Please see post #33.
SDS200 speaker pops at beginning and end of transmissions
- Thread starter Kaleier1
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Please see post #33.
No hum or popping if using the Ethernet connection.
Hum or popping can appear if using the copper connection. An isolation transformer will fix that.
It appears with the internal speaker. This is the basis for my request of videos from users who say their scanner doesn't pop.
Maybe tomorrow. I'd have to shut down all the other scanners I've got running to get clear audio.
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Here is a video of my sds200 taken with an iPhone about 6 inches from the front with the internal speaker. There are various volume levels, etc. Some shots showing the popping when going from 0->1 on the volume. I was controlling the volume from proscan.
->link<- to my thread about this showing details.
->link<- to my thread about this showing details.
Sounds about right. Now I want to see who DOESN'T have that issue and what's different about their units.
Yep, quite annoying. Not acceptable for a $700 scanner
The crackling you hear around :03 and :09 is coming from the table I was resting on to hold my phone steady, not the scanner.
My unit doesn't have the factory grounding part, but it does have the StaticDischarge fix done.
tvengr
Well Known Member
Jon, what do you know about the audio output circuitry in the SDS200? Usually, a pop or thump is caused by DC voltage applied to the speaker. Is there a possibility of a shorted output capacitor or a DC imbalance in the output of the amp if it is direct coupled. I would check to see if there is any measurable DC voltage across the speaker. If so, the level should change when the pop occurs.
Been listening to my SDS200 until I return it after the New Year. I noticed the humming seems to be getting louder and within the hum I hear what sounds like random static. Would be happy to do the Static Discharge fix but I don't know that it would fix the popping noise from the internal speaker. No sense in messing with it and getting the return denied due to mucking something up. I can hear the popping noise from 6 feet away and it isn't dependent on volume. It is always the same level.
Although I know you can set volume offsets for channels, and I believe talk groups, I wish you could set them for individual radio IDs. I am listening to DMR at a comfortable volume, and can hear some people who are speaking quietly, but there are some people who sound like they got their microphone in their mouth and are yelling. Wish there was some sort of audio limiting.
Although I know you can set volume offsets for channels, and I believe talk groups, I wish you could set them for individual radio IDs. I am listening to DMR at a comfortable volume, and can hear some people who are speaking quietly, but there are some people who sound like they got their microphone in their mouth and are yelling. Wish there was some sort of audio limiting.
If there is a capacitor inline with the output (and there usually is, specifically to block DC voltages), you won't see a DC voltage across the speaker. But when the amp powers on and off, that can change a DC voltage on the input side of a capacitor and cause a thump or pop as the capacitor charges or discharges. I don't have access to a schematic, so I couldn't tell you specifically what is happening.
I suspect there is some separation between the headphone jack and the internal speaker, perhaps a different final amp, because I can hear a little bit of a pop in the headphones at the beginning and end of transmissions, but there's no trace of it in the main speaker or in the digital output.
tvengr
Well Known Member
I have had experience where the coupling caps to the output ladders of audio distribution amps would short and cause pops in the audio when switching between sources due the DC levels. If an output cap became leaky or shorted, that could pass changing DC levels from the amp to the speaker. Quite often, a balanced audio amp can be directly coupled to a speaker without using a coupling cap. In its quiescent state, there should be no more than a couple of mV of DC across the speaker. I agree that a DC voltage change on the input side of a coupling cap can cause a pop or a thump. The time constant of a cap charging will usually minimize a pop compared to an immediate change in DC level.
I could say the same thing about my DMR radio.
The "static" is RFI from the CPU leaking into the audio circuitry because of improper grounding. The StaticDischarge fix solves that problem. My -200 has the StaticDischarge fix, and doesn't have any RFI noise or popping in the internal speaker.
tvengr
Well Known Member
I did the fix also and it is indeed very effective.
I can vouch for that! 
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I hear the popping sound now, very slightly. But I only hear it because I went listening for it due to reading this thread. If I had not seen this thread I would not have even noticed it.
I don't know (but I hope) it doesn't get worse over time. I've only had this unit for a few days so still working my way around operating it.
I believe the mitigation piece for the "hum" is pre-installed on mine since I do hear that but only if I quiet the room and listen for it within a foot or so of the speaker.
I don't know (but I hope) it doesn't get worse over time. I've only had this unit for a few days so still working my way around operating it.
I believe the mitigation piece for the "hum" is pre-installed on mine since I do hear that but only if I quiet the room and listen for it within a foot or so of the speaker.
StaticDischarge
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Does it have the latest firmware? If not, what version is it?
Both had Main version 1.06.25 and Sub version 1.01.10 when I got them but I updated both to the latest version.
I was careful to listen for the popping on the new replacement before updating the firmware in case it made a difference.
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