Strange Soundcard Calibration?

[Veleric]

I'm embarrassed to admit it it, but I've taking REW measurements for some time now, and somehow never bothered to do the soundcard calibration step!
So anyway, I finally did it and this is what I got (see image below, cal file attached).
I did not get any error message, but compared to the examples in the helpfile, the rolloff at low frequency seems huge!

Is this okay to use this or do I have a problem to solve?

I'm using the Realtek Audio sound card in my PC.

One thing I'm suspicious of is the HDMI to RCA converter i'm using. For normal measurements, I send the the HDMI output of the PC to a an old Sherwood 4109 Receiver which powers the speakers. But since the Sherwood has no HDMI inputs, I use an HDMI to RCA converter and connect that to the CD inputs of the Sherwood.

https://www.bestbuy.com/site/insignia-hdmi-to-rca-converter-black/6134314.p?skuId=6134314&extStoreId=580&ref=212&loc=1&gclid=EAIaIQobChMIscS_nMbj_wIV2NzICh0O0gSpEAQYASABEgKGGPD_BwE&gclsrc=aw.ds

So for the soundcard calibration, I connected the PC's HDMI output to the same HDMI to RCA converter, and connected that to the PC's mic jack using an RCA to trs cable adapter.

Is this the reason for the seemingly funky calibration results? Should I be making the connections differently?

Thanks,
Eric

 

[Veleric]

@John Mulcahy
Hey John, would appreciate any comments you might have about the soundcard calibration in the previous post. Is it okay, or is there a problem?

Anyone else's input would also be appreciated.

Thanks,
Eric

 

[John Mulcahy]

It appears to have a 170 Hz first order high pass applied to it, which isn't OK. You are using quite an old REW build, you could try the 5.20.13 current release and choose the device entries that start EXCL to use WASAPI exclusive drivers, that may bypass any Windows processing. Otherwise check what processing may be applied elsewhere in the measurement path.

 

[Veleric]

It appears to have a 170 Hz first order high pass applied to it, which isn't OK. You are using quite an old REW build, you could try the 5.20.13 current release and choose the device entries that start EXCL to use WASAPI exclusive drivers, that may bypass any Windows processing. Otherwise check what processing may be applied elsewhere in the measurement path.

Thanks John, I'll check those out.
Eric

 

[Veleric]

John,
I downloaded the 5.20.13 release. I can make measurements using either the default drivers or the EXCL drivers, but, when I try to calibrate the soundcard, the "next/cancel" buttons never appear. What might be causing that?
Thanks,
Eric

 

[John Mulcahy]

when I try to calibrate the soundcard, the "next/cancel" buttons never appear

Can you post a screenshot of the soundcard preferences after you press Calibrate soundcard?

 

[Veleric]

John,
Here is what it looks like:
I tried changing the Input and Loopback inputs (L/R) to both R, but the result was the same. No "Next" button appears.
Thanks,
Eric

 

[John Mulcahy]

The screen resolution is too low to show the full panel so the buttons are off the bottom. Next is automatically selected so you could just hit the space bar, but the V5.20.14 early access build should fit the screen better and does away with those buttons, https://www.avnirvana.com/threads/v5-20-14-early-access-build.11154/

 

[Veleric]

John,
Okay, hitting the space bar works to advance through the steps, until I have the input level set. Then when I press the space bar nothing happens....
Any ideas? Else I guess I'll try the early access build.
Thanks,
Eric

 

[John Mulcahy]

If you interact with any other controls the next button will no longer have focus.

 

[Veleric]

John,
Thanks. So I was finally able to run the soundcard calibration using the EXCL drivers. By "preadjusting" the level, I was able to "space bar" through the calibration.
Unfortunately, the result was the same (see below).

I've searched the soundcard settings for anything that looks like a possible source of the high pass filter, but there's nothing obvious (at least not to me!). Should I be looking for something on the "output" side or "input" side, or either?

If I got a UMIK-1 USB mic, would that necessarily avoid this problem?

Thanks,
Eric

 

[John Mulcahy]

USB mics don't use soundcard calibration, but if the issue is on output it would persist. If you go to the Windows sound control panel and select Properties for the playback device and then the recording device and in each case select Disable all enhancements on the Enhancements tab that should eliminate any Windows processing and any 3rd party processing. You may also need to check the Windows speaker configuration to make sure that isn't set for small desktop speakers or similar.

 

[Veleric]

Thanks John, I'll look one more time for those specific settings.
Is there any chance the issue is in the HDMI to RCA converter that I'm using to take the PC HDMI output to the input of the Receiver (for measurments) or mic/phono combo jack (for Soundcard calibration)?
Should I be using something else?

https://www.bestbuy.com/site/insignia-hdmi-to-rca-converter-black/6134314.p?skuId=6134314&extStoreId=580&ref=212&loc=1&gclid=EAIaIQobChMIscS_nMbj_wIV2NzICh0O0gSpEAQYASABEgKGGPD_BwE&gclsrc=aw.ds&irclickid=2ZcyEJxObxyPWXs2fyzGyz4vUkF2OH38STnhUg0&irgwc=1&ref=198&loc=Skimbit%20Ltd.&acampID=0&mpid=10078

Eric

 

[John Mulcahy]

It's probably not the HDMI to RCA converter, but a basic stereo USB soundcard would be much better than using the PC's HDMI output when the device you are connecting to doesn't have an HDMI input.

 

[Veleric]

John,
Could it be something as basic as this? Would I also be able to do impedance measurements using this?

Behringer U-Control UCA202 USB Audio Interface

16-bit/48kHz, 2-channel USB Audio Interface with Optical Out

www.sweetwater.com

Eric

 

[John Mulcahy]

That's OK for SPL measurements but not good for impedance, it has a lot of low frequency crosstalk which badly affects the results below about 30 Hz.

 

[Veleric]

That's OK for SPL measurements but not good for impedance, it has a lot of low frequency crosstalk which badly affects the results below about 30 Hz.

What about this? Any better?


If not, then this Steinberg UR12?


If I get a UMIK-1 and use it in combination with either of these USB interfaces for SPL measurements, would I still be connecting the UMIK-1 directly to the PC? And hence I'd still be using the be using the PC's soundcard for the mic input and using the USB interface only for the output to the speakers?

Thanks, Eric

 

[John Mulcahy]

The UR12 has 1 mic input and 1 high impedance line input, impedance measurement requires two inputs of the same type so that isn't suitable. UR22C would be a good choice, as would a Focusrite 2i2, but both are more expensive.

The Startech interface should be OK for SPL measurements and may be OK for impedance measurements.

USB mics like the UMIK-1 connect to a USB port.

 

[Veleric]

Okay, I'm leaning toward the Startech. Assuming I get the Startech 7.1 USB Sound Card, and UMIK-1, would the following be the right way to set up?

FOR SPL MEASUREMENTS

UMIK-1 to PC USB port (#1)
Startech USB Sound Card to PC USB port (#2)
Startech "Front Speakers" output (circled in red below) to Sherwood Receiver "CD IN" or "AUX IN" via TRS to RCA stereo breakoput cable
Sherwood speaker out (left or right) terminals to test speaker

Is this correct?

and FOR IMPEDANCE MEASUREMENTS

Startech to PC USB port
Use Startech "HEADPHONES" jack for output into the impedance rig
Use Startech "LINE-IN" jack for input from the impedance rig.

With this arrangement should I be able to use the "simple" 100 ohm rsense impedance rig (i.e. without any resistive divider and zener diodes)?

Alternatively for impedance, should/could I?:

Connect the Startech to the Sherwood Receiver (like for measurements) but then use the "PHONES" jack on the Sherwood for output into the impedance rig (instead of the Startech "HEADPHONES" jack
Use Startech "LINE-IN" jack for input from the impedance rig.

Would using the Sherwood PHONES jack be any better or worse than using the Startech HEADPHONES jack for the output? Are there any implications for design of the impedance rig?

Thanks,
Eric

 

[John Mulcahy]

Should be OK using the Startech as you set out above, with the simple impedance jig.

 

[Veleric]

Should be OK using the Startech as you set out above, with the simple impedance jig.

So there’s no reason to include the Sherwood in the set up for the impedance measurement? Is that correct?

 

[John Mulcahy]

Yes, unless the Startech headphone output is particularly feeble. Low output impedance and high output current are desirable in the impedance drive stage, especially if you plan to use low sense resistor values, but budget headphone drivers rarely offer either. That isn't usually a problem for the typical 100 ohm sense resistor though.

 

[Veleric]

thanks John!

 

[Veleric]

The Startech interface should be OK for SPL measurements and may be OK for impedance measurements.

USB mics like the UMIK-1 connect to a USB port.

I got the Startech Interface and the Umik-1 mic and have successfully loaded the cal file, set up the inputs and outputs, and made measurements. All seems to be working as expected there.

Then I was curious how the results with the Umik-1 would compare with the Dayton imm-6 mic that that I had been using previously.

I was also able to make measurements with the imm-6 mic (also using the Startech interface), and the results were quite similar (virtually identical) to those with the Umik-1. But the one thing that was odd is that when I ran a sweep using the imm-6, the meter display graph on the bottom left of the measurements page shows no increase in the input signal during the sweep measurement. Likewise, duing the "check level" test on the measurements page. That makes me wonder if something I've done in the setup is still not quite right. What would be the cause of that?

Thanks, Eric

 

[John Mulcahy]

IMM-6 requires a TRRS headset jack, the Startech doesn't appear to have one.