Minelab Audio Enhancements/Speaker Units?

[Mechanic]

Originally Posted by ivconic


Also speaker can produce loopback interferences
I think Minelab did not include such audio and internal speaker because SD,GP and GPX machines are considered as "profy" and for "serious" metal detecting, especially nugget hunting, where slightest change in treshold can make huge difference and we know that such changes are not easy to hear via ordinary speaker.

Yes the speaker loopback interference can be a real pain especially when using large coils.

Wm6, good idea!

I still prefer good headphones though, blanks out all of the other noises like wind, leaves crushing under your feet, trees falling on top of you If you were having trouble hearing the threshold an amp between the detector and headphones would be advantageous. A good pair of headphones will make a big difference over crappy ones. I have tried the underchin headphones you get from the cheapie shops, they leave a lot to be desired $2. The cheap buggers only use 1 conductor in the lead!!! I found some good ones that cost $6 at an electronics store and I bought a couple of pairs. Unfortunately they no longer stock them Luckily though, I am still on my first pair! The next ones in the chain cost about $15 and they range up to over $100 for ear plug type headphones

Cheers Mick

[bklein]

What is loopback interference? Is that the e-magnetic signal from the speaker being picked up by the RX coil? So the speaker box needs to be shielded somehow to prevent this... or more distant...?
Aren't piezo's like pictured too limited in frequency range?
In the TI site they talk a little about ceramic speakers. What are these? Are they really talking about piezo's or?
Is there an optimum load resistance for the GP output? I read somewhere where that may be 1K but thought I'd ask.

Finderskeepers - best to start a new thread on your question as I'm sure several would like to then discuss SD2000 circuitry and debugging. Sounds like a cool challenge.