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Re: Let's Talk Audio Amplifiers

PostPosted: Sat Jun 08, 2019 7:53 am
by L4R3L2
madsamurai, thank you for your suggestion for a quick and cheap audio amplifier. I finally got the parts you suggested and it does work well. However, the Lock Amp I picked up does have significantly more gain than the pieced together unit. In that regard, the lock-specific unit is much superior.

The pieced together amp is great for learning, where one can essentially put the piezo pickup on the lock case itself, but it is barely helpful in the case of thicker, insulated doors unless you place the pickup on the dial itself, which can be done by hand when listening for contact points. The Lock Amp (and probably other, well-made lock-specific amplifiers) is a huge improvement. The biggest down side is that the gain is so high that background noises can be a distraction. Even my stomach gurgling a foot away from the pickup sounded like the pickup was literally inside my stomach! Any way, there is a big difference. I'm sure there may be other amplifiers and/or pickups that may be better suited to configure for lock work.

The last safe I bought took several hours to manipulate, and the timing of acquiring the Lock Amp could not have been more perfect. It helped immensely for precisely determining contact point locations. Even though the lock is a basic 6730, there were some lessons to be learned from this particular lock, with this particular combination. I left the combination on this lock so I can learn from it when I have the time. In short, pay attention to the left contact point too!

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Re: Let's Talk Audio Amplifiers

PostPosted: Thu Jun 13, 2019 12:24 am
by Oldfast
Sure is nice to see you're still hard at it and goin' strong Terry.

Re: Let's Talk Audio Amplifiers

PostPosted: Thu Jun 20, 2019 9:40 am
by Visitor
The older I get the harder it is to hear anything coming through my headphones so I've had an idea to order one of the cheap oscilloscope kits from banggood, it will allow me to use any type of sensor I want and I'll see the interaction on the screen so I'm thinking a decent pickup should give some good results.
For less than a pack of cigarettes I'll have a mobile phone sized oscilloscope in my pocket which I could also use for digi safes so I'll let you know how I get on (even though I need an amp less and less these days I like to be prepared). The amp I've used all these years eats batteries so a usb recharable unit will be a nice change.

Re: Let's Talk Audio Amplifiers

PostPosted: Tue Nov 16, 2021 4:15 pm
by femurat
Resurrecting an old thread to thank you all for making me buy a cheap amplifier. I followed madsamurai suggestion and got a mini piezo pickup for guitars and a headphone guitar amp.

Is it safe to glue a magnet to the pickup? I'm worried I can break it, so I'm thinking to use electrical tape to attach it to the safe door.

What should I do now? Pay attention to the sound made by contact points? I've tried it on a lock I have on a wooden stand and it surely let me hear the contact points. Anything else?

Thanks :)

Re: Let's Talk Audio Amplifiers

PostPosted: Tue Nov 16, 2021 4:49 pm
by MartinHewitt
I have never noticed, that a magnet has a negative effect on the piezo.

Yes, it is the click a pin makes when it is clashing with a fly.

Re: Let's Talk Audio Amplifiers

PostPosted: Sat Nov 20, 2021 4:58 pm
by pickmonger2
When using an audio amp do I just listen to what the amp gives or does it help to attenuate or amplify certain frequencies.

Any suggestions what frequencies I should experiment with or are there to many variables to even hazard a guess.