B&W804 D3 Mid Range Problem

[Mal165]

I have a problem with my system and would be grateful for opinions/advice.
One mid range drive unit on my B&W 804 D3 speakers was not working i.e. no sound output, no cone movement. Both cabinets were returned to an authorised B&W dealer who replaced both mid range matched pair drive units.
On reconnecting the speakers back at home the problem persists. I am unsure if it is the same speaker cabinet which is faulty as I hadn't marked the original fault cabinet.
My system consists of Cyrus Signature equipment specifically 2 x Mono x300 amps and
a DAC XP. etc
I have tried a number of fault finding eliminations i.e. swapping amps, XLR leads, cables etc but the fault persists.
The dealer returned both of the 'old' mid range drivesbut did not identify which was the faulty one. Out of curiosity I checked both with a multimeter and both give a reading of 3.4 - 3.5 ohms.
I'm assured the drive units were checked and the fault identified prior to replacement. Also that both speaker cabinets were working properly on testing before being collected by myself.
Obviously the dealer will be looking into this in the new year but I would really appreciate any thoughts/ suggestions in the meantime.

 

[Gray]

I'm assured the drive units were checked and the fault identified prior to replacement.

Before you mention your meter readings:
Ask for them to confirm the precise nature of the fault that they identified (don't accept vagueness like, "one of the drivers was faulty").
We might expect them to say that one driver coil was open circuit - which would fit your original fault description - but would, of course, go against your resistance readings on the returned drivers.

Their answer will be interesting.

 

[Mal165]

Before you mention your meter readings:
Ask for them to confirm the precise nature of the fault that they identified (don't accept vagueness like, "one of the drivers was faulty").
We might expect them to say that one driver coil was open circuit - which would fit your original fault description - but would, of course, go against your resistance readings on the returned drivers.

Their answer will be interesting.

Thanks. I'll get back to them and let you know.

 

[nopiano]

Apologies if I’ve missed something, but it’s still only one speaker(the mid-range driver in one cabinet) that doesn’t work properly?

The returned ones - do they both crackle if you pop an AA battery across the terminals?

 

[Mal165]

Hi, thanks for your response.
Yes only one speaker , mid range driver in one cabinet, that doesn't work at all
No output no movement.
Both returned units crackled when connected to an AA battery. One cone shows more movement than the other.

 

[Gray]

I'll get back to them and let you know.

You certainly need an explanation / resolution as it's a bit of a mystery as things stand.

Meantime, no harm in putting your multimeter across the speaker terminals on each of your x300.
Amps on, with no music playing and DC range on the meter - ideally you want below 20 millivolt offsets

 

[Mal165]

Z

 

[Mal165]

Hi, speaker cabinet, 2 x mono amps, xlr leads, dac xp and 'old' drivers dropped off this morning to dealer. Was sent videos later 'showing' the speaker working (eh!!). Went to collect late this afternoon. "All working fine" cabinet boxed up, one 'old' speaker box now marked 'bad'.
Back home connected up.. Same problem!!
This is getting beyond a joke

 

[nopiano]

Hi, speaker cabinet, 2 x mono amps, xlr leads, dac xp and 'old' drivers dropped off this morning to dealer. Was sent videos later 'showing' the speaker working (eh!!). Went to collect late this afternoon. "All working fine" cabinet boxed up, one 'old' speaker box now marked 'bad'.
Back home connected up.. Same problem!!
This is getting beyond a joke

The mystery deepens! I wouldn’t expect to see any movement from a mid driver unless played very loud indeed, using music. But I’d expect to hear, for example, speech through it.

Maybe you can make a video for the dealer of a signal frequency sweep* through the defective unit. There should be an obvious drop out in the mid range, which is actually the majority of what we hear - from 350Hz to 3kHz or whatever the spec says (it doesn’t appear on the manufacturer page that I can find).

* usual caution, begin at very low volume!

 

[Gray]

This is getting beyond a joke

It was beyond a joke in your original post.
And you're still none the wiser with regard to the fault they originally 'found'.

What was the original purchase date?
How long after did the fault occur?

You must do whatever it takes to be with them to witness things working to your satisfaction nothing less.

 

[Mal165]

Forgot to mention further about today.
I had contacted the dealer about the fault originally befor Christmas . The customer service manager ordered replacement drivers (I had to pay up front) He then instructed the technician to swap over the speakers and it turns out the originals were not tested at all prior to swap !!!
More of a joke!!