Banging head off wall CCTV Mic problem

[bowlingo]

Hi all,

I am trying to connect a mic to my 4 way cctv dvr unit of which has a mono audio in and audio out BNC socket.

Today I bought a set of pc speakers with amp in and connected it to the mono audio out via BNC to phono adaptor - phono to 3.5mm jack socket adaptor and the speakers are working fine...they are humming etc when I turn the relevant camera on

I then did the same connection routine on the BNC mono input socket (BNC to phono adaptor - phono to 3.5mm jack adaptor)

I then connected the mic from my pc headphones of which are a 3.5mm jack but they dont work no matter what I do

I have tried mono - stereo adaptors also

I have contacted the company who sold me the 4 way dvr and spoke to the tech support and he said its set up correctly but said he has never tried connecting a non cctv mic (the cctv mics seem to have a red power connection and a white phono sound connection)

Tomorrow I am getting a 3.5mm jack "Audio Technica ATR4697 Omnidirectional Condenser Boundary Microphone" delivered and am pretty sure it wont work due to the headphone mic not working...this new mic is to be put into an external rabbit hutch so I can record the neighbours shouting abuse across our garden etc

I have tested the headphone mic on my pc and its working fine

Can anyone put me out of my misery please

Thanks

 

[OwainDIYer]

The audio input is probably at line level and the 'cctv microphones' incorporate a pre-amplifier.

You need a mic with a pre-amplifier like this

http://www.maplin.co.uk/cctv-audio-module-24992

or this

http://www.maplin.co.uk/miniature-cctv-microphone-27695

Cable would be this or similar

http://www.maplin.co.uk/18m-cctv-audio-video-and-power-cable-228843

or if you want to use an unamplified microphone you'd use a pr-eamplifier like this

http://www.maplin.co.uk/microphone-preamplifier-29908

Maplin items shown as examples only.

 

[bowlingo]

The audio input is probably at line level and the 'cctv microphones' incorporate a pre-amplifier.

You need a mic with a pre-amplifier like this

http://www.maplin.co.uk/cctv-audio-module-24992

or this

http://www.maplin.co.uk/miniature-cctv-microphone-27695

Cable would be this or similar

http://www.maplin.co.uk/18m-cctv-audio-video-and-power-cable-228843

or if you want to use an unamplified microphone you'd use a pr-eamplifier like this

http://www.maplin.co.uk/microphone-preamplifier-29908

Maplin items shown as examples only.

Thanks for your reply....

The CCTV mics ive seen dont look like they will pick up a good all around signal.

So it would seem I need to use the pre amp and things are getting complicated..As I see it to use the amp I will need to get a

1/4 inch jack - 3.5mm jack converter http://www.maplin.co.uk/1-4-mono-plug-to-3.5mmmono-socket-adaptor-1277 and put it in the left input....I will then have to get a lead with 1 x male phono connector on each end http://www.maplin.co.uk/phono-plug-to-plug-lead-1019..plug one end into the BNC - female phono connector http://www.maplin.co.uk/bnc-plug-to-phono-socketadaptor-1593 on the dvr then plug the other end into the left hand output of the amp?

Does this look correct before I go and buy the amp tomorrow? im a bit confused about using one side of the amp as it will be mono and not sure how this will work i.e will it come out of one speaker only?

Thanks

 

[OwainDIYer]

Thanks for your reply....

The CCTV mics ive seen dont look like they will pick up a good all around signal.

They won't. But mics that will, externally, will cost £££s.

A google suggests the one you intend buying (a) comes with a 1/4" plug adapter, and (b) runs off a watch battery, which may need rather frequent changing.

So it would seem I need to use the pre amp and things are getting complicated..As I see it to use the amp I will need to get a

1/4 inch jack - 3.5mm jack converter http://www.maplin.co.uk/1-4-mono-plug-to-3.5mmmono-socket-adaptor-1277 and put it in the left input....I will then have to get a lead with 1 x male phono connector on each end http://www.maplin.co.uk/phono-plug-to-plug-lead-1019..plug one end into the BNC - female phono connector http://www.maplin.co.uk/bnc-plug-to-phono-socketadaptor-1593 on the dvr then plug the other end into the left hand output of the amp?

The microphone apparently comes with 1/4" adapter.

You can get phono-BNC leads that would go from the pre-amp output to DVR input without adapters
http://www.maplin.co.uk/bnc-phono-video-lead-1047?ordercode=L48BA

(They're labelled for video but will be fine for audio in this application)

Does this look correct before I go and buy the amp tomorrow? im a bit confused about using one side of the amp as it will be mono and not sure how this will work i.e will it come out of one speaker only?

You will need to connect the audio output from the DVR to both L & R line inputs on your speakers or TV. If your DVR has an output on SCART it will usually do this for you.


If you want to go from BNC mono audio to 3.5mm stereo audio you'd probably need to solder up a cable.

Soldering up some custom cables would be easier anyway.

 

[bowlingo]

A google suggests the one you intend buying (a) comes with a 1/4" plug adapter, and (b) runs off a watch battery, which may need rather frequent changing.

The guy from tech support seems to think one battery will last for 1000 hours....I think this is a bit adventurous..but at 76p a battery I dont mind changing every couple of weeks

The microphone apparently comes with 1/4" adapter.

Im going to get a 3.5mm - 1/4 inch convertor just in case the mic dosent arrive tomorrow and I can test using headphone mic

You will need to connect the audio output from the DVR to both L & R line inputs on your speakers or TV. If your DVR has an output on SCART it will usually do this for you.

It dosent have scart but can be networked to a pc (right next to it) once ive got it working via pc speakers ive bought for £10 ill rig it to the pc


If you want to go from BNC mono audio to 3.5mm stereo audio you'd probably need to solder up a cable. Soldering up some custom cables would be easier anyway.

Mono is fine as long as it works through both speakers

 

[Alarm]

Just go to a decent supplier and ask for a microphone that runs off the power of the camera.
You will obviously need a spare pair to connect. And the DVR to have audio input. And realise it will not be able to have audio from every camera, unless you have switching relays.