[Mark Roberts]

I recently discovered that the 2" soft-cone midrange driver on one
of my 25-year-old ADS L710 speakers has a dent in it.

I was motivated to start checking system components after a
persistent "grittiness" started showing up in the audio. I first
thought it was multipath from one of my FM tuners. But I could not
seem to get rid of it by changing antenna location, and it didn't
appear when listening on headphones. Then I started hearing it
on other program sources. I took a processor out of circuit. Still
heard it. So I took a close look at the speakers and that's
when I found the damage.

Does it seem to make sense for the sound to be adversely affected
by this dent? Is there any way of getting the driver back to being
(semi)spherical again, other than replacing it? I don't really want
to replace it, because my repair skills are extremely basic and I
run the risk of messing up the speaker far worse than it is now.

How did the dent happen? I don't know; the original grilles are still
on the speakers and they've been in the same spot for almost five
years.

Any insight appreciated. Thanks.


--
Mark Roberts - Oakland, CA - NO HTML MAIL
Permission to archive this article in any form is hereby explicitly denied.
That includes quoting the article in its entirety.

[Mark D. Zacharias]

Mark Roberts wrote:
I recently discovered that the 2" soft-cone midrange driver on one
of my 25-year-old ADS L710 speakers has a dent in it.

I was motivated to start checking system components after a
persistent "grittiness" started showing up in the audio. I first
thought it was multipath from one of my FM tuners. But I could not
seem to get rid of it by changing antenna location, and it didn't
appear when listening on headphones. Then I started hearing it
on other program sources. I took a processor out of circuit. Still
heard it. So I took a close look at the speakers and that's
when I found the damage.

Does it seem to make sense for the sound to be adversely affected
by this dent? Is there any way of getting the driver back to being
(semi)spherical again, other than replacing it? I don't really want
to replace it, because my repair skills are extremely basic and I
run the risk of messing up the speaker far worse than it is now.

How did the dent happen? I don't know; the original grilles are still
on the speakers and they've been in the same spot for almost five
years.

Any insight appreciated. Thanks.

This dent probably should not be the cause of your problem. Would probably
affect dispersion more, I would think... unless the damage is more sever
than it looks.

I use tape (Scotch packing tape) to pull out dents. I've heard of people
using vacuum cleaners - though extreme caution is advised with any technique
you might try. That driver is probably no longer available.


Mark Z.

[Laurence Payne]

On Tue, 18 Jul 2006 02:30:03 -0000, (Mark
Roberts) wrote:

I recently discovered that the 2" soft-cone midrange driver on one
of my 25-year-old ADS L710 speakers has a dent in it.

I was motivated to start checking system components after a
persistent "grittiness" started showing up in the audio. I first
thought it was multipath from one of my FM tuners. But I could not
seem to get rid of it by changing antenna location, and it didn't
appear when listening on headphones. Then I started hearing it
on other program sources. I took a processor out of circuit. Still
heard it. So I took a close look at the speakers and that's
when I found the damage.

Does it seem to make sense for the sound to be adversely affected
by this dent? Is there any way of getting the driver back to being
(semi)spherical again, other than replacing it? I don't really want
to replace it, because my repair skills are extremely basic and I
run the risk of messing up the speaker far worse than it is now.

Disconnect one speaker. Swap the speakers. Find out if the gritty
sound is specific to one channel, one speaker or one location in your
room.

Pull the dent out with sticky tape. Or suck it out through a
handkerchief, if you can get your mouth down there. Or approach it
cautiously with a vacuum cleaner hose. But, of itself, the dent
probably has little effect on the sound. It may, however be a symptom
of someone having poked it with a pencil. Any children in our
household?

[Robert Gault]

Mark Roberts wrote:

I recently discovered that the 2" soft-cone midrange driver on one
of my 25-year-old ADS L710 speakers has a dent in it.
snip

Very unlikely (impossible) that the dent could make your sound "gritty".
However, you should consider what might have caused the dent and how
much more invisible damage may have occurred at that time. If the voice
coil was distorted and it now rubs in the gap, you will certainly hear that.

One way to "prove" that the noise is from the damaged speaker would be
to turn off one speaker with your balance control. Turn off the "bad"
speaker and listen to the "good" channel. Then swap the speaker wires so
that the "bad" speaker is on the "good" channel. If the sound changes,
the speaker is the problem.

Look for other damage. A speaker that is 25 years old may well have
deteriorated surrounds. That's the foam/rubber ring that connects the
cone to the frame. When that goes, the speaker will make very strange
noises.

Both the dust cap and surround can be replaced as a home project. There
is little to lose if the speaker is bad by trying to repair it.

[Laurence Payne]

On Mon, 24 Jul 2006 00:21:04 -0000, (Mark
Roberts) wrote:


The effect that I described before is transitory and hard to pin
down. Obviously, some more investigation is in order. It may just be
time to give in and get some new speakers, even though I tend to feel
that audio equipment these days plays second fiddle to home-theater
setups; thus audio-oriented equipment just doesn't get the attention
to accuracy and quality that it did even 10 or 15 years ago. But this
is in a room that will eventually be getting a home-theater setup
anyway, so that may be acceptable.

I fear that may be a backward move. There MAY be home-theatre setups
that aren't obsessed with style and compact size over sound quality,
but I haven't seen one.

[Barry Mann]

In , on 07/24/06
at 12:21 AM, (Mark Roberts) said:


[ ... ]

By the way, here's what the dent looks like:
http://www.cosmos-monitor.com/etc/ADS-L710.midrange.jpeg

The obvious dent at about 10 o'clock is insignificant. There are some
shadows indicting there were two much more significant dents, possibly
from the midrange being "pinched" with three fingers. If your cleaning
crew guess is correct, they may have bumped the unit, inspected it and
attempted to pull out the dent. The pull out operation could have
caused more damage.

If the dome is stretched, nothing will pull out the dent because the
dome is larger than before. G-E-N-T-L-Y heating the dome will help. I'd
leave this one alone, but if you must fuss with it, heat it and
C-A-R-E-F-U-L-L-Y use a vacuum cleaner.

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