hissing sound coming from behind woofer on one side AR11

Looks like a closed box and my first thought is an leak. Don't understand"behind woofer" Inside ?? Outside ?? Or sounds like behind woofer from the front.

I would troubleshoot a woofer with low frequency test tones, without any high frequencies being generated. I used to do a quick test with AM radio.

Changing frequency will likely change the sound. Get close, feel around. Can't tell from your description, but could be the woofer itself making mechanical surround, voice coil, or suspension sounds.

greg

If the AR11 were a ducted-port speaker (I don't think it is), it would likely be the "port noise complaint" (OUCH!), with air "rushing" or "whistling" through the port.

It's hard to believe the sound /is/ coming from the speaker when you say "it isn't related to the music or any movement of the cone or any signal put through it". Speakers are passive, and do not produce sounds on their own -- other than, perhaps, loud crashing/breaking noises when they're knocked off a shelf.

Make sure a snake hasn't crawled behind the speaker.

On Tue, 20 Jul 2010 20:57:56 +0000 (UTC), Meat Plow put finger to keyboard and composed:

- Franc Zabkar

--
Please remove one 'i' from my address when replying by email.

If there is a cross-over board in the case, you may have an electrolytic capacitor going bad. When they over heat, they'll make those sort of noises.

"Reverend Fuzzy"

If there is a cross-over board in the case, you may have an electrolytic capacitor going bad. When they over heat, they'll make those sort of noises.

** That is utterly bizarre crap.

.... Phil

My guess is that the suspension for the woofer cone has come unglued. This can allow the voice coil to rub on the magnet, which makes sounds that are mechanical and vary with volume.

To check for this, you'll need to remove the grill cloth so you can get to the speakers. Gently press all five fingers of one hand against the woofer cone, next to the center dome. Push sideways on the cone; try several directions. It should not want to move. It may be useful to do this on both speaker (stereo, right?) so you can be sure of any differences.

You may see that the "surround" has disintegrated. That would be an obvious flaw. There is also a lower support called a spider which centers the cone near its small end. If the spider has come unglued, it can be reglued while holding the cone centered.

Older AR speakers used wirewound controls for the tone controls. These corrode and lose contact. The effect of this is to lose the midrange or tweeter completely. They can be disassembled and cleaned, but they don't tend to make extra noises. The capacitors in decent speaker crossovers are never electrolytics, so they don't generally deteriorate over time.

Not half as bizarre as your instant flaming of something I have seen happen in my personal experience. If you haven't seen it, yourself, don't just call my answer crap... PROVE it can't happen.

"Jim Adney"

You may see that the "surround" has disintegrated.

** Happens to ALL speakers made with foam surrounds - like the AR11.

That would be an obvious flaw.

** Obvious only if you look, the OP must be blind.

If the spider has come unglued,

** Very unlikely.

Older AR speakers used wirewound controls for the tone controls.

** Not the AR 11 - it uses a switch.

The capacitors in decent speaker crossovers are never electrolytics,

** Fraid that is just not true.

Most famous brand name hi-fi speakers use bi-polar electros for the larger values at least.

.... Phil

"Reverend Fuzzy" "Phil Allison"

Not half as bizarre as your instant flaming of something I have seen happen in my personal experience.

** What you wrote here is bizarre crap.

What you might have seen elsewhere at sometime is another matter.

If you haven't seen it, yourself,

** Your post here is bizarre crap.

Electros used in hi-fi speakers like the AR11 do not "over heat" and hence are not the source of peculiar hissing noises.

Ever worked on an AR11??

I have.

.... Phil

Never? I haven't checked "decent" speakers lately, but the AR11 is from an era when non-polar electrolytics were commonly used. Even inexpensive Mylar caps cost more than electrolytics.

The tendency toward two-way designs (the AR11 is three-way) has raised the crossover point to a frequency that makes the use of a film cap more-practical. But even "the" classic two-way speaker (The Advent Speaker) used an electrolytic.

The DQ-10 was one of the first speakers to use film caps. The original version used mostly electrolytics; the changeover occurred several years into production. In exchange for loaning him a pair of Pearl mics, Jon sent me a box of cheap Mexican Mylar caps, and I repopulated the crossovers. I was in such a rush to get it all done, that I didn't leave one of my four DQ-10s unmodded, and wasn't able to make a valid comparison.

I /was/ going to suggest a mechanical problem with the woofer or midrange, but the OP /specifically stated/ that the hissing sound had no relationship with what was playing, or how loud it was, or /any movement of the cone/.

And you've seen electrolitics in cross-overs overheating and hissing? I'm with Phil on this one...

Can't say I've heard an x-over cap his but I've seen them over heat as evidenced by broken and distored shrink wrap covering .

I dont know why but the first thing I tried was pushing the cone in to see if I could identify that rasping effect when a speaker has blown. Dont know why I did this as the speaker has obviously not blown (the bass is still quite good. And for some reason I have never understood, the surrounds in those old speakers aren't made of rubber which disintegrates so that isnt a problem) in that way but what I didnt try was to push eccentrically and see if there was any resistance.

I suspect I am going to have to get them over to Miller Sound at some time to rebuild (along with a pair of AR3s I have which have badly corroded cross-overs) but what I was wondering was whether this sound was likely to make the speaker terminal.

Incidentally the snake behind the woofer is the best description of what I can actually hear! (a snake with a volume control, that is)

For once, so am I, although oddly enough, just today I had a non-polarised electro in the crossover of a JVC home cinema speaker, that had bulged so badly that it had split open. I suppose that when the can actually ruptured, it might have hissed for a few microseconds ... :-)

Arfa

"Amanda Ripanykhazov"

And for some reason I have never understood, the surrounds in those old speakers aren't made of rubber which disintegrates so that isnt a problem

** The AR11 woofer has a FOAM surround - all foam surrounds disintegrate after about 10 to 20 years.

Most woofers made these days use rubber (aka roll) surrounds which have an indefinite life excepting the odd case of adhesive failure.

.... Phil

I know it is a silly question, but are you SURE that the hiss isn't coming out of your amplifier? (have you put a scope on the speaker lines or substituted either speaker or amp?)

From your description, it isn't clear to me that you have eliminated the 'more obvious' possibility that your amplifier is putting out white noise, perhaps intermittently varying in amplitude.

he

Yeah, switching one speaker pretty much solved that one.

What, solved it as in proved that the amplifier *was* the cause, or solved it as in it wasn't ?

Arfa