DIY Talkback tech advise needed

[The Turtle]

Hi all,

I'm need to make up a real simple hardwired talkback system.

The idea is to go from a mic to headphones now i no there are preamps that can do this but the whole system just needs to be really simple no switches or buttons.

It just needs to go from the mic soldered into some kind of preamp then a pair of headphones soldered on the out no need for stereo just two mono is fine, also phantom power is always needed so of power i want just a mains lead agin soldered in. The idea is so nothing can be taken apart and lost.

I'm happy with the actual making it but when it comes to the design i get a bit stuck.


Ok well I have got to the point with the starts of a schematic. Would i need a mic pre and a headphone amp of just mic pre straight to headphones?

 

[Phrasemaker]

Hi, to be honest I think the cost of a budget box capable of performing your desired function is cheap to the extent that finding a small amp with a spec that suits your need and packaging it would be a whole load more hassle. If you are determined to go the made to measure route there are probably a number of low output amp projects available at a major electronics retailer which can be housed in a case which such outlets also sell.

Whether you need a pre-amp then something to drive the headphones is dependent upon the sensitivity of the input of the amplifier. There is much to consider, as mics vary impedance wise, also a degree of equalization occurs via additional circuitry in purpose built devices. Having an audible sound which represents the input source then output through headphones would be tiresome if too fat or thin or tonally poor in some other respect.

I'm not sure if you are also meaning that you'd like this device to provide phantom power, as I find your comment about just soldering in a mains lead slightly worrying. I think that maybe down to the slight vagueness of your set of objectives in respect of how you aim to satisfy them.

A simple, low cost mic pre-amp such as some of the tube pre-amps would drive headphones and provide phantom to a mic. You also need to bear in mind that you'll have to short the L/R of the headphones so you don't end up with only one side of the phones providing the sound from the microphone.

Time is money, if you are dead set on having all soldered connections, maybe get a small pre-built unit and butcher it to suit your needs, unless I really need to make an item that's going to be crucial and nothing off the peg will do, I consider my hourly rate when working and base my decision upon whether the item works out cheaper to buy when made by someone else using their time.

Regards

Tim

 

[Steenamaroo]

What's your background? This sounds like quite a task to take on, and like phrasemaker, I was a little worried about your use of the word mains.

Basically what you want is a mic preamp with a headphone output, which exists as a standalone unit anyway. You can go and buy one of those.
An old mbox with the knob turned to monitor would do exactly what you want, but would obviously require a usb connection for power.
That may result in the L/R issue that Phrase mentioned; I can't remember.


Maybe I've missed something, but who are you planning to talk to? Presumably whoever's wearing the headphones can't hear anything else anyway, so just use a phone.

 

[moresound]

Hello .

 

[Steenamaroo]

Edison?

Just realised this is a dead thread walking.
Man i need to get more sleep.

 

[PRHunt]

Although I have no real clue of the use for the project, I was going to make a sensible suggestion like getting some kits for pre-amp and phantom and headphone driver, and stringing them together in box, and powering it by a wall wart, so no mains wiring necessary. But I guess I won't bother now.

Paul