannot-measure-the-correct-depth.11825/
(Thread is not only about the Cosmos APU, also with some experimentation I have)
John is helping me out (again) to fully understand the use of a notch filter.
I have seen Archimago taking measurement's with his Victor's osc. to reach -150dB
I can reach -143dB with my hacked Behringer (@MagicBus balanced board)
Not that I really need this, it's just for the sport of it, nothing else... Think i reached the limit here...
Please note, that it's actually not necessary to "check" the manual fundamental, as long as you keep the system calibrated.
Looking at the picture show's that I unchecked this box, and having the same value's.
Jesper.
Hi Magic.
Yes the Magicbus balanced board hacked Behringer is nice to have
Actually I can do as you wrote Stable and repeatable measurement's, so that's nice.
Well well...
With respect to post https://www.diyaudio.com/community/threads/behringer-umc-202hd-for-measurements.341309/post-6917928
I would really like to know the Zi of my Behringer (with potentiometer (100k) in mind ofcause).
I use light bulb's in place of them 33k/3W resistors.
Maybe I can measure it?
Attached schematic and input impedance specs. of the OPA1656
Yes the Magicbus balanced board hacked Behringer is nice to have
Actually I can do as you wrote Stable and repeatable measurement's, so that's nice.
Well well...
With respect to post https://www.diyaudio.com/community/threads/behringer-umc-202hd-for-measurements.341309/post-6917928
I would really like to know the Zi of my Behringer (with potentiometer (100k) in mind ofcause).
I use light bulb's in place of them 33k/3W resistors.
Maybe I can measure it?
Attached schematic and input impedance specs. of the OPA1656
OPA1632 alone was giving really impressive screenshots but useless because of its lowish Zin. OPA1656 was added for its high Zin. And still good THD+N. That makes the total Zin of the buffer essentially the pot's resistance, 100k per side. And if I'm not missing something, if you keep it floating it should be 100k*2. High so to speak and it will reveal any weak points of the interconnects used. But I can see you are doing well!
That's great...
Regarding how I connect my equipment.
As now I only have SE stuff.
Long ago I tested the connections a lot, and I found out that connecting RCA shield to both S and R on Behringer input gives best results.
I installed a little switch which cut's the GND from the female TRS jack inside the Behringer.
When I set GND to OFF, the input will be "floating"
My Topping test dac (E30II) likes when I cut the GND OFF, It have some spurs/grass around the 998Hz fundamental. Them spurs dissapear when GND is disconnected
The switch is nice to have, as I don't have to fiddle with the jack's connection then.
Well reason I asked about the Zin is that I would like to try using some voltage divider's for some testing.
I will try to calculate them, for having 1V input at different levels, just like an autoranger do.
I will see if I get better or worse measurement's this way?
When doing this I will leave the 100K pot at max input (no resistance)
http://www.mh-audio.nl/Calculators/VD.html
Btw. : Is Greak easter this year starting april 16 ???
Jesper.
Regarding how I connect my equipment.
As now I only have SE stuff.
Long ago I tested the connections a lot, and I found out that connecting RCA shield to both S and R on Behringer input gives best results.
I installed a little switch which cut's the GND from the female TRS jack inside the Behringer.
When I set GND to OFF, the input will be "floating"
My Topping test dac (E30II) likes when I cut the GND OFF, It have some spurs/grass around the 998Hz fundamental. Them spurs dissapear when GND is disconnected
The switch is nice to have, as I don't have to fiddle with the jack's connection then.
Well reason I asked about the Zin is that I would like to try using some voltage divider's for some testing.
I will try to calculate them, for having 1V input at different levels, just like an autoranger do.
I will see if I get better or worse measurement's this way?
When doing this I will leave the 100K pot at max input (no resistance)
http://www.mh-audio.nl/Calculators/VD.html
Btw. : Is Greak easter this year starting april 16 ???
Jesper.
Your soundcard looks like Janus https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjiwO3Fg5j-AhVMRvEDHYzwB6IQFnoECB8QAQ&url=https://en.wikipedia.org/wiki/Janus&usg=AOvVaw1UKVEs0KSofuvUv7ugg6wq
Normally, this ground switch should be left permanently off no matter if the DUT is SE or balanced. If you feel like experimentizing you could make an interconnect with a twisted pair plus shield -XLR cable. Hot to tip, cold to ring and shield to sleeve. At the RCA side only hot and cold connected.
The input pot is a practical necessity. For critical measurements it would be good to keep it full open and use a custom voltage divider. But instead of 1V try for something that takes the ADC close to full scale. If memory serves, it should be around 1,25V.
Yes, Greek Easter usually is out of phase with Catholic.
Normally, this ground switch should be left permanently off no matter if the DUT is SE or balanced. If you feel like experimentizing you could make an interconnect with a twisted pair plus shield -XLR cable. Hot to tip, cold to ring and shield to sleeve. At the RCA side only hot and cold connected.
The input pot is a practical necessity. For critical measurements it would be good to keep it full open and use a custom voltage divider. But instead of 1V try for something that takes the ADC close to full scale. If memory serves, it should be around 1,25V.
Yes, Greek Easter usually is out of phase with Catholic.
You guy's mervelous to know
I tried to "BackCalculate", using this site as before as a' ref. http://www.mh-audio.nl/Calculators/VD.html
Everything verified with scope & DMM etc.. both with and without inserted (loaded) into the Behringer.
Voltages seem's to match very closely to the calculator.
I'am not sure, it can be BackCalculated like this, but I have no other possibilities to check the impedance of the Behringer.
Please take a look at my finding's...
Jesper.
100000 / 68000 ohm divider / Zi ~ 518600 ohm (100K/68K / Zi:518.6K)
100000 / 27000 ohm divider / Zi ~ 970000 ohm (100K/27K / Zi:970K)
100000 / 68000 ohm divider / Zi ~ 990000 ohm (100K/68K / Zi:990K)
I tried to "BackCalculate", using this site as before as a' ref. http://www.mh-audio.nl/Calculators/VD.html
Everything verified with scope & DMM etc.. both with and without inserted (loaded) into the Behringer.
Voltages seem's to match very closely to the calculator.
I'am not sure, it can be BackCalculated like this, but I have no other possibilities to check the impedance of the Behringer.
Please take a look at my finding's...
Jesper.
100000 / 68000 ohm divider / Zi ~ 518600 ohm (100K/68K / Zi:518.6K)
100000 / 27000 ohm divider / Zi ~ 970000 ohm (100K/27K / Zi:970K)
100000 / 68000 ohm divider / Zi ~ 990000 ohm (100K/68K / Zi:990K)