Hello all.
I’m currently using a VM100 module (with a 2x30VCA) to power my Home Cinema SubWoofer
It works very well except when I power it off: a “PLOP” sounds in the sub at any time…
PS: I tried to stop first the source or first the VM100… same issue…
Do you have any idea on how to avoid this ?
It is normal for the amp to produce a light ‘plop’-sound at power off.
The enclosure of the sub can amplify this ‘plop’-sound.
It is difficult for us to determine if the sound is excessive or not.
Please measure if a DC offset is present at the speaker output.
Do you hear the ‘plop’-sound immediately when the power switch is turned off or after a couple of seconds ?
Hi VEL417 
Thanks for taking ownership on my issue.
The PLOP actually occurs after a couple of seconds after the turn Off (around 5 seconds) -> Do you want me to measure the exact delay ?
I’ll measure the DC offset at the speaker output this evening.
–> do you want me to measure it, with or without the Speaker ?
–> I planned to connect my Voltmeter in // of the Speaker output and in DC mode. Is it the right way to measure the DC offset you asked for ?
Thanks for your feedback,
Cheers
If it appears a couple of seconds after turn-off, it is quite normal.
The discharging of the caps is never symmetric, so that causes the ‘plop’.
Just in case, you can measure the DC offset by putting a DVM in parallel with the speaker (no signal at input). A couple of tens of mV is normal, a couple of volts is not normal.
Good morning Sir,
As promised, I did some measures:
. the PLOP comes 8 seconds after turn-off (and the speaker moves 5 mm)
. the DC offset is between 29 and 30 mV (with and without speaker)
Based on this measures you will probably consider nothing is wrong…
But how do amp manufacturers manage to eliminate this PLOP ?
Adding a K4700 module (which is stéreo, provides more than needed and owns its own supply, and at the end is quite expensive compared to VM100 price)?
Would you suggest a similare circuit that could be integrated with VM100 module (Mono, reuse the same supply -30V- if supply needed , focussed on this PLOP) ?
Many thanks for your advise…
In most amps the speakers are decoupled by means of a relay.
We do not carry an anti-plop circuit for mono amps…
I actually didn’t see any such module in you catalog…
My request is (just) to get support/advise/URL to get a simple schema of such small/simple module I could build, in order to cut the speaker immediately at turn-off.
Thanks to you and all forum members for feecback here…