r3wt
Member
Yet another "my BCD536HP has audio issues" thread, but I don't believe this is related to other issues...
Scanner was purchased new back in July and everything was fine for about 2 months, until one day things went horribly wrong. Nothing was changed on that day or for at least a week prior. I have a sample of the bad audio and a diagram of the entire setup available at these URLs:
http://hoff.mn/scanner/files/BCD536HP-audio-problems.mp3
http://hoff.mn/scanner/files/diagram.png
Equipment list:
DPD OmniX
Alpha delta GBWM/ATT3G50N
PAR notch filters (152.5/162.5)
4-port Keyspan RS-232 interface
USBpre2 audio interface
Mac mini (latest generation)
APC SU1000
Audio interface was connected to the headphone jack using a 3.5mm mono to RCA adapter. I tried connecting only tip, but that just made the problem worse (and increased the noise floor by about 60dB). I also restarted the scanner, restarted the computer, swapped out the USBpre2, and connected audio to internal sound interface instead, all with no improvement.
I later decided to give the external speaker jack a try, connecting 3.5mm tip to RCA tip and chassis ground to RCA shield. Much better - the distortion is gone, but the noise floor is 30-40dB higher than the headphone jack (up to -72dB). Volume level with the headphone jack was at max, down to 18 for the ext speaker jack (both set to peak around -10dBV, which is RCA line level). Also, it seems the problem isn't present with the internal speaker or when headphones are connected to the headphone jack.
Some other observations...
-Headphone sleeve is bonded to the chassis only when squelch is closed
-With squelch open, headphone sleeve has the inverse signal of the tip present on it, about 12-14dB lower (connecting the RCA cable to left channel results in the right channel having the inverse signal, which didn't happen originally)
You can listen to my feed on RR to hear how the external speaker output sounds, for a comparison.
Any thoughts? I'm leaning towards component failure within the scanner at this point.
Scanner was purchased new back in July and everything was fine for about 2 months, until one day things went horribly wrong. Nothing was changed on that day or for at least a week prior. I have a sample of the bad audio and a diagram of the entire setup available at these URLs:
http://hoff.mn/scanner/files/BCD536HP-audio-problems.mp3
http://hoff.mn/scanner/files/diagram.png
Equipment list:
DPD OmniX
Alpha delta GBWM/ATT3G50N
PAR notch filters (152.5/162.5)
4-port Keyspan RS-232 interface
USBpre2 audio interface
Mac mini (latest generation)
APC SU1000
Audio interface was connected to the headphone jack using a 3.5mm mono to RCA adapter. I tried connecting only tip, but that just made the problem worse (and increased the noise floor by about 60dB). I also restarted the scanner, restarted the computer, swapped out the USBpre2, and connected audio to internal sound interface instead, all with no improvement.
I later decided to give the external speaker jack a try, connecting 3.5mm tip to RCA tip and chassis ground to RCA shield. Much better - the distortion is gone, but the noise floor is 30-40dB higher than the headphone jack (up to -72dB). Volume level with the headphone jack was at max, down to 18 for the ext speaker jack (both set to peak around -10dBV, which is RCA line level). Also, it seems the problem isn't present with the internal speaker or when headphones are connected to the headphone jack.
Some other observations...
-Headphone sleeve is bonded to the chassis only when squelch is closed
-With squelch open, headphone sleeve has the inverse signal of the tip present on it, about 12-14dB lower (connecting the RCA cable to left channel results in the right channel having the inverse signal, which didn't happen originally)
You can listen to my feed on RR to hear how the external speaker output sounds, for a comparison.
Any thoughts? I'm leaning towards component failure within the scanner at this point.