Speaker Protection Kit for under $5

[jacques antoine]

I use separated small transformer for the speaker protection. I cost approx. 2Euro, and PCB mounted.

Same here, adapted from a Buildaudioamps schematics.

Jacques

 

[AndrewT]

Do these little guys protect against turn off thump? I have some compression drivers I'd rather not destroy 😉

delay to ON and instant OFF isolates the speaker before tha amplifier starts to shut down.

Instant OFF requires detection of the AC waveform and that loss of AC triggers the circuit.

This can be used for input mute of a Power Amplifier and can also be used as an output mute of a Source.

 

[sajti]

Instant OFF requires detection of the AC waveform and that loss of AC triggers the circuit.

Or simply use the smallest possible capacitor in the protection PSU. I use 470uF only, followed by common 3 terminal regulator.

Sajti

 

[AndrewT]

too slow.

 

[thimios]

Same here, adapted from a Buildaudioamps schematics.

Jacques

Can you share files,pcb and schematic?

 

[sajti]

too slow.

No. It works well in practice.

Sajti

 

[scottjoplin]

Not a universal solution. AC detection is the only way to be certain of the fastest possible off.

 

[sajti]

Not a universal solution.

No, but easy to adopt, and easy to try in practice.

Sajti

 

[jacques antoine]

Can you share files,pcb and schematic?

Hi Thimios,
Other Audio Related Projects | BuildAudioAmps
For the BOM you have to subscribe (it's free).
Cheers,
Jacques

 

[silverprout]

too slow.

You should use very low Z relays without any capacitor after the rectifier.

PS : others should try to plug and unplug several times their boards to see what happened 😀

 

[AndrewT]

You should use very low Z relays without any capacitor after the rectifier.

PS : others should try to plug and unplug several times their boards to see what happened 😀

You are reading but not assessing the content. Read and understand and discard the chaff.

Add the time to detect the loss of AC waveform. That amounts to ~10ms.
Add on the electronic delay, maybe another ms.
Add on the relay drop out time, maybe another 2 to 5ms
That totals 12ms to 18ms.
Waiting for the DC on the power supply to sag enough to allow the relay to drop out could take 10000ms, or if you arrange for a very low charge storage one could get down to maybe 1000ms
Too slow, by more than a decade and could be three decades slower to isolate.

 

[sajti]

Waiting for the DC on the power supply to sag enough to allow the relay to drop out could take 10000ms, or if you arrange for a very low charge storage one could get down to maybe 1000ms

This is simply not true, in this format.

Sajti

 

[scottjoplin]

You either protect your speaker or you don't, I don't see the point of maybe protecting your speaker

 

[sajti]

Here is the simulation.

15V transformer, 220uF, 12V 3 terminal regulator. The relays are simulated as 180ohm load (2xOmron G2RL2 12V coil).
Sine wave runs up to 2s. The output voltage falls to 1V in 70ms(blue line) . Relay must release at 1,2V.

Sajti

 

[AndrewT]

This is simply not true, in this format.

Sajti

Have you analysed what needs to change to allow the relay to drop out?

Edit:
You have now analysed, but your estimates are out by a long margin.

 

[sajti]

You have now analysed, but your estimates are out by a long margin.

Is 70ms is too long? How is it compares to Your 10000ms estimation?

Sajti

 

[AndrewT]

waiting for the PSU to slowly discharge.

 

[Vrystaat]

Does this look like a viable solution after the smoothing caps ?
A DC Fault Protection Circuit for Audio Amplifiers
Sorry not $5.

 

[sajti]

waiting for the PSU to slowly discharge.

I give it up.

Sajti

 

[Vrystaat]

This is a schematic from Quasi. Cheap and it works.