PoE camera Speaker ideas and help

[bug99]

I have been trying to see if I can use any of the newer Hikvision dome or min-dome PoE IP cameras for entrance. It is starting look like a poor option at this point. I have thus far failed at the audio output. The audio in is easy enough with a simple electret mic element utilizing the internal 2k 5V bias from the camera audio output circuit or the built in mic in the mini-domes (with the –S option).

The problem with the audio output is twofold. First it appears that Hikvision chose to not integrate a simple $0.5 class D output driver for the audio out line, thus preventing the use of a simple speaker on the connection, needing rather an amplifier and then a speaker (amplified speaker if you prefer). Second, a search on the net thus far has revealed no elegant micro amplified speakers (outdoor rated ~1 cubic inch, something like 30mm dia x 12mm thick) that can be mounted proud on the wall near the camera. Even if I found an amplified speaker, getting power to it will be a bit of a pain in the ass.

To me this is a serious engineering over-site on the designs with the audio options. It is so much easier and cheaper to simply install an internal 1W class D amplifier within the camera and push it out. This will not prevent the use of remote powered speakers.

On to my questions. Has anyone solved this audio out issue with the newer Hikvision cameras? If not, does another brand & model have an internal amplifier to drive an external speaker (8 ohm to 16 ohm)? Recommendations and links are welcome here. Perhaps going to an inside camera with the amp and speaker and microphone built in would be the easiest if they can handle condensing but sheltered outdoor weather?

 

[nayr]

Audio out sucks so bad nobody cares to bother.. Its not full duplex.. you can listen to audio or talk, but not both at same time.. and with the second or two latency from video stream its like talking on a walkie-talkie routed through a satellite.

Doorbell cameras use VoIP for 2-way full duplex audio with no perceivable latency.. your camera is not using VoIP, the experience will be shit in comparison.

 

[Fastb]

Larry Seibold,

Welcome to the forum!

I tried mightily to have an audio out solution usable outdoors. I used an amplified motorcycle speaker
Amazon.com: BOSS AUDIO MC300 Weatherproof 2.5" 400 Watt Motorcycle/ATV Amplified Speaker System With Chrome and Black Grilles, 3.5 mm Aux Input, Volume Control and Handlebar Mount: Car Electronics
It handles the elements (sealed), has a built in amp, and uses 12V DC. I would have used a POE splitter to power the mic and speaker, to avoid pulling a dedicated power line for the amp.

I was never able to get it working satisfactorily. nayr lays out serious issues. I'll expand from there.

Half duplex is lame, but in this application, it has a near-fatal drawback. When I'd be talking (audio out), the mic (audio in) isn't working. Meaning I wouldn't be recording audio when I was talking.

Also, toggling between talk and listen was clunky and slow. It's definitely not like a walkie talkie with a convenient PTT button (Push To Talk).

The true design shortcoming is not capable of full duplex audio. The lack of a built-in audio amp pales in comparison, IMHO.

In your application (entrance control) the dialogue with someone seeking entrance would be "back and forth", meaning several questions and answers. Interactive.

It is starting look like a poor option at this point.

I agree with your conclusion.

Fastb

 

[bug99]

I agree with both of you. I did not realize that the audio ckt was simplex. I have chosen to go with the fully integrated Ring Pro for now. If only i could send the real time or alerts to BI.

 

[Jayal]

Hola Fastb (and all)! Trust all is fine! My first post in this Forum. Hope someone of you can help me with an answer What kind of power Supply did you use (since its 400W speakers the Ampere must have been high enough)? Thanks in advance, Sincerely Joakim

 

[Fastb]

Hola Joakim!

There are several ways that speaker power can be measured, so the wattage rating of audio amps vary greatly.
I doubt the 400W spec of the system. And some reviewers say the same thing.

I used a regular 12V supply. When bench testing, I knew if I was drawing too much power from the 12V supply, it would get warm and the audio would have "motor-boat" sound effect. I didn't experience either, even with volume very loud. Also, this is a stereo amp, with two speakers. I'm only using one speaker, so I have that as "margin"

Fastb

 

[Jayal]

Hi Fastb! Much appreciated, thank you for your response! I dug around some more and found the manual (stupid me not looking into that first). Manual mentions 12V 5 A Power source. Im not 100% sure on how you can get 400W out from that but maybe someone more knowledgeable than me may explain
Thank you so much!
Sincerely Joakim

 

[Fastb]

Sure, 12V @ 5A = 72watts (ignoring efficiency loss)
It's a bit of measurement trickery... As explained below, from the internet, regarding how audio wattage is measured:

"There was Continuous or RMS, but since this was the smallest, least-impressive number, it was always listed last, in small print, if listed at all.


Double the RMS was “Dynamic” or “Peak” or “Music” power—the rationale being that an amplifier could likely deliver about double its continuous rating on a temporary peak in the music.


Double that was a really bogus number called “IPP” or Instantaneous Peak Power. The flimsy rationale was that an amplifier—if it had enough of a power supply—could probably muster about double its Peak power for the briefest of instants, if it had the wind at its back and you completely disregarded the distortion.


So a 30-watt/channel RMS stereo amplifier became a 60-watt/ch peak amp, which became a 120-watt IPP amp. Adding together the two channels, manufacturers would advertise, “240-watt Amplifier!” for a 30-per-side unit. Ugh."

Power supplies have capacitors on their output. Caps store & release energy, so the output voltage stays stable and consistent. When the music has a peak, say when the drummer strikes the drum, the audio signal spikes up. For this short period of time, the cap can supply the current needed, even if the current exceeds the amount of current the power supply can steadily produce.

Also, even though the amp's input voltage is 12V, that can be stepped up to a higher voltage inside the amp. If it didn't, your speaker could only see an audio signal that is + 6v (for a 12V swing). But by converting the 12V input to say, 36V, the audio signal can achieve a higher voltage. Then the caps can provide the current needed for the "instantaneous peak power" for loud drum spikes...

That's the short answer....

The wonders of Marketing and specmanship....

Fastb

 

[alastairstevenson]

Good information as always.
You are right about the bogus power values - pure marketing, unrelated to the real world.

But just to add a couple more comments :

your speaker could only see an audio signal that is + 6v (for a 12V swing).

Amps powered by a low, easy to provide, voltage such as 12v often have a bridge output as opposed to a single-ended output, so the peak amplitude is very nearly equal to the power supply voltage, so peak-to-peak would be 24v with a 12v power supply.
So with the power being proportional to the square of the voltage, a bridge output stage can provide 4 times the power of a single-ended stage for the same supply voltage.

 

[Fastb]

alastairstevenson,

Good point!
I didn't even think of a bridge amp!
Funny, since I once built a bridge amp for my car cassete deck, which only had pre-amp outputs!
I used an off-the-shelf bridge amp chip, added big electrolytic cap on input, some ignition noise filtering, a heatsink, and installed in my VW.
Back when having a cassette deck mounted in-dash was the bee's knees!

On second thought, maybe some memories are best lost to the fogs of time....

 

[VorlonFrog]

Funny, since I once built a bridge amp for my car cassete deck, which only had pre-amp outputs!
I used an off-the-shelf bridge amp chip, added big electrolytic cap on input, some ignition noise filtering, a heatsink, and installed in my VW.
Back when having a cassette deck mounted in-dash was the bee's knees!

On second thought, maybe some memories are best lost to the fogs of time....

Oh, those wild and wooly 1970s and Craig Powerplay coaxial speakers.