Restoring B&W 2200

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This may well be a lost cause, but ...

Having given me many years of pleasure (I bought them in a dutch auction 10 years ago for the equivalent of USD100!) there are now problems.

The 2200 has dual bass/mid drivers, one of which is "scraping", ie the voice coil is touching the magnet causing a rasping sound.

At first I thought it was gravity ( it gets to us at my age:xeye: ) but turning the driver through 180deg did not help.

I can fell the effect by carefully pushing the driver in at four points with my fingers. The other three do not do this.

The surrounds are not foam and look to be very good.

B&W in the UK emailed to say that these are 20 year old devices and the only info they could send me was a .pdf of the crossover pcb layout!

Worth saving? Scapping? What would you do?
 
The driver is "off centre", it's a common failure mode for speakers.

It's disappointing that a major top class manufacturer like B&W can't help, even though it is fairly old.

However, you might try Wilmslow Audio, certainly in the past they were excellent at providing replacement drivers for high quality speakers. They helped me out many years ago at work with some FAR older B&W speakers - they belonged to a local doctor, and while he was on holiday his son had a party, and blew the bass units in both speakers!.
 
I did email B&W and the XO layout was the only info they had. :cannotbe:

I have since taken it apart. Not so impressed: Chipboard (a lower desity than mdf) particle board, no bracing and a rather feeble looking XO board and connectors.

You can see from the photo that the chassis cut-outs on the drivers is going to make finding a replacement rather difficult :xeye:

Realising that these speakers have had only a few hours use in the last 3 years (it is on my second system: Yamaha receiver and TV) I have taken the "rasping" driver out and put it on the bench.

Maybe the driver has stiffened up from lack of use? Anyway, I am feeding it with 15volts of 20Hz - 1Khz swept tone and we will see if it has losened up tomorrow!

Both 8" drivers are the same, ome covering "low bass" the other "middle bass".

I have drawn out the XO in case anyone is interested. (How can I get more than one picture in a post ??:
 
This is the Crossover.

I have been out of electronics for 10 years (I have been doing IT networks, to put bread on the table) and do not have any current versions of schematic layout or simulator, hence the scruffy drawing.

Does anyone have the time and inclination to do a plot on this schematic? I hope this is not bad forum etiquette, but I am new around here.
 

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DM 220

Hi.
If it helps at all,I have done work on these units in the past with excellent results.
I had the same problem with mine,as well as two of the units being blown,and ended up removing the cones from the cage altogether,repairing the breaks in the coil,cleaning the coils,and re-centering them back in the cage.
I had them for ages after that and they remained working well long after I sold them.
If you have no luck obtaining a direct replacement,then give me an email and I may be able to run you through it,or I may be persuaded to do it for you.
Cheers,
Simon.
 
Re: DM 220

mschwilson said:
Hi.
If it helps at all,I have done work on these units in the past with excellent results.
I had the same problem with mine,as well as two of the units being blown,and ended up removing the cones from the cage altogether,repairing the breaks in the coil,cleaning the coils,and re-centering them back in the cage.
I had them for ages after that and they remained working well long after I sold them.
If you have no luck obtaining a direct replacement,then give me an email and I may be able to run you through it,or I may be persuaded to do it for you.
Cheers,
Simon.

A very civil gesture - I'll keep in touch!

(I don't quite know why I lie the DM220s so much - I mostly prefer them to my DM603 S3s!)
 
David Gatti said:
Are you sure that circuit diagram is right?
There is a capacitor in series with the bass/mid drivers !!


It doesn't look right, I agree. I'll check again tonight. I told you I was very rusty!

I couldn't sleep last night, so I DLd a copy of LT spice and started to put together a model. It is slowly coming back to me but the UI is a bit wierd.

How does one model a Speaker? Or do I just use is R value? I don't have any parameters for these drivers, nor an easy way of measuring inductance.
 
And the plot

Both 8" drivers share up to 2Khz, with the mid driver rolling off earlier.

No suprises, but an interesting design.

The bass is (was :xeye: ) very punchy.

The faulty driver has been cycling on a sweep with about 2cm extension for 24 hours.

Now to see if it has helped at all.
 

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David Gatti said:
Good work Cliff.
So it's a standard 2.5 way design. Maybe you should try to find a couple of cheap drivers at Parts Express.

Thanks!

What does 2.5 mean in this context? Using two identical drivers for bass/mid? I have googled it but there is some ambiguity.

This box is sealed. AFAIR porting is used to "flatten" the box / driver resonant peaks. How foes this work with no port?


I may think about putting a new pair of 8" drivers in there, but it will require sone surgery of the front.
 
2.5 way means you have both bass/mids covering the the lower frequency range to compensate for "baffle-step" (i.e falling bass response as longer wavelengths wrap around the enclosure).
One of the drivers is then rolled off at about 300Hz while the other continues up to the tweeter crossover point.
Porting is normally used to extend the bottom end but it has it's drawbacks. I've always preferred sealed.
 
cliffforrest said:
This is the Crossover.

I have been out of electronics for 10 years (I have been doing IT networks, to put bread on the table) and do not have any current versions of schematic layout or simulator, hence the scruffy drawing.

Does anyone have the time and inclination to do a plot on this schematic? I hope this is not bad forum etiquette, but I am new around here.


I suspected there are something wrong about the position of C1, C2 and C3. Otherwise in this network, the bass unit won't deliver bass and will reveal a deep hollow in midrange.
 
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