Microphone recording static plus sound

aikempshall · 03-28-2020, 05:25 AM

I have an ASUS Z87-K motherboard with built-in soundcard - about 5 years old. The audio is a Realtec ALC887 8-channel High Definition Audio CODEC.

I think the sound element of the motherboard has or is about to die.

With a microphone plugged in and when recording voice I get a lot of static plus the voice. I'm using audacity.

If I unplug the microphone and record again I get a lot of static, though not as much as with the microphone plugged in.

I suspect a faulty component, maybe a capacitor. Maybe it's interference from the fans. It's all guesswork.

I get the same symptoms with arecord / aplay

Code:

$ arecord -f dat -d 10 -r 48000 test.wav                                                                                                                                                                              
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo                                                                                                                                                               
$ aplay test.wav                                                                                                                                                                                                       
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo

I'm using slackware 14.2 with pulse. I've tried two different models of microphones. The microphones are ancient. 20+ years old.

I've added

Quote:

load-module module-echo-cancel

to /etc/pulse/default.pa

I have no problems with playback from the internet -or watching videos. To my ears the sound is good quality.

lspci

gives

Quote:

00:00.0 Host bridge: Intel Corporation 4th Gen Core Processor DRAM Controller (rev 06)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06)
00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06)
00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06)
00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05)
00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5)
00:1c.2 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5)
00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation Z87 Express LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05)
00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 11)

arecord -l

gives

Quote:

**** List of CAPTURE Hardware Devices ****
card 1: PCH [HDA Intel PCH], device 0: ALC887-VD Analog [ALC887-VD Analog]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 2: ALC887-VD Alt Analog [ALC887-VD Alt Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0

Should the next stage be buying a suitably priced sound card? I'm not currently using any of the expansion slots. So I should have available various versions of pcie slots.

Alex

wpeckham · 03-28-2020, 07:40 AM

First, I would borrow a good quality microphone with connecting wire (in good quality equipment that wire should be twisted and/or shielded) in excellent condition. Also, ground the case or the outside of the connector (to ground the wire shield). It is possible that the wires and traces are acting as antenna and picking up noise through induction. Shielding from that, or porting it to ground, should damp the noise if this is the issue. It is worth testing, and if this does not help you have ruled out one common cause.

ondoho · 03-28-2020, 08:23 AM

Rummaging around 'alsamixer', there's a setting called (Front/Rear) Mic Boost. Maybe helps turning that up?
Not sure how that translates into pulseaudio though.

fatmac · 03-28-2020, 10:05 AM

Make sure your mic wire is nowhere near a power cable, as that will introduce noise into a recording.

wpeckham · 03-28-2020, 02:32 PM

Quote:

Originally Posted by fatmac

Make sure your mic wire is nowhere near a power cable, as that will introduce noise into a recording.

Also away from LED and CFL lamps and cords for those lamps. Most of them broadcast a bit of "noise".
On that subject, I would also make sure the mic cord avoids proximity with your WIFI NIC and router, or any microwave oven.

(Yeah, no one has a microwave on their workbench or desk, but still!)

aikempshall · 03-30-2020, 08:14 AM

Quote:

Originally Posted by ondoho

Rummaging around 'alsamixer', there's a setting called (Front/Rear) Mic Boost. Maybe helps turning that up?
Not sure how that translates into pulseaudio though.

Thanks ondoho.

My understanding, from when I looked into it last week, is that one would increase Mic Boost if the microphone was having difficulty picking up sounds. My microphone picks up sounds perfectly well, but with a lot of background static.

aikempshall · 03-30-2020, 08:37 AM

Quote:

Originally Posted by wpeckham

First, I would borrow a good quality microphone with connecting wire (in good quality equipment that wire should be twisted and/or shielded) in excellent condition. Also, ground the case or the outside of the connector (to ground the wire shield). It is possible that the wires and traces are acting as antenna and picking up noise through induction. Shielding from that, or porting it to ground, should damp the noise if this is the issue. It is worth testing, and if this does not help you have ruled out one common cause.

Thanks wpeckham

With coronavirus I suspect it 's going to be quite difficult to borrow a good quality microphone, but will try.

Not sure if I can do anything about grounding. My soundcard is part of the motherboard. I'm assuming that my case and motherboard are grounded to mains through the psu. The case is metal - not aluminum.

aikempshall · 03-30-2020, 09:09 AM

Quote:

Originally Posted by fatmac

Make sure your mic wire is nowhere near a power cable, as that will introduce noise into a recording.

I shall have a look inside the case to see if there could be problems with cabling, Also, as advised by wpeckham, I've increased the distance between speaker and microphone and also increased the distance between my microphone and monitor.

I signed up to Skype on Friday on the first call the static was very bad when I was listening, but when I was talking the static disappeared. Made three subsequent calls and these have been effectively static free, though on one call I'm sure I detected some very faint static.

The problem must be something more subtle.

If I turn the volume down on my speaker I can get a balance between not hearing the static but still hearing the voice.

Alex

Hermani · 03-30-2020, 02:50 PM

Depending on the application:

You can get a decent USB microphone adapter from China for just a couple of dollars
You can get a simple USB audo mixer with USB interface. These can act as an input as well as an output. They come with something called "phantom power" for those professional microphone jacks.
You should still do what has previously been recommended.

Recently I shot some video using a Lavalier mike (that means one of those small microphone you can attach to your shirt) with a LONG cable. Of course, the cable picked up a large amount of static including what came from the TL tube lightning. The sound was a mess and I could barely make it usable.

Later, I used a shotgun microphone right on top of the camera, and the sound was WAY better with NO static even though it was recorded from 2 meters away.