I refurbished an old radio. My setup is a raspberry pi 2 with volumio 1.55 and the hifiberri amp+. I’m using a couple of Monacor 5" speakers (SPH 60, goo.gl/bs3kVY). Everything has been working nicely for a while, but last week I noticed a crackling sound. I experimented a bit, and found out that is caused by low freqs:
Playing this video (youtube.com/watch?v=M8gjsefNYpE, a tone from 2KHz to 0Hz) makes the crackling appear at around 225Hz and it’s specially noticeable from 50Hz and below. I tried different songs and when they are relatively quiet, the bass parts cause the crackling (but some songs might be able to mask the noise).
So far, only one of the speakers present the problem, and when switching the outputs (left speaker to right and vice versa) the behaviour is the same (the same speaker fails, the other works perfectly), confirming that only one of the speakers present the problem, and that the amp+ board is working. I checked the speaker and nothing seems to be out of the ordinary: wiring is still firmly soldered, no cracks in the cones, rubber parts are in perfect condition.
Given that I’m not knowledgeable at all in this matters, is something wrong with my testing? Should I try to do something else to confirm that the speaker is the problem? Sadly, I don’t have any other amps at hand to test the speaker.
Hi!
When reading what you describe, we can think to a mechanical problem with the speaker such a misaligned coil, or a damage coil due to a too loud use… Now (maybe) the paper that support the coil rubbing the magnet. Or check (if you can) that there no acoustic insulation piece that moved and touching the membrane.
I know that everything points to “you blew the speakers”, but I’m quite surprised of having done that, as I am using a “25W” amp and a “60W, 30Wrms” speaker (quotes on the power ratings, as I know that you have to take them with a pinch of salt). I use it on a 4x4m room and I always listen to moderate volume levels. Plus, if it was a overdriving issue, I guess that the chances of blowing the two of them would be quite high (but I also understand that it one thing doesn’t exclude the other).
In any case, the faulty one clearly makes a rubbing sound when the membrane is pushed by hand, whereas the good one doesn’t, so either the coils are blown or something is broken or loose inside.
To sum up, I just want to know what did I do wrong, in order to not do it again. It’s hard to believe for me that I blew a hefty 5" speaker weighing around 1kg with an amp that doesn’t even have a heatsink (I know it’s a class D amp, and thus doesn’t require them, but even though…), listening to music at reasonable levels (and by reasonable I really mean it!).
I get the same popping noises periodically when listening to quieter songs. I was originally using Volumio with a hifiberry HD. I installed the hifiberry OS and the popping noise went away. I recently switched to an Allo Boss2 and installed Volumio. The popping noise is back. I haven’t made any changes with the speakers, amps, or their connections. It really seems like the issue is with Volumio.
I’m bit late in the party, put you just told the most likely reason that the speaker blow.
killing speaker voice coil with amplifier which does not put out a lot of wattage is most easy way, because you easily overdrive it already on listening levels you might find reasonable. Most Speakers can withstand 1.5-2 times the rated wattage if there is no distortion, when installed properly.
I’m also experiencing a similar crackling issue using Pi4, volumio with Hifiberry Dac2HD.
At low frequenies, my left speaker will occasionally crackle. Its not the speaker or the amp as I have tested with a bluetooth adapter - not with the pi. I’ve also swapped over speaker cables and it will happen in the right speaker. So strange. I’ve reinstalled, restarted. etc. Anyone find a fix for this?
strangely enough I had an external dac that crackled very slightly with certain songs but not with a full frequency sweep. I did all the swaps until it came down to the dac. Tried a different dac and no problems.