*pop* goes the woofer ....

rozeboosje

Strange thing going on with my subwoofer. Occasionally it starts "popping".

Nothing to do with the volume; this even happened when the music was merely set to "background" level during a sit-down meal, so nowhere near loud enough to interfere with the conversation.

At first I thought that somebody outside was slamming a car door. Then I realised that the sound was happening at regular intervals. And then I realised it was coming from the subwoofer.

What could be causing such a thing?

WillyFXP

Does the amp have a sub level input setting? Some sub woofers cut in and out depending on the input level, mine sometimes pops like this when the bass frequency levels are too high and the sub automatically cuts out.

rozeboosje

The music was playing at "polite conversation" background level ... You'd have to stop talking and listen carefully to be sure what song was playing.

WillyFXP

rozeboosje wrote: »

The music was playing at "polite conversation" background level ... You'd have to stop talking and listen carefully to be sure what song was playing.

Kinda my point, the lower the volume the lower the power going to the sub, hence why I asked if the amp has a sub level settings, maybe crossover or levels

rozeboosje

I don't know is the honest answer....

rozeboosje

What would a "sub levels" level look like on an amp?

So, basically then you're suggesting that this problem could happen when the volume level is "too low" for the sub-woofer to handle? In that case, would you expect the problem, if it occurs again, to go away when you turn up the volume?

And, finally, if you're right about this problem, would it be a problem with the amp, the subwoofer, or both perhaps? And if so, can it be fixed?

WillyFXP

There may be a crossover frequency setting for the sub somewhere in the amp menu, check its set correctly to the subs rated frequency. What's the amp make and model?

rozeboosje

WillyFXP wrote: »

There may be a crossover frequency setting for the sub somewhere in the amp menu, check its set correctly to the subs rated frequency. What's the amp make and model?

It's a Yamaha RX-V350

But the plot thickens. Last night the missus and I were sitting watching the telly. The amp was switched off. OFF. When suddenly, out of nowhere, the sub went *pop* ... O_o

ZENER

Does it POP at listening levels ? Are the pops in time with bass notes from music or completely random or at a regularity not that of the music you're listening to ? Is the sub a powered type independent of the rest of your system or is it a system type with other speakers connected to it and powered by it ?

Might be worth checking its power lead for loose connections, any signal cables for integrity and any possible sources of electrical interference from nearby mains loads. For example heavy loads like electric heaters that may have built in thermostats switching a high current load like a heating element etc.

If it's a standalone sub then try disconnecting it's input signal from the sub end and see if the popping still happens.

Ken

rozeboosje

Hi Ken,

The other day it "popped" even while the amplifier was switched off.

It's part of a Bose system of speakers (5.1) - If memory serves it's an Acoustimass 6 system.

The sub has its own power supply. I'm not sure how this works for all the other speakers. The leads do go from the amp to the sub and from there to the other speakers.

Not entirely sure how the "pops" occur. I have had the system taken off the power for a few days, and I switched it on this morning. So far, no pops. I do think that it takes a while before it starts "popping", and that is regardless of whether there is music playing or not. When it does start, the "pops" come in fairly regular intervals, at most a minute or so between "pops", and completely independent of what is playing (or whether the amp is even switched on - see above).

rozeboosje

There are no electric heaters or anything of that nature near the sub. I have made sure all connections are secure (insofar as I can). I don't think any of the leads are "loose". But I haven't got equipment that would allow me check for integrity ...

ZENER

Sounds like a possible fault with the Sub. Might be worth disconnecting the input leads from the back of the sub just to completely remove the amplifier from the equation.

From what I can work out the satellite speakers are fed directly from the Yamaha via the Subs rear connectors. The internal LF speaker is powered by the Subs internal amplifier but it's not clear what signal from the amplifier feeds the input, I'm presuming there is no connection to the SUB OUT on the back of the Yamaha which is a Line level signal as opposed to a Speaker level signal. Is this correct ?

The last paragraph on POST 10 above would convince me the problem lies in the Sub itself.

Ken

rozeboosje

Hi Ken

Hm. Ok.

I just turned up the volume to above "background murmur" level (I'm working from home right now, so I don't need the distraction, I just want something above Total Silence to keep me company ;-) ). And I notice there was no Base. Tilted the Sub and gave the power lead a good solid shove in, and the bass came back. Don't know whether that has anything to do with anything. I'll keep monitoring it. I might swap its power lead with another "figure 8" power lead. Maybe this one is just a bit out of shape and it doesn't connect properly.

Having said that, I also checked the connection to the amp, so I could answer your question. The 5 "surround" speakers all have direct connections to the Yamaha. One for each speaker. However, there is also a blue audio Jack labeled "LFE" and it is connected to the corresponding connector on the Yamaha as well.

Cheers


Pino

rozeboosje

Sorry - I meant ... the 5 surround speakers are connected directly from the Yamaha through the Sub ... as indicated earlier.

rozeboosje

Hi Ken,

Well, that's interesting.

I'm sorry if this sounds a bit [cough] "suggestive" but I found another "figure 8" power lead connected to a battery charger. Confirmed both the Sub's and the Charger's lead had similar sized fuses (5 amp, so grand), I took out the sub's lead, and shoved in the charger's lead instead, and I must say that as I shoved it in it felt like it was making a much more satifying "connection" than the original lead. (yipes that DOES sound suggestive)

Damn! Could it be that all this was simply caused by a slightly mis-shapen power lead!?!

Anyway - time will tell. By the way - this confirmed that the other 5 speakers are directly wired to the Yamaha, even though the connection goes through the Sub, but the Sub doesn't seem to "do" anything with their signal; when I took the lead out of the sub, the Low Frequencies obviously stopped as the Sub wasn't getting any power, but the 5 surround speakers happily carried on :-)

Pino

ZENER

Hopefully that's all she wrote on that one ! Good job you spotted it sooner rather than later, could quite easily have caused damage to the Bass driver or the internal amp if it had continued.

Let us know how it goes ?

Ken

rozeboosje

Will do. Thanks for the help!

rozeboosje

Alas ...

As you know, I was working from home day before yesterday, and listened to some background music after having replaced the power lead. No popping. That evening I turned off the amp. No popping. As I told you yesterday morning, I had noticed no popping. At that stage, everything had been switched off since Tuesday evening. But of course the sub-woofer is "always on", even if the amp is switched off.

Anyhow, when I got home yesterday evening my wife told me that when *she* got up a little later there was a pop coming out of the subwoofer.

So this has been the pattern then. I take the subwoofer off the power, and of course everything's silent. After a day or so I switch the power back on again, and everything is fine for several hours, nearly a day even. Then, regardless of whether there is music playing or not, this regular "pop" or (soft) "slam" noise occurs.

At this stage I think I have to conclude that either the power supply to the sub is dodgy, and while it's ok when it's cold, once it has warmed up to a certain point something starts happening. Maybe something arcs, I don't know. But once the sub is "warm" after having been on for a while, regular as clockwork ... *pop* or *slam*, whatever you want to call it. Either that, or there's a dodgy capacitor in there somewhere that, over time, builds up an unwanted charge and then starts discharging that at regular intervals.

I think I'll just drop it into the Bose shop in Dundrum in the next few days, let someone who knows what they're doing (i.e. not me) look at this. *sigh*

rozeboosje

Well the plot thickens. The subwoofer has just come back to the shop. They couldn't find anything wrong with it. So it appears to be the amplifier that is the problem.

Phoned Yamaha and they suggest a Factory Reset for starters. Here we go. Round two.

*sigh*

ZENER

Didn't you disconnect the signals from the Sub and still get the popping ? I know it was at least a suggestion on one of the posts here. Can you try that and let it sit for a day just to see ? Where are you based by the way ?

Ken

rozeboosje

Hi Ken,

I just re-read the thread and you're right; you suggested that earlier on. After the thing popped when the amp was switched off I went off on a tangent and I completely forgot to check that scenario. It'll be one of the first things I will check after I get my sub-woofer back.

From various phone calls - to Peats in Parnell street and Yamaha - a number of suggestions were made:

1) It could be a faulty heat-sink in the amp. Or damage to the LFE channel. In both cases I'd have to send it off for repairs.
2) It could be a problem with the amp's setup, and that is why the Yamaha guy suggested a factory reset. I guess that's an easy one to do, so I'll try that one.
3) It could be a problem caused by one of the peripherals plugged into it. I have a sky box, a WDTV Live ... and I'm not sure whether the Wii is currently plugged into the amp. The Yamaha guy suggested starting off with nothing plugged in, then if there's no popping start plugging in one thing at a time to see if / when it starts happening again.

I'm in North Wicklow

Pino

ZENER

Let's start by just disconnecting everything from the Sub and see what happens first.

Ken

rozeboosje

Will do - of course I have to go to the Bose shop to get it back first - but yeah. Will do that.

rozeboosje

A week later ...

Got my woofer that very evening, and plugged it in. Had the other 5 satellite speakers plugged into it alright, but I didn't have it connected to the amp. Left that for a day. No pops/slams.

After having spoken to the Yamaha guy, I decided that there would be no harm in addressing the two things he suggested. In my original setup, my amp was in a shelved unit, enclosed from all sides except the front. There was about 2cm, less than an inch, space around its sides. After the Yamaha guy mentioned "heat sink" issues, I thought that it may just be possible that in that enclosed space the amplifier would be building up just enough residual heat which then got trapped around it and start causing problems. Maybe if I worked the amp harder it might actually cut out completely due to safety switches, or maybe there IS a problem with its safety cut-out mechanism. Dunno, but, long story short, I took it out of there, and it's now sitting proudly on top of the unit, with nothing but empty space around it. The air can flow freely.

The other thing he had suggested was to give it a factory reset. I downloaded the manual and did that.

Plugged in the amp and left it sitting for a few hours. No pops.

I have now plugged in my two optical (Toslink/SPDIF) connections - the WDTV and the Sky box. I reckoned that those were extremely unlikely to cause electrical interference as they're, well, optical. I've used it for the last week, and watched TV and listened to music. No pops.

Happy days.