Suppressed sound

[Cladpirate]

Baracuda works well, detects gold. However the sound from speakers is very lathargic. I can barely hear anything with a 50mm piezo. I have ok soundd with a small 8 ohm speaker. What could be the deal?

[Cladpirate]

Do I need to fit an audio transformer? I like it to be really loud please.

[waltr]

Baracuda works well, detects gold. However the sound from speakers is very lathargic. I can barely hear anything with a 50mm piezo. I have ok soundd with a small 8 ohm speaker. What could be the deal?

Only thing I can think of is an impedance mismatch. An 8 Ohm speaker does not need Voltage since it is Current driven whereas the Piezo is more a Voltage driven device. However, there are many piezo speaker with varying impedance.

A transformer to change from 8 Ohm to maybe a 1k Ohm may work.
Or try increasing the value of R37 to a kOhm or more.

[kt315]

[Denots]

Hi, I just finished my baracuda circuit last night, checked all soldering from below with a torch, cleaned the underside of the board with iso and a toothbrush, every component was tested before assembly but I have really muffled sound as well.
Tried with two piezo buzzers and get the same result, I will try again with a small speaker and report back

edit:
8ohm speaker made no difference

[kt315]

night time is not good time. put pics of board.

[Cladpirate]

Mine woks with an 8 ohm speaker just not as loud as I am used to on my other detectors. I bought a mono amplifier from sparkfun and that amped the sound but seemed to be injecting a lot of noise into the system. I'm going to tey and make my headphones better and see if that improves things by waterproofing some 8 ohm speakers.

[Denots]

night time is not good time. put pics of board.

will do, the board is fitted ina box at the moment but I should have it out later so I?ll take some photos.

Mine woks with an 8 ohm speaker just not as loud as I am used to on my other detectors. I bought a mono amplifier from sparkfun and that amped the sound but seemed to be injecting a lot of noise into the system. I'm going to tey and make my headphones better and see if that improves things by waterproofing some 8 ohm speakers.

Yeah mine works with 8ohm speaker too but just not nearly as loud as it should be, even the instructions describe it as being really loud. I wonder if we bought our kits close together and we may have got a batch of dodgy components, seems strange we are both having this issue, couldnt find any other mention of it happening to someone else. I might try replacing components in the audio circuit one by one and see if that fixes it

[Cladpirate]

The board with the low sound is a green one from silverdog. I never got my red one working so nothing to compare to. The detector works well ennough at the moment and I have a coil that can pick up a 5g ring at about 11 and a half inches so I'm not going to push my luck. I'll just make the headphones well and call it done.

[dbanner]

Easiest way is to put small output transformer. I have salvaged such a transformer from ancient AM pocket transistor radio with 8 Ohm speaker for my surf PI. The audio becomes very loud! I soldered the tiny transformer directly onto back of speaker terminals, then I run wires for optional headphone jack. Simple hack.
A more elaborate approach would be to use a three terminal headphone jack between the tranformer and speaker in order to switch out the speaker when the headphones are connected.

[Suvabard]

I'm sure you've covered this but just in case (from the build guide):

One word of warning. For some inexplicable reason, small (polarity sensitive) piezo speakers will
function with a 12V supply even if connected the wrong way round. However, once the battery
voltage drops to around 11V, they stop working. If this happens, then check you have the piezo
connected correctly.