[Tom[_6_]]

I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

Anyone know where I can find exact or suitable replacement
speakers ?

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Tom

[George Graves]

On Mon, 16 Jul 2007 16:05:01 -0700, Tom wrote
(in article ):

I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

Anyone know where I can find exact or suitable replacement
speakers ?

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Tom

I doubt that the crossover is damaged. Being made up of passive components,
it would be real difficult to damage one.

Find an authorized B&W dealer. They should be able to tell you how to obtain
service and parts, but I suspect that B&W won't sell you the parts, but will,
instead, insist that you send the speaker pair to them for repair. Its
probably best in the log run that you do so.

BTW, replacing the drivers with another make or model won't get you anywhere.
There is just no way to know what replacements will match the enclosure or
the crossover components of the complete system. IOW, they won't sound the
same and likely will sound worse.

[[email protected]]

On Jul 16, 7:05 pm, Tom wrote:
I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

www.bowers-wilkins.com

B&W Group North America
54 Concord Street
North Reading, Massachusetts
01864
Tel: +1 (978) 664 2870
Fax: +1 (978) 664 4109
Email:

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Possible, but unlikely. When you replace them, listen at
a low level. If the crossover is damaged, it should be
plainly audible at these levels as a gross difference
between the two speakers. If they sound okay, listen
louder, and keep increasing until you get to the levels
you'll be listening to. If at each stage, they sound okay,
then you're all set.

[Peter Wieck]

On Jul 16, 7:05 pm, Tom wrote:
I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

OK.... before you go willy-nilly replacing parts or blaming the
crossovers, please check a few things first.

By implication, you are running the original ST-70 into these same
speakers? If not, what are you running into them?

If it is the original ST-70, _PLEASE_ check them with another
amplifier to make sure that the amp is not the source. Similarly, use
a couple of different signal sources, CD, Tuner, etc.

Make sure that the speakers are in-phase. Try switching the speakers
from channel to channel, not the parts within them.

It is *absolutely* possible that a capacitor (if any) within the
speaker crossover has crapped out and that could be the cause of your
problems. I am not familiar with the components within that crossover,
but most of the time and type did have at least one electrolytic cap
within them. And they deteriorate with age in many cases.

It is quite unusual that bass drivers are damaged by anything other
than direct physical damage (a foot through them, for example).
Sometimes the surrounds rot, those may be replaced quite easily, even
by an amateur with patience and steady hands.

There are far too many additional tests to make before blaming the
individual drivers.

Peter Wieck
Wyncote, PA

[BEAR]

Tom wrote:
I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

Anyone know where I can find exact or suitable replacement
speakers ?

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Tom

Removed the speakers from the cabinets and swapped them??

Think I'd have subbed in another amp first or at least swapped the channels of
the ST-70. The ST-70 is more likely to have a fault, bad tube, bad cap, etc.,
than the bass driver being bad.

It is possible that the bass driver *is bad*, but less so.

The driver*s* (? two of them?) can be tested alone.
Remove them from the cabinet.
Run each of them with clip leads, magnet side down on a soft surface or hung
from a wire with test tones. Your computer can be made to make test tones using
either a test CD or some freeware that you can download to emulate a signal
generator. If the speaker is bad, you'll here buzz or other distortion. You
may find only one is bad or none.

Worst case use some music that you know makes it easy to hear this fault.
The tones are better.

Contact B&W as DP suggested if one or both drivers are bad.

_-_-bear

[Tom[_6_]]

Thanks ! I've contacted B&W directly and they are sending me two new
drivers. I found an 800 number (800) 370-3740 for their tech support.
Cost
was $143.90 each. With any luck I'll have them in a few days. I'll
post my
results.

On Jul 16, 11:31 pm, wrote:
On Jul 16, 7:05 pm, Tom wrote:



I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

www.bowers-wilkins.com

B&W Group North America
54 Concord Street
North Reading, Massachusetts
01864
Tel: +1 (978) 664 2870
Fax: +1 (978) 664 4109
Email:

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Possible, but unlikely. When you replace them, listen at
a low level. If the crossover is damaged, it should be
plainly audible at these levels as a gross difference
between the two speakers. If they sound okay, listen
louder, and keep increasing until you get to the levels
you'll be listening to. If at each stage, they sound okay,
then you're all set.

[Steven Sullivan]

Tom wrote:
Thanks ! I've contacted B&W directly and they are sending me two new
drivers. I found an 800 number (800) 370-3740 for their tech support.
Cost
was $143.90 each. With any luck I'll have them in a few days. I'll
post my
results.

Shouldn't you have tried swapping the 'bad' drivers into the 'good'
cabinet, first? If they didn't sound distorted , it wasn't
a driver problem in the first place.

On Jul 16, 11:31 pm, wrote:
On Jul 16, 7:05 pm, Tom wrote:



I recently took ownership of a set of B&W speakers that were my
fathers. They saw a lot of use over the years but appeared to be in
fine shape. He had them connected to a modified ST-70. My mom wasn't
very interested in having a tube amp and set of B&W's so I took them
off her hands :-)

When I got them back home, I noticed distortion from the low-freq
drivers on one speaker. These speakers have two 8" woofers and both
were distorting even at low volumes. The
midrange and tweeter sounded fine. ( These are B&W model DM640. )

I ended up swapping the drivers from the other speaker into the one
that was distorting to
determine if it was the crossover and they sounded fine. So, I figure
I need to replace the
two 8" LF units. I have no idea where to get these. I'm also not sure
how they got damaged.
The B&W website doesn't have a contact address or any US distributors
listed.

www.bowers-wilkins.com

B&W Group North America
54 Concord Street
North Reading, Massachusetts
01864
Tel: +1 (978) 664 2870
Fax: +1 (978) 664 4109
Email:

Is it possible the crossover is damaged and could ruin my replacement
speakers ?

Possible, but unlikely. When you replace them, listen at
a low level. If the crossover is damaged, it should be
plainly audible at these levels as a gross difference
between the two speakers. If they sound okay, listen
louder, and keep increasing until you get to the levels
you'll be listening to. If at each stage, they sound okay,
then you're all set.

--

___
-S
"As human beings, we understand the world through simile, analogy,
metaphor, narrative and, sometimes, claymation." - B. Mason