Blown speakers(again)
Discussion
Hi All,
I'm hoping someone more tech aware may be able to offer advice. I've a sonos amp (sonos connect) driving in ceiling speakers. My problem is that on three occasions the speakers have blown, at different times. The bass driver has blown, tweeter is always fine. I'm on my third set of speakers and second amp. The tech guys at Sonos have exchanged the amp as a gesture of goodwill as their remote diagnostics didn't flag any amp faults. Monitor Audio are at the end of their tether as they're fed up sending replacement speakers. This was a pro instal and speaker cable is good quality (i'm told). The installer has checked his cables and they're fine.
Spec as follows
Sonos Amp - Class-D. Rated output 110W RMS (2x55W continuous average power into 8 ohms, THD+N<0.02%) with both channels driven, 22Hz-20KHZ-AES17 measurement bandwidth.
Speakers - Monitor Audio CPC Radius in ceiling, 6ohms, 88 dB, power 70w, recommended amp 5 - 60watts.
We don't run high volumes, it's a kitchen so normally just radio. It sounds great when it's on but I just don't know where to go now.
Any of you guys offer a tuppenceworth?, cheers in advance for reading.
Ginger
I'm hoping someone more tech aware may be able to offer advice. I've a sonos amp (sonos connect) driving in ceiling speakers. My problem is that on three occasions the speakers have blown, at different times. The bass driver has blown, tweeter is always fine. I'm on my third set of speakers and second amp. The tech guys at Sonos have exchanged the amp as a gesture of goodwill as their remote diagnostics didn't flag any amp faults. Monitor Audio are at the end of their tether as they're fed up sending replacement speakers. This was a pro instal and speaker cable is good quality (i'm told). The installer has checked his cables and they're fine.
Spec as follows
Sonos Amp - Class-D. Rated output 110W RMS (2x55W continuous average power into 8 ohms, THD+N<0.02%) with both channels driven, 22Hz-20KHZ-AES17 measurement bandwidth.
Speakers - Monitor Audio CPC Radius in ceiling, 6ohms, 88 dB, power 70w, recommended amp 5 - 60watts.
We don't run high volumes, it's a kitchen so normally just radio. It sounds great when it's on but I just don't know where to go now.
Any of you guys offer a tuppenceworth?, cheers in advance for reading.
Ginger
Hi,
Thanks for replying, cable from amp to speakers approx 3m and uninterrupted (good quality i'm told), library is sourced from a NAS via wifi, teenager in house but sonos were able to tell me how loud and how often the amp was used. (I gave permission for the amp to be monitored) other than that I'm at a loss too. It's too consistent to be a random fault, three decent speakers replaced, all with blown bass drivers.
Anyway, hopefully someone has a eureka as I've run out.
Cheers again guys, Ginger
Thanks for replying, cable from amp to speakers approx 3m and uninterrupted (good quality i'm told), library is sourced from a NAS via wifi, teenager in house but sonos were able to tell me how loud and how often the amp was used. (I gave permission for the amp to be monitored) other than that I'm at a loss too. It's too consistent to be a random fault, three decent speakers replaced, all with blown bass drivers.
Anyway, hopefully someone has a eureka as I've run out.
Cheers again guys, Ginger
I wonder if there is a fault with the amp that is passing DC current to the speaker. That your tweeter isn't effected would make sense as the crossover circuit would probably remove any DC from the tweeter's circuit. The way you could tell is if you watch the cone with the grille off: When you turn the Sonos on if the cone jumps either in or out and then stays in that position, there is DC reaching the bass driver. This combined with the music would be causing the speaker to reach the end stops, either that or continuous DC through the cone will burn it out after a while. It might not even need to be very high current.
Just a theory and it's late at night, so maybe not the clearest of heads, but worth looking into I think.
Just a theory and it's late at night, so maybe not the clearest of heads, but worth looking into I think.
OldSkoolRS said:
I wonder if there is a fault with the amp that is passing DC current to the speaker. That your tweeter isn't effected would make sense as the crossover circuit would probably remove any DC from the tweeter's circuit. The way you could tell is if you watch the cone with the grille off: When you turn the Sonos on if the cone jumps either in or out and then stays in that position, there is DC reaching the bass driver. This combined with the music would be causing the speaker to reach the end stops, either that or continuous DC through the cone will burn it out after a while. It might not even need to be very high current.
Just a theory and it's late at night, so maybe not the clearest of heads, but worth looking into I think.
I agree with OldSkool - there is something very wrong somewhere. With the amp off does a multimeter give any reading at the speaker end of the cable? I'm wondering if a downlight has burnt through the cable or something.Just a theory and it's late at night, so maybe not the clearest of heads, but worth looking into I think.
Cheers Oldskool/Northdave,
This is a new (replacement) amp so hopefully we can discount that. I'll check the speaker cable as they're the only part we haven't replaced. I also wondered if the incoming mains supply to the amp needed surge protection but don't know if i'm off on a tangent with that one. You guys looking at the spec on the speakers and amp, are they matched appropriately and if all else fails should I maybe look at bigger speakers?
Cheers again for your info,
Ginger
This is a new (replacement) amp so hopefully we can discount that. I'll check the speaker cable as they're the only part we haven't replaced. I also wondered if the incoming mains supply to the amp needed surge protection but don't know if i'm off on a tangent with that one. You guys looking at the spec on the speakers and amp, are they matched appropriately and if all else fails should I maybe look at bigger speakers?
Cheers again for your info,
Ginger
Apart from the speakers being lower impedance than the Sonos is rated for, then it all looks OK. It shouldn't make that much difference running 6 ohms instead of 8 ohms, but I don't know much about the Sonos amps I only have experience of Denon, NAD and Arcam amps. The lower impedance will draw more current from the amp, so was the original amp confirmed as faulty? If so maybe it doesn't like the low impedance and causes a fault perhaps. In this case the new amp could have developed the same fault again...
I've always used amplifiers more powerful than the speakers can handle - that shouldn't be an issue. Obviously you'd know not to run at full volume.
It's been my experience that the majority of speakers blow due to being driven to hard - either by a clipping amp, or simply too much power.
With my detective hat on (!) you have good quality circuitry in the Sonos and excellent quality in Monitor Audio (at least they always used to be - I haven't bought any MA gear for a long time). You have decent quality cabling. Therefore the only way the speakers could be blowing is through high volume..... Check your play queues! Has the teenager left AC/DC on there to give you a clue?
I'm only half joking....
The Sonos would be damaged first in the line in any power surge (normally) and amps can normally survive + they're fused.
Running them out of phase wouldn't hurt them..... Shorting the wires would damage the amp, not the speakers.
I'm at a loss other than suggesting they've been damaged by volume.
It's been my experience that the majority of speakers blow due to being driven to hard - either by a clipping amp, or simply too much power.
With my detective hat on (!) you have good quality circuitry in the Sonos and excellent quality in Monitor Audio (at least they always used to be - I haven't bought any MA gear for a long time). You have decent quality cabling. Therefore the only way the speakers could be blowing is through high volume..... Check your play queues! Has the teenager left AC/DC on there to give you a clue?
I'm only half joking....
The Sonos would be damaged first in the line in any power surge (normally) and amps can normally survive + they're fused.
Running them out of phase wouldn't hurt them..... Shorting the wires would damage the amp, not the speakers.
I'm at a loss other than suggesting they've been damaged by volume.
Unless there is a track with some very low bass at high levels then I'm a bit at a loss too (other than the 6 ohm issue I mentioned already). I managed to damage the driver on my Monolith subwoofer on War of the Worlds, even though it wasn't at a very high level (there was some 5Hz content apparently), but that's a bit different to playing some radio at modest levels.
Cheers NDA,
There is a teenager present and the queue that I have checked on the sonos amp indicates 50%(ish) volumes. You're absolutely right that she promises never to have played it loud when the girls are in! If the system were on occasion taking abuse in my absence, would more powerful speakers cope?
Cheers again guys,
Ginger
There is a teenager present and the queue that I have checked on the sonos amp indicates 50%(ish) volumes. You're absolutely right that she promises never to have played it loud when the girls are in! If the system were on occasion taking abuse in my absence, would more powerful speakers cope?
Cheers again guys,
Ginger
Is there a tone control or bass boost function? Even at 50% volume, if this was turned up/on then that could be enough to blow the driver (+12db bass boost for example might be the equivalent of turning it right up).
Bass boost or 'loudness' should only be used at low levels to overcome the ear's tendency to hear less bass at lower levels.
Bass boost or 'loudness' should only be used at low levels to overcome the ear's tendency to hear less bass at lower levels.
Megaphone,
The fault was loss of bass (I assumed faulty bass driver)Two speakers went back to MA but I have one in the attic with the same fault on the bass driver. Am I just checking for driver movement and obvious broken wires?. I'm willing to attempt repairs as they're excellent speakers,
Cheers again,
Ginger
The fault was loss of bass (I assumed faulty bass driver)Two speakers went back to MA but I have one in the attic with the same fault on the bass driver. Am I just checking for driver movement and obvious broken wires?. I'm willing to attempt repairs as they're excellent speakers,
Cheers again,
Ginger
Yes, more powerful speakers would offer greater protection. The balance can be that powerful speakers can sound a bit thin at lower volumes - so try before you buy if possible.
I'm wondering if there's a widget you could buy to enable your speakers to have an in line fuse to protect them?
I had a pair of Missions in my youth that were (thankfully) fused! They had great review too - so some fuse wire in the circuit should not erode the sonic quality.
Sonos amp > MA C180-T2 here, I have this in the bathroom and it's gets played at about 90% volume every morning (well the shower's noisy )
It's done this faultlessly for about two years now so I doubt that the 6ohm thing is an issue, your Sonos has been changed and the speakers too, the enviroment is less harsh than a bathroom (?), so you're left with the wiring and the teenager factor.
)It's done this faultlessly for about two years now so I doubt that the 6ohm thing is an issue, your Sonos has been changed and the speakers too, the enviroment is less harsh than a bathroom (?), so you're left with the wiring and the teenager factor.
Interesting to hear from 'Himself' with such a similar set up.
I'm definitely erring towards the teenager!!
I can't really see wiring being an issue (famous last words of course). I have a recording studio and all sorts of thumps and bumps are made when things are suddenly plugged in at volume - wires switched around etc. Crossing or cuttng wires normally hits the amp first.
Can you ban the teenager from using your gear and see how long the speakers last?!
I'm definitely erring towards the teenager!!
I can't really see wiring being an issue (famous last words of course). I have a recording studio and all sorts of thumps and bumps are made when things are suddenly plugged in at volume - wires switched around etc. Crossing or cuttng wires normally hits the amp first.
Can you ban the teenager from using your gear and see how long the speakers last?!
Edited by NDA on Sunday 13th January 15:59
?NDA said:
I can't really see wiring being an issue (famous last words of course).
TBH neither can I, unless there's a break in a wire, but that would surely cause the sound to break up.I've just played some Black Eyed Peas at 100% volume, I was more concerned about the ceiling than the speaker.
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