Low Input Volume

Moderator: flatmax

Post Reply
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Low Input Volume

Post by jerry110 » Sun Jul 30, 2017 4:32 pm

Since i cant search because "its too common words" (search is totally useless) i'll ask what is the secret? I have a lot of hiss and very low volume ...I'm only using one channel to record a scanner BCD996p2 rec port using radiosave.sh script.....I've gone thru the setup and i have adjusted alsamixer........Id hate to have to put a hardware preamp on it.....I would upload a sample file but the board dost allow mp3's? on an audio board forum.........seriously?
Here is the relevant part of the script

Code: Select all

 #  Save the timestamp / filename:
        echo `date +%F-%a-%H%M` > $WORKDIR/radiosave.idx
 (arecord --quiet --rate=$RATE & echo $! > $WORKDIR/radiosave.pid ) | \
           lame --quiet --tt `date +%F-%a-%H%M` --ta "$ID3V2ARTIST" \
           --tl "$ID3V2ALBUM" - $WORKDIR/`cat $WORKDIR/radiosave.idx`.mp3 &
}
Top
flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: Low Input Volume

Post by flatmax » Mon Jul 31, 2017 12:07 am

OK - thanks for pointing this out, I have added the following :
aiff
au
flac
mp2
mp3
snd
voc
w64
wav
wavpcm

As far as your mixer setup, what does the command amixer report ?
What are you using for sample format settings ?

Is there ground loop hum at all ?

thanks
Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Tue Aug 01, 2017 10:00 am

Outstanding Thanks I'll let you hear it.....
They both have separate wall warts powering them...
doesn't sound like a ground loop hum sounds more of an amplifier hum...

Sample rate is

Code: Select all

. $CONFIGFILE
RATE=11025      # Sampling rate, adjust for best quality vs file size
#######  SUBROUTINES   #######
in the script
I used the sample config in the thread here....
I have tried the mixer settings high low inbetween and upside down....
This file is coming out of the scanner rec port....not sure what the issue could be......
sample_scanner.mp3
(79.57 KiB) Downloaded 174 times
#########################REPORT#################################

Code: Select all

pi@policescanner:~/scripts $ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 115 [91%] [-6.00dB]
  Front Right: Playback 115 [91%] [-6.00dB]
Simple mixer control 'Master Playback ZC',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [off]
  Front Right: Playback [off]
Simple mixer control 'Sidetone',0
  Capabilities: pvolume pvolume-joined
  Playback channels: Mono
  Limits: Playback 0 - 3
  Mono: Playback 0 [0%] [-15.00dB]
Simple mixer control 'Line',0
  Capabilities: cswitch
  Capture channels: Front Left - Front Right
  Front Left: Capture [on]
  Front Right: Capture [on]
Simple mixer control 'Mic',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic Boost',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 1
  Mono: 0 [0%] [0.00dB]
Simple mixer control 'Playback Deemphasis',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Capture',0
  Capabilities: cvolume
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 31
  Front Left: Capture 20 [65%] [-4.50dB]
  Front Right: Capture 20 [65%] [-4.50dB]
Simple mixer control 'ADC High Pass Filter',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Input Mux',0
  Capabilities: enum
  Items: 'Line In' 'Mic'
  Item0: 'Line In'
Simple mixer control 'Output Mixer HiFi',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Output Mixer Line Bypass',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Output Mixer Mic Sidetone',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Store DC Offset',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
pi@policescanner:~/scripts $
Last edited by jerry110 on Tue Aug 01, 2017 10:18 am, edited 1 time in total.
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Tue Aug 01, 2017 10:14 am

My intentions are once i get this stable and built to release it as a pre configured box (for two scanners) on radioreference for the scanner enthusiasts and move to ver 2.0 and buy the octo card for multiple scanner recording (each rca input a separate scanner)
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Tue Aug 01, 2017 2:01 pm

I bumped up the bit rate to 128k ....seemed to have fixed the humm but the audio is low and blown out at the same time LOL
oh man this is frustrating....
I love the board don't get me wrong it just seems to be finicky or the software...
This audio should be BOOMING unless i'm missing something........Which as this point is more then likely :shock:
Can the line in (rca Inputs) take headphone level input? or would that blow the frontend right out of the board?
sample2.mp3
(103.37 KiB) Downloaded 145 times
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Tue Aug 01, 2017 2:38 pm

Did a little more testing with lame with scale i got the audio booming now BUT THE HISS IS BACK LOL
here is how i'm executing it

Code: Select all

arecord --quiet --rate=128000

Code: Select all

  lame --quiet -m s --scale-l 10 --tt 2017-08-01-Tue-0419 --ta SOMETHING --tl Scanner Recordings - /recordings/tmp/2017-08-01-Tue-0419.mp3
If i can get the hiss out it would be ok so i can run a strip out of silence....
If i can get the hiss out and the blown out audio down it would be utopia

Next i am going to try to power the Pi with a battery bank and see if the noise is coming in on the wall wart......
Attachments
Sample3.mp3
(135.62 KiB) Downloaded 145 times
Top
flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: Low Input Volume

Post by flatmax » Tue Aug 01, 2017 8:34 pm

Here is the output of my amixer - I have set the input gain to 12 dB (what does yours report ?) :

Code: Select all

pi@raspberrypi:~ $ amixer
Simple mixer control 'Master',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 121 [95%] [0.00dB]
  Front Right: Playback 121 [95%] [0.00dB]
Simple mixer control 'Master Playback ZC',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [off]
  Front Right: Playback [off]
Simple mixer control 'Sidetone',0
  Capabilities: pvolume pvolume-joined
  Playback channels: Mono
  Limits: Playback 0 - 3
  Mono: Playback 0 [0%] [-15.00dB]
Simple mixer control 'Line',0
  Capabilities: cswitch
  Capture channels: Front Left - Front Right
  Front Left: Capture [on]
  Front Right: Capture [on]
Simple mixer control 'Mic',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic Boost',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 1
  Mono: 0 [0%] [0.00dB]
Simple mixer control 'Playback Deemphasis',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Capture',0
  Capabilities: cvolume
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 31
  Front Left: Capture 31 [100%] [12.00dB]
  Front Right: Capture 31 [100%] [12.00dB]
Simple mixer control 'ADC High Pass Filter',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Input Mux',0
  Capabilities: enum
  Items: 'Line In' 'Mic'
  Item0: 'Line In'
Simple mixer control 'Output Mixer HiFi',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Output Mixer Line Bypass',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Output Mixer Mic Sidetone',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Store DC Offset',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Wed Aug 02, 2017 12:04 pm

This is what mine reports
I'm sorry to say battery power dose not clean the audio up at all.....

Code: Select all

Simple mixer control 'Master',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 121 [95%] [0.00dB]
  Front Right: Playback 121 [95%] [0.00dB]
Simple mixer control 'Master Playback ZC',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [off]
  Front Right: Playback [off]
Simple mixer control 'Sidetone',0
  Capabilities: pvolume pvolume-joined
  Playback channels: Mono
  Limits: Playback 0 - 3
  Mono: Playback 0 [0%] [-15.00dB]
Simple mixer control 'Line',0
  Capabilities: cswitch
  Capture channels: Front Left - Front Right
  Front Left: Capture [on]
  Front Right: Capture [on]
Simple mixer control 'Mic',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]
Simple mixer control 'Mic Boost',0
  Capabilities: volume volume-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 1
  Mono: 0 [0%] [0.00dB]
Simple mixer control 'Playback Deemphasis',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Capture',0
  Capabilities: cvolume
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 31
  Front Left: Capture 23 [74%] [0.00dB]
  Front Right: Capture 23 [74%] [0.00dB]
Simple mixer control 'ADC High Pass Filter',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Input Mux',0
  Capabilities: enum
  Items: 'Line In' 'Mic'
  Item0: 'Line In'
Simple mixer control 'Output Mixer HiFi',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Output Mixer Line Bypass',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Output Mixer Mic Sidetone',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Simple mixer control 'Store DC Offset',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [off]
Top
jerry110
Posts: 7
Joined: Sun Jul 30, 2017 4:19 pm

Re: Low Input Volume

Post by jerry110 » Thu Aug 03, 2017 8:24 am

I think i figured out the issue....The signal coming out of the scanner is at "mic level" the soundcard is expecting "line level" the noise is just the gain to try to get the weak signal up....i'll test with a mic level soundcard
Top
flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: Low Input Volume

Post by flatmax » Tue Aug 08, 2017 9:29 pm

OK - I wonder if it is possible to connect it to the electret microphone connector ?
Beware it has a DC offset, which you can measure and if necessary put a decoupling cap between the two systems.

That input line has PLENTY of gain.

Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector
Top
Post Reply

Return to “Stereo soundcard for the Raspberry Pi”

Who is online

Users browsing this forum: No registered users and 5 guests